US20080065080A1 - Mobility kits for enabling axial access and procedures in the spine - Google Patents

Abstract

Disclosed are surgical tools, tool sets and methods for percutaneously accessing and preparing treatment sites within the spine for subsequent treatment procedures. The treatment site may be an inter-vertebral motion segments in the lumbar and sacral regions of the spine. The tool set may comprise introducer tools and bone dilators for accessing and tapping into a targeted site, such as, for example, the anterior surface of the S1 vertebral body. The tool set may also comprise cutters and extractors for preparing the treatment site for subsequent treatment procedures. The tool set may additionally comprise a bone graft inserter, an exchange system, and/or a temporary distraction tool for further preparing the treatment site for subsequent treatment procedures.

Description

RELATED APPLICATIONS
• This is a divisional application of U.S. patent application Ser. No. 10/971,780, filed Oct. 22, 2004, which claims priority benefit under 35 U.S.C. § 119(e) of Provisional Application 60/513,899, filed Oct. 23, 2003, the entire contents of each of the aforementioned U.S. patent applications are hereby incorporated by reference into this application.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates generally to instrumentation systems and methods for accessing and preparing treatment sites within the spine (e.g., inter-vertebral motion segments) for subsequent therapeutic procedures, such as, for example, spinal arthroplasty, partial or total disc replacement, annulus repair, vertebroplasty, arthrodesis (fusion), or the like. Disclosed herein are various tools and methods of use (e.g., surgical cutting devices, tissue extractors, etc.) for performing any number of minimally-invasive treatment procedures (e.g., low trauma disc nucleectomy via trans-sacral axial access). The methods can involve, among other things, facilitating the removal of resulting tissue fragments, preparing an intervertebral disc space for subsequent deployment of spinal fusion designed to relieve lower back pain, or motion preservation devices, e.g., dynamic stabilization, devices, prosthetic nucleus devices and total disc replacements designed to relieve lower back pain and to restore physiological function of the lumbar spine, maintain and possibly improve disc health and prevent progression or transition of disease.
• 2. Description of the Related Art
• Chronic lower back pain is a primary cause of lost work days in the United States, and as such is a significant factor affecting both workforce productivity and health care expense. Therapeutic procedures for alleviating back pain range from conservative methods, e.g., with intermittent heat, rest, rehabilitative exercises, and medications to relieve pain, muscle spasm, and inflammation, to progressively more active and invasive surgical means which may be indicated if these treatments are unsuccessful, including various spinal arthroplasties, and eventually even spinal arthrodesis, i.e., surgical fusion.
• There are currently over 700,000 surgical procedures performed annually to treat lower back pain in the U.S. In 2004, it is conservatively estimated that there will be more than 200,000 lumbar fusions performed in the U.S., and more than 300,000 worldwide, representing approximately a $1B endeavor in an attempt to alleviate patients' pain. In addition, statistics show that only about 70% of these procedures performed will be successful in achieving this end.
• Moreover, there may be multiple causes for a patient's lower back pain, where the pain generators are hypothesized to comprise one or more of the following: bulging of the posterior annulus or PLL with subsequent nerve impingement; tears, fissures or cracks in the outer, innervated layers of the annulus; motion induced leakage of nuclear material through the annulus and subsequent irritation of surrounding tissue in response to the foreign body reaction, or facet pain. Generally it is believed that 75% of cases are associated with degenerative disc disease, where the intervertebral disc of the spine suffers reduced mechanical functionality due to dehydration of the nucleus pulposus.
• The intervertebral discs, located anterior to the vertebral canal, are formed of fibrous cartilage, and comprise the posterior and anterior longitudinal ligaments and the annulus fibrosis, circumferentially enclosing a central mass, the. The nucleus pulposus provides for cushioning and dampening of compressive forces to the spinal column. In a healthy adult spine, it comprises 80% water.
• Surgical procedures, such as spinal fusion and discectomy, may alleviate pain, but do not restore normal physiological disc function.
• With reference toFIGS. 1A and 1B, the vertebrae are the bony building blocks of the spine. Between each of the vertebral bodies are the spinal discs and this unit, comprising two vertebral bodies interfaced by an intermediate spinal disc, is known as a spinal motion segment. The spine has seven vertebrae in the neck (cervical vertebrae), twelve vertebrae in the mid-back (thoracic vertebrae), and five vertebrae in the low back (lumbar vertebrae). All of the vertebrae and discs are held together or surrounded by means of ligaments, which are strong fibrous soft tissues that firmly attach bones to bones. Ligaments contribute to the normal physiologic range of motion of the spine, and if injured, e.g., due to disc degeneration (described below) and ensuing impact on distribution of physiologic loads, they similarly may contribute to the resulting pain.
• Thus, the bony spine is designed so that vertebrae “stacked” together can provide a movable support structure while also protecting the spinal cord's nervous tissue that extends down the spinal column from the brain from injury. Each vertebra has a spinous process, which is a bony prominence behind the spinal cord that shields the cord's nerve tissue. The vertebrae also have a strong bony “body” in front of the spinal cord to provide a platform suitable for weight-bearing.
• The spinal discs serve as “dampeners” between each vertebral body that minimize the impact of movement on the spinal column. Each disc is comprised of the nucleus pulposus, a central, softer component, contained with in the, a surrounding outer ring.
• With age, the water and protein content of the body's cartilage changes resulting in thinner, more fragile cartilage. Hence, the spinal discs and the facet joints that stack the vertebrae, both of which are partly composed of cartilage, are subject to similar degradation over time. The gradual deterioration of the disc between the vertebrae is known as degenerative disc disease, or spondylosis. Spondylosis is depicted on x-ray tests or MRI scanning of the spine as a narrowing of the normal “disc space” between adjacent vertebrae.
• Radiculopathy refers to nerve irritation caused by damage to the disc between the vertebrae. This occurs because of degeneration of the annulus fibrosis of the disc, or due to traumatic injury, or both. Weakening of the annulus may lead to disc bulging and herniation, i.e., the nucleus pulposus or softer portion of the disc can rupture through the annulus and abut the spinal cord or its nerves as they exit the bony spinal column. When disc herniation occurs, the rupture of the nucleus pulposus the annulus fibrosis may irritate adjacent nervous tissue, causing local pain, or discogenic pain, in the affected area. Any level of the spine can be affected by disc degeneration. When disc degeneration affects the spine of the neck, it is referred to as cervical disc disease, while when the mid-back is affected, the condition is referred to as thoracic disc disease. Disc degeneration that affects the lumbar spine causes pain localized to the low back and is sometimes common in older persons and known as lumbago Degenerative arthritis (osteoarthritis) of the facet joints is also a cause of localized lumbar pain that can be diagnosed via x-ray analysis.
• The pain from degenerative disc or joint disease of the spine may be treated conservatively with intermittent heat, rest, rehabilitative exercises, and medications to relieve pain, muscle spasm, and inflammation, but if these treatments are unsuccessful, progressively more active interventions may be indicated, including spinal arthroplasty including prosthetic nucleus device implantation; annulus repair, and total disc replacement, and eventually, even spinal arthrodesis. The intervention performed depends on the overall status of the spine, and the age and health of the patient. Procedures include removal of the herniated disc with laminotomy (a small hole in the bone of the spine surrounding the spinal cord), laminectomy (removal of the bony wall), by needle technique through the skin (percutaneous discectomy), disc-dissolving procedures (chemonucleolysis), and others.
• When narrowing of the spaces in the spine results in compression of the nerve roots or spinal cord by bony spurs or soft tissues, such as discs, in the spinal canal this condition is known as spinal stenosis. Spinal stenosis occurs most often in the lumbar spine, i.e., the lower back, but also occurs in the cervical spine and less often in the thoracic spine. It is most often caused by degeneration of the discs between the vertebrae due to osteoarthritis. Rheumatoid arthritis usually affects people at an earlier age than osteoarthritis does and is associated with inflammation and enlargement of the soft tissues of the joints. The portions of the vertebral column with the greatest mobility, i.e., the cervical spine, are often the ones most affected in people with rheumatoid arthritis. Non-arthritic causes of spinal stenosis include tumors of the spine, trauma, Paget's disease of bone, and fluorosis
• In the context of the present invention, therapeutic procedures to alleviate pain are restore function are described in a progression of treatment from spinal arthroplasty to spinal arthrodesis. As used herein, spinal arthroplasty encompasses options for treating disc degeneration when arthrodesis is deemed too radical an intervention based on an assessment of the patient's age, degree of disc degeneration, and prognosis.
• A wide variety of efforts have been proposed or attempted in the prior art, in an effort to relieve back pain and restore physiological function. Notwithstanding these efforts, there remains a need for methods and tools for accessing and preparing an intervertebral motion segment for subsequent therapeutic procedures, which can be accomplished in a minimally invasive manner.
SUMMARY OF THE INVENTION
• The preferred embodiments of the invention involve surgical tools sets and methods for accessing and preparing vertebral elements, such as inter-vertebral motion segments located within a human lumbar and sacral spine, for therapeutic procedures. In the context of the present invention, “motion segments” comprise adjacent vertebrae separated by intact or damaged spinal discs.
• In particular embodiments of the present invention, instrumentation system components and their means of use, individually and in combination and over or through one another, form or enlarge a posterior or anterior percutaneous tract; access, fragment and extract tissue (e.g., nucleus pulposus,); or otherwise prepare vertebral elements and inter-vertebral motion segments for fusion or dynamic stabilization via implantation of therapeutic agents and materials and spinal devices, are disclosed. It will be noted that the tools described can be used for and with the introduction of any number of devices, such as, for example, fusion devices, mobility devices, etc. Instrumentation is introduced and aligned (e.g., via preferably fluoroscopy, endoscopy, or other radio-imaging means, used as guidance to insure that the channel is positioned mid-line or along another desired reference axis relative to the anterior/posterior and lateral sacral view) through the percutaneous pathways and according to the trans-sacral axial access methods disclosed by Cragg, in commonly assigned U.S. Pat. Nos. 6,558,386, 6,558,390, and 6,575,979, each incorporated herein in their entirely by reference.
• In another aspect, the present invention provides a series of surgical tools and devices, wherein the preferred embodiments of each are configured and constructed (e.g., cannulated; solid; blunt; beveled; angled; retractable; fixed; tilted; axially aligned; offset; extendible; exchangeable; stiff; flexible; deformable; recoverable; anchored; removable; biocompatible; able to be sterilized & machined; moldable; reusable; disposable) in accordance with optimal intended function and in deference to biomechanical and safety constraints.
• Certain of the surgical tools take the form of elongated solid body members extending from proximal to distal ends thereof. Such solid body members may be used in combination or sequentially with elongated, cannulated body members. Hence, for example, design constraints, in addition to outside diameter (O.D.) tolerances and limitations imposed by virtue of patient anatomies, such as tube wall thickness, material selection/mechanical strength, and inside diameter (I.D.) also become considerations, e.g., to enable unrestricted passage over guide members or through hollow body members without incurring deformation that may impair or otherwise preclude intended function. Certain of these solid body and hollow body members can have distal means, mechanisms, or apertures that may be configured or manipulated for either precluding or facilitating engagement with tissue; the latter including piercing; tapping; dilating; excising; fragmenting; extracting; drilling; distracting (e.g. elevating); repairing; restoring; augmenting; tamping; anchoring; stabilizing; fixing, or fusing tissue. Certain of these solid body and hollow body members can have proximal means, mechanisms, pins, slots or apertures that may be configured or manipulated to engage; grasp; twist; pilot; angle; align; extend; expose, retract; drive; attach or otherwise interact to enable or facilitate the functionality of other components within the surgical tools set, e.g., the distal means and mechanisms noted above in this paragraph. In accordance with the certain embodiments disclosed herein, the individual components comprised in the tools sets, or kits, may include a guide pin introducer; guide pins with various distal end and proximal end configurations (e.g., tips; handles, respectively); soft tissue and bone dilators and dilator sheath(s); cutters; tissue extraction tools; twist drills; exchange systems comprising exchange bushing and exchange cannula assemblies; distraction tools; augmentation materials, and repair tools.
• In a particularly preferred procedure, these instrumentation system components are aligned axially, under visualization, and progressively inserted into a human lumbar-sacral spine through the minimally invasive percutaneous entry site adjacent the coccyx to access the L5-S1 or L4-L5 disc space to perform a partial or total nucleectomy, without compromising the annulus fibrosis, unlike current surgical discectomy procedures. Conventional discectomies are performed through a surgically created or enlarged hole in the annulus that remains post-operatively, and represents a undesirable pathway due to the potential for extrusion and migration of natural or augmented tissue, or implants, and that also compromise the biomechanics of the physiological disc structure.
• Moreover, in accordance with the techniques and surgical tool sets, and in particular the cutters and extraction tool configurations disclosed herein, a substantially greater amount (volume) of intradiscal material e.g., nucleus pulposus and cartilage, in comparison with other dissectomy procedures in practice, may be removed, as needed. In particular, the instrumentation systems and techniques embodied in the present invention more effectively, with less immediate trauma, and without residual negative physiological impacts that may occur as a result of invasion of the annulus, prepare an inter-vertebral motion segment for subsequent receipt of therapeutic procedures, and enables axial placement of implants close to and in alignment with the human spine's physiological center of rotation.
• Other specific advantages over current practice include: the patient is in a prone position that is easily adaptable to other posterior instrumentation; blood loss is minimal soft tissue structures, e.g., veins, arteries, nerves are preserved, and substantially less surgical and anesthesia time are required compared with conventional procedures.
• There is provided in accordance with one aspect of the present invention, an access kit for enabling access to a site in a bone. The kit comprises a guide pin introducer, a stylet, a guide pin, and a guide pin handle. The kit may additionally comprise a guide pin extension, at least one bone dilator, and at least one bone dilator with a removable sheath. The access kit may additionally comprise at least one cannulated slap hammer, and at least one twist drill.
• In accordance with a further aspect of the present invention, there is provided a disc preparation kit for preparing a disc space for a subsequent procedure. The disc preparation kit comprises at least one cutter, for disrupting material in the disc space, and at least one tissue extraction tool for extracting disrupted material from the disc space.
• The disc preparation kit may additionally comprise at least three cutters, and at least three tissue extractions tools. The disc preparation kit may additionally comprise a bone graft inserter.
• In accordance with a further aspect of the present invention, there is provided a spinal fusion kit. The fusion kit comprises an access tool, for providing access to a disc space and a cutter, for disrupting material in the disc space. The kit additionally comprises a tissue extraction tool, for removing disrupted material from the disc space, and a fusion rod, for expanding the disc space and enabling fusion of adjacent vertebral bodies across the space. The spinal fusion kit may additionally comprise a bone growth material inserter, or a bone paste inserter.
• In accordance with a further aspect of the present invention, there is provided a mobility kit. The mobility kit comprises an access tool, for providing access to a treatment site and a cutter for disrupting material in the treatment site. A tissue extraction tool is provided for removing disrupted material from the treatment site, and a mobility device for spanning at least a portion of the treatment site and enabling motion across the treatment site is also provided.
• The mobility kit may additionally comprise an augmentation material inserter, and a driver tool, for delivering the mobility device to the treatment site. At least a portion of the driver tool may comprise a hexagonal cross section. The treatment site may comprise a disc, or an intervertebral space. The mobility device may comprise a motion preservation device as is disclosed elsewhere herein.
• These and other advantages and features of the surgical tools sets and techniques disclosed in the present invention will be more readily understood from the following detailed description of the preferred embodiments thereof, when considered in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1A provides a lateral view of a normal spinal column.
• FIG. 1B illustrates examples of normal, degenerated, bulging, herniated, and thinning spinal discs.
• FIG. 1C is a lateral view of the lumbar and sacral portion of the spinal column depicting the visualized anterior axial instrumentation/implant line (AAIIL) extending cephalad and axially from the anterior laminectomy site target point.
• FIG. 1D is an illustration of an anterior target point on the sacrum
• FIGS. 1E and 1F are cross-sectional caudal views of a lumbar vertebrae depicting one and two trans sacral axial implants respectively within corresponding TASII bores formed in parallel with the visualized AAIIL ofFIG. 1C.
