US20060036324A1 - Adjustable spinal implant device and method - Google Patents

Abstract

A spine implant, in particular a stabilization or distraction device, is provided with an adjustable length.

Description

RELATED APPLICATION DATA
• The present application claims the priority of Provisional Application No. 60/598,882, filed Aug. 3, 2004 and entitled: Spine Treatment Devices and Methods.
FIELD OF THE INVENTION
• The invention relates to devices to treat the spine, including but not limited to spinal stabilization devices, dynamic stabilizers, spinal deformity correction devices, devices to treat pain associated with the spine, and other spinal treatment devices.
BACKGROUND
• Certain spine conditions, defects, deformities (e.g., scoliosis) as well as injuries may lead to structural instabilities, nerve or spinal cord damage, pain or other manifestations. Back pain (e.g., pain associated with the spinal column or mechanical back pain) may be caused by structural defects, by injuries or over the course of time from the aging process. For example, back pain is frequently caused by repetitive and/or high stress loads on or increased motion around certain boney or soft tissue structures. The natural course of aging leads to degeneration of the disc, loss of disc height, and instability of the spine among other structural manifestations at or around the spine. With disc degeneration, the posterior elements of the spine bear increased loads with disc height loss, and subsequently attempt to compensate with the formation of osteophytes and thickening of various stabilizing spinal ligaments. The facet joints may develop pain due to arthritic changes caused by increased loads. Furthermore, osteophytes in the neural foramina and thickening of spinal ligaments can lead to spinal stenosis, or impingement of nerve roots in the spinal canal or neural foramina. Scoliosis may also create disproportionate loading on various elements of the spine and may require correction, stabilization or fusion.
• Pain caused by abnormal motion of the spine has long been treated by fixation of the motion segment. Spinal fusion is one way of stabilizing the spine to reduce pain. In general, it is believed that anterior interbody or posterior fusion prevents movement between one or more joints where pain is occurring from irritating motion. Fusion typically involves removal of the native disc, packing bone graft material into the resulting intervertebral space, and anterior stabilization, e.g., with intervertebral fusion cages or posterior stabilization, e.g., supporting the spinal column with internal fixation devices such as rods and screws. Internal fixation is typically an adjunct to attain intervertebral fusion. Many types of spine implants are available for performing spinal fixation, including the Harrington hook and rod, pedicle screws and rods, interbody fusion cages, and sublaminar wires.
• Spinal stenosis pain or from impingement of nerve roots in the neural foramina has been treated by laminectomy and foraminotomy, and sometimes reinforced with rod and screw fixation of the posterior spine. More recently, surgeons have attempted to relieve spinal stenosis by distracting adjacent spinous processes with a wedge implant. Pain due to instability of the spine has also been treated with dynamic stabilization of the posterior spine, using elastic bands that connect pedicles of adjacent vertebrae.
• The typical techniques for fusion, distraction, decompression, and dynamic stabilization require open surgical procedures with removal of stabilizing muscles from the spinal column, leading to pain, blood loss, and prolonged recovery periods after surgery due in part to the disruption of associated body structures or tissue during the procedures.
• To reduce the invasiveness of fusion procedures, some methods of fusion have been proposed that do not require the extensive stripping of muscles away from the spinal column of earlier approaches. These involve posteriorly or laterally accessing the spine and creating spaces adjacent the spine for posterior stabilization. Some of these procedures include fusion via small working channels, created with dilator type devices or an external guide to create a trajectory channel between two ipsilateral neighboring pedicle screws. Also, placing support structures between adjacent pedicle screws and across a joint requires accessing and working in an area from a difficult angle (the support structure is typically oriented somewhat perpendicular to an angle of access and through muscle and connective tissue). Furthermore, these stabilization devices typically involve the use of 4 pedicle screws (each having a risk associated with it when placed in the spine), two on each side of a motion segment, and are not ideally suited for percutaneous stabilization required across more than one or two segments. Accordingly, it would be desirable to provide a less invasive or less disruptive segmental spine stabilization procedure and implant that has a reduced risk of damage or injury to associated tissue. It would also be desirable to provide an implanted posterior spine system that may be used to stabilize more than two motion segments in a less disruptive or less invasive manner.
• One method of fusing a vertebra has been proposed using bilateral screws through the lamina using a posterior approach. However, geometric placement of the device is difficult and the procedure is considered dangerous because the laminar screws could enter through anteriorly into the spinal canal and cause nerve damage.
• Accordingly, it would be desirable to provide a device that reduces the difficulties risks of the current procedures. It would also be desirable to provide a device that can be placed in a less disruptive or less invasive manner than commonly used procedures.
• Unintended consequences of fixation include stress shielding of bone, as well as transfer of load to adjacent, still dynamic motion segments, and eventual degeneration of adjacent motion segments. Flexible stabilization of motion segments with plastic, rubber, super-elastic metals, fabric, and other elastic materials has been proposed to provide a degree of dynamic stabilization of some joints. Many of these constructs are not load bearing. Dynamic stabilization from pedicle screw to pedicle screw along the length of the spine has been proposed. However, this device has the disadvantage of requiring placement of 4 pedicle screws and associated tissue disruption.
• Due to the risks, inconvenience, and recovery time required for surgical implantation of spinal devices, some patients may continue to prefer rigid fixation of a painful or degenerative motion segment over dynamic stabilization of the joint. In addition, doctors may be reluctant to recommend dynamic stabilization for patients with back pain, because it may not alleviate pain to a patient's satisfaction.
• Furthermore, even in patients who experience good relief of pain with dynamic stabilizers, it is anticipated that while the onset of arthritic changes may be deferred, many patients will still eventually proceed to develop degeneration, and require fixation of the motion segment to obtain pain relief. Repeat spine procedures to remove one implant and replace it with another are associated with complications related to bleeding, surgical adhesions, destruction of bone, and other generic risks associated with surgical procedures. Accordingly, improved devices that address these issues would be desirable.
• A number of spinal deformities exist where the spine is abnormally twisted and or curved. Scoliosis is typically considered an abnormal lateral curvature of the vertebral column.
• Correction of scoliosis has been attempted a number of ways. Typically correction is followed by fusion. A Harrington rod has been used where a compressing or distracting rod is attached above and below a curved arch of the deformity. The spine is stretched longitudinally to straighten the spine as the rod is lengthened. The spine is then fused. The correction force in this device and in similar devices is a distraction force that may have several drawbacks including possible spinal cord damage, as well as the high loading on the upper and lower attachment sites. Nowadays, segmental hook and screw fixation exists for distraction and derotation corrective forces.
• A Luque device has been used where the spine is wired to a rod at multiple fixation points along the rod and pulls the spine to the rod. The spine is pulled to the rod with a wire and the spine is then fused. This does not provide significant adjustment over time and requires fusion. Once completed this does not provide an opportunity for delayed adjustment over time. Anterior procedures also exist in the form of fusion and newer technology involving staples across the disc space that obviate the need for fusion but still correct the deformity. The corrective force is derotation with or without compression.
• Accordingly it would be desirable to provide an improved corrective device for treating scoliosis or other deformities. It would also be desirable to provide a device that may be used without fusion.
• Spine surgeons commonly use metallic or polymeric implants to effect or augment the biomechanics of the spine. The implants frequently are attached or anchored to bone of the spine. Sites typically considered appropriate for boney attachment have high density or surface area, such as, for example, the pedicle bone, the vertebral body or the cortical bone of the lamina. The spinous process contains thin walls of cortical bone, and thus, has been considered as not ideal for anchoring spinal implants as they may not support the implants under physiologic loads, or the intermittent high loads seen in traumatic situations. Fixation has been attempted from spinous process to spinous process with poor results.