• FIGS. 2A and 2B are a perspective view and a side cross-sectional view of one embodiment of a guide pin introducer, respectively, with pin and slot configuration.
• FIG. 2C is a side cross-sectional view of one embodiment of a stylet with pin configuration.
• FIG. 2D is a perspective view of one embodiment of a guide pin introducer-stylet-pin and slot configured assembly.
• FIG. 2E is a side cross-sectional view of the assembly ofFIG. 2D.
• FIG. 3A is a perspective view of one embodiment of a guide pin introducer.
• FIG. 3B is a side cross-sectional view of the guide pin introducer ofFIG. 3A.
• FIG. 3C is a side cross-sectional view of one embodiment of a stylet with multi-start thread configuration.
• FIG. 3D is a perspective view of one embodiment of a guide pin introducer-stylet multi-start thread configured assembly.
• FIG. 3E is a side cross-sectional view of the assembly ofFIG. 3D.
• FIGS. 4 and 5 are lateral, partial cross-sectional views of the lumbar and sacral portion of the spine depicting delivery of the distal end of guide pin introducer-stylet-assembly to the anterior surface of the S1 vertebral body.
• FIG. 6A is a side view of a guide pin detailing distal and proximal ends.
• FIG. 6B is a side view of the distal end of one embodiment of a guide pin with a trocar tip configuration.
• FIG. 6C is a side view of the distal end of an embodiment of a guide pin with a beveled tip configuration.
• FIG. 6D is a side view of the proximal end of a preferred embodiment of a guide pin with a hex and flat configuration as means for tip alignment and axial and rotational locking.
• FIG. 7A is a cross sectional view of a guide pin-guide pin handle assembly.
• FIG. 7B is a cross sectional view of a guide pin handle.
• FIG. 7C depicts the thumb screw, for locking the guide pin.
• FIG. 7D illustrates a means for guide pin stop and steering.
• FIG. 7E depicts a guide pin assembly inserted within an introducer illustrating the guide pin tip extending beyond the distal end of the introducer.
• FIG. 7F is a cross section view illustrating a guide pin handle assembly, showing a releasable engagement means with the guide pin.
• FIG. 8A illustrates a guide pin-guide pin extension assembly with a threaded engagement coupling.
• FIG. 8B is a detailed view of guide pin-guide pin extension assembly with a threaded engagement coupling.
• FIG. 8C illustrates a guide pin with a cross-sectional view of female thread engagement coupling.
• FIG. 8D is an enlarged view of the female thread engagement coupling inFIG. 8C.
• FIG. 8E illustrates the guide pin extension with a cross-sectional view of a male thread engagement coupling.
• FIG. 8F is an enlarged view of the male thread engagement inFIG. 8E.
• FIG. 8G illustrates an alternative embodiment of a guide pin-guide pin extension assembly with a friction fit engagement coupling.
• FIG. 9 is a side view of a slap hammer and a dilator handle on an extended guide pin.
• FIG. 10 is an elevated view of three differently sized dilators.
• FIG. 11 is a perspective view of one embodiment of a dilator.
• FIG. 12 is a side cross-sectional view of the distal portion of the dilator inFIG. 11.
• FIG. 13A is a perspective view of one embodiment of a large dilator with a dilator sheath.
• FIG. 13B is a side cross-sectional view of a distal portion of the large dilator within the dilator sheath ofFIG. 13A.
• FIG. 13C is a perspective view of the sheath of the large dilator ofFIG. 13A.
• FIG. 13D is a perspective view of another embodiment of a large dilator sheath.
• FIG. 14 is a side view of one embodiment of a twist drill.
• FIG. 15 shows a cutter extending through a dilator sheath (docking cannula) in the L5-S1 disc space.
• FIG. 16A is a perspective view of one embodiment of a cutter assembly that comprises a down-cutter.
• FIG. 16B is a side cross-sectional view of the cutter assembly ofFIG. 16A.
• FIG. 16C is an exploded, perspective view of the distal portion of the cutter assembly ofFIG. 16A.
• FIGS. 16D and 16E are elevated views of one embodiment of a small down-cutter.
• FIG. 16F is a cross sectional view of a proximal cutter blade arm (402′) for nucleectomy prior to a mobility preservation procedure taken along theline16F-16F inFIG. 16E.
• FIG. 16G is a cross sectional view of a proximal cutter blade arm (402′) for nucleectomy prior to a fusion procedure taken along theline16F-16F inFIG. 16E. The inclined plane (421) is a mirror image of that in ofFIG. 16F.
• FIG. 16H illustrates one embodiment of an upcutter (452).
• FIG. 16I is a cross sectional view of a distal sleeve-shaft configuration showing a retraction stop mechanism for both a tissue cutter.
• FIG. 17A is an exploded, perspective view of the distal portion of a cutter assembly that comprises a debulker.
• FIGS. 17B-17C are elevated views of the debulker of the cutter assembly ofFIG. 17A.
• FIGS. 17D-17E are elevated views of one embodiment of a large debulker.
• FIG. 18A is an elevated view of one embodiment of a large teardrop debulker.
• FIG. 18B is a rear elevational view of the portion teardrop debulker ofFIG. 18A which attaches to the rotatable shaft.
• FIG. 18C is another elevated view of a larger teardrop debulker ofFIG. 18A.
• FIG. 18D is an elevated view of one embodiment of a standard or medium size teardrop debulker.
• FIG. 18E is a side isometric view of one embodiment of a large teardrop down-cutter.
• FIG. 18F is a side isometric view of one embodiment of a medium teardrop down-cutter.
• FIG. 18G is a side isometric view of one embodiment of a small teardrop down-cutter.
• FIG. 19A is a side elevated perspective view of one embodiment of an extractor assembly unit.
• FIG. 19B is a side elevated, partial cut-away view of the extractor assembly unit ofFIG. 19A.
• FIG. 19C is a side cross-sectional view of the extractor assembly unit ofFIG. 19A.
• FIG. 19D is a side elevated view of an extractor head prior to having its component wires unwound.
• FIG. 20 illustrates the distal end of one embodiment of an extraction tool with tissue fragments within its wire strands.
• FIGS.21A-B illustrate one embodiment of an extractor tool with its head extended into an exposed position and then pulled back into a delivery sleeve.
• FIGS.21C-D illustrate another embodiment of an extractor tool with its head in the extended position.
• FIGS.22A-B illustrate another embodiment of an extraction tool.
• FIG. 23A is a perspective view of one embodiment of an insertion tool assembly comprising a packing instrument and a delivery cannula.
• FIG. 23B illustrates engagement of the packing instrument with the delivery cannula, both fromFIG. 23A.
• FIG. 23C is perspective view of the packing instrument ofFIG. 23A.
• FIG. 23D is a perspective view of the delivery cannula ofFIG. 23A.
• FIG. 24A is a perspective view of one embodiment of a paste-inserter assembly.
• FIG. 24B is a side cross-sectional view the assembly ofFIG. 24A.
• FIG. 25A is a perspective view of one embodiment of an allograft placement tool.
• FIG. 25B is a side cross-sectional view of the tool ofFIG. 25A.
• FIG. 25C is a side cross-sectional view of the allograft tip of the tool ofFIG. 25A.
• FIG. 26 is a side elevated view of an exchange bushing.
• FIG. 27 is a side view of one embodiment of an exchange system assembly comprising an exchange bushing and an exchange cannula.
• FIG. 28A is a side elevated, cut-away view of one embodiment of an exchange cannula ofFIG. 27, in an open configuration.
• FIG. 28B is a side elevated view of the exchange cannula ofFIG. 27, in a closed configuration.
• FIGS.29A-B illustrate the use of the exchange system ofFIGS. 26-28 to deliver a distraction device or an axial spinal implant of larger diameter than the dilator sheath.
• FIG. 30A is side cross-sectional view of another embodiment of an exchange system assembly comprising an exchange bushing and an exchange tube.
• FIG. 30B is a side cross-sectional view of the exchange bushing ofFIG. 30A.
• FIG. 30C is a side cross-sectional view of the exchange tube ofFIG. 30A.
• FIG. 30D is a perspective view of another embodiment of an exchange system comprising an exchange bushing and an exchange tube.
• FIG. 30E is a bottom perspective view of the exchange system ofFIG. 30D.
• FIG. 31 is a perspective view of one embodiment of a temporary distraction rod and a tool that can be used to deliver or remove the rod from a treatment site.
• FIG. 32A is a perspective, partial cut-away view of the temporary distraction rod ofFIG. 32A and the distal portion of a tool that can be used to deliver the rod to the treatment site.
• FIG. 32B is a perspective, partial cut-away view of the temporary distraction rod ofFIG. 32A and the distal portion of a tool that can be used to remove the rod from the treatment site.
• FIG. 33A is a perspective, partial cut-away view of the distal portion of one embodiment of a temporary distraction rod.
• FIG. 33B is a side cross-sectional view of the rod distal portion ofFIG. 33A.
• FIG. 33C is a perspective view of the proximal portion of one embodiment of a temporary distraction rod.
• FIG. 33D is another perspective view of the rod proximal portion ofFIG. 33C.
• FIG. 33E is a side cross-sectional view of the rod proximal portion ofFIG. 33C.
• FIG. 34A is an exploded perspective view of one embodiment of a distraction-rod-assembly shown with the insertion tool.
• FIG. 34B is a perspective view of the insertion tip of the assembly ofFIG. 34A.
• FIG. 34C is another perspective view of the insertion tip of the assembly ofFIG. 34A.
• FIG. 35A is a perspective, exploded view of one embodiment of a temporary distraction-rod-assembly, shown with the removal tool.
• FIG. 35B is a front perspective view of the tip of the removal tool assembly ofFIG. 35A.
• FIG. 35C is a rear perspective view of the tip of the removal tool assembly ofFIG. 35A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• In accordance with one aspect of the embodiments described herein, there are provided surgical instrumentation systems and techniques for efficiently and atraumatically accessing and preparing treatment sites within the spine, such as, for example, vertebral motion segments, for subsequent therapeutic spinal procedures. In one approach, the step of accessing the treatment site includes using fluoroscopic imaging to visually align one or more components of the instrumentation system via a percutaneous, anterior trans-sacral axial approach. In another aspect, the treatment site includes a spinal disc and the subsequent therapeutic procedure includes nucleectomy. In yet another aspect, the therapeutic procedure includes immobilization devices to facilitate fusion; deployment of augmentation media; deployment of dynamic stabilization implants, or mobility devices to preserve or restore physiologic function.
• In accordance with one aspect of the embodiments described herein, there are provided surgical tool sets and methods of using the tool sets. The tools of the tools sets can be used individually and/or in combination with each other. As will be explained in further detail below, in one approach, certain tools fit over other tools, and therefore can be used over each other. In another approach, the tools fit through each other, and therefore can be used through one another.
• It will be understood that the access methods described can include the step of utilizing an anterior or posterior trans-sacral pathway. The therapies to the spinal discs and vertebral bodies described herein can be conducted on one or more spinal discs or vertebral bodies. In one approach, therapeutic procedures are performed through or on at least one spinal disc and at least one vertebral body traversed by at least one working channel.
• For convenience, the exemplary access by a single anterior method, and treatment of only a single spinal disc or vertebral body is described herein. It will be understood, however, that the tools and methodologies described herein are applicable to any spinal access pathway, including without limitation open surgical procedures from any access orientation, and to any number of spinal discs and/or vertebral bodies.
• FIGS.1C-D schematically illustrate the anterior trans-sacral axial spinal instrumentation/implant (TASII) approaches in relation to the lumbar region of the spinal column, and FIGS.1E-F illustrate the location of a TASII implant or pair of implants within an anterior TASIIaxial bore152 or pair of TASII axial bores22₁,22₂, or152₁,152₂. Two TASII axial bores and spinal implants or rods are shown inFIG. 1F to illustrate that a plurality, that is two or more, of the same may be formed and/or employed in side by side relation parallel with the anterior axial instrumentation/implant line (AAIIL).
• The lower regions of the spinal column comprising the coccyx, fused sacral vertebrae S1-S5 forming the sacrum, and the lumbar vertebrae L1-L5 described above are depicted in a lateral view inFIG. 1C. The series of adjacent vertebrae located within the human lumbar and sacral spine have an anterior aspect, a posterior aspect and an axial aspect, and the lumbar vertebrae are separated by intact or damaged spinal discs labeled D1-D5 inFIG. 1C.FIG. 1D depicts the anterior view of the sacrum and coccyx.
• The method and apparatus for forming an anterior TASII axial bore initially involves accessing an anterior sacral position, e.g. an anterior target point at about the junction of S1 and S2 depicted inFIGS. 1C and 1D. One (or more) visualized, imaginary, axial instrumentation/implant line extends cephalad and axially in the axial aspect through the series of adjacent vertebral bodies to be fused or otherwise treated, L4 and L5 in this illustrated example. The visualized AAIIL through L4, D4, L5 and D5 extends relatively straight from the anterior target point along S1 depicted inFIGS. 1C and 1D, but may be curved as to follow the curvature of the spinal column in the cephalad direction.
• It will be noted that the terms trans-sacral axial spinal instrumentation/implant (TASII), and anterior axial instrumentation/implant line (AAIIL), as used herein, are analogous to the terms trans-sacral axial spinal instrumentation/fusion (TASIF), and anterior axial instrumentation/fusion line (AAIFL). The analogous terms generally refer to the same percutaneous pathways, the primary difference being the types of treatments and implants delivered through the respective percutaneous pathways.
• U.S. Pat. No. 6,575,979, issued Jun. 10, 2003, titled METHOD AND APPARATUS FOR PROVIDING POSTERIOR OR ANTERIOR TRANS-SACRAL ACCESS TO SPINAL VERTEBRAE, hereby incorporated in its entirety into this disclosure by reference, discloses in detail tools and methodology for accessing targeted treatment sites, such as, for example, inter-vertebral motion segments.
• Certain of the access and preparation surgical tools, as explained in U.S. Pat. No. 6,575,979, take the form of elongated solid body members extending from proximal to distal ends thereof. Elongated solid body members in medical terminology include, for example, relatively stiff or flexible needles of small diameter typically used to penetrate tissue, wire stylets typically used within electrical medical leads or catheters to straighten, stiffen, or impart a curved shape to the catheter, guidewires that are used to traverse body vessel lumens and access remote points therein (certain hollow body guidewires have lumens for a number of uses), and obturators. Obturators are typically formed as rods provided in various diameters with blunt distal tips that can be manipulated to penetrate, separate or manipulate surrounding tissue without cutting or damaging the tissue.
• As used herein, the term “guide pin” can include solid body members (e.g., guidewires) employed to perform the functions of guide pin delivery and guidance described herein, unless the exclusive use of a given one of such solid body members is explicitly stated. Such solid body members can be stiff or flexible and can include distal anchoring mechanisms, e.g., sharpened or beveled tips.
• Certain others of the surgical tools take the form of hollow body, tubular members having lumens extending from proximal to distal ends thereof. Such hollow body, tubular members can take the form of medical catheters, medical cannulas, medical tubes, hollow needles, trocars, sheaths, or the like, or variations thereof. Such hollow body tubular members employed in various embodiments described herein can be stiff or flexible and can include distal fixation mechanisms.
• As used herein, anterior refers to in front of the spinal column (ventral) and posterior refers to behind the column (dorsal). As used herein, proximal (caudal) refers the end or region that is closer to the surgeon or sacral region of the spine, while distal (cephalad) refers to the end or region that is closer to the patient's head.
• In accordance with one aspect of the embodiments described herein, there is provided a guide pin introducer that can be used to facilitate access to the sacrum for delivery of at least one guide pin, which in turn serves as means over which other instruments of the surgical tools set can subsequently be delivered to target sites to perform their intended procedural functions, individually or in combination, over or through one another.
• With reference to FIGS.2A-B, in one aspect theguide pin introducer100 comprises anintroducer tube102 and anintroducer handle110. Theintroducer tube102 extends between adistal end104 and aproximal end106, and defines an inner,tubular member lumen108. The length of thetube102 is typically in the range of about 4″ (100 mm) to about 12″ (310 mm), often about 5″ (120 mm) to about 9″ (230 mm). In one exemplary embodiment, the length of thetube102 is approximately 7″. Thetube102 is preferably long enough to extend from askin incision190 near the paracoccygeal region, through the pre-sacral space, to ananterior target point192, as shown, for example, inFIGS. 4 and 5.
• With reference toFIGS. 3A and 3B, an exemplary embodiment of a guide pin introducer withmulti-start thread199 assembly engagement means is shown. The inner diameter (I.D.) of theintroducer tube102 is typically in the range of about 2 mm to about 5 mm, often about 3 mm to about 4 mm. In one exemplary embodiment, I.D. of thetube102 is about 3.5 mm (0.13″). The outer diameter (O.D.) of thetube102 is typically in the range of about 4 mm to about 7 mm, often about 5 mm to about 6 mm. In one exemplary embodiment, O.D. of thetube102 is about 5.5 mm, with an I.D. dimensioned to slidably receive the distally locatedblunt tip122 of thestylet119, as shown inFIGS. 2C-2E
• It will be noted that the actual dimensions (e.g, length, inner diameter, outer diameter, etc.) of thetube102 or any of the tools and components parts thereof described herein will depend in part on the nature of the treatment procedure and the physical characteristics of the patient, as well as the construction materials and intended functionality, as will be apparent to those of skill in the art.
• The edge105 at thedistal end104 of thetube102 can comprise any number of configurations. In one embodiment, the edge105 is at approximately a 90 degree angle relative to the longitudinal axis of thetube102. In another embodiment, the edge105 is beveled at an angle relative to the longitudinal axis of thetube102. In one exemplary embodiment, the edge105 is beveled at an angle of about 45 degrees. Thetube102 can be made from any of a number of known suitable materials, such as, for example, stainless steel, Ni—Ti alloys, or structural polymeric materials, or composites thereof.
• With continued reference toFIGS. 4 and 5, in one mode of use, the guidepin introducer tube102 serves as an enlarged diameter anterior tract sheath through which a guide pin, described in further detail below, can be introduced into the targetedsite192.
• With reference toFIG. 2A-2B, theintroducer handle110 extends between adistal end111 and aproximal end113, and defines atubular member lumen109 that is stepped or tapered toward thedistal end111. Thehandle110 comprises a slot at its distal end which is dimensioned to receive a section of thetube102 beginning at the tubeproximal end106. Thehandle110 andtube102 can be molded, machined or otherwise formed as an integral unit, or can be affixed to each other by any of a variety of known attachment means, such as, for example, thermal bonding, adhesives, or press fits.
• The introducer handle110 can be made from any of a number of known suitable materials, such as, for example, polysulfone, polyvinylidene fluoride, polyethylenes, PEEK, or composites thereof. In one embodiment, introducer handle110 is fabricated from an injection-molded part, made from an acetal-based copolymer, such as Delrin™ obtained from the DuPont Company in Wilmington, Del., that is then machined with an I.D. of about 13 mm (0.50″) and an O.D. of about 19 mm (0.75″). Here, the overall length of the guide pin introducer100 (i.e., the length of thetube102 andintegral handle110, in total) is about 300 mm (11.95″).
• In accordance with one aspect of the embodiments described herein, there is provided a stylet with a blunt distal tip that can inserted into the guide pin introducer described above to facilitate advancement of the guide pin introducer to the targeted site without causing damage to surrounding tissue.
• With reference to FIGS.2D-E, in one embodiment, thestylet119 comprises an elongate body orrod120 that extends between adistal end122 and aproximal end124. Thedistal end122 of thestylet rod120 preferably comprises a blunt tip, thereby preventing damage to surrounding soft tissue as the guide pin introducer-stylet-pin-slot configuration assembly134 (the approach assembly), which comprises theintroducer100 andstylet119, described in further detail below, is advanced toward the targeted site, such as, for example,target point192, shown inFIG. 4B.
• With reference toFIGS. 2C-2E andFIGS. 4 and 5, in order to advance theintroducer tube102 through an anterior tract to thetarget point192 without concomitant damage to surrounding soft tissue, astylet119 can be used in combination with theguide pin introducer100 by advancing the introducer-stylet-approach assembly134 to the target area orpoint192.
• The length of therod120 should be designed so that the stylet'sblunt tip122 extends beyond thedistal end104 of the guidepin introducer tube102. In one embodiment, therod120 has an O.D. of about 3.2 mm (0.125″), which is less than the I.D. of theguide pin introducer100. Thestylet rod120 can be made from any number of known suitable materials, such as, for example, stainless steel or the like.
• The stylet handle126 extends between adistal end128 and aproximal end130, and comprises a distally located bore129 to receive the section of thestylet rod120 beginning at the rodproximal end124.
• The length of thestylet handle126 is typically in the range of about 3″ (75 mm) to about 7″ (175 mm), often about 4″ (100 mm) to about 6″ (150 mm). The O.D. of thehandle126 is typically in the range of about 0.25″ (6 mm) to about 0.75″ (20 mm), and generally dimensioned to cooperate with the introducer handle110 to form the introducer (approach)assembly134.
• In one embodiment, thestylet handle126 has a diameter of about 12 mm to about 13 mm (e.g., about 0.50″) at thedistal end128 that increases to about 20 mm (0.75″) at theproximal end130. The length of the exposedrod120 and narrow portion of thehandle126 together is about 300 mm (12″) so that just thetip122 of thestylet119 will protrude from thedistal end104 of theintroducer tube102 upon assembly with theguide pin introducer100. The narrow portion of thestylet handle126 is configured to fit in atubular member lumen109 machined to receive it within thehandle110 of theguide pin introducer100.
• The stylet handle126 can be formed from any of a variety of materials, such as, for example, polymeric materials having desired properties (e.g., able to be machined or an injection-moldable polymer). Suitable materials include, but are not limited to polysulfone, polyvinilydene fluoride, acetal-copolymer; acrylic, high density polyethylene, low density polyethylene, nylon, polycarbonate, polypropylene, PVC, or the like, or combinations thereof.
• With reference toFIGS. 2A-2E andFIGS. 4 and 5, in one aspect, theguide pin introducer100 can be provided with a releasable interlock that prevents the blunt-tippedstylet119 from retracting proximally within thelumens108,109 of the cannulatedguide pin introducer100, thereby maintaining the extension and exposure of theblunt tip122 of thestylet119 beyond thedistal end104 of thetube102 as the introducer (approach)assembly134 is advanced by the surgeon toward thetarget point192, optionally with the assistance of any known suitable visualization technique.
• The releasable lock may comprise any of a variety of interference fit or friction fit surfaces carried by thestylet119 for cooperating with a complementary structure on theintroducer100. It will be noted that the releasable interlock can be on and between any of theapproach assembly134 components described herein.
• In one embodiment, illustrated in FIGS.2A-E the releasable interlock of theintroducer100 comprises atrack112 that is configured to accept thelocking pin139 of thestylet119, described in further detail below. Thehandle110 of theintroducer100 comprises an axially extending slot or track112, machined or otherwise formed through the wall of thehandle110.Track112 is positioned with an open end beginning at theproximal end113 and extends longitudinally in the distal direction along thehandle110 with acircumferentially extending notch107 at the distal end of thetrack112.
• The stylet handle126 comprises a radially outwardly extending engagement structure such as alocking pin139 that is configured to slideably fit within thetrack112 of theintroducer handle110. As thestylet handle126 is advanced distally into engagement with theintroducer handle110, the lockingpin139 advanced distally through the opening on theproximal end113 of theintroducer handle110, and along theaxially extending track112. Once thestylet handle126 has been advanced fully into engagement with theintroducer handle110, rotation of the stylet handle126 with respect to the introducer handle110 advances thelocking pin139 into thecircumferentially extending notch107. Thelocking pin139 serves as an interior stop or locking lug that releasably secures the stylet handle126 within theintroducer handle110. In one embodiment, the lockingpin139 comprises a 0.125″ (3.2 mm)×0.625″ (15.8 mm) dowel pin.
• In one embodiment, shown inFIGS. 2D-2E, theapproach assembly134 comprises theintroducer100 and thestylet119 which are releasably interlocked to each other. Thestylet handle126 and theguide pin introducer100 can be mutually releasably engaged by the above-describedlocking pin139, other complementary surface structures, twist-lock mechanisms, such as in a preferred multi-start thread configuration shown inFIGS. 3A-3E; a modified Luer lock, or any other known suitable mechanism that enables mechanical quick release (e.g., relative to another embodiment that uses a press-fit method of engagement of the respective handles). With respect to the multi-start thread configuration shown inFIGS. 3A-3E, theguide pin introducer100 hasinternal threads199 on theproximal end113 that engage withexternal threads198 onstylet handle126. Engagement and disengagement of theassembly134′ is by means of twist-lock. These quick release mechanisms facilitate disengagement of the stylet handle126 from the guide pin introducer handle110 once thedistal end104 of the guidepin introducer tube102 is brought into relatively close proximity to thetarget192. Thestylet119 can be disengaged from the rest of theapproach assembly134 and removed from the patient's body.
• With reference toFIGS. 2D-2E, in one exemplary method of use, thestylet119 is inserted into thelumens108,109 of theintroducer tube100 in a manner and configuration such that theblunt tip122 extends and is preferably exposed from about 1 mm to about 2 mm beyond thedistal end104 of theguide pin introducer100. In this manner, theblunt tip122 of thestylet119 serves as a soft tissue dilator that assists in the safe and atraumatic positioning of thedistal end104 of the guidepin introducer tube102 in close proximity to theanterior target site192.
• Thestylet rod120 is inserted into the cylindrical polymeric handle126 so that about 200 mm (about 7.76″) of therod120 extends out of thehandle126, into and throughintroducer tube102, and beyond the introducer tubedistal end104, so that the distal endblunt tip122 of therod120 is exposed at the distal most end of the approach orintroducer assembly134.
• As shown inFIGS. 4 and 5, in one exemplary method of use, the spine is accessed via asmall skin puncture190 adjacent to the tip of the coccyx bone. The pre-sacral space is entered using any known suitable percutaneous technique. Theintroducer assembly134, with the stylet'sblunt tip122 serving as a dilator, is advanced through the paracoccygeal entry site. Once thetip122 of thestylet119 is advanced through the facial layer, theblunt tip122 is positioned against the anterior face of the sacrum and advanced along the anterior surface of the sacrum to the desired position or targetedsite192—here, the S1 vertebral body. In one embodiment, the distal portion of theapproach assembly134 is advanced to the targeted site under fluoroscopic guidance, as is described in co-pending U.S. patent application Ser. No. 10/125,771, filed on Apr. 18, 2002, titled METHOD AND APPARATUS FOR SPINAL AUGMENTATION.
• Thestylet119 is released and removed from theapproach assembly134 after the distal portion of theassembly134 is advanced to the targetedsite192, thereby leaving the distal portion of theintroducer100 at the targeted site, to preface the introduction of a guide pin through theintroducter100 to the targetedsite192
• In accordance with one aspect of the embodiments described herein, there is provided a guide pin that can be delivered to the targeted site through the use of a guide pin introducer, such as, for example,introducer100 described above. In one embodiment, shown inFIG. 7A theguide pin assembly140 has anelongate guide pin142 that extends between adistal end144 and aproximal end146. Theguide pin assembly140 also has a sharpguide pin tip145 at thedistal end144 and a preferablyreleasable handle150 engaged at theproximal end146.
• The length of theguide pin142 is typically in the range of about 9″ to about 15″, often about 11″ to about 13″. In one exemplary embodiment, the length of theguide pin142 is approximately 12″. The length of theguide pin142 is typically sufficiently long so that thetip145 extends beyond thedistal end104 of the guidepin introducer tube102 when theguide pin assembly140 is inserted within theintroducer100, as shown inFIG. 7E.
• Theguide pin142 can be made from any of a number of suitable materials, such as, for example, stainless steel, NiTi alloys, or composites thereof. In one embodiment, theguide pin142 is formed from substantially the same materials (e.g., stainless steel) as thestylet119 and comprises a solid,elongated body142 with an O.D. of between about 2.2 mm (0.090″) to about 3.4 mm (0.13″) and a length of about between about 300 mm (12.00″)-600 mm (24″).
• Unlike thestylet119, theguide pin tip145 is not blunt, and may be shaped according to one among various configurations. In one embodiment, not illustrated, the guide pin tip is formed as a simple conical or two sided wedge pointed tip. In another embodiment, shown inFIG. 6B, thetip145′ is formed as a trocar tip that has a three-sided bevel at 15 degrees. In still another embodiment, shown inFIG. 6C, thetip145″ is formed as a beveled tip that has one side beveled at an angle. The angle can range, for example, from about 30 degrees to about 60 degrees relative to the longitudinal axis of theguide pin142. The selection of thetip145 geometry is influenced by the need to initially tack theguide pin142 into the target, such as, for example, the sacral face, without having theguide pin142 slip off or slide up the target surface. Pointed tip geometries enable theguide pin142 to snag the sacral face, and thus eliminate “skidding” effects that may otherwise accompany tapping the target surface.
• With continued reference toFIG. 7A-7D, in one embodiment, theguide pin assembly140 comprises a guide pin handle150′ that comprises adistal end152′ and aproximal end154′, and comprises a distally locatedlumen175 to receive a section of theguide pin142′ beginning at the guide pinproximal end146′. In one aspect, the guidepin handle assembly180 shown inFIG. 7F comprising the guide pin handle150 and thumb/setscrew element170 is configured to align and releasably engage theguide pin142. In method of use, for example, a flat on guide pin142 (seeFIG. 6D) is positioned in a predetermined relationship to the bevel onguide pin tip145, so that when the guide pin is assembled and locked within the guide pin handle, wherein the thumb screw is advanced against the flat of the guide pin, this enables the clinician to determine, with reference to the thumb screw, visual or tactile indicia on the proximal handle which will indicate the rotational orientation of the beveled tip. Thus in this manner, the surgeon is able to determine, and adjust or “steer” theguide pin tip145 position. In another aspect of alignment and releasable engagement mechanisms, the guidepin handle assembly180 comprises a metal hexagonal orsquare socket178 within theinsert172 of the guidepin handle assembly180 when mated with the proximal end of theguide pin hex181 and flat182 (FIG. 6D) it provides a positive stop precluding longitudinal and rotational motion of theguide pin142 relative to theguide pin handle150.
• In one embodiment, thehandle150 has an O.D. of about 12 mm (0.50″) on itsdistal end152, an O.D. of about 20 mm (0.75″) on itsproximal end154, and is approximately 100 mm (4″) in length. Abore175 is formed in thedistal end152 extending substantially through the guide pin handle150, of about 3.5 mm (0.13″) (i.e., substantially the same as the O.D. of the guide pin142), into which theguide pin142 can be releasably inserted.
• The guide pin handle150 can be formed from any of a variety of materials, such as, for example, polymeric materials having desired properties (e.g., able to be machined or an injection-moldable polymer). Suitable materials include but are not limited to sterilizable polymeric materials, e.g., polyvinilidine fluoride; polysulfone; acetal-copolymer; acrylic, high density polyethylene, low density polyethylene, nylon, polycarbonate, polypropylene, PVC, or the like, or combinations thereof.
• The guide pin handle150 is configured to be able to “steer” aguide pin142 in the event that there is axial misalignment of the its after insertion. In the context of the present invention, “steer” refers to an ability to manipulate by turning and make controlled positional adjustments of aguide pin142 once it is tapped through the cortical bone of itsanterior target192. Specifically, the thumb/set screw170 (FIG. 7C) serves as a point of reference to thetip145 orientation and is particularly configured to mark the alignment of the guide pin'sbeveled tip145, as opposed to the face of the beveled plane. When the guide pin is advanced it will tend to deviate in the direction of beveled tip, which is indicated, e.g., by the thumb screw. For example, if upon insertion the beveled plane of thetip145 faces anterior, theguide pin142 will track in the posterior direction when advanced.
• While the visualization of theguide pin142 in situ is facilitated, for example, by fluoroscopy, resolution limitations are frequently less ideal with respect to theguide pin tip145 configuration. For this reason, the addition of the set screw155 and thus the ability to steer theguide pin142 via itshandle150 represent a significant procedural advantage enabled by the tools and techniques of the present invention.
• One exemplary method of use involves: advancing the distal portion of a delivery assembly159 to the targeted site; removing the guide pin handle150; removing theintroducer100; and leaving theguide pin142 at, and attached to, the targetedsite192. In one approach, the guide pin handle150 and theintroducer100 are removed separately. In another approach, thehandle150 and theintroducer100 are removed together, leaving only theguide pin142 in place.
• Disengagement of the guide pin handle150 from theproximal end146 of theguide pin142 enables extension of the guide pin's elongate body length through the addition of anextension160 that can be attached to extend the length of the pins, thereby resulting in an extended guide pin, such as, for example, thelong guide pin164″ ofFIG. 8A which extends between adistal end144″ and aproximal end146″.
• In accordance with one aspect of the embodiments described herein, there is provided a guide pin that can be extended in length to facilitate the subsequent delivery and utilization of other access and preparation tools.
• With reference toFIG. 8G, in one embodiment, theguide pin142 can be extended in length along its longitudinal axis via the addition of anextension160, which has aconnector162 on its distal end. In this exemplary embodiment, theextension160 comprises an exchange pin, and theconnector162 comprises a roll pin.
• Theguide pin142 has a bore that is located at itsproximal end146 and that is dimensioned to receive a distal portion of theconnector162. Theextension160 has a bore that is located at its distal end and that is dimensioned to receive a proximal portion of theconnector162.
• In one embodiment, theguide pin142,extension160, andconnector162 are releasably interconnected by any known suitable approach, such as, for example, an interference fit or friction fit or the like. In one embodiment, theconnector162 is fixedly secured to the distal end of theextension160 and the connector is releasably secured to the proximal end of theguide pin142.
• With reference to FIGS.8A-F, in a preferred embodiment, theextended guide pin164″ comprises aguide pin142″ and anextension160″ that are connected to each other through the use of aconnector165, which protrudes from the distal end of theextension160″. The proximal end of theguide pin142″ has a threaded bore148 at itsproximal end146″ that is dimensioned to receive theconnector165.
• In this preferred embodiment, theconnector165 comprises a threaded stud. Theconnector165 extends between adistal end166 and aproximal end167 and has a smaller outer diameter towards itsdistal end166, as compared to the larger outer diameter toward itsproximal end167. Theconnector165 comprisesscrew threads168 for releasably securing theextension160″ to theguide pin142″, which itself has a threaded bore148 having threads149 that is complementary to thethreads168 of theconnector165.
• The length of the extended guide pins (e.g.,164,164″) can range from about 400 mm to about 800 mm, often about 500 mm to about 700 mm. In one embodiment, the length ofpin164 is about 600 mm (24.00″).
• In one exemplary method of use, following the delivery of the introducer-stylet approach assembly134 to the targetedsite192 and removal of thestylet119 from theintroducer100, a guide pin-guidepin handle assembly140 is inserted into the cannulatedguide pin introducer100. As theguide pin142 is initially tapped into the sacrum it is in effect serving as a bone dilator. Once theguide pin tip145 has been inserted (tapped) into the anterior face of the S1 vertebral body, theguide pin introducer100 and the guide pin handle150 are removed, to enable engagement of theguide pin142 with theguide pin extension160.
• Subsequent components from among the surgical tools sets described herein, which generally have a greater O.D. than theextended guide pin164, are introduced to thetarget site192 by concentric passage over theextended guide pin164. The subsequent components can be advanced over theextended pin164 individually or in combination, over or through one another, to the targetedsite192. For example, in one approach, the first tools in the sequence of instruments to be delivered over theguide pin164 are bone dilators, described in further detail below.