• A translaminar facet screw as used by some surgeons goes through the base of spinous process to access the cancellous bone of the lamina. A disadvantage of this device is that it is not suitable for attaching to a pedicle screw and the depth and angle during deployment can be very difficult to track or visualize, thus increasing the possibility that the screw would extend into the spinal canal. A facet screw is screwed between opposing facets of a zygapophyseal joint.
SUMMARY
• One aspect of the present invention is directed to providing a device and method for alleviating discomfort and or deformity associated with the spinal column. Another aspect of the present invention is directed to providing a minimally invasive implant and method for alleviating discomfort associated with the spinal column. Another aspect of the present invention provides an anchoring device and method that requires less surrounding tissue damage or disruption. Another aspect of the present invention provides reinforcement of the spinous process for use in various spinal systems. Another aspect of the invention provides a minimally invasive, non-invasive, or remote adjustment or lengthening of an orthopedic device. Another aspect of the invention provides a minimally invasive, non-invasive, or remote adjustment, lengthening or shortening of a stabilization device. Another aspect of the present invention also provides an implant system and device suitable for minimally invasive, minimally disruptive and/or percutaneous posterior deployment across a plurality of motion segments and more than two motion segments. Different aspects of the invention may provide distraction forces to relieve pressure on certain structures, compression forces to fix or stabilize motion across structures, shock absorbing qualities to help relieve load from certain structures, and therapeutic activity to reduce inflammation and pain. Other aspects of the invention may supplement or bear load for degenerated, painful, or surgically removed joints, e.g., the facet joint. Another aspect of the invention may provide a method and system for treating deformities such as scoliosis. Other aspects of the invention may include sensors associated with implants or implanted at or near the bones, soft tissue, or joints of the spine and may provide feedback regarding the joint on an ongoing basis. The sensors may also be part of a feedback system that alters a property of an implant in response to sensing information. Another aspect of the invention may provide a device or method for delivering therapeutic substances at or near the spine.
• In accordance with one aspect of the invention, a reinforcement structure is provided for supporting the spinous process and if desired, in addition, the lamina of a spine. The invention further provides a method and system for forming or implanting such structure in the spinous process or a region of cancellous bone in the lamina of a spine. The reinforcement system may include one or more systems of reinforcement and may be used before, during and/or after a spinal device (e.g. a stabilization, distraction or prosthetic device, etc.) is coupled to the spinous process.
• Various aspects of the invention are set forth in the description and/or claims herein.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1A is a lateral posterior view of a vertebra with a reinforcement structure in accordance with the invention.
• FIG. 1B is a side view of the vertebra and reinforcement structure ofFIG. 1A.
• FIG. 2A is a lateral posterior view of a vertebra with a reinforcement structure in accordance with the invention.
• FIG. 2B is a side view of the vertebra and reinforcement structure ofFIG. 2B.
• FIG. 3A is a lateral posterior view of a vertebra with a reinforcement structure in accordance with the invention.
• FIG. 3B is a side view of the vertebra and reinforcement structure ofFIG. 3A.
• FIG. 4A is a lateral posterior view of vertebrae with a reinforcement structure and implant in accordance with the invention.
• FIG. 4B is a side view of the reinforcement structure and implant ofFIG. 4A.
• FIG. 4C is a top view of a reinforcement structure and implant in accordance with the invention.
• FIG. 4D is a posterior view of the reinforcement structure and implant ofFIG. 4C.
• FIG. 5 is a posterior view of a reinforcement structure and implant in accordance with the invention.
• FIG. 6 is a posterior view of a reinforcement structure and implant in accordance with the inventionFIG. 7A is a top view of an implant implanted adjacent a motion segment in accordance with the invention.
• FIG. 7B is a posterior view of the implant as shown inFIG. 7A.
• FIG. 8A is a top view of an implant implanted through the lamina and the zygapophyseal joint in accordance with the invention.
• FIG. 8B is a posterior view of the implant as shown inFIG. 8A.
• FIG. 9A is a top view of a dynamic implant in accordance with the invention.
• FIG. 9B is a posterior view of the implant as shown inFIG. 9A.
• FIG. 10 is a schematic posterior portal cross sectional view of a reinforcement device and implant in accordance with the invention.
• FIG. 11 is schematic posterior partial cross sectional view of a reinforcement device and implant in accordance with the invention.
• FIG. 12A is an exploded perspective view of a reinforcement device and implant in accordance with the invention.
• FIG. 12B is a top view of the reinforcement device and implant ofFIG. 12A.
• FIG. 13A is a schematic partial cross sectional view of an implant in accordance with the invention in a first position.
• FIG. 13B is a schematic partial cross sectional view of the implant ofFIG. 13A in a second, and implanted position.
• FIG. 14A is a schematic partial cross sectional view of an implant in accordance with the invention in a first position.
• FIG. 14B is a schematic partial cross sectional view of the implant ofFIG. 14A in a second position.
• FIG. 4B is a posterior lateral perspective view of a distraction system implanted in a spine in accordance with the invention.
• FIG. 15 is a schematic side view of a connector of an implant in accordance with the invention.
• FIG. 16 is a schematic side view of a connector of an implant in accordance with the invention.
• FIG. 17 is a schematic perspective view of a connector in accordance with the invention.
• FIG. 18 is a schematic side perspective view of a dynamic element in accordance with the invention.
• FIG. 19 is a schematic side perspective view of an adjustable implant element in accordance with the invention.
• FIG. 20 is a schematic side perspective view of an adjustable implant element in accordance with the invention.
• FIG. 21 is a schematic side perspective view of an adjustable implant element in accordance with the invention.
• FIG. 22A is a schematic view of a spine deformity correction device in accordance with the invention.
• FIG. 22B is a cross section ofFIG. 22A along the lines22B-22B.
• FIG. 22C is a schematic view of an adjustable pedicle attachment device in a first position in accordance with the invention.
• FIG. 22D is a schematic view of the adjustable pedicle attachment device ofFIG. 22C in accordance with the invention.
• FIG. 22E is a schematic side partial cross sectional view of an alternative connector of the spine deformity device ofFIG. 22A.
• FIG. 22F is a schematic side partial cross-sectional view of an alternative connector of the spine deformity device ofFIG. 22A.
• FIG. 22G is a schematic side partial cross sectional view of an alternative connector of the spine deformity device ofFIG. 22A.
• FIG. 22H is a schematic side partial cross sectional view of an alternative connector of the spine deformity device ofFIG. 22A.
• FIG. 23A is a schematic side view of a spine deformity correction device in accordance with the invention.
• FIG. 23B is a posterior view.
• FIG. 24 is a schematic top view of an implant in accordance with the invention.
• FIG. 25 is a schematic posterior lateral perspective view of a therapeutic substance delivery device in accordance with the invention.
• FIG. 26 is a schematic posterior lateral perspective view of a therapeutic substance delivery device in accordance with the invention.
DETAILED DESCRIPTION
• FIGS. 1A and 1B illustrate a reinforcedposterior arch100 of afirst vertebra91 of aspine90, including aspinous process101 andlamina103. Thefirst vertebra100 of thespine90 as illustrated includes a firstspinous process101 with asuperior portion102 having aposterior ridge104 into which ahole105 is drilled. Thehole105 may be drilled with a drill, a trocar, a large bore IV needle or similar sharp object through the external and relatively hard cortical bone, to reach the internal cancellous bone within thespinous process101 and adjacent thelamina103.
• Once the cancellous bone is accessed, optionally, a tool such as a balloon tamp, or other expandable member or small crushing or drilling member is used to create acavity107 or cavities within the cancellous bone by compressing, crushing or drilling out the bone material. X-rays may be used to determine how far to drill into the bone. Thecavity107 may be in the spinous process, through to the base of the spinous process, or through the spinous process and into the lamina. In one embodiment the cavity is cone shaped or widens as it moves anteriorly towards the lamina.