• In accordance with one aspect of the embodiments described herein, there are provided certain materials which can enhance visualization of tools via radio-imaging (e.g., fluoroscopy). Examples of such materials include stainless steel where tools or portions thereof comprise metal, and powders, such as barium sulfate, for components configured from polymeric materials, e.g., bushings, that may be inserted within the body cavity. It will be understood that such materials can be incorporated during the formation of certain metal or polymeric compounds comprised in the surgical tools sets and devices disclosed herein.
• Although dilation of soft tissue is common for certain surgeries, dilation of bone tissue is generally not a common technique for orthopedic procedures. In one approach, dilating bone in the spine involves: widening the axial pathway or channel in preparation for subsequent treatments by compressing cancellous bone or cortical bone shell to the side rather than removal via cutting or coring such bone material.
• Compression is usually a less traumatic procedure than coring with, for example, an electrically powered drill, as the latter may inadvertently cut or tear soft tissue, including nerves or blood vessels. Less bleeding of the bone occurs with dilation, which is an unanticipated benefit. It is believed that the compression of the bone by the dilator results in a tamponade effect so that the amount of bleeding from bone accompanying this procedure is reduced. Compression appears to afford stronger “anchoring”, for subsequent implants (e.g., implants with threading) within an inter-vertebral space. It is also possible that compression may have a long term beneficial impact via the initiation of subsequent osteogenic (bone growth) effects.
• In accordance with one aspect of the embodiments described herein, there are provided bone dilators that can be used to create and widen one or more channels in the vertebral bodies for the ensuing passage of other instruments and devices. In one embodiment, the dilators are cannulated and can be delivered accurately to the target site, following removal of any preceding dilators, in succession one after another, each directly over the guide pin. In another embodiment, the dilators are configured to pass concentrically over a previously delivered smaller dilator (i.e., a dilator having a relatively smaller O.D than the ID of successive dilators.), without the extraction of the smaller dilator over the guide pin.
• With reference toFIGS. 11-12, in one embodiment, thedilator200 comprises a cannulateddilator rod202 extending between adistal end204 and aproximal end206, and defines aninner lumen212. Thedilator200 comprises atapered dilator tip208 with a distal end opening214 at thedistal end204 and ahandle210 at theproximal end206.
• The length of the cannulateddilator202 is typically in the range of about 150 mm to about 450 mm, often about 250 mm to about 350 mm. In one exemplary embodiment, the length of therod202 is approximately 300 mm (12.00″).
• The I.D. of the cannulateddilator rod202 is typically in the range of about 2.5 mm to about 4.5 mm, often about 3 mm to about 4 mm. In one embodiment, therod202 has an I.D. slightly larger than about 3.5 mm (i.e., greater that the O.D. of the extended guide pin164) and an O.D. of about 6 mm.FIG. 10 illustrates threebone dilators200₁,200₂, and200₃having O.D. of 6 mm, 8 mm, and 10 mm, respectively.
• Thetapered dilator tip208 is usually tapered at about 5 to about 45 degrees from O.D. to I.D. In one embodiment, thetip208 of thedilator200 is tapered at approximately 8 degrees from O.D. to I.D. In another embodiment, thetip208 is tapered at about 13 degrees from O.D. to I.D.
• The cannulateddilator rods202 can be made from any known suitable material, such as, for example, stainless steel, aluminum, or composites thereof. In one embodiment, thedilator200 and its component parts are machined from stainless steel tubing. Here, eachdilator200 has ahandle210 that is affixed to the dilatorproximal end206. Thehandle210 is about 100 mm (4.00″) long and is engaged (e.g., by welding; press fit, etc) in the middle to assure a secure fit with the rod. With reference to FIGS.13A-C, in one embodiment, there is provided alarge dilator construct199, configured as adilator sheath220 and adilator rod assembly200_Lthat comprises a dilator shaft202_Ladilator handle210_L, and twopins218 as engagement means for theconstruct199 The cannulateddilator shaft202_Lextends between adistal end204_Land aproximal end206_Land defines aninner lumen212_L. Theshaft202_Lcomprises a taperedtip208_Lwith a distal end opening214_Lat thedistal end204_L. Thedilator rod assembly200_Lcomprisespins218 extending out from the outer wall of thedilator shaft202_L.
• The length of the cannulateddilator rod assembly200_Lis typically in the range of about 8″ to about 16″, often about 11″ to about 13″. In one embodiment, length of thedilator rod assembly200_Lis approximately 300 mm (12.00″). In one embodiment, the larger diameterproximal end206_Lof thedilator shaft202_Lis about 75 mm (3″) in length while the overall length of thedilator rod assembly200_Lis about 300 mm. (12.00″).
• In one embodiment, the cannulateddilator shaft202_Lhas two different outer diameters. More specifically, there is a smaller diameter section of thedilator shaft202_Lconfigured to be covered by thesheath220. The O.Ds. are typically in the range of about 5 mm to about 12 mm, often about 6 mm to about 11 mm. In a preferred embodiment, thedilator shaft202_Lhas a smaller O.D. of about 9 mm (0.35″) and a larger O.D. of about 10 mm. The I.D. of thedilator shaft202_Lis typically in the range of about 2.5 mm to about 4.5 mm, often about 3 mm to about 4 mm.
• Thetapered dilator tip208_Lis usually tapered at about 5 to about 45 degrees from O.D. to I.D. In one embodiment, thetip208_Lof thedilator shaft202_Lis tapered at about 13 degrees from O.D. to I.D. In one preferred embodiment, this taper oftip208_Lis substantially the same as the taper of thetip226 at thedistal end222 of thedilator sheath220.
• Thesheath220 comprises asheath tube221 that extends between adistal end222 and aproximal end224, and is configured to be releasably attachable to thedilator rod assembly200_L. In one embodiment, thesheath tube221 comprises atip226 at thedistal end222 and two tracks (one shown)229 machined into the wall of thetube221, that is positioned to begin at theproximal end224 and extend longitudinally along thesheath tube221 with a slight circumferential notch at the distal end of thetrack229.
• Thetrack229 accepts thepin218 mounted on thedilator shaft202_L, thereby providing a releasable interlock of thedilator shaft202_Lwith thesheath220. In another embodiment, thelarge dilator construct199 comprises any known suitable releasable lock comprising any of a variety of interference fit or friction fit surfaces carried by thedilator shaft202_Lfor cooperating with a complementary structure on thesheath220.
• In one embodiment, thelarge dilator construct199 comprises twotracks229 and two locking lugs218. In another embodiment, thelarge dilator construct199 comprises onetrack229 and onepin218.
• Both thedilator shaft202_L, thesheath220, and their respective component parts can be made from any known suitable material, such as, for example, stainless steel, aluminum, or composites thereof. Thesheath220 is preferably fabricated from a material of sufficient stiffness to maintain its structural integrity when other access and preparation tools are subsequently introduced and utilized through the sheath cannula.
• In one embodiment, thedistal end222 of thesheath220 is beveled to match the taper of thedilator tip208_Lof the large dilator rod assembly200_L(e.g., 10 mm dilator), thereby facilitating insertion of therod202_Linto thesheath220.
• The length of thesheath220 is typically in the range of about 7″ to about 10″, often about 8″ to about 9″. In one embodiment, thesheath220 is approximately 200 mm (8.5″) in length.
• The wall thickness of thesheath220 is typically in the range of about 0.005″ to about 0.040″, often about 0.008″ to about 0.030″. In one embodiment, thesheath220 has an I.D. of about 9 mm (0.35″) and an O.D. of about 10.5 mm (0.413″).
• The actual dimensions of the largedilator rod assembly200_Land its components will depend in part on the nature of the treatment procedure and the anatomical characteristics of the patient. For example, the O.D. is about 9.5 mm (0.375″) for asheath220 used in treating relatively smaller patients, while the O.D. for the same is about 10.5 mm. (0.413″) for relatively larger patients. As shown inFIG. 13C, in one embodiment, there is provided adistal end taper228 as a transition to enable use of a smaller distal OD dilator sheath220 (e.g., 0.375″) with a sturdier proximal wall thickness, where clinically appropriate. In another embodiment, there is no taper to the distal end of thedilator sheath220′ (FIG. 13D). In another embodiment, thesheath220,220′ has abeveled tip226 at thedistal end222, which facilitates docking of thesheath220,220′ to the targetedsite192, i.e., the anterior surface of the S1 vertebral body.
• The largedilator rod assembly200_Lis preferably releasably interlocked to theproximal end224 of thedilator sheath220 and is preferably capable of being released and removed thereby facilitating the withdrawal of the largedilator rod assembly200_Lwhile leaving thesheath220 to serve as a working cannula into the targeted site, such as, for example, the anterior surface of the S1 vertebral body.
• With reference toFIG. 9, in one exemplary method of use, thedilator200 is tapped with a cannulatedslap hammer230 that slides onto theextended guide pin164. Successive movements distally and proximally over theextended guide pin164 that repeatedly tap against the dilator handle210 will to advance the dilator, longitudinally, into the sacrum. In one embodiment (not shown), thehammer230 has a flat on it to give another hammering surface, as well as for ease of use, where the additional flat prevents the hammer from rolling off of the table.
• The use of theslap hammer230 engaged on theextended guide pin164, as opposed for example, to the use of an unengaged mallet in “free space” on theproximal end206 of adilator200, enables the surgeon to focus his attention on the visualization monitor while simultaneously tapping and dilating. The axial alignment of theslap hammer230 resulting from its use in combination with theextended guide pin164 is advantageous in that it transfers force solely in the longitudinal direction, which precludes misshapen pathways or misalignment of subsequently introduced tools.
• In one embodiment, thehammer230 has a length of about 4″ (100 mm). The I.D. of the cannulatedhammer230 is configured to slide over the guide pin. In one exemplary embodiment, the hammer has a lumen ID of about 3.5 mm (0.13″). The cannulatedslap hammer230 can be made from any known suitable material, such as, for example, stainless steel or the like.
• With reference toFIG. 10, in one exemplary method of use, a series ofbone dilators200₁,200₂, and200₃, having O.D. of 6 mm, 8 mm, and 10 mm, respectively, are advanced directly over theguide wire164, and tapped with aslap hammer230 to progressively widen the intervertebral channel in a stepwise manner. The last and largest dilator200_L(200₃in the present embodiment) is assembled with asheath220. Thedilator200_Lcan be inserted as a preface to the subsequent introduction of successive instruments in the surgical tools sets described herein. Thelarge dilator sheath220 is preferably left behind to serve as a protected portal to the target location.
• In one embodiment, the dilators and sheaths (e.g., sheath220) are coated with a surfactant, hydrophilic hydrogel, or the like to facilitate passage of surgical tools and/or implants through thesheath220. In another embodiment, the surgical tools and/or implants inserted into thesheath220 are coated with a surfactant, hydrophilic hydrogel, or the like.
• In accordance with one aspect of the embodiments described herein, there are provided twist drills that can be used to extend the working channel within the spine, such as, for example, a channel that extends cephalad from the anterior surface of the S1 vertebral body.
• With reference toFIG. 14, there is provided a twist drill withhandle300. that a configured as atwist drill301 having adistal end302 comprising afluted section306 withhelical flutes308 and aproximal end304, and ahandle310 engaged at theproximal end304 of thetwist drill301. Thehelical flutes308 facilitate boring as thehandle310 is turned in the appropriate direction—here, clockwise to advance thetwist drill301 distally into the working channel.
• The twist drill withhandle300 is typically fabricated from hardened stainless steel or the like. The length of the twist drill withhandle300 typically ranges from about 11″ (275 mm) to about 13″ 330 mm. In one embodiment, the twist drill withhandle300 is approximately 300 mm (12.00″) long. The twist drill withhandle300 typically ranges in diameter from about 5 mm (0.20″) to about 13 mm (0.50″). In one embodiment, the twist drill withhandle300 has a diameter of about 9 mm.
• In one mode of use, the twist drill withhandle300 is used to extend the working channel in the spine to the treatment area (e.g., a disc space) after bone dilators are used to expand the diameter of the proximal portion or entry/targetedsite192 of the working channel.
• In one exemplary method of use, where the targetedsite192 is the anterior surface of a sacral vertebral body and where the dermal entry site is near the paracoccygeal region, a twist drill withhandle300 having an O.D. of about 9 mm and is inserted into the lumen at theproximal end224 of thedilator sheaths220 or220′, each of which is used as a protected portal to the sacrum. The twist drill withhandle300 is advanced by turning thehandle310 at theproximal end304 of thetwist drill301 so that thehelical flutes308 at thedistal end302 of thetwist drill301 progressively bore into and penetrate through the superior S1 bone end plate and into the L5-S1 disc space. Following nucleectomy and preparation of the disc space by means of the cutters and tissue extraction tools and methods described below, the twist drill withhandle300 can again be used to penetrate the L5 inferior bone end plate and vertebral body, prior to the removal of thedilator sheath220 or220′, using, for example, a 6 mm or a 7.5 mm twist drill withhandle300 as needed based on the patient's anatomy.
• In one mode of use, the twist drill withhandle300 is used to drill about halfway into the depth of the L5 vertebral body in preparation for subsequent anchoring of implants, or through the vertebral body to gain axial access to more distal inter-vertebral disc spaces, e.g., L4-L5, for therapeutic procedures.
• In one embodiment, not illustrated, the twist drill unit comprises a bushing portion configured to compensate for the (mismatch) differences between the I.D. of thedilator sheath220 or220′ and the O.D. of the twist drill withhandle300, thereby precluding “wobble” in the disc space en route to the L5 target, and thus enabling on-center axial alignment and use. The bushing portion is preferably located on thetwist drill301 near theproximal end304 that is sufficiently distant from thedistal end302 so that it remains within the confines of thedilator sheath220 or220′ during operation of the tool for its intended purpose. In one embodiment, the bushing portion is made from a polymer, such as, for example, Delrin™, PTFE, PVDF, or the like. In a preferred embodiment the bushing is integral with thetwist drill301, i.e., formed from the same rod blank.
• On advantage of the present embodiment is that the twist drill configuration, mode of delivery, and use at the target site are no longer dependent on electrical or motorized drilling, thereby eliminating the risks of tissue damage associated with electric drill slippage and recoil.
• In accordance with one aspect of the embodiments described herein, there are provided nuclectomy and cutting tools and techniques having advantages over conventional cutting tools and techniques. Certain conventional procedures rely on brute force to scrape, tear or break away the material. For example, rongeurs, or “pliers-like” devices, are often utilized to reach in through an access hole cut into the annulus, grab an amount of nucleus tissue and then to rip it out. In another example, curettes or various flat blades with sharpened edges are inserted and scrapped against the bone in an attempt to separate the nucleus from the bone. Another conventional approach involves using enzymes, such as, for example, chemopapain, to chemically dissolve or break-down the nuclear tissue. Such conventional approaches and techniques are often inexact, incomplete and potentially dangerous to the patient. Often the extent of the surgical exposure, and therefore the resulting trauma, is dictated by the nucleus removal procedure and not the subsequent fusion or repair procedure, which is the true end goal of the procedure. In contrast to the conventional techniques, methods, and instrumentation described above, the apparatuses and methods described herein are not reliant on the application of strength and high forces and are designed be more effective in complete removal of tissue and clean preparation of any bone surfaces.
• Co-pending U.S. patent application Ser. No. 10/853,476, filed May 25, 2004, teaches various types of instrumentation and techniques for the removal of tissues and preparation of treatment sites in the spine, such as, for example, inter-vertebral motion segments located within the lumbar and sacral regions.
• With respect to the present invention, it is anticipated that one or more nucleectomies can be performed extending into successively cephalad intervertebral disc spaces. For example, a disc recess354′ is depicted in disc L4-L5 A wide variety of cutter blade and edge configurations as bore enlarging means can be employed to perform nucleectomies of the L5-S1354, and L4-L5354′ disc spaces, wherein the cutter means are delivered and operated through the anterior TASII axial bore(s). Certain of these methods are described in further detail in U.S. patent application Ser. No. 09/710,369, the content of which is incorporated in its entirety into this disclosure by reference.
• Co-pending U.S. patent application Ser. No. 09/782,534, filed on Feb. 13, 2001, teaches various types of techniques for using cutting tools for removing disc material and preparation of spinal treatment sites that comprise a spinal disc, for example, a method of removing at least a portion of the nucleus through a TASII axial bore while leaving the annulus AF intact.
• Referring toFIG. 15, anucleectomy instrument400 is inserted through the axially alignedanterior tract372 defined by the lumen of thedilator sheath220 and the TASIIaxial bore370. Thenucleectomy instrument400 comprises a cutting blade (e.g.,cutter blade453 which refers collectively to any blade configuration) which is remotely manipulatable, i.e., a retractedcutter blade453 is first advanced through the TASIIaxial bore370 and then extended laterally into the nucleus of the spinal disc. More specifically, thecutting blade453 is mounted into an extendible or steerable distal end section382 of nucleectomy instrument, i.e.cutter assembly400 extending through the TASIIaxial bore370 andanterior tract372.
• Thecutter assembly400,cutter blade454 andcutter assembly shaft410 are shown schematically inFIGS. 16-18 and not necessarily to scale to one another or to the TASIIaxial bore370.
• In accordance with one aspect of the embodiments described herein, there are provided surgical cutters that can be used to perform nucleectomy via insertion into a disc space to excise, fragment and otherwise loosen nucleus pulposus and cartilage from endplates from within the disc cavity and from inferior and superior bone end plate surfaces. The cutters described herein represent a significant advance to current clinical techniques for access and preparation of intervertebral bodies for the subsequent insertion of therapeutic devices, such as prosthetic nucleus and fusion implants, and in particular for axially aligned implants, or for insertion of therapeutic materials, e.g., for osteogenesis, spinal arthroplasty, or annuloplasty.
• With reference to the exemplary embodiments of FIGS.16A-C, thecutter assembly400 comprises: acutter shaft410 extending between adistal end412 and aproximal end414; acutter blade453 at thedistal end412; ahandle416 at theproximal end414; acutter sheath430 placed concentrically over theshaft410; and ashaft sleeve418 at thedistal end412.
• It will be understood, however, that the cutter components and structures described herein are suitable for the assembly and application of cutter assemblies that comprise, for example, up-cutters452,debulkers450, down-cutters454, or the like, or variations thereof. InFIGS. 16A-16E, the cutter comprises a down-cutter454. In another embodiment, the cutter comprises an up-cutter452 (seeFIG. 16H) In still another embodiment, the cutter comprises a debulker450 (see FIGS.17A-E). These and other types of cutters are described in further detail below, with reference to preferred embodiments which comprise teardrop-shapedcutter blades460,460′,490,490′,490″ shown inFIGS. 18A-18G.
• With reference to the embodiments ofFIGS. 16C and 17A, in assembling thecutter assembly400, thelongitudinal portion406 of the cutter blade (e.g.,debulker450, up-cutter452, or down-cutter454) is placed into aslot413 near thedistal end412 of theshaft410. In one embodiment, thecutter blade hole407 is aligned with a strategically placedcutter shaft hole411 within theshaft slot413.
• Theshaft slot413 is dimensioned to accommodate acutter blade453 such as, for example, a debulker450 (17A), an up-cutter452, a down-cutter454 (16C), or the like, or variations thereof. The width of theslot413 is approximately the same as the width of thelongitudinal portion406 of thecutter blade453. The curvature at the distal end of theslot413 accommodates the curvature of thecutter blade453 between thelongitudinal portion406 and the laterally extending portion of the blade arm402 (which defines the reach or throw of the cutter blade453). Theslot413 provides torsional support to thecutter blade arm402 while the curvature at the distal end of theslot413 provides axial support to thecutter blade arm402, necessary, in conjunction with cutter blade edge geometries (described in detail below; seeFIGS. 16D-6H and17B-17E, and18A-18F) to the cutting effectiveness of thecutter blade453.
• Ashaft sleeve418 may be placed over the assembly shown inFIGS. 16C and 17A comprising theshaft410 and thecutter blade453. Theshaft sleeve418 when pinned effectively serves to align and fix theshaft410 and thelongitudinal portion406 of thecutter blade453. While any of variety of other fastening techniques may also be used, the preferred pin technique is described below.
• In one embodiment, theshaft sleeve418 comprises a strategically placedshaft sleeve hole419 that aligns with thecutter shaft hole411 of theshaft slot413 and thecutter blade hole407. Thesleeve418 can be securely fixed to the rest of the assembly by inserting across pin409 through theshaft sleeve418 and thelongitudinal portion406 of thecutter blade453 into theshaft410. In one embodiment, thecross pin409 that fixes thecutter blade453 to theshaft410 is approximately 0.06″ in diameter. The rest of theassembly400 components can be fixedly secured to each other using any known suitable fixation mechanisms, as described in further detail below.
• With reference to an exemplary embodiment in FIGS.16D-E, the cutter blade453 (as shown, a down-cutter454) comprises ablade arm402 and a longitudinally-extendingportion406. Theblade arm402 begins from the proximally-located, longitudinally-extendingportion406, and extends laterally to comprise any number of suitable shapes or configurations, such as, for example, a “J” shape or “S” shape, as shown. It is understood that in the context of the present invention, configurations of the types as just described may comprise a plurality ofcutter blade arms402. In a preferred embodiment, described in further detail below, thecutter blade453 comprises a “teardrop” shape (460,460′,490,490′,490″) shown inFIGS. 18A-18G.
• Thecutter blades453 generally comprise at least one sharpened cutter blade edge401 (collective). With reference to FIGS.16D-E, in one embodiment, the cutter blade arms402 (collective) of the down-cutters454 have three cutter blade edges401 includingcutter blade arms402′ (proximal), and402″ (distal) separated lateral bend403. In other words, the cutter blade edges may be continuous with each other around the lateral bend403 or may be interrupted. The illustrated blade edges401 are illustrated on a leadingsurface405 of thecutter blade arm402. A trailingsurface415 is illustrated as a blunt side, without a sharpenedcutter blade edge401. Since the cutter blade edges401 are on the same (leading) edge or side of thecutter blade arms402, thecutter blade454 is considered to be single-sided in this regard. In this embodiment, the single-sidedcutter blade arms402 cut when turned in a clockwise manner but do not cut when rotated in a counter-clockwise direction. The direction of the rotation (clockwise or counterclockwise) is determined from a perspective that is proximal relative to the distally-located cutter. In another embodiment, not illustrated, thecutter blade arms402 have cutter blade edges401 on both the leadingsurface405 and trailingsurface415 of thecutter blade arms402, so that cutting can be accomplished with this double-sidedcutter blade arms402 by means of either clockwise or counterclockwise rotation.
• As will be described in further detail below, all of the cutter blade edges401 disclosed herein may be optimally configured for preparing an intervertebral motion segment for either a subsequent fusion procedure or a subsequent procedure in which mobility of the intervertebral motion is to be preserved. More specifically, for nucleectomies preceding fusion procedures, cutter blade edges401—regardless ofcutter blade arm402 configuration—will contact the spinal disc inferior or superior endplates, while for mobility procedures, the cutter blade edges401 will be spaced apart from the spinal disc endplates.
• As an example. referring toFIG. 16G, there is illustrated a cross-sectional view throughcutter blade arm402 of thecutter blade454 illustrated inFIG. 16E. In that illustrated embodiment, a leadingside405 is provided with a sharpenededge420 fabricated by means of cutting, grinding or other manufacturing technique. The sharpenededge420 is formed at the intersection of the declinedface421 and thesurface424 of thecutter blade arm402′ and402″. Thiscutter blade454 configuration is optimized for use against an inferior endplate in preparation for a fusion procedure. When theproximal surface424 is placed in contact with an inferior endplate of a spinal disc and rotated in a clockwise direction, the sharpenededge420 on leadingsurface405 will scrape against said endplate. This can be used to scrape away the cartilaginous endplate and roughen the vascularized vertebral body so as to cause bleeding, which is desirable in order to facilitate bone growth and achieve fusion of the vertebral bodies that are superior and inferior to the spinal disc being treated
• However, in a procedure to prepare the nucleus space for implantation of a mobility preserving device, roughening the endplate of the spinal disc may be undesirable. As shown inFIG. 16F, for this procedure, the sharpenededge420′ is desirably positioned at the intersection of theinclined face421 and thesurface424, such as by mirroring the angle of inclination of the declinedface421. In this configuration, the sharpenededge420′ will be spaced apart from the inferior endplate of the spinal disc by a distance which is equal to the thickness of the proximalcutter blade arm402′, thereby minimizing the chance of the bone bleeding, that would promote unwanted fusion.
• With respect to thecutter arm blade402, the mirrored blade of proximalcutter blade arm402′ is shown inFIG. 16F andFIG. 16G as distalcutter blade arm402″.
• A sharpened edge (not shown) may alternatively be positioned partway between theproximal surface422 and thedistal surface424, such as providing a first and second inclined face on the leadingsurface405, which intersect at a sharpenededge420. In the atraumatic cutter design, intended for use in preparation for a procedure which preserves mobility, the sharpenededge420 is preferably spaced apart from the surface of the cutter adapted for sliding contact with a boney end plate. Although the sharpenededge420 may optimally be spaced apart from the bone contacting surface by the full thickness of the cutter blade, as discussed above, a sharpenededge420 may be positioned in-between theproximal surface422 and thedistal surface424 by a sufficient distance to prevent injury to the bone. The distal and proximal orientation of the sharpenededge420 described above may be mirrored on a given cutter blade, depending upon whether the cutter is intended to be placed in sliding contact with an inferior or superior spinal disc endplate, as will be apparent to those of skill in the art in view of the disclosure herein. Again, the foregoing sharpened edge orientation may be applied to any of the cutter configurations disclosed herein.
• In one embodiment, shown inFIG. 16H, the cutter of theassembly400 comprises an up-cutter blade452. As with the above-described down-cutter blade454, the up-cutter blade452 generally comprises acutter blade arm402 and a longitudinally extendingbase portion406. Thecutter blade arm402 begins from a proximally located, longitudinally extendingbase portion406 that extends generally distally and inclines laterally outwardly to aradial limit404. Thearm402 curves to form a proximally facing concavity with a distal limit. The cutter may comprise any number of suitable shapes or configurations, such as, for example, a “J” or question mark shape. In another embodiment, described below, the cutter comprises a “teardrop” shape.
• With reference to the embodiments shown in FIGS.16D-H, the down-cutters454 and up-cutters452 have single-sided blade arms402 that are bent at an angle from between about 40 degrees to about 140 degrees relative to thelongitudinally extending portion406. Theblade arms402 can optionally be canted between about 5 to about 25 degrees, preferably about 15 degrees, so that the cutting edge is rotated radially outwardly relative to the trailing edge. Theblades arms402 of the up-cutters452 and down-cutters454 are preferably angled vertically steeper relative to the longitudinal axes of the shafts to which they are affixed, as compared to those ofdebulkers450, described in further detail below.
• The tilt of theblade arm402 in the proximal direction inFIGS. 16D, 16E and16H is configured to allow for maximum engagement of the blade cutting edge with the distally facing surface of the bone end plate, while severing nucleus material. Thus, for an up-cutter452, an angle less than about 90 degrees relative to the axis of theshaft410 generally would not enable adequate engagement of the blade cutting edge(s)401 with the superior bone end plate. For a down-cutter454, an angle greater than about 90 degrees relative to the axis of theshaft410 generally would not facilitate adequate engagement of the blade cutting edge with the inferior bone end plate, and ablade arm402 at about a 40 degree angle of tilt of theblade arm402 operates preferably (is “vertically steeper”) than one at 70 degrees.
• The “throw” i.e., the reach of theblade arm402 is measured from the central longitudinal axis of thecutter shaft410 radially outward to its radial limit404 (FIG. 16H). In other words, blade arm throw as used herein refers to the radius of the circle cut by a full revolution of the blade arm.
• For up-cutters452 and down-cutters454, theblade arm402 throw are generally within the range of from about 6 mm to about 18 mm. In one embodiment, the blade arm throw of thecutters452,454 are about 12 mm.
• In accordance with one aspect of the embodiments described herein, the cutter blade of theassembly400 comprises adebulker450 Up-cutters452 and down-cutters454, as illustrated inFIGS. 16D, 16E and16H may not be ideal initiators of nucleus tissue fragmentation. For one, theirblade arms402 and cuttingedges401 do not easily bend or sweep without space, particularly in terms of angles, having first been created by one or more debulkers450.
• With reference to FIGS.17B-E, adebulker450 comprises acutter blade arm402 that begins from a proximally-located, longitudinally-extendingbase portion406 and extends laterally to comprise any number of suitable shapes or configurations, such as, for example, a “J” or “U” shape, as shown.
• In one embodiment, thedebulker450 comprises a shorter throw than thecutter blade454, which allowsdebulkers450 to retain their shape better than cutters with longer arms upon initial entry into the disc space, providing improved engagement of effective cutting edge surface with nucleus material. FIGS.17B-C illustrated one embodiment of a relatively smallersized debulker450. FIGS.17D-E show one embodiment of adebulker450′ having a greater cutting radius.
• In one embodiment, theblade arm402 configuration of adebulker450 resembles a “J” in shape. The functional advantage of such blade vertical elements in the “J” shape is the increased efficiency of cutting per unit of throw or the increased cutting edge surface contact with the material to be fragmented.
• In the embodiments of FIGS.17B-C and17D-E, thedebulkers450,450′ have single-sided blades (i.e., cutter blade edges401 on one of the cutter lateral sides). In another embodiment, not illustrated, thedebulkers450 have double-sided blades (i.e., blade edges on both of the cutter lateral edges), which enables bi-directional cutting when thecutter handle416 is manipulated to rotate theblade arm402.
• In one mode of operation,debulkers500 with shorter arm lengths, and hence shorter “throws” in terms of circumferential cutting diameter, are first introduced through thelarge dilator sheath220 into the disc space and used to fragment the tissue within the disc space. In one mode of operation, one or more down-cutters, up-cutters, or the like, or variations thereof are used to further fragment the tissue within the disc space.
• In accordance with one aspect of the embodiments described herein, there are provided cutters that comprise a closed loop such as a “teardrop” shape configuration, which provides more cutter rigidity and reduces the risk of fracture of the cutters during use (e.g., when a leading cutting edge of the cutter becomes embedded in bone during use). It will be understood that the any of the cutters (e.g., down-cutters, up-cutters, debulkers) described herein can comprise a “teardrop” or other closed loop shape.
• Cutters (e.g., debulkers, up-cutters, down-cutters, etc.) that comprise a closed loop generally provide a more robust and overall more efficient cutting device that can be used for any number of surgical procedures, such as, for example, nucleectomy. Closed loop cutters may have a variety of advantages over cutters having only a single attachment point to the rotatable support. For example, in one embodiment, the closed loop shape allows for two fully supported cutting edges (e.g., top and bottom) on any given lateral side of the cutter. The closed loop shape also allows for side or end edges in the curve where the blade or cutter arm doubles back on itself.
• With reference to embodiment shown in FIGS.18A-B, there is provided a standard size closedloop debulker460. In the illustrated embodiment, thecutter arm462 of the closedloop debulker460 doubles back upon itself to form adistal segment470 and aproximal segment468. Both thedistal segment470 andproximal segment468 are secured to therotatable shaft410, resulting in the distribution of any stress in thearm462 over two segments rather than over a single segment arm. The distributed stress can result from the torque of turning theshaft410 or the resistance of the disc material on the blade(s)461.
• Thearm462 of the closed loop cutter begins from a proximally locatedend480, extends distally to provide an attachment surface and then laterally outward to form thelower segment468. Thearm462 then doubles back atjuncture482, the location of which defines the cutting radius. Thearm462 then extends laterally inward, turns, and then proximally towardproximal end484, to provide an attachment surface. The proximal anddistal segments468,470 each comprise asharp edge461.
• Thedistal segment470 comprises an attachment structure such as aslot472 near the proximally locatedend484. Thelower segment468 also comprises an attachment structure such as acutter blade hole467 near the proximally locatedend480. Theshaft slot472 enablesend470 to slide relative to thecross pin409 during extension and retraction of the cutter blade (e.g.,460 or490) of theassembly400.
• With reference to the embodiment shown in FIGS.18C-D, there is provided a large teardrop shapeddebulker460′, having a longer laterally extending portion andlonger blades461′, relative to thedebulker460 of FIGS.18A-B. A longer teardrop configuration generally allows for further reach than smaller ones. In general, thecutter blades460,460′,490,490′ ofFIG. 18A-FIG. 18D, when rotated through a complete revolution will cut a transversely circular cavity having a diameter within the range of from about 10 mm to about 30 mm.
• In each of the closed loop cutters illustrated inFIGS. 18A through 18D, theproximal segment468,468′ anddistal segment470,470′ extend radially outwardly from the axis of rotation generally in parallel with each other. However, alternative configurations may also be used, such as by imparting curvature to one or both of theproximal segment468 anddistal segment470. One or both of the segments may be provided with a curve having a concavity facing in the distal direction; a concavity facing in the proximal direction, or concavities opposite to each other, depending upon the desired clinical result. In addition, in the illustrated embodiments, thecutter blade arm462 formed by theproximal segment468 anddistal segment470 extends radially outwardly at approximately a 90 degree angle from the longitudinal axis of therotatable shaft410. Thecutter blade arm462 may alternatively be inclined in either a proximal or distal direction (not shown) depending upon the desired performance, and, for example, whether the cutter is intended to operate against an inferior or superior spinal disc endplate. For example, thecutter blade arm462 may incline in a distal direction or a proximal direction by as much as 45 degrees away from the perpendicular
• With reference to the embodiments shown inFIGS. 18E, 18F, and18G, there are provided teardrop shaped down-cutters490,490′,490″ having large, medium, and small sizes, respectively. The length of the teardrop shaped cutters varies in the range between about 0.25″ to about 1.00″. These arcuate cutters can extend linearly within a deployment sheath and “curve” as they are advanced distally out of the sheath into the disc space, instead of extending axially until fully deployed from the sheath and then “flopping over” which requires a lateral advance through the nucleus material as well as sufficient axial clearance to allow deployment within the disc. Due to the limited disc height in most fusion/mobility patients, the cutter preferably has a low profile during extension, use, and retraction. Straight bladed cutters will extend linearly in the axial direction of the deployment sheath during extension and long versions may actually hit the upper endplate, causing the cutter to get stuck or inhibiting complete deployment.