• A reinforcing material is then delivered into the cancellous bone orcavity107 of thespinous process101 and/or within thelamina103. The material is selected to provide reinforcing properties to thespinous process101 and/orlamina103 sufficient to support (whether alone or in combination with other support elements) a spine support structure, a prosthesis, or other device attached to the spinous process and or supported lamina. The material may be a bone cement or polymer with strength and hardness properties selected to provide sufficient reinforcement to the region so that the spinous process may be used at least in part, to support an implant structure for attaching to and manipulating the biomechanics of the spine. Examples include but are not limited to polymers such as acrylic cement developed for use in vertebroplasty procedures. The material may be a flowable polymer material that cures within the cavity. Suitable materials may be readily selected by one of ordinary skill in the art.
• Reinforcement structures may be placed within the cavity prior to, during or after injection of flowable material for further strength properties. As illustrated, anadditional support structure106 is provided within the cavity. Thesupport structure106 may be inserted through a cannula and released to expand as a spring-like or self-expanding member, into the cavity. Thesupport structure106 provides further support of the spinous process and/or lamina. Alternatively, or additionally, one or more posts or struts may be provided within the cavity or extending out of the spinous process or lamina from the area of cancellous bone, to supplement the support of the spinous process or lamina in combination with the polymer or other curable material. The reinforcement structures may be formed of a number of different materials such as, e.g., a metal or biocompatible polymer. Such reinforcement structures may also be used in other bony areas of the spine including the vertebra, the pedicles, facets, the transverse process, etc.
• As shown inFIGS. 2A and 2B, aninferior portion109 of aspinous process108 may also be reinforced. Similarly ahole110 is drilled in the inferior portion of thespinous process108 and acavity111 is formed. Thecavity111 is similarly filled with a curable polymer and is reinforced by reinforcingelements112 positioned within the cavity.
• The reinforcement structure may be used in a number of applications including increasing the strength of healthy bone to support the load and fixation of orthopedic implants, as well as increasing the strength of bone weakened by osteoporosis, chronic steroid use, avascular necrosis, weakened by injury and cancer involving the bone. According to one aspect, the reinforcement structure comprises a material that provides sufficient strength including but not limited to suitable polymers, e.g. PEAK, titanium, steel and carbon fiber.
• The stabilizing and/or distracting devices described herein may be formed of a material that provides sufficient column strength including but not limited to suitable polymers, e.g. PEAK, titanium, steel, and carbon fiber.
• Referring toFIGS. 3A and 3B, analternative support structure120 is illustrated. Thesupport structure120 allows the anchoring of implants under physiologic loads on thespinous process101 while shielding underlying bone from loads that would normally cause the bone to fracture. (The implants may alternatively or in addition be anchored or attached to thelamina103, e.g., with addition of small screws, barbs or adhesive that engage with the lamina while avoiding injuring the spinal cord surrounded by the lamina.) Thesupport structure120 comprises a hood like element positioned over theposterior arch100, i.e., thespinous process101 andlamina103 of aspine90. Thesupport structure120 may be made of a moldable or malleable material (e.g. putty, formable ceramic, clay-like material, or a moldable polymer or malleable alloy or metal) that cures into or forms a solid, strong structure. Heat, light, catalysts, precursors, or local pressure and force, for example, may be used to make the hood moldable or firm. The support structure of filling material to support the spinous process may be constructed or formed of moldable composites that can cure into hard material such as, e.g., ground glass powder or glass fiber fillers mixed into an acrylic matrix and activated with light or other biophysical modalities. Other cements or other curable materials may be suitable as well. Thesupport structure120 further comprisesopenings121 to guide drill bits and/or for the placement of screws, reinforcement posts, or other instruments or supplemental support structures. The guide may insure accurate positioning of the implant. Thesupport structure120 may be anchored on the posterior arch by mold bending or forming the structure about the anatomy. Thesupport structure120 may be anchored into the lamina or spinous process by anchoring elements, such as, e.g., screws or barbs. Thesupport structure120 may also be anchored via screws or posts. Alternatively, thesupport structure120 could be a preformed implant with contours that fit the anatomy of theposterior arch100 or that are malleable or moldable to the anatomy. Also, the support structure20 may be anchored into thepedicles122 with screws, into the underlying bone with barbs, screws, bone anchors, or adhesives, over the edges of structures with hooks, or may be constructed of a plurality of pieces that may be assembled into one piece around the bone.Wings120aof support structure may be placed over the lamina to spread the force of any device attached to thesupport structure120
• As illustrated inFIGS. 3A and 3B, asensor120bis positioned on thesupport structure120. Thesensor120bmay be embedded in the material. The sensor may sense stress on thesupport structure120 from implants secured to it, or may sense other information that may be desirable to monitor. The sensor may include a communication element configured to communicate sensed information to an external device, e.g., when interrogated.
• Referring toFIGS. 4A-4D, asupport structure130 is illustrated positioned over aposterior portion132 of aspinous process131 withwings130aover thelamina103 includingsmall screws130bintolamina103.Wings130amay help spread the force from any devices attached or coupled to thesupport structure130. Pedicle screws135 are anchored intopedicles136 and are further anchored into thespinous process131 throughscrews134 positioned throughholes133 in thesupport structure130. As shown inFIG. 4C, thescrew134 includes asensor134athat may be used to sense loads on the device. Use of such sensors is described further herein. Thepedicle screw135 includes ascrew capture device135afor receiving a screw or rod of a spinous process screw or other rod. Thecapture device135amay be a polyaxial head of a pedicle screw it may include a hole, a threaded screw hole with a washer or cap.Cross bar135bis positioned across the spine between heads ofpedicle screws135 to prevent pedical screws from creeping laterally. A wedge shapednut134dbetween thehead134cof thescrew134 and the support structure. Anothernut134bmay be positioned betweensupport structure120 and pedicle screw, and secure against thesupport structure120. These features may be used in a similar manner in the embodiments described herein.
• FIG. 5 illustrates the spinous process screws134 coupled to aspinous process101 of afirst vertebra91 through a hood orsupport structure130 in a manner similar to that described above with respect toFIGS. 4A-4D. Thescrews134 extend bilaterally across the posterior of asecond vertebra92 and are anchored to captureelements135aofpedicle screws135 anchored intopedicles93aof athird vertebra93.
• FIG. 6 illustrates a device for stabilizing or distracting the spine withpedicle screws135 andcross bar135bpositioned as inFIG. 4D.Hood structure132 includes openings for receivingscrews132bcoupled to thehood132 on one end and to theheads135aofpedicle screws135 and on the other end. Thescrews132bdo not penetrate the spinous process. Obliquely threaded nuts secure thescrews132bagainst thehood132.
• The reinforcement or supporting devices described herein may be used in conjunction with a number of different spine devices, including, for example, the various distraction, fusing or dynamic stabilizing devices described herein. The hoods or reinforcement devices herein may also be customized, for example by using stereolithography. The hoods or reinforcement devices may be used for example with a brace. The pedicle screw may be telescoping as described with respect toFIGS. 22C and 22D.
• The devices described herein may be coupled to the spinous process using minimally invasive techniques. These techniques may include percutaneously accessing the spinous process and/or using dilators to access the spinous process at an oblique angle with respect to median plane m and/or horizontal plane h through the spine of the patient.
• FIG. 7A is a side view of a joint of the spine with a fixation device percutaneously implanted to fuse adjacent vertebrae by fixation of the facet joints.Pedicle screw146 in thepedicle143 of the adjacentvertebral members141,142. As illustrated inFIG. 7B, thepedicle screw146 has apolyaxial screw head147 for receiving aspinous process screw148 having a tapered tip. Thespinous process screw148 is screwed from the contralateral side of the spinous process, through thespinous process140 ofvertebral member141, adjacent the facet joint149 between thevertebral member141 andvertebral member142, and then captured or placed into thehead147 of thepedicle screw146.
• When implanted, the pedicle screws are positioned in the pedicles in a generally known manner. The facet joint or facet joints between the spinal members that are to be fused, are debrided and grafted. A flank stab wound is made to expose the base of the spinous process. The spinous process screw is then inserted and navigated through the wound to the spinous process and/or soft tissue. Tissue dilators or retractors may be used to facilitate insertion of the spinous process screw through soft tissue. Thespinous process screw148 is then placed through thespinous process140, and into and captured by thehead147 of thepedicle screw146. Compression across and the facet joint149 may be provided using a nut placet in the polyaxial head of the pedicle screw. Alternatively, external compression may be used prior to placement of the oblique rod of the spinous process screw. A similar screw may also be placed from thespinous process140 to the contralateral pedicle. Thespinous process140 may be reinforced prior to or after placing thescrew148.
• Referring toFIG. 8A, a similar fusion system as illustrated with respect toFIGS. 7A and 7B.Pedicle screw156 is positioned in thepedicle153 of the adjacentvertebral members151,152. Thepedicle screw156 has apolyaxial screw head157 for receiving aspinous process screw158 having a tapered tip. Thespinous process screw158 is screwed from the contralateral side of thespinous process150, through thespinous process150 ofvertebral member151, through the facet joint159 between thevertebral member151 andvertebral member152 and then into thehead157 of thepedicle screw156.
• An oblique skin stab wound is made to navigate to the base of thespinous process150, which may be exposed under direct vision. The spinous process screw158 (or other device) is then placed through thespinous process150, across (adjacent or through) the facet joint159, and into thehead157 of the pedicle screw156 (or otherwise attached to a pedicle attachment device for attaching devices to the pedicle), immobilizing the facet joint159. A similar screw may also be placed from thespinous process150 to the contralateral pedicle. The spinous process may be reinforced prior to or after placing the screw or other device. The other devices attached or coupled to the spinous process as described herein may be similarly deployed.
• The devices described herein may be coupled to the spinous process using minimally invasive techniques. These techniques may include percutaneously accessing the spinous process and/or using dilators to access the spinous process at an oblique angle with respect to median plane and/or horizontal plane through the spine of the patient.
• Referring toFIGS. 9A and 9B, a spine is illustrated with a spinal fusion system in place. Aspinous process screw168 is placed from the contralateral side of thespinous process160, through thespinous process160 of afirst vertebra161 and across the facet joint169 between thefirst vertebra161 and an adjacentsecond vertebra162, and into thepedicle164 of thesecond vertebra162.
• Another feature of the spinous process screw ofFIGS. 9A-9B is that it may be configured to exert flexible, stabilizing, nonfusion forces to the motion segment. For example, this may be used in the event that patient suffers from pain due to laxity or other dysfunction of the spinal structures (e.g. degenerative spondylolisthesis). In other words, the looseness or other dysfunction of the joint and surrounding tissue may cause pain. The present invention provides a device and method for dynamically stabilizing (or reducing) such a joint while allowing some flexibility and movement. The device and method provide such stabilization on an oblique angle with respect to the rotational axis of the spine, i.e. at an oblique angle with respect to the median and horizontal planes of the spine. The spinous process and a pedicle could also be used to anchor a device exerting a stabilizing or compression or contractile force between the two anchors on an oblique angle. Devices that may be used to exert such a contractile force may include, for example, polymeric materials, super elastic metals, and fabrics. Thespinous process screw168 includes asensor165athat may be used to sense motion of the distraction device. The forces or stresses on the device may be monitored and used to determine if it is necessary to convert the device to a fusion type device or to otherwise reduce or alter motion. The sensor may also be used as a diagnostic device to measure the amount of joint motion upon insertion of the implant or over time.
• The system illustrated inFIGS. 9A and 9B may also be used for the treatment of spondylolysis, to attain stability across the pars interarticularis.
• The spinous processes140,150,160 may be reinforced in a manner as described herein. The various rods or screws through thespinous processes140,150,160 may also be positioned through a posterior arch reinforcing member as described herein.
• FIG. 10 illustrates a spinous process rod or screw60 in accordance with the invention. The spinous process rod or screw60 comprises anelongate portion61 configured to extend through the reinforcement hood51 (for example, as described in further detail herein with reference toFIGS. 3A-4D positioned aroundspinous process50 and into an adjacent element such as, e.g. a pedicle screw. The spinous process rod or screw60 may include threaded portions. Thedistal end62 of the rod may be threaded or otherwise configured to engage an adjacent element. The spinous process screw orrod60 further comprises a proximal securingelement65 located on theproximal portion64 of the spinous process screw orrod60. Theproximal securing element65 is configured to engage afirst wall52 portion of thespinous process60 orreinforcement hood51. (“Engage” as used herein means to either directly or indirectly engage.) As illustrated, thedistal securing element63 comprises an obliquely threaded nut that is configured to receivescrew61 which is coupled to thehood51 at an oblique angle with respect to thewall53. The oblique threaded nut may be used in other applications where a screw is oblique with respect to the abject to which is engaged, coupled or attached. The obliquely threaded nut may have a predetermined angle at which it directs the screw with respect to the hood to guide the desired angle or directions of the screw placement. This may be predetermined base on imaging of a particular patient's anatomy. Adistal securing element63 is provided more distal of the proximal securingelement65. The distal securing element is configured to engage asecond wall portion53 generally opposite thefirst wall portion52 so that the spinous process element is secured or fixed to the hood and spinous process. (The term “fix” as used herein means either directly or indirectly fix to and may include dynamic elements.)
• FIG. 11 illustrates a spinous process rod or screw80 in accordance with the invention. The spinous process rod or screw80 comprises anelongate portion81 configured to extend through the reinforcement hood71 (for example, as described in further detail herein with reference toFIGS. 3A-4D) positioned aroundspinous process70 and into an adjacent element such as, e.g. a pedicle screw. The spinous process rod or screw80 may include threaded portions. Thedistal end82 of the rod may be threaded or otherwise configured to engage an adjacent element, e.g. with a connecting member, including but not limited to connecting members described herein. The spinous process screw orrod80 further comprises a proximal securingelement85 located on theproximal portion84 of the spinous process screw orrod80. Theproximal securing element85 is configured to engage afirst wall72 portion of thespinous process70 orreinforcement hood71. (“Engage” as is used herein to mean either directly or indirectly engage.) A hollow space orchamber74 is formed in thereinforcement hood71 so that the hollow chamber may engageably receive one or more securing elements, e.g. first and second securingelements86,87 therein. The securingelements86,87 may be positioned on either or both sides of thespinous process70 through which the screw orrod80 is positioned. As illustrated inFIG. 11, securingelement86 is positioned on theproximal portion84 of thescrew80 while securingportion87 is positioned on thedistal portion82 of thescrew80. Securingelements86,87 may be obliquely threaded nuts, for example, as described with respect tonut80binFIG. 3E. Securing elements may be attached a variety of ways, for example as illustrated inFIGS. 12A-12B and13A-13B.FIGS. 12A-12B illustrate manual insertion of securing elements in accordance with the invention. Spinous process screw80ais placed through both wings of thehood71 while passing throughholes1000 as shown. Securingelements86aand87aare inserted into receivingholes1001 within thehood71 and receivingholes1002 within the spinous process screw80a. Securingelements86a,87aprevent movement of the spinous process screw80a.FIGS. 13A-13B illustrate automatic deployment of securing elements in accordance with the invention. The securingelements86band87bcould be positioned inrecesses1004 in thespinous process screw80band spring loaded withsprings1003 attached inside of therecesses1004. Anexternal sheath1005 is positioned around thespinous process screw80b. Thescrew80bis positioned through a spinous process and a hood. The securing elements are then deployed upon removal of anexternal sheath1005. The securingelement86,86a, or86bis configured to engage the first wall portion of the spinous process (or hood) from within thehood71. The securingelement87,87a, or87bis configured to engage asecond wall portion73 generally opposite thefirst wall portion72 so that the spinous process element is secured to the hood and spinous process.