• With reference to the exemplary embodiment ofFIG. 18E, the double-back structure of the teardrop down-cutter490 begins from a proximally locatedend480, extends distally along thelower segment468, extends laterally outward and downward (i.e., proximally) to form a proximally facing concavity, along thelower segment468, doubles back atjuncture482, extends laterally inward and upward (i.e., distally), and then extends proximally along theupper segment470 toward proximally locatedend484. At least one and preferably both of lower andupper segments468,470 comprise ablade461.
• Theupper segment470 comprises aslot472 near the proximally locatedend484. Thelower segment468 comprises a cutter blade hole (not shown) near the proximally located480. Theshaft slot472 enablesend484 to slide relative to thecross pin409 during extension and retraction of the cutter blade (e.g.,490,490′,490″) of theassembly400.
• In the embodiments illustrated inFIGS. 18E through 18G, the separation distance between the first and second cutting edges is a controllable variable in manufacturing (e.g., predetermined during cutter blade formation, i.e., heat treatment of the pinned Nitinol shape memory alloy) and varies from about 2 mm to about 8 mm, and, often is about 3 mm to about 4 mm. The maximum separation483 in the illustrated embodiment is located within about the radially outwardly most one third of the total blade length. Alternatively, the maximum separation483 may be positioned within the radially inwardly most third of the blade length, or within a central region of the blade length, depending upon the desired deployment and cutting characteristics.
• In accordance with one aspect of the embodiments described herein, theblade arms402 and thecutter blades453 in general can be formed from strip material that is preferably a shape memory alloy in its austenitic phase at room and body temperature and that ranges in width from about 0.10-0.20″ and in thickness from about 0.015-0.050″.Blade arms402 formed in accordance with the present embodiment are generally able to be flexed in excess of 100 cycles without significant shape loss, and twisted more than 1 and ½ full turns (about 540 degrees) without breakage.
• In one embodiment, thecutting blade453 andcutter blade edge401 is formed from a super-elastic, shape memory metal alloy that preferably exhibits biocompatibility and substantial shape recovery when strained to 12%. One known suitable material that approximates the preferred biomechanical specifications forcutter blades453 and cutter blade edges401 andblade arms402 is an alloy of nickel and titanium (e.g., Ni₅₆—Ti₄₅and other alloying elements, by weight), such as, for example, Nitinol strip material #SE508, available from Nitinol Devices and Components, Inc. in Fremont, Calif. This material exhibits substantially full shape recovery (i.e., recovered elongation when strained from about 6%-10%, which is a factor of ten better than the recovered elongation at these strain levels of stainless steel).
• The shape and length of the formedcutter blade453 in general varies for the different cutting modes. The shape memory material can be formed into the desiredcutter blade453 configuration by means of pinning alloy material to a special forming fixture, followed by a heat-set, time-temperature process, as follows: placing the Nitinol strip (with the blade's cutting edge(s)401 already ground) into the forming fixture and secured with bolts; and placing the entire fixture into the oven at a temperature ranging from about 500° C. to about 550° C. (e.g., where optimum temperature for one fixture is about 525° C.) for a time ranging from between about 15 to about 40 minutes (e.g., where the optimum time for one fixture is about 20 minutes). Flexible cutter blades formed from Nitinol in this manner are particularly suited for retraction into a shaft sleeve, and are able to be extended to a right angle into the disc space. Moreover, they are able to mechanically withstand a large number of cutting “cycles” before failure would occur.
• Thecutting blade edges401 are preferably ground with accuracy and reproducibly. The angle of the inclined surface (e.g.,421,421′,461,461′,461″) of the blade relative to the blades's flat side surface typically ranges from about 5 degrees to about 60 degrees, often about 20 degrees to about 40 degrees. In one embodiment, the blade angle is approximately 30 degrees relative to the blade's side surface.
• In one embodiment, theshaft410 of theassembly400 is formed from solid stainless steel or other known suitable material. In one embodiment, the shaft has a diameter of approximately 0.25″ (6.3 mm). Theshaft sleeve418 may be formed from stainless steel tubing or other known suitable material tubing, and has a length of about 0.7″.
• Thecutter sheath430 can be fabricated from polymeric material, stainless steel, or other metal tubing. Thesheath430 typically has an outer diameter (O.D.) of about 0.31″ (7 mm) to about 0.35″ (9 mm). With reference toFIG. 16I, in a preferred embodiment, thesheath430 is configured with ashoulder499 bored into its inner wall which serves as a stop that precludes theshaft410, along with its attachedblade arm402 and handle416, from becoming fully disengaged from thecutter sheath430 when theblade arm402 is retracted into thesheath430. When retracted proximally, the proximal end of theshaft sleeve418 bumps into theshoulder499, thereby preventing theshaft410 from being fully disengaged from thesheath430. It will be understood that one or more analogous shoulder structures can be implemented in any of the tools described herein, such as, for example, the sheaths used with the tissue extractors, etc.
• In accordance with one aspect of the embodiments described herein, there is provided a handle configured as a lever which is affixed to the proximal end of the cutter shaft. Referring to FIGS.16A-B, the illustratedhandle416 is affixed to theproximal end414 of the cutter shaft by means of across-pin set screw415, which reduces the risk ofhandle416 disengagement from the cutter shaft410 (e.g., unthreading by rotational manipulation during cutting). Thehandle416 is preferably affixed so that it is in rotational positional alignment with theblade arm402 and serves as a reference marker for the blade arm's in situ orientation.
• In one embodiment, thehandle416 of thecutter assembly400 is. configured as a turn knob fabricated from a polymeric material, such as, for example, ABS polymer or the like, that is injection moldable and that may be machined, and is affixed to thecutter shaft410 by means of threaded or other engagement to the cutter shaftproximal end414.
• Thehandle416 may serve as a stop against which the proximal end of thecutter sheath430 abuts, thereby maintaining the engagement of theshaft410 andcutter sheath430, when theblade arm402 is extended distally and is exposed from the distal end of the cutter tube lumen, for example, as a result of having pushed on thehandle416 to advance theshaft410 distally to expose thecutter blade453 andcutter blade edge401.
• Due to the inevitable accumulation of severed tissue on and within the debulker250 and other cutter assembly components (e.g., up-cutters452, down-cutters454, etc.), it is preferred that they be disposable. In accordance with one aspect of the embodiments described herein, there are provided cutter assembly components that are disposable. Two or three or four our more of any of these components may be provided in a kit, enabling the clinician to dispose of one as desired and to introduce a new one into the procedure.
• In accordance with one aspect of the embodiments described herein, there are provided blade arms and cutters that are designed to be rotated and used in one direction (i.e., clockwise or counter-clockwise). In one aspect, for the single-sided cutter blades450 illustrated in FIGS.17B-C, rotational motion ofblade arms402 in only one direction (e.g., clockwise) will initiate severing of nucleus material (see also up-cutters452 and down-cutters454 described herein). The intended motion during the use of theseblades401 is similar to the back and forth motion of a windshield wiper—wherein the excision with respect to these cutters occurs in the sweep that is clockwise in direction.
• In one embodiment (not shown), one or more stops are placed within thecutter shaft410 to control blade arc or range of motion. In another embodiment (not shown), one or more stops are fitted onto thedilator sheath220 to control the blade arc or range of motion.
• Theshaft410,cutter sheath430 and thehandle416 components are preferably co-configured to enable thecutter blade arm402 and theshaft410 to which it is attached be able to be “pushed-pulled” so as to retract theblade arm402 into and extended theblade arm402 from the lumen434 at thedistal end432 of thecutter guide tube430, as needed. More specifically, the cutter blade edges(s)401 of thecutter blade453 are retracted into thecutter sheath430 for delivery into the disc space. Once thesheath430 is in position, the cutter blade edges (s)401 are extended distally and rotated using thehandle416 to cut nucleus material. The cutter blade edge(s)401 are again retracted into thecutter sheath430 for removal of thecutter assembly unit400 from the spine.
• In one mode of use, particularly suitable for performing a nucleectomy of the L5-S1 intervertebral disc space, a series of cutting tools comprising debulkers, up-cutters, and/or down-cutters are used to separate disc material (e.g., nucleus pulposus and cartilage from within the disc space).
• In one embodiment, the terms “debulking”, “up-cutting”, and “down-cutting” refer to the blade arms configurations that are used in a sequential and progressive fragmentation of the core nucleus pulposus within the central or core portion of the disc, the surface of the superior bone end plate, and the surface of the inferior bone end plate, respectively.
• In one method of use, one or more debulkers450, with blade arm lengths successively increasing from about 8 mm to about 15 mm, are used in the initial steps of performing nucleectomy. In one mode of operation, three debulkers—namely, asmall debulker450_S, amedium debulker450_M, and alarge debulker450_L—having blade arm lengths of about 8 mm, 11 mm, and 15 mm, respectively, are used prior to introduction of the cutters (e.g., up-cutters452 and/or down-cutters454).
• In accordance with one aspect of the embodiments described herein, there are provided cutter configurations that advantageously enable the surgeon to have more precision and control with respect to the excision of nucleus material from the endplates. Some level of bone bleeding is generally associated with decortication (i.e., the scraping of the cutters against the surfaces of the end plates). Such bleeding can advantageously promote bone healing and/or osteogenesis in the normally a vascular area of the disc. This is particularly advantageous when the disc space is being prepared for subsequent procedures or implants where there is a need for accompanying bone growth. The cutter configurations and techniques of the present invention assist the surgeon in achieving an appropriate amount of bleeding in a controlled manner which does not otherwise compromise the bone endplate or adjacent structures.
• In accordance with one aspect of the embodiments described herein, there are provided extraction tools for extracting tissue fragments from a treatment site, such as, for example, a disc space. While the extraction tools and devices are described in the context of their application to the removal of nucleus pulposus and cartilage material excised from the a spinal disc via axial access to a disc space, it will be understood that they can be used to remove other tissue fragments from the same or different treatment sites, or for lateral access into a disc space as well.
• The extractor devices include configurations that can be inserted into the disc space through an axial approach to the lumbar spine. Such configurations include, but are not limited to, “wheel”, “end” or “bottle” multifilament configurations. At the same time, the tools should be small enough to allow atraumatic entry into the disc via a cannulae (e.g., the large dilator sheath). The extractor tools are generally used to remove tissue fragments in the treatment site by snagging and pulling them out.
• With reference to the embodiment of FIGS.19A-D, there is provided aretractable tissue extractor500 comprising anelongate extractor shaft512 that extends between adistal end514 and aproximal end516. Theextractor500 preferably comprises adelivery sheath520 that extends between adistal end522 and aproximal end524.
• Theextractor500 comprises anextractor head509 engaged with thedistal end514 and ahandle518 affixed to theproximal end516. Theextractor head509 may be glued and pinned into or otherwise attached to the distally located receiving section of theextraction tool500. The extractor handle518 may be configured, constructed, and affixed to the extractor shaft in accordance with substantially the same means and materials as previously described and disclosed herein for cutter handles.
• Theextractor assembly500 of FIGS.19A-D is shown in its “pre-splayed” state, which refers to a first configuration or first, reduced cross sectional profile in which the filaments orwires530 of theextractor head509 on the distal end ofextractor assembly500 are in a reduced cross sectional orientation, to facilitate assembly into theshaft512. In one aspect, the “pre-splayed” individual wires orfilaments530 ofextractor head509 are comprised as part of a multi-filar and/or multi-layer wound coil. The windings of the layers can be left-handed and/or right-handed, although it is preferred that all layers be wound in the same direction, and that a wound configuration for the individual filaments is preferable to a straight-filament configuration in order to assure that thefilaments530 will retain a helical or coiled configuration when unwound.
• In the context of the present invention, as used herein the terms spiral, helical, or kinked refer to the fact that the filaments are not straight, and it is understood that they are not necessarily “uniformly” formed (e.g., not as reproducibly spaced coils).
• In one embodiment, theextractor head509 may be formed from a cable that is wound as 4 concentrically coiled, multi-filar layers (e.g., 6, 7, 8, 9 filaments or filars per layer) fabricated from the highest-tensile strength stainless steel wires commercially available. As will be described below, it is the combination of the tensile strength, diameter and helical or coiled configuration of thewires530 when unraveled enable wire entanglement to effectively extract tissue fragments. Theextractor head509 is capable of being transformed from a first “pre-splayed” state (e.g., where the wires are wound together in a cable that has a bundle diameter of about 0.15″) to a second, “splayed” state (i.e., a second, expanded cross sectional profile) by the unwinding of the wires530 (e.g., stainless steel wires) with diameters of about 0.01″.
• With reference toFIG. 20, there is provided one embodiment of the extractor assembly500 (with theextractor head509 in a splayed state) that can be used to remove entrappedtissue fragments502 from the treatment site. As shown, the tissue fragments502 are entangled in the inter-wire spaces of themultiple strands530.
• In one embodiment, theextractor head509, once unraveled and splayed, the reach or total spread of theextraction filaments530, tip-to-tip is from about 0.50″ to about 1.50″. In a preferred embodiment, the reach of theextraction filaments530 tip-to-tip is about 1.00″.
• The wires orfilaments530 are preferably stainless steel and of a diameter and tensile strengths, that enable retraction and delivery through thedelivery sheath520 without deforming extensively e.g., theindividual filaments530 retain their helical configuration and collectively maintain the radial reach ofextractor head509. In alternative embodiments, the wires can comprise, nickel alloys, nickel-titanium alloys, cobalt alloys, or the like.
• In one embodiment, shown in FIGS.21C-D, thehelical wires530 of theextractor head509 are splayed in a non-uniform pattern, so that thewires530 overlap with each other. Thewires530 are preferably sufficiently stiff to snag tissue fragments502, yet be pliable enough to compress and bend when tugged withtissue fragments502 in tow. The mechanical properties, number, and spatial relationship among of thewires530 impact effective tissue extraction of tissue fragments502 as will be explained below.
• Tissue fragments502 are captured by theextractor head509 in part as a result of the wires' surface areas, in part due to their own (inter-wire) physical entanglement with a concomitant entrapment of additional material as theextractor tool500 is manually rotated or twisted and the spatial orientation amongwires530 changes. The tips at the distal end of thewires530 are also sharp to assist in snagging.
• Thewires530, however, are preferably not so stiff as to preclude deflection upon contact with stiffer/more solid elements other than fragmented and loosened tissue. Thetissue extractor wires530 are preferably soft enough to deform and conform to the irregularities of the bone surface and neither cut or erode other vertebral structures, such as bone or the annulus, so there is also no concomitant risk of further spine or spinal cord damage.
• The density ofwires530 within the disc space is also a significant factor with respect to maximum tissue removal. When wire or bristle density (# wires per unit volume of disc space) is too high, theextractor head509 tends to push material to the disc perimeter rather than collecting it. In one embodiment, theextractor head509 comprises about 30wires530, each with a diameter of about 0.010″. The disc space is typically small, with a cavity volume of about 6-8 cc, so a density with too many wires530 (e.g., 50 strands, each with a diameter of about 0.010″), precludes their optimum interaction in removingtissue fragment502. Extractor heads having at least about 5 to about 10, but often no more than about 40 or 50 strands, depending upon strand length and diameter, and desired clinical performance, are contemplated.
• In one embodiment, theproximal end534 of the wire cable comprising theextractor head509 is brazed to theextractor shaft512, which is formed of stainless steel tubing. In another embodiment, (FIG. 19B), theproximal end534 of theextractor head509 is affixed to theextractor shaft512 by means of apin508, as well as adhesively affixed. Any of a variety of other attachment techniques may also be used, such as gluing, crimping and various potting techniques. Alternatively, theextractor head509 may be sufficiently axially enlongated to extend to theproximal end516 of theextractor shaft512.
• In one embodiment, theshaft512 is formed from a solid polymer rod. Suitable rod materials include, but are not limited to, polymers which are machined and/or injection molded, and are able to be sterilized. Examples of such materials include acetal copolymer, acrylic, polyethylene, nylon, polycarbonate, polypropylene, PVC, ABS, or the like.
• In one embodiment, theextractor shaft512 is about 0.25″ in diameter and is approximately 12.00″ in length. As previously noted, theextractor assembly500 should be small enough to allow atraumatic entry into the disc via a cannulae (e.g., the large dilator sheath220).
• In one embodiment, theextractor sheath520 is formed from stainless steel tubing with an I.D. of about 0.26″ and an O.D. of about 0.35″.