• FIGS. 14A and 14B illustrate a spinous process rod or screw54 in accordance with the invention. The spinous process rod or screw54 comprises an elongateouter tube portion55 and aninner rod portion56. Theinner rod portion56 is configured to move longitudinally within thetube portion55 to lengthen or shorten the spinous process screw orrod54. The inner wall of thetube portion55 may include a threaded inner wall that mates with a threaded outer wall of therod54 so that the rod may be screwed to advance therod56 and thereby lengthen or shorten the spinous process screw orrod54. Once theouter rod55 and screw56 are positioned within a spinous process orhood51 the spinous process screw orrod54 may then be lengthened as shown inFIG. 14B to extend through thereinforcement hood51. The lengthened spinous process screw may be used to distract the spinal segment or segments as well.
• The pedicle attachment devices herein may include a sensor that may be used to sensor one or more parameters e.g., strain, pressure, motion, position change, that provides information about possible screw failure. The sensor may communicate the information to an external device, e.g. telemetrically, and may be passively powered by an external device.
• According to another aspect of the invention a rod is provided that is anchored to with pedicle screws with screw heads made of or attached to swivel collars, polyaxial heads, or other movable fasteners to allow for near physiologic levels of motion of the spinal motion segment. Angular movement may be provided where a distracting element attaches on either side of a motion segment so that when distracting or lengthening the device, there is accommodation in the device for the change of angle that occurs.
• FIG. 15 illustrates an enlarged portion of a spinal prosthesis. Theprosthesis280 may provide support of the load on the spine where a facet has been removed or may provide other support or distraction. Theprosthesis280 comprises adistraction bar281 used to distract a motion segment of the spine in a number of manners including the distraction devices described herein. Apedicle screw283 is screwed into a pedicle of the spine or other anatomical location. Thedistraction bar281 includes and articulatingcup282 having aninner surface282a. Thepedicle screw283 has aball284 received by and coupled to thecup282 of thedistraction bar281. In addition to shock absorbing capabilities described in various embodiments herein, thedistraction bar281 also articulates with a portion of the spine to which thepedicle screw283 is attached.
• FIG. 16 illustrates a variation of theprosthesis280 described with respect toFIG. 15. Theprosthesis285 comprises adistraction bar286 and an articulatingball287 configured to engage and couple with anarticulation cup289 of apedicle screw288. Theprosthesis285 operates in a similar manner asprosthesis280.
• FIG. 17 illustrates a variation of theprostheses280,285 described herein respectively with respect toFIGS. 15 and 16. Theprosthesis290 comprises adistraction bar291 having anend292 with alumen293 for slidably receiving theend296 of apedicle screw295. Theend296 of thepedicle screw295 comprises aball portion297 attached to aneck298. Theball297 portion is configured to slide within thelumen293 of thedistraction bar291 which contains theball portion297. Theneck298 of thepedicle screw295 extends out of thedistraction bar291 through alongitudinal slit294 that slidably receives thenarrower neck portion298 of thepedicle screw295.
• One embodiment of the invention is a rod anchored at each end across a motion segment that can be “switched” between dynamic stabilization and rigid fixation in a minimally invasive, percutaneous, or non-invasive fashion. One way for this to occur is injection of a flowable material within the lumen of the device, which would cure, and immobilize the components which allow for motion. Electrical current, heat, mechanical energy, or other techniques could also be used to render movable components fixed. Another method is insertion of a rigid implant axially along the length of the dynamic implant. This method of rendering a flexible prosthesis rigid may be applied to the design of other combination motion/fixation prostheses, including disc, facet hip, knee, fingers shoulder, elbows, and ankle prostheses, etc.
• FIGS. 18-21 illustrate convertible or adjustable dynamic stabilization devices for joints. The stiffness or flexibility of the device may be altered or titrated after implantation to adapt the stiffness to a particular patient, and/or to adjust the stiffness over time, for example when laxity of the joint increases with age. Referring toFIG. 18 illustrates adynamic stabilization prosthesis350. The prosthesis comprises aflexible coil352 contained in atube member351 comprising telescoping tubes. Theprosthesis350 may be used in a number of manners affixed across a joint motion segment to dynamically stabilize the joint. Thecoil352 may be energy absorbing. Thecoil352 may also be configured to exert a distracting force on the joint when implanted.FIG. 19 illustrates thedynamic stabilization prosthesis350 ofFIG. 18 converted to a rigid or more rigid prosthesis. Theprosthesis350 includes aslit353 for receiving arigid wire member354. InFIG. 19 therigid wire member354 is inserted into theslit353 to form the prosthesis from a dynamic prosthesis into a rigid prosthesis. As an alternative to a rigid wire member, a flexible coil of a selected stiffness may be inserted to change the stiffness of the dynamic prosthesis. The tube may alternatively comprise a ferromagnetic material contained therein and an electromagnetic field is applied that causes the prosthesis to become stiffer. The field may be varied to provide a variety of gradients in stiffness. The device may also include a sensor that operates as sensor170adescribed herein. Feedback may be provided and the stiffness of the prosthesis adjusted accordingly. The stiffness may be varied when implanted using patient feedback so that the implant is more or less flexible depending upon an individual patient's needs. In addition the stiffness may be changed at different times during the course of the implants lifetime. For example, the stiffness may be increased when an increased amount of stabilization is required.
• FIG. 20 illustrates analternative prosthesis360 also comprising aflexible coil362 contained in atube member361. The tube member is configured to receive a fluid material such as acurable polymer364 that cures in the tubular member to create a rigid prosthesis. As illustrated inFIG. 20 a rigid prosthesis is formed from a dynamic prosthesis by injecting thepolymer material364 into thetubular member361. The flexibility/stiffness properties of the prosthesis may be selected by selecting such properties of the polymer to be injected.
• As illustrated inFIG. 21 aflexible prosthesis365 is illustrated. The flexibility of theprosthesis365 is adjustable by injecting a polymer material into one or more of thecolumnar cavities367,368,369. The polymer may be injected into each cavity at a different time so the stiffness of the prosthesis may be increased gradually over time. The stiffness/flexibility properties of the polymer injected may also be selected according to a desired stiffness/flexibility of the implant.
• According to an embodiment of the invention, the dynamic stabilizer may comprise a shock absorber that has both energy absorbing and energy dissipating properties. The tension band effect of the posterior columns may also offload the pressures borne by anterior column of the spine. So in addition to helping to protect the facet joints, other aspects of the invention would help slow the progression of degenerative disc disease, annular degradation, disc herniation, and vertebral compression fractures.
• Another aspect of the invention is to supplement implants or repair procedures of the anterior column with a posterior shock absorber device (rod, screw, plate). Examples of these implants or procedures include total disc replacements, annular repair, artificial nucleus, and vertebroplasty/kyphoplasty.
• Another aspect of the invention is to supplement implants or repair procedures of the posterior column with a shock absorber rod. Examples of these implants or procedures include interspinous distraction wedges, facet joint replacements, and posterior arch replacements.
• Another aspect of the invention provides a posterior support implants with shock absorbing properties, to decrease or remove the load experienced by the facets. Implant components may include springs, coils, hydraulic or fluid filled piston chambers, or elastic materials. Each end of the device could be anchored in such a fashion so the rod bridges the facet joint, reducing the loads borne by the joint. This is believed to reduce wear of the facets and resulting pain and altered spinal biomechanics.
• An improved device is provided that utilizes the spinous process, the pedicle, adjacent ribs and/or a transverse process or a combination including one or more of these anatomical structures, to correct or stabilize a deformed spine. The device may be used to correct scoliosis using one or more of these anatomical structures and multiple points at a plurality of spine segments. The correction may be made incrementally over time and may or may not include a fusion process.
• In one embodiment, a percutaneously and obliquely placed rigid or dynamic stabilizer is provided. Stabilizer segments are anchored to base of spinous process at one end and a pedicle screw at the other end, as a unilateral temporary stabilizer. The dynamic stabilizers described herein may be adjusted over time to gradually bring the spine in alignment. The stabilizer may be used to derotate (untorque) and correct the spine. A stabilizer placed across a motion segment, i.e., not at the same vertebral level may be used to create overgrowth where desired, i.e. on the non-instrumented side of the motion segment. Such overgrowth may help stabilization or correction of the spine.
• FIGS. 22A-24 illustrate an explantable, temporary scoliosis stabilization device. The system is configured to be manipulable once it is installed. The systems illustrated are configured to alter the orientation of a vertebral body and in particular to untorque the spine about the axis of the spinal column as well as applying a corrective straightening or translation force with respect to a vertical rod. According to one aspect of the invention, a device for correcting deformities of the spine is provided where the device may be adjusted over time to direct the corrective forces as needed over time. According to another aspect, a multipoint stabilizing device is coupled to the posterior portions of the spine.
• The systems illustrated inFIGS. 22A-24 comprise a multipoint anchoring mechanism that provides for multidimensional correction of the spinal or spinal segments by positioning the anchor at a plurality of locations on a spine. As illustrated for example inFIGS. 22A-22H, the multiple locations include the spinous process and pedicle of a particular vertebra. A bar is attached between the spinous process and pedicle. A force directing device couples the bar to a vertical rod. As illustrated inFIGS. 23A-23B, the multiple locations include the spinous process of one level and the pedicle of another level (e.g. an adjacent level). As illustrated inFIG. 24, the multiple locations include the spinous process, through atransverse process605 into a costal aspect of arib606. The vertical rod in these figures is attached or coupled to the spine at neutral and balanced vertebra, typically only at the most upper and most lower positions.
• The device comprises a telescoping rod (or plate)536 to which various segments of the spinal column are to be fixed. Therod536 telescopes to adjust the height to accommodate particular segments or a height of the spine. As illustrated inFIG. 22A aportion500 of the spine comprises a plurality ofadjacent segments501,502,503,504,505, (additional adjacent segments may also be corrected). Theportion500 of the spine exhibits a concave curvature betweensegments501 and505. Pedicle screws506,507,508,509,510 are attached to pedicles ofsegments50,502,503,504,505, respectively.Dynamic stabilizers516,517,518,519,520 are attached to pediclescrews506,507,508,509,510 and tospinous processes521,522,523,524,525 respectively ofsegments501,502,503,504,505.Wires526,527,528,529,530 attached to therod536 viahooks531,532,533,534,535 attached to therod536. Thewires526,527,528,529,530 are used to tension the portion of thespine500 to pull on the concavity. If the portion has a convexity, rods may be used in place of wires to push on the convexity to straighten the spine.
• FIG. 22B is a cross section ofFIG. 22A along the lines22B-22B. Thepedicle screw508 includes ascrew capture device508afor receiving a screw head or rod of a dynamic stabilizer, in this case, aspinous process screw518. The capture device may be a hole, a threaded screw hole with a washer or cap. Thepedicle screw508 may be configured to telescope outwards or inwards to be positioned to receive the screw head or rod of adynamic stabilizer518 as shown inFIGS. 22C and 22D. Thespinous process screw518 is shown in22C where, given the trajectory of thespinous process screw518, its end does not intercept thecapture device508aof thepedicle screw508. As shown inFIG. 22D the pedicle screw'strunk508bis lengthened with a telescoping or other similar lengthening mechanism so that the end of thespinous process screw518 may be positioned in thecapture device508a.
• Thespinous process screw518 is anchored through the reinforced spinous process523 (having areinforcement hood523aor is otherwise reinforced as described herein. Note that the reinforcement hood may have a single lamina wing where a single screw is attached as opposed to bilateral screws.) with ahead portion518aengaging thepedicle screw503 and arod portion518bextending through a reinforcedspinous process523. Thedynamic stabilizer518 includes aloop connector end518cfor receiving ahook518dof a wire (or a telescoping rod)528 that is attached to therod536 with a ratchetedconnector533. The wire may also be a rod, spring, elastic band or other force-directing device. Theloop connector end518cmay also be a poly axial connector that allows translation in a variety of directions or places, i.e., so that an oblique angle rod can be captured. (for example, similar topedicle screw503 and capture device503a) Thewire528 may be adjusted or tightened at various times with the ratchetedconnector533, e.g., during a period of time where the spine is being corrected. As the spine is straightened, excess wire may be trimmed off. This procedure may be done percutaneously, e.g. by accessing wire near the skin. Each dynamic stabilizer is similarly constructed.
• FIGS. 22E-22H illustrate various dynamic stabilizers that may be used to correct spinal deformity.Dynamic stabilizers518e,518i, and518mare coupled by coupling mechanisms541a-cto thetelescoping rod536. The coupling mechanisms541a-cmay be positioned on or through the plate ortelescoping rod536. Dynamic stabilizer518eincludesrod518fthat will extend through a reinforced spinous process and is coupled by acoupling mechanism518gtorod518hin an end-to-end fashion.Rod518hslidably extends through opening incoupling mechanism541aattached to thetelescoping rod536. Therod518his adjustable within thecoupling mechanism541ato lengthen or shorten the distance of the dynamic stabilizer518ebetween the spinous process and thetelescoping rod536. Thecoupling mechanism541ais configured to clamp down on therod518hto secure it in place once the distance has been adjusted. The coupling mechanisms541a-cmay include a screw, cam or clamp mechanism to clamp or lockably engagerods518h, l, andpas described in use herein.
• Similarly,dynamic stabilizer518iincludesrod518jthat will extend through a reinforced spinous process and is coupled by acoupling mechanism518kto rod518lin an end to side fashion. Rod518lslidably extends through opening incoupling mechanism541battached to thetelescoping rod536. The rod518lis adjustable within thecoupling mechanism541bto lengthen or shorten the distance of thedynamic stabilizer518ibetween the spinous process and thetelescoping rod536. Thecoupling mechanism541bis configured to clamp down on the rod518lto secure it in place once the distance has been adjusted.
• Dynamic stabilizer518mincludes arod518nthat will extend through a reinforced spinous process and is coupled by a threaded coupling518otorod518p. Therod518pis slidably and rotatably positioned within a cylindrical hole incoupling mechanism541cattached to thetelescoping rod536. Therod518pmay be rotated, i.e., screwed or unscrewed so that the stabilizer lengthens or shortens at the threaded coupling518o. The rotation or screwing may be actuated at or near the skin where therod518pis positioned in thecoupling mechanism541c.
• Dynamic stabilizer518qincludes arod518rthat will extend through a reinforced spinous process and is coupled by amultiaxial coupling518ssimilar to a multiaxial screw head type coupling, torod518t. Therod518tis a telescoping rod and is coupled bycoupling mechani8sm541dto thevertical rod536.
• Each of the dynamic stabilizers may include sensors located thereon to sense data corresponding to a parameter of the dynamic stabilization device or the spine.FIG. 22E-22H illustrate sensors542a-542dlocated on the dynamic stabilizer. The sensors may comprise, e.g., a strain, stress, pressure, position or motion sensor. Such sensors may include a variety of sensors that are generally know. For example, strain gauges, accelerometers or piezo electric sensors may be employed to sense parameters that correspond, e.g., to the position of the spine, a vertebra, a dynamic stabilizer, as well as the parameters relating to the forces or mechanical loads that are effecting the device. Each of the sensors may individually sense information or information relative to each of the other sensors may be sensed and compared. The information may be used to set tension on the device, to identify when repositioning is necessary or to otherwise provide information as to the status of the device or portions thereof, or status of the spine that is being treated. The sensors may include some level or circuitry including, e.g. a telemetry circuit that transmits information concerning the sensors to an external device. The sensors may be battery powered or may use passive circuits that are powered by an external device. The information may be used to identify when one of the stabilizers no longer has tension associated with the stabilizer thus identifying when the tension needs to be modified in the device. Accordingly, each segment may be moved separately, monitored separately and adjusted separately form the other segments. Each segment may be moved to a different degree and in different directions or at different angles with varying forces.