• With reference toFIGS. 19A-19C, theextractor shaft512 also may comprise ahandle518 that is affixed to itsproximal end516, to facilitate manipulation of the tool when removing tissue, and also to enable extension and retraction of theextractor head509 as noted and described elsewhere. In order to prevent over-extension and over-retraction theextractor assembly500 comprises stop means. One such stop means is shown inFIG. 19A, comprising astop pin515 and a slot562. Thestop pin515 is affixed to theshaft512 and configured to extend throughslot526 in theextractor sheath520. The length of theslot526 limits the travel of the pin and in turn theshaft512, limiting extension and retraction of theshaft512 and thus theextractor head509. In one embodiment, thehandle518, which is of larger diameter then theextractor sheath520, serves as an extension stop. More specifically, distance between theproximal end524 of thesheath520 and the distal end of thehandle518 controls the amount of exposure of theextractor head509. A longer distance betweenend524 and thehandle518 will result in anextractor500 with ashaft512 that can be distally advanced a longer distance, thereby resulting in increased exposure of theextractor head509.
• With reference toFIG. 16 I, as was previously described with respect to thecutter sheath430, in a preferred embodiment, theextractor sheath520 is configured with ashoulder499 bored into its inner wall which serves as a stop that precludes theshaft512, along with itsextractor head509 and handle518, from becoming fully disengaged from theextractor sheath520 when theextractor head509 is retracted into theextractor sheath520.
• With reference to FIGS.22A-B, in another aspect, theextractor head509 comprises wires(s)550 at least some of which, and in one embodiment all of which, are configured with hooks558 on the distal ends554 of thestrands550, for extracting tissue. Thewires550 are constructed from a metal such as stainless steel with a wire strand diameter from about 0.004″ to about 0.020″. Again, for theextended extractor head509, the reach or total spread of the hookedwires550, tip-to-tip is from about 0.50″ to about 1.50″. In a preferred embodiment, the reach of theextraction filaments530 tip-to-tip is about 1.00″.
• Theextractor head509 comprising the hookedwires550 is affixed to theextractor shaft512 in substantially the same manner as previously described, above. In this embodiment as just described it is the hooked configuration of thewires550 which extract tissue fragments502 as opposed to the entanglement among individual wires with respect to the preferredkinked filaments530. The hookedwires550 are configured so as not to excise, abrade, or otherwise compromise adjacent structures (e.g., the annulus).
• Extractor heads509 configured according to the embodiment of FIGS.22A-B can snag material for removal with a lower strand density (i.e., number of strands per unit volume of disc space). In one approach, as few as two strands can be used operatively. Again, if the density ofstrands550 is too high, theextractor head509 tends to push tissue fragments502 to the disc perimeter rather than collect it. In one embodiment, the head comprises fewer than about 30wires550.
• With reference to FIGS.19A-D and21A-D, there is provided anextractor sheath520 which restrains theextractor head509 in the first, reduced configuration, which is retracted into or extended from the lumen at thedistal end522 of theextractor sheath520 as theextractor assembly unit500 is inserted or removed from the disc space, through the protected portal of thelarge dilator sheath220.
• In one mode of use, the targeted tissue site comprises a disc space and the tissue fragments to be extracted comprise nucleus material. In one mode of use, theextractor500 is used to remove nucleus material after tissue cutters (e.g., debulkers, down-cutters, up-cutters, etc.) have been used to loosen up nucleus material within the disc cavity and end plate surfaces. In another approach,extractors500 are used concurrently with the tissue cutters. In one method of use, approximately fiveextractor assembly units500 are utilized in each procedure (i.e., during the nucleectomy of one disc).
• In one embodiment, theextractor assembly500 is a disposable, one-time use unit. Here, each extractor head510 is only inserted once, in situ, into a disc cavity.
• In accordance with one aspect of the embodiments described herein, there are provided various material inserters than can be used to deliver any number of suitable materials to a treatment site.
• In accordance with one aspect of the embodiments described herein, there is provided a bone graft insertion tool that can be used to insert and pack bone material or paste into the disc following nucleectomy.
• With reference to FIGS.23A-D, in one embodiment, the bone graft inserter assembly (or bone growth material inserter)600 comprises apacking instrument602 and adelivery cannula604, as shown inFIGS. 23C and 23D.
• Referring toFIG. 23C, the packing instrument orpacker602 comprises arod610 that extends between adistal end612 and aproximal end614. In one embodiment, the rod is made from stainless steel or the like. Therod610 is configured to be inserted into a central lumen extending through thedelivery cannula604. In one embodiment, therod610 has a diameter of about 0.156″.
• Thepacker602 comprises an impactor mass such as a ball or handle616 which may be attached to theproximal end614. In one embodiment, theimpactor ball616 is press fit to theproximal end614. Theball616 is preferably solid and may be formed from a polymeric material, such as, for example, an acetal copolymer. In one embodiment, theball616 comprises a bore or aperture for receiving theproximal end614 of therod610. In one embodiment, this bore is about 0.15″ in diameter and about 0.50″ deep. In one embodiment, the diameter of the ball is about 1.00″.
• The illustratedpacker602 comprises abushing618 attached to thedistal end612. In one embodiment, thebushing618 is press fit to thedistal end612. Thebushing618 may be a solid cylindrical structure and formed from a known suitable polymeric material. In one embodiment, the O.D. of thebushing618 is about 0.29″.
• In one embodiment, thebushing618 comprises one or more O-rings619 which provides a tight sliding fit between thebushing618 and the inside wall of the central lumen extending through thedelivery cannula604, enabling insertion of bone growth facilitation materials which are less viscous, e.g., paste or liquid.
• Referring toFIG. 23D, thedelivery cannula604 comprises atube620 that extends between adistal end622 and aproximal end624. In one embodiment, thetube620 is machined from stainless steel tubing with an O.D. of about 0.31″ and an I.D. of about 0.30″.
• Thedistal end622 of thecannula604 comprises atip626 that is preferably beveled at an angle to facilitate directional control of material as it is delivered into the treatment site, such as, for example, a disc space. In one embodiment, thetip626 is beveled at an angle of approximately 45 degrees relative to the longitudinal axis of thecannula604.
• Theproximal end624 of thecannula604 comprises afunnel628. In one embodiment, the distal portion of thefunnel628 has an I.D. of about 0.30″. The funnel increases in diameter toward its proximal end. In one embodiment, thefunnel628 is engaged with thetube620 via brazing. In another embodiment thefunnel628 is engaged with thetube620 by means of press fit. In one embodiment, the overall length of thetube620 and funnel628 is about 13.00″. Thefunnel628 may be fabricated from a polymeric material such as acetal copolymer.
• In one mode of use, thecannula604 is docked or otherwise secured to the entry to the treatment site. Bone paste or osteogenic material is inserted into thecannula604 via thecannula tip626 or by means of thefunnel628. Thepacker602 is inserted into thefunnel628 and advanced distally to push bone paste out of the cannuladistal end622 and into the treatment site (e.g., a disc space). In one embodiment, as the packingrod610 is advanced distally into thecannula604, theimpactor ball616 hits thefunnel628 just as thebushing618 reaches thedistal end622 of thecannula604.
• In accordance with another aspect of the embodiments described herein,FIGS. 24A-24B illustrate abone paste inserter640 comprising a cannulatedtube642 that extends between adistal end644 and aproximal end646. Thetube642 defines aninner lumen648.
• Apreferred assembly640 also comprises a distally-located threadedportion650 that may be formed directly on thetube642 or engaged to thedistal end644 via any known suitable attachment technique. The threadedportion650 is configured to engage with the threaded proximal ends of implants (e.g., and axial fusion rod) to facilitate the delivery of bone paste into the treatment site. In another embodiment, theassembly640 lacks a threadedportion650.
• Theassembly640 also comprises a quick connect fitting such as aluer lock652 at theproximal end646. In one embodiment, theluer lock652 is a 10 gauge luer lock. Thetube642 and threadedportion650 is typically machined from stainless steel or other suitable material known in the art.
• In one mode of use, bone paste is delivered through thepaste inserter assembly640 beginning at theluer lock652, and through thetube642, and into the treatment site viadistal end644.
• In accordance with one aspect of the embodiments described herein, there is provided an allograft placement tool. With reference to FIGS.25A-C, in one embodiment, the allograft placement tool (or augmentation material inserter)950 comprises a cannulatedtube952 that extends between adistal end954 and aproximal end956, and that defines aninner lumen955.
• Thetool950 comprises anallograft delivery tip958 attached to thedistal end954 via any known suitable attachment technique, such as, for example, press-fit, adhesive material, or the like. In one embodiment, thetip958 is secured to thetube952 with one ormore pins953 positioned within one or more transverse hole(s) on thetube952 and intocorresponding apertures968 on thetip958. Thetip958 comprises a stop such as anannular flange structure970 which abuts the distal end of thetube952 and which supports the position of the allograft during insertion.
• Thetip958 comprises adistal opening960, aproximal opening962, and aninner lumen964 that is in communication with thetube lumen955. Thetip958 comprisesthreads966 or other engagement structure to engage with the allograft being inserted into the treatment site.
• It will be understood that any of the material inserters described herein can be used with any suitable material(s), depending on the particular type of treatment procedure and treatment site. For example, any one the material inserters described above (e.g., 600, 640, and 950) can be used for the delivery of augmentation materials (e.g., a hydrogel) to a treatment site (e.g., a disc space), thereby making the material inserter an augmentation material inserter.
• In accordance with one aspect of the embodiments described herein, there is provided an exchange system providing a protected portal to the treatment site (e.g., the sacrum) for the insertion of instrumentation or implants having O.D. dimensions (e.g., greater than about 0.35″) that are too large to be accommodated through the working and docking portal provided by the large dilator sheath (e.g.,sheath220 described above).
• With reference toFIGS. 26-27 and28A-B, in one embodiment, the exchange system assembly comprises anexchange bushing702 and anexchange cannula704.
• The shapedexchange bushing702 extends between adistal end710 and aproximal end712. The elongate, cannulatedexchange bushing702 is shaped and tapered toward itsdistal end710. In one embodiment, thebushing702 is cannulated with a central lumen having an inner diameter of about 0.14″ (i.e., slightly larger than a diameter of a typical guide pin). In one embodiment, the length of thebushing702 is approximately 14.00″.
• Bushing702 has a taperedtip714 at itsdistal end710. In one embodiment, the taperedtip714 starts at the inner diameter of thebushing702 and continues at approximately an 18 degree angle for about 0.5″ after which the taper cuts sharply back (i.e., flares out) towards the center of thebushing702 and begins the taper again at about an 18 degree angle out to the outer diameter of thebushing702. This creates an annular recess region in which theexchange fingers724 of thecannula704 can nest, thereby providing a protected profile during delivery (i.e., thebushing702 protects the exchange fingers724) SeeFIG. 27. Delivery may be accomplished over an extended guide pin.
• In one embodiment, theexchange bushing702 comprises a polymeric material, such as an acetal copolymer or the like. In another embodiment theexchange bushing702 is fabricated from a metal or metal alloy, e.g., stainless steel. Theexchange bushing702 can be either machined or injection molded.
• With reference to the embodiments inFIGS. 27 and 28A-B, there is provided an exchange system that comprises a “fingered”exchange cannula704, which works in combination with thebushing702. Theexchange cannula704 extends between adistal end720 and aproximal end722 and defines aninner lumen728.
• Theexchange cannula704 comprises a plurality of distally extending “fingers”724 at thedistal end720 that are generally triangular in shape.FIG. 28A shows theexchange cannula704 in the “open” position with itsfingers724 extended radially outward compared to the “closed” position.FIG. 28B shows theexchange cannula704 in the “closed” or insertion position with itsfingers724 congregated about a central axis, thereby forming a conical tip726. The conical tip726 is designed to enter the sacral bore, and to hold dilation and position intact during subsequent deployment of instrumentation or implants.
• In one embodiment, theexchange cannula704 is formed from polymeric tubing (e.g., such as acetal copolymer) In one embodiment, thecannula704 is about 8.00″ in length, and comprises from 3 to 8 “fingers”724 at thedistal end720 that are approximately triangular in shape. Here, thefingers724 are approximately 1.00″ in length and configured so as to collapse towards the longitudinal axis of the cannula at approximately a 30 degree angle.
• In one mode of use, theexchange cannula704 is seated on the outside of the shapedexchange bushing702 during insertion into the sacrum following removal of the large dilator sheath220 (i.e., working cannula that was used for cutting and extraction). Once the shapedexchange bushing702 is seated in the sacrum, theexchange cannula704 is advanced distally and into place. Thefingers724 of theexchange cannula704 slip into the hole or entry point leading to the treatment site, and the shapedexchange bushing702 is withdrawn enabling the insertion of subsequent instrumentation or other devices and implants through thelumen728 of theexchange cannula704 and into the treatment site. In one approach, the subsequent instruments can optionally be advanced through thecannula704 in combination with a guide pin.
• With reference to FIGS.29A-B, the largest O.D. of the to-be-deployed device800 (i.e., the O.D. toward the proximal end of the device800) exceeds that of thedilator sheath220 and that of theexchange cannula704 while in its “closed” configuration. Thedevice800 is subsequently delivered to the treatment site by radially outwardly displacing thefingers724 of theexchange cannula704 to create a pathway that has a diameter large enough to accommodate the passage of thedevice800, while isolating the working channel from adjacent organs or anatomical structures.
• In accordance with another aspect of the embodiments described herein, there is provided an exchange system that provides a protected a portal to a treatment site, and that comprises an exchange bushing and an exchange tube. With reference to FIGS.30A-C, in one embodiment, there is providedexchange system assembly730 comprising anexchange bushing732 and anexchange cannula734.
• Theexchange bushing732 comprises atube740 that extends between adistal end742 and aproximal end744, and defines aninner lumen741. The bushingdistal end742 is typically beveled at an angle of about 20° to about 70°, often about 30° to about 60°. In one embodiment, the distal end is beveled at an angle of about 45°. The outside diameter may also be tapered to a reduced diameter at thedistal end742 to facilitate advance through the tissue tract.
• Thebushing732 is typically machined or injection molded from stainless steel, delrin etc. or any other known suitable material.
• Theexchange cannula734 comprises atube750 that extends between adistal end752 and aproximal end754, and defining aninner lumen751. The tubedistal end752 is typically beveled at an angle of about 20° to about 70°, often about 30° to about 60°. In one embodiment, thedistal end752 is beveled at an angle of about 45°.
• Theexchange cannula734 is typically formed from stainless steel, or from a suitable polymer, such as acetal copolymer, or the like.
• With reference to theexchange assembly730 shown inFIG. 30A, the distal portion of theexchange bushing732 protrudes fromdistal end752 of theexchange tube734. In one mode of use, thebushing732 is distally advanced into the sacrum over thedilator sheath220 described above. Once thebushing732 is advanced over thesheath200 and seated on the sacrum, theexchange cannula734 is distally advanced over thebushing732 and into place. Thebushing732 is then withdrawn over thedilator sheath220, which is then also removed, enabling the insertion of subsequent instruments, devices, or implants through thelumen751 of thetube734. In one embodiment, the subsequent instruments, devices, or implants are advanced through thelumen751 over a guidewire. In another embodiment, the subsequent instruments, devices, or implants are advanced through thelumen751 without the aid of a guidewire.
• With reference to FIGS.30D-E, in a preferred embodiment, theexchange system730′ comprises abushing732 and anexchange cannula734′. Theexchange cannula734′ comprises a handle such as anannular band756 at theproximal end754′. Theannular band756 or other aspect ofproximal end744 comprises one or more indicium such as lines, pins ornotches768,769, as orientation indicators to show the rotational alignment of the bevel of thedistal end752′ of theexchange cannula734′.
• In accordance with one aspect of the embodiments described herein, there is provided a temporary distraction device for separating adjacent vertebral bodies. In one mode of use, the temporary distraction tool is used for preparation of a disc space for receipt of augmentation materials (e.g., osteogenic materials, or annulus repair or sealant materials). In another mode of use, the temporary distraction tool is used to prepare a disc space for subsequent soft fusion (e.g., osteogenic, osteoconductive, or osteoinductive procedure without a fusion rod). In another mode of use, the temporary distraction tool is used to accommodate subsequent implantation of fusion or motion preservation devices. Background information on distraction devices in general appears in co-pending U.S. patent application Ser. No. 10/309,416, filed on Dec. 3, 2002, the content of which is incorporated in its entirety into this disclosure by reference.
• In an application where only temporary distraction is desired, a temporary distraction device should be able to cause a separation of the adjacent vertebral bodies, and thereafter be removed without causing compression of the intervening disc. This is accomplished in accordance with the present invention by providing a temporary distraction working tip on a temporary distraction tool which is similar to thedistraction implant800 previously described. However, by providing the device in two pieces as described below, the structure may be utilized to achieve distraction by rotation in a first direction, and the device may thereafter be removed from the patient without causing compression.
• In accordance with one aspect of the embodiments described herein, there is provided a two-piece temporary distraction device for achieving separation of adjacent vertebral bodies, while permitting removal of the device without recompressing the intervening disc space. In one embodiment, shown in FIGS.31,32A-B and33A-E, the two-piecetemporary distraction device860 comprises adistal piece862 and aproximal piece864.