• FIG. 23A illustrates an alternative configuration of the correction device according to the invention. Aportion550 of the spine comprises a plurality ofadjacent segments551,552,553,554,555,555a(additional adjacent segments may also be corrected). Theportion550 of the spine exhibits a concave curvature betweensegments551 and555a. Pedicle screws556,557,558,559,560 are attached to pedicles ofsegments551,552,553,554,555, respectively.Dynamic stabilizers566,567,568,569,570 are attached to pediclescrews556,557,558,559,560 and through spinous processes,572,573,574,575,576 respectively ofadjacent segments555a,551,552,553,554. Thus, the dynamic stabilizers are positioned across the motion segments between the corresponding adjacent segments. Thedynamic stabilizers566,567,568,569,570 attached to thetelescoping rod576 in one or more manners such as, for example, thedynamic stabilizers518,518e,518i,518m,518qas illustrated inFIGS. 22A-22H, herein. Thedynamic stabilizers566,567,568,569,570 are used to tension the portion of thespine500 to pull on the concavity, or if the portion has a convexity, to push , pull on, or translate the convexity to straighten the spine. Thus each of the dynamic stabilizers are attached a plurality of locations on the spine and operate to stabilize adjacent segments with respect to each other.
• FIG. 23B illustrates a pedicle screw and dynamic stabilizer in greater detail. Thepedicle screw558 is screwed into pedicle563 ofvertebra553. Thepedicle screw558 includes a screw hole558afor receiving a screw head or rod of adynamic stabilizer568. A screw capture device568bsuch as a nut or a threaded portion of the pedicle screw is configured to capture and receive the dynamic stabilizer screw or rod portion568a. The capture device568bof the stabilizer engages thepedicle screw558 and a rod portion568bextends through a reinforcedspinous process574. Thedynamic stabilizer568 includes a connector end580 for receiving a wire578 or a hook of a telescoping rod that is attached to thetelescoping rod576. Thedynamic stabilizer568 is anchored through the reinforcedspinous process574 of an adjacent vertebra554 (FIG. 17A) thus immobilizing or stabilizing the motion segment between thevertebra553,554. This device may also be used in fusion, i.e. to fuse the motion segments across vertebra of a multipoint connector. The device may also be used to encourage overgrowth at certain locations. In particular it may encourage overgrowth on the non-fused lateral side of a vertebra (opposing the fused lateral side) stabilized with the multipoint connector between two vertebrae.
• FIG. 24 illustrates a device for treating a deformity such as scoliosis. The device includes adynamic stabilizer600 comprising aspinous process screw601 and apedicle screw602 including a spinous processscrew capture device603. The spinous process screw is configured to be positioned through a reinforcedspinous process604 and through atransverse process605 into a costal aspect of arib606. Thedynamic stabilizer600 includes aconnector portion607 configured to be connected to a telescoping rod as described herein with reference to FIGS.22A-H and23A-23B. Similar to FIGS.22A-H and23A-23B, a plurality of segments may be secured to a telescoping rod with a plurality of dynamic stabilizers. The pedicle screw in this and all other embodiments described in this application may include a telescoping portion that can adjust the length of the screw head from the anchoring point where the pedicle screw is anchored into the bone. Thepedicle screw602 also includes a sensor608 located thereon (or incorporated therewith). The sensor may comprise, for example, a motion detector, a position detector, a pressure sensor, a strain gauge, and ultrasonic transducer/sensor. The sensor may sense a change in strain on the screw that may be due to loosening or repositioning of the screw. The sensor may also sense a change in position of the screw that indicates a change in alignment and corresponding loosening or repositioning of the screw. The sensor may also sense a change in pressure due to loosening or repositioning of the screw. The sensor may also include an ultrasonic transducer and transmitter that can determine change in positioning of the screw, e.g. loosening of the screw indicated by a change in interfaces of materials or characteristic property change indicating screw loosening or repositioning. The sensor may include some electronics such as a telemetry circuit that allows it to communicate with an external device. The sensor may also be powered by an external device e.g., in a manner generally known in the art.
• The various embodiments of the invention described herein may include sensors integrated with or provided on a structural spinal implant. A number of factors may be detected as described herein. Additional factors may include, e.g., local inflammation, pressure, tension, edema, motion, water content, and electrolytes or other chemicals. The sensors allow a doctor to monitor patients for response to healing, or may be used by the doctor to guide serial adjustments to the patient's treatment. For example, measurements from the sensing means could lead the doctor to change the length or tension of a distraction rod or stabilization device. Patients could adjust therapy based on measurements from the sensing device, or could be alerted to notify their doctor should certain measurements be of concern. The sensor is configured to be adjustable to sensed stresses. The sensor may for example, be a strain gauge, a pressure sensor accelerometer, position sensor, imaging device, etc. The sensor may be used in the initial adjustment of the prosthesis or may be monitored over time. The sensor may sense shear/torsion tension/compression. Sensors may sense stresses at various motion segments. The sensor may be used to compare stresses at various motion segments or locations. Various sensors may be selected from sensors that are known to one of skill in the art or that are commercially available.
• Anchoring of Therapeutic Devices
• Some patients obtain back pain relief with injections of steroids and anesthetic agents at the site of pain; however the relief is temporary requiring that patients return for repeat injections when their pain recurs.
• One embodiment of the invention comprises an anchor device with a therapeutic substance or drug delivery device, e.g. a drug port and/or reservoir, or matrix attached to a vertebra. In one embodiment, the device is anchored adjacent a site near where pain is present. The port is configured to deliver steroids or anesthetic agents via a catheter to a desired location, for example, the facet joint, neural foramen, vertebral body, annulus, nucleus, back muscles, back ligaments, bone metastases, intrathecal space, epidural space, or other targets in, on, or around the spine. The catheter can direct the drug to the correct location by positioning the end of the catheter at a target location. The port is configured to be refilled periodically percutaneously, e.g. using an imaging device and a percutaneously placed needle that can inject the refill into the port, e.g. through a biocompatible polymer or rubber type port access mechanism. The device further comprises a patient actuation mechanism for patient control of drug delivery as needed for pain relief, manually or remotely using a telemetrically triggered delivery from an external telemetry control device. According one aspect of the invention such a device is attached to a boney structure of the spine. Other device that may be attached to the spine may include sensory or therapeutic devices, including nerve stimulators, bone growth stimulators and radioactive seeds.
• In addition, a structural implant could be anchored to bone, to which a sensory or therapeutic device could be attached. The sensory or therapeutic device could be placed external to the bone, on the surface of the bone, or internal to the bone.
• FIGS. 25 and 26 illustratedrug delivery devices370,380, respectively, in accordance with the invention. Thedrug delivery device370 includes areservoir375 attached by ananchor371 configured to anchor thereservoir375 to the bone of the spine. In particular, in this embodiment, theanchor371 comprises a pedicle screw that anchors the device to thepedicle373 of avertebra372. Thereservoir375 includes acatheter376 in communication with the contents of thereservoir375 and having an end positioned adjacent or in a zygapophyseal joint378 where the drug is directed to have a therapeutic effect on the joint378. The device may include a telemetrically actuable pump mechanism for delivering the drug to the joint upon telemetric actuation by an external control device. Thedevice370 further comprises aport377 for receiving (e.g. via a percutaneously introduced needle) into thereservoir375, refills of the therapeutic substance or drug.Device380 comprises asimilar catheter386, andreservoir385 attached by ananchor381 to thespinous process383 or alternatively anadjacent lamina384. Thespinous process383 orlamina384 may be reinforced prior to attachment of theanchor381 or may be attached to a reinforcement device positioned at the posterior arch of the spine, as described herein with reference toFIGS. 1A-7B.

Claims (20)

1. A spinal implant comprising a first portion configured to be coupled to a first bony portion; and a second portion configured to be coupled to a second bony portion,

wherein the spinal implant permits movement between the first bony portion and the second bony portion and wherein the spinal implant is adjustable to change an amount of said movement between said first bony portion and said second bony portion after the implant is implanted.

2. The spinal implant ofclaim 1 wherein the implant has a flexibility when implanted and wherein the implant is adjustable to change the flexibility after the implant is implanted.

3. The spinal implant ofclaim 1 wherein the implant is adjustable to decrease the amount of movement after implanted to reduce laxity of a joint between the first bony portion and the second bony portion.

4. The spinal implant ofclaim 1 wherein the implant comprises at least one cavity, and wherein the spinal implant is adjustable to change the amount of said movement by inserting a material in said cavity.

5. The spinal implant ofclaim 4 wherein the implant is adjustable to change the amount of said movement by inserting a curable polymer in said cavity.

6. The spinal implant ofclaim 4 wherein the implant comprises of plurality of cavities.

7. The spinal implant ofclaim 1 further comprising at least one insertable support member, wherein the implant is configured to receive said at least one support member, and wherein the spinal implant is adjustable to change the amount of movement by inserting said at least one support member.

8. The spinal implant ofclaim 7 wherein said at least one support member comprises a plurality of support members.

9. The spinal implant ofclaim 8 wherein each of said support members has a different flexibility.

10. The spinal implant ofclaim 7 wherein said support member comprises a spring.

11. The spinal implant ofclaim 10 wherein said support member has shock absorbing properties.

12. A spinal implant comprising:

a proximal portion configured to engage a spinous process of a first vertebra;

an elongate rod portion configured to extend adjacent a motion segment between the first vertebra and a second vertebra;

a distal portion configured to be fixed to a bony portion of a second vertebra; and

a motion portion configured to permit motion at the motion segment.

13. The spinal implant ofclaim 12 wherein the motion portion comprises a flexible portion located with the elongate rod portion.

14. The spinal implant ofclaim 12 wherein the flexible portion comprises a spring member.

15. The spinal implant ofclaim 14 wherein the flexible portion comprises a coil.

16. The spinal implant ofclaim 12 further comprising a spinous process reinforcement element.

17. The spinal implant ofclaim 16 wherein the proximal portion is attached to the spinous process reinforcement element.

18. The spinal implant ofclaim 12 wherein the distal portion is configured to be attached to a pedicle attachment device attached to the second bony portion.

19. The spinal implant ofclaim 12 further comprising a securing member configured to secure the proximal portion to the spinous process.

20. The spinal implant ofclaim 12 further comprising:

a second proximal portion configured to engage the spinous process of the first vertebra;

a second elongate rod portion configured to extend adjacent a second motion segment between the first vertebra and the second vertebra;

a second distal portion configured to be fixed to a bony portion of a second vertebra; and

a second motion portion configured to permit motion at the second motion segment.

Images