• The distal andproximal pieces862 and864 comprise screwexternal threads863 and865, respectively. The thread pitches of theexternal threads863 and865 are chosen to achieve the desired or targeted level of distraction, as explained in further detail in co-pending and commonly assigned U.S. patent application Ser. No. 10/309,416 filed on Dec. 3, 2002, which is incorporated herein in its entirety by reference.
• With reference to FIGS.33A-B, thedistal piece862 extends between adistal end872 and aproximal end874 and hasexternal threading863 along at least a portion of its longitudinal axis. Theproximal end874 of thedistal piece862 comprises an externalnon-threaded segment875. In the present embodiment,non-threaded segment875 comprises the male portion of a lap joint that engagesfemale portion885 ofproximal piece864, as described in further detail below.
• Theexternal threading863 typically has a pitch of about 10 to about 16 threads per inch, often about 10 to about 14 threads per inch. Theexternal threading863 typically has a major diameter of about 0.350″ to about 0.550″, often about 0.400″ to about 0.500″. Theexternal threading863 typically has a minor diameter of about 0.230″ to about 0.490″, often about 0.280″ to about 0.380″. In one embodiment, theexternal threading863 ondistal piece862 extends about 1.00″ along the longitudinal axis of thedistal piece862.
• Thedistal piece862 comprises acavity877 defined by aninternal unthreaded segment878 and an internal threaded segment879. The dimensions ofsegments878 and879 are chosen to facilitate temporary engagement with theinsertion tip900 of theinsertion assembly901, as well as temporary engagement with theextraction tip920 of theextraction assembly921, as described in further detail below.
• Internal segment878 is typically non-circular in cross-section. For example, in the present embodiment, thesegment878 comprises a rectangular cross-section. In another embodiment, not illustrated, thesegment878 comprises a hexagonal or other polygon or non circular cross-section. In general, cross-sectional shape of thesegment878 is complementary to the shape or geometry ofsegment910 of theinsertion tip900 of theinsertion assembly901, described in further detail below, to allow torque transmission from theinsertion assembly901 to thedistal piece862.
• Internal threaded segment879 comprises internal threading880 that is complementary toexternal threading930 on theextraction tip920 of theextraction assembly921, described in further detail below. The portion of thecavity877 defined by the segment879 typically has a larger diameter than that defined by thesegment878.
• The length of thedistal piece862 is typically in the range of about 0.5″ to about 2.00″, often about 1.00″ to about 1.25″. In one exemplary embodiment, the length of thedistal piece862 is approximately 1.125″.
• The actual dimensions (e.g, length, inner diameter, outer diameter, etc.) of thedistal piece862,proximal piece864,device860, etc. described herein will depend in part on the nature of the treatment procedure and the physical characteristics of the patient, as well as the construction materials and intended functionality, as will be apparent to those of skill in the art.
• With reference to FIGS.33C-E, theproximal piece864 extends between adistal end882 and aproximal end884 and hasexternal threading865 along a portion of its longitudinal axis. Thedistal end882 of theproximal piece864 comprises an internalnon-threaded segment885 In the present embodiment,non-threaded segment885 comprises the female portion of a lap joint that engagesmale portion875 ofdistal piece862.
• Theproximal piece864 comprises acavity887 defined byinternal unthreaded segment888 and internal threaded segment889. The dimensions ofsegments888 and889 are chosen to facilitate temporary engagement with theinsertion tip900 of theinsertion assembly901, as well as temporary engagement with theextraction tip920 of theextraction assembly921, as described in further detail below.
• As withinternal segment878 described above,internal segment888 is typically non-circular in cross-section. For example, in the present embodiment, thesegment888 comprises a polygon such as a rectangular cross-section. The cross-sectional shape of thesegment888 is complementary to the cross-sectional shape ofsegment910 of theinsertion tip900 of theinsertion assembly901.
• As with internal threaded segment879 described above, internal threaded segment889 comprises internal threading890 that is complementary to theexternal threading930 on theextraction tip920 of theextraction assembly921. The portion of thecavity887 defined by the segment889 typically has a larger diameter than that defined by thesegment888.
• The length of theproximal piece864 is typically in the range of about 0.5″ to about 1.75″, often about 0.75″ to about 1.25″. In one exemplary embodiment, the length of theproximal piece864 is approximately 1.00″.
• The outer diameter (O.D.; i.e., the major thread diameter) of theproximal piece864 is typically in the range of about 0.40″ to about 0.70″, often about 0.5″ to about 0.6″. In one exemplary embodiment, the O.D. of theproximal piece864 is approximately 0.550″.
• The threading865 typically has a pitch of about 8 to about 12 threads per inch, often about 9 to about 11 threads per inch. The threading865 typically has a minor diameter of about 0.240″ to about 0.620″, often about 0.380″ to about 0.480″.
• In one embodiment, internal threaded segment889 has a length of about 0.375″ along the longitudinal axis. In one embodiment, theinternal unthreaded segment888 has a length of about 0.625″ along the longitudinal axis.
• In one embodiment, thedistal piece862 andproximal piece864 of thetemporary distraction device860 are positioned relative to each other by engaging the male portion of lap joint875 with thefemale portion885.
• The length of the assembleddevice860 is typically in the range of about 1.50″ to about 2.50″, often about 1.90″ to about 2.10″. In one exemplary embodiment, the length of thedevice860 is approximately 2.00″.
• The distal andproximal pieces862,864 are typically made from any known suitable material, such as, for example, stainless steel, titanium, aluminum, or the like, or composites thereof.
• In accordance with one aspect of the embodiments described herein, there is provided an insertion assembly for delivering a two-piece temporary distraction device into the treatment site.
• In one embodiment, shown in FIGS.32A and34A-C, theassembly901 comprises a two-piecetemporary distraction device860, aninsertion tip900, and adriver tool855.
• With reference to FIGS.34A-C, theinsertion tip900 extends between adistal end902 and aproximal end904 and comprises a distally-locatedsegment910 that is designed to releasably engage withinternal segments878 and888 of the two-piece device860. In the present exemplary embodiment, thesegment910 comprises a rectangular structure. In another embodiment, not illustrated, thesegment910 comprises a hexagonal, or other noncircular longitudinally extending structure.
• Theinsertion tip900 comprises a proximally-locatedsegment915 that is shaped and dimensioned to engage with thedriver tool855, described in further detail below. In the present exemplary embodiment, thesegment915 comprises a hexagonal cross-section. In another embodiment, thesegment915 comprises an octagonal or other non-circular longitudinally extending structure.
• Theinsertion tip900 may also be provided with one or more attachment structures such as holes or recesses917 positioned to align with corresponding structure such as hole(s)859 of thedriver tool855 to receive one or more screws orpins854 to secure thetip900 into thedriver tool855.
• The length of thesegment910, is typically in the range of about 0.50″ to about 1.50″, often about 0.90″ to about 1.10″. In one exemplary embodiment, the length of theinsertion tip900 is approximately 1.00″.
• Theinsertion tip900 is typically made from any known suitable material, such as, for example, stainless steel (e.g., 17-4 alloy), titanium, or the like, or composites thereof.
• With reference toFIGS. 31, 32A and34A-C, thedriver tool855 comprises ashaft899 that extends between a distal end856 and aproximal end857. Thetool855 comprises a proximally-locatedhandle858 and one or more distally-locatedholes859 positioned to align with the hole(s)917 of the insertion tip900 (described above) or the extraction tip920 (described below), and to receive one or more screws orpins854 to securetips900 or920 into thetool855.
• The distal end856 of thedriver tool855 comprises anaperture850 for receiving the proximally-locatedsegments915 and935 of thetips900 and920, respectively. In general, the cross-sectional shape and longitudinal length of theaperture850 is complementary to that ofsegments915 and935. For example, in the illustrated embodiment, both theaperture850 andsegments915 and935 comprise a hexagonal cross-section and have a length of about 0.375″.
• The overall length of thedriver tool855 is typically in the range of about 12.00″ to about 16.00″, often about 13.00″ to about 15.00″. In one exemplary embodiment, the length of thedriver tool855 is approximately 14.00″.
• The outer diameter (O.D.) of thedriver tool855 is typically in the range of about 0.25″ to about 0.50″, often about 0.35″ to about 0.40″. In one exemplary embodiment, the O.D. of thedriver tool855 is approximately 0.375″.
• Thedriver tool855 and its component parts are typically made from any known suitable material, such as, for example, stainless steel, titanium, aluminum, or the like, or composites thereof. Thehandle858 is typically welded over theproximal end857 of thetool855.
• In accordance with one aspect of the embodiments described herein, there is provided an extraction assembly for removing a temporary distraction device without causing compression across the intervening disc space.
• In one embodiment, shown in FIGS.32B and35A-C, theassembly921 comprises a two-piecetemporary distraction device860, anextraction tip920, and adriver tool855.
• With reference to FIGS.35A-C, in one embodiment, theextraction tip920 extends between adistal end922 and aproximal end924 and comprises a distally-located threadedsegment931 that is designed to releasably engage with the receiving segments879 and889 of thedistal piece862 andproximal piece864, respectively of thedistraction device860.
• In one embodiment, the distally-located threadedsegment931 of theextraction tip920 comprises left-handedexternal threads930 that complement left-handed internal threads880 and890 of the receiving segments879 and889, respectively. The left-handedness of thethreads880,890,930 make it possible to rotate theextraction tool assembly921 in a counter-clockwise direction, to engage eachpiece862 andpiece864, and remove or extract each of them sequentially, proximal864 first, from the treatment site while rotating theassembly921 in the counter-clockwise direction to unscrew each of the pieces of thedistraction device860 from the bone.
• Theextraction tip920 comprises a proximally-located attachment surface onsegment935 that is shaped and dimensioned to releasably engage with a corresponding surface ondriver tool855. In the present exemplary embodiment, thesegment935 comprises a hexagonal cross-section. In another embodiment, not illustrated, thesegment935 comprises an octagonal cross-section or other non-circular longitudinally extending structure.
• Theextraction tip920 also comprises a releasable engagement structure such as one ormore holes937 positioned to align with hole(s)859 of thedriver tool855 and receive one or more screws orpins854 to secure thetip920 into thedriver tool855. Preferably, the components of the system are configured such that thesame driver tool855 can be used to extract both theproximal piece864 anddistal piece862 from the treatment site.
• The length of theextraction tip920 is typically in the range of about 0.50° to about 1.50″, often about 0.90″ to about 1.10″. In one exemplary embodiment, the length of theextraction tip920 is approximately 1.00″. Theextraction tip920 is typically made from any known suitable material, such as, for example, stainless steel, titanium, or the like, or composites thereof.
• In accordance with one aspect of the modes of use described herein, there are provided methods of using a two-piece distraction device to temporarily separate two or more vertebral bodies in the spine.
• In one mode of use, for a two vertebral body application, the two-piecetemporary distraction device860 is introduced into the treatment site by advancingsegment910 of theinsertion tip900 coaxially into engagement withinternal segments878 and888 of thedevice860, and then rotating thedevice860 into an axial bore as described elsewhere herein, under force applied generally distally. In one typical application, thedevice860 is used to cause the separation of two adjacent vertebral bodies along the AAIIL. Thedevice860 is advanced through a caudal, proximal vertebral body, through an intervertebral disc, and into a cephalad, distal vertebral body, thereby causing distraction of the cephalad and caudal vertebral bodies, relative to each other. Rotation is continued until the desired degree of distraction has been achieved, as may be evaluated using conventional imaging technology. Over distraction can be corrected by rotating thedistraction device860 in an opposite direction.
• Once the desired distraction has been achieved, thedevice860 may be removed from the treatment site piece-by-piece by sequentially removing theproximal piece864 and thedistal piece862 in a proximal direction. Following proximal retraction of the insertion tool,segment931 of theextraction tip920 is distally advanced to and rotatably engaged with the internal segment889 of theproximal piece864, and then rotated in a predetermined direction to cause disengaged of theproximal piece864 from thedistal piece862, and thereby facilitating removal of theproximal piece864 from the treatment site. Thesegment931 is then readvanced distally through the access bore and engaged with the internal segment879 of thedistal piece862, and then rotated in a predetermined direction to cause of thedistal piece862 to be extracted from the treatment site.
• In one mode of use, the above-described two-piece device860 andassemblies901 and921 are used to achieve temporary distraction (i.e., restoration of disc height) in preparation for implantation of either a fusion or a mobility restoration or preservation device as noted above. In one approach, distraction is maintained following removal of thedistraction device860 and before implantation of the therapeutic implant by having the patient lie in a prone or flat position on a horizontal surface, thereby relieving the patient's spine of axial compressive forces resulting from load bearing, motion, and the effects of gravity. In a fusion application, an implantable distraction device or other fusion implant may be supplemented by subsequent posterior insertion of facet or pedicle screws.
• Various combinations of the tools and devices described above may be provided in the form of kits, so that all of the tools desirable for performing a particular procedure will be available in a single package. Kits in accordance with the present invention may include access kits, such as for achieving percutaneous access to the sacrum, and access kits for achieving soft tissue access to the sacrum and access through the sacrum into the desired treatment zone. Kits may also be provided with the tools necessary for disc preparation. Further kits may be provided with temporary distraction and/or insertion tools for insertion of implants.
• Access kits may include all or any sub-combination of the following components, which have been described previously herein: one or more guide pin introducers, stylet, guide pin, guide pin handle, and guide pin extension. Each of these components may be either reusable or disposable. The access kit may additionally include one or more dilators, such as a 6 mm dilator and 8 mm dilator, and a 10 mm dilator with sheath. In one implementation of the kit, each of the dilators is reusable, and the sheath is disposable. The access kit may additionally include twist drills, such as a 6 mm, 7.5 mm and 9 mm drills which may be reusable.
• Disc preparation kits may differ, depending upon whether the procedure is intended to be one level or multi-level. The disc preparation kit may include a plurality of cutters. In a single level kit, anywhere from 3 to 7 cutters and, in one embodiment, 5 cutters are provided. In a two level kit, anywhere from 5 to 14 cutters may be provided, and, in one embodiment, 10 cutters are provided. All of the cutters may be one time use disposable.
• The disc preparation kit may additionally include one or more tissue extraction tools, for removing fragments of the nucleus. In a one level kit, 3 to 8 tissue extraction tools, and, in one embodiment, 6 tissue extraction tools are provided. In a two level disc preparation kit, anywhere from about to 8 to about 14 tissue extraction tools, and, in one embodiment, 12 tissue extraction tools are provided. The tissue extraction tools may be disposable.
• The disc preparation kit may additionally include a bone graft inserter, which may be disposable.
• An allograft kit may be provided including, in addition to the tools in the access and disc preparation kits, an allograft inserter tool and a temporary distraction tool. A selection of twist drills may be provided, such as a 9.5 mm, 10 mm, 10.5 mm, 111 mm or 11.5 mm twist drill, depending upon the size of the desired graft. The allograft kit may additionally include an exchange system, including a cannula and bushing, as have been described previously herein.
• A fusion kit intended for a one level fusion may include, in addition to the tools in the access and disc preparation with bone graft inserter kits a one piece fusion rod, a rod driver, and a paste inserter. The fusion kit may additionally include a plug, a plug driver, and one or more twist drills such as a 7.5 mm and a 6 mm. The fusion kit will additionally include an exchange system as has been discussed. The rod driver and twist drills may be reusable.
• In an alternate fusion kit, intended for two-level fusion, the kit may include one, two-pieces fusion rods, or one, one-piece fusion rod and one mobility implant, or a two-piece implant, one of which is a fusion implant and one of which is a mobility device The fusion kit additionally includes a rod driver, a paste inserter, one proximal and one distal plugs and two plug drivers. The fusion kit may additionally include one or more twist drills, such as a 7.5 mm and a 6 mm twist drill. The fusion kit will additionally include an exchange system.
• Although the present invention has been described in terms of certain preferred structures and embodiments, variations on the foregoing will become apparent to those of skill in art in view of the disclosure herein, and are considered to be within the scope of the present invention. Accordingly, the present invention is not intended to be limited by any of the forgoing disclosure, and is instead intended to extend to the full scope of the following claims.

Claims (7)

1. A mobility kit, comprising:

an access tool, for providing access to a treatment site;

a cutter for disrupting material in the treatment site;

a tissue extraction tool, for removing disrupted material from the treatment site; and

a mobility device, for spanning at least a portion of the treatment site and enabling motion across the treatment site.

2. A mobility kit as inclaim 1, further comprising an augmentation material inserter.

3. A mobility kit as inclaim 1, further comprising a driver tool for delivering the mobility device to the treatment site.

4. A mobility kit as inclaim 3, wherein at least a portion of the driver tool comprises a hexagonal cross section.

5. A mobility kit as inclaim 1, wherein the treatment site comprises a disc.

6. A mobility kit as inclaim 1, wherein the treatment site comprises an intervertebral space.

7. A mobility kit as inclaim 1, wherein the mobility device comprises a motion preservation device.

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