US20180064555A1 - Expandable interbody implant - Google Patents

Abstract

An intervertebral implant that can be surgically introduced between adjacent vertebrae and expanded in situ to occupy an optimal space between the vertebrae. The implant is inserted into the evacuated disc space obliquely and then oriented so as to extend laterally across the anterior adjacent vertebrae with its outer ends of the implant supported by the cortical rims on the opposite sides of the vertebrae. The implant has two body members with a space therebetween so the implant may be then distracted and a spacer of predetermined thickness that may be inserted within the space between the body members so as to maintain a desired amount of distraction. The upper and lower surfaces of the implant may have a desired lordotic angle. A method of using an implant is disclosed which permits endoscopic visualization of the disc space.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• “This application is a continuation application of and claims priority to co-pending application Ser. No. 14/966,604 filed Dec. 11, 2015, which is a continuation of application Ser. No. 14/520,892, filed Oct. 22, 2014 now U.S. Pat. No. 9,211,195, which is a continuation of application Ser. No. 13/543,126 filed Jul. 6, 2012, now U.S. Pat. No. 8,906,099, which is a continuation-in-part of application Ser. No. 12/899,625 filed Oct. 7, 2010, now U.S. Pat. No. 9,180,017 and continuation-in-part of application Ser. No. 13/030,618 filed Feb. 18, 2011, now U.S. Pat. No. 8,480,748. Application Ser. No. 13/543,126 also claims priority to U.S. Provisional Application No. 61/610,198 filed Mar. 13, 2012. Application Ser. No. 12/899,624 claims priority to Provisional Application 61/356,851 filed Jun. 21, 2010 and Provisional Application No. 61/251,002 filed Oct. 13, 2009. All of the foregoing prior applications are incorporated herein by reference in their entirety.”
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• Not Applicable.
BACKGROUND OF THE DISCLOSURE
• This disclosure relates to intervertebral disc prostheses, and more particularly to an intervertebral disc prosthesis that can be surgically introduced between adjacent vertebral bodies, preferably between lumbar vertebrae, and adjusted or expanded in situ to occupy an optimal or desired space between the vertebral bodies.
• In recent years, surgical procedures have been developed in which two or more vertebrae are joined or fused together. Such procedures are now common in the treatment of spinal disorders such as spondylolisthesis, scoliosis, and disc degeneration. Certain of these fusion surgeries include Posterior Lumbar Interbody Fusion (PLIF), Transforaminal Lumbar Interbody Fusion (TLIF), Anterior Lumbar Interbody Fusion (ALIF), and DLIF (Direct Lateral Interbody Fusion). These procedures are well known to spinal surgeons.
• Interbody vertebral spacers are known that are inserted between the vertebrae bodies to replace a collapsed, degenerated, or unstable disc. However, these prior spacers were typically of a predetermined thickness and thus it was difficult to size the thickness of the spacer to result in the desired amount of distraction between the vertebrae bodies in order to achieve the desired amount of distraction between the adjacent vertebra bodies. Such prior spacers are commercially available from Stryker Spine of Mahwah, N.J., from Medtronic, Spinal and Biologics Business, Memphis, Tenn., from Spinal Concepts, Inc. of Austin Tex., and from NuVasive, Inc. of San Diego, Calif.
• Certain adjustable height interbody fusion devices are known, such as described in U.S. Pat. No. 6,080,193 that vary the distance between the portions of the spacer that engage the endplates of the adjacent vertebrae. However, these adjustable fusion devices rely on cams and other complicated mechanisms for adjustment purposes.
• In general, lordosis is the curvature of the spine with the convexity forward. Lordosis is not necessarily a disease state, but rather the normal anterior physiologic curve of the neck or low back. This disclosure is primarily concerned with lumbar lordosis. Most lumbar disc spaces in healthy spines are generally parallel or nearly 0 degree lordotic, and is particularly true for L1/2, L2/3, and L3/4 However, the L4/5 may have a lordotic angle ranging between about 0°-12°, and L5/S1 may also range between about 0°-12°. Therefore, in reconstructing a disc space that has some lordosis it would be advantageous to have an implant matching the existing anatomy so that the two surfaces of the implant would better conform to and better fit the shape of the disc space so that load sharing occurs over the whole implant. Otherwise, an implant having parallel upper and lower surfaces used in a disc space having, for example, 8 degrees of in situ lordosis would result in only part of the implant contacting its respective vertebrae bodies and thereby lessening the corrective support applied to the spine and thus predisposing the implant to subsidence. That is, subsidence refers to an increased tendency of the implant, over time, to telescope, settle or project into the adjacent vertebrae bodies with loss disc space height back to preoperative levels. When using conventional implants, it is frequently observed that such telescoping or settling occurs with such implants placed wholly within the disc space, rather than having the implant bearing on and distracting from the cortical rim/apophyseal ring of the adjacent vertebrae as disclosed in my Co-pending U.S. patent application Ser. No. 12/899,625, now U.S. Pat. No. 9,180,017. Additionally, a more conformal fit in a disc space with lordosis will allow more uniform distribution of corrective forces applied during distraction. Thus, it would be desirable to provide an expandable (variable height) implant, as described in my above-noted pending application that would provide options for encountered or desired disc space lordosis. It would also be desirable to use either a variable or a fixed height implant that could reconstruct any disc space anatomy or morphology surgically encountered including lordotic conditions with the surgical procedures described in my above-identified U.S. Patent application and patents in the present disclosure.
SUMMARY OF THE DISCLOSURE
• The present disclosure relates to an intervertebral disc prostheses, and more particularly to an intervertebral disc prosthesis that can be surgically introduced between adjacent vertebral bodies, preferably between lumbar vertebrae, and adjusted or expanded in situ to occupy an optimal or desired space between the vertebral bodies. The implant is preferably inserted into the evacuated disc space obliquely and then oriented so as to extend laterally across the adjacent vertebrae bodies anteriorly occupying the disc space with the outer ends of the implant being supported at least in part by the cortical rims on opposite sides of the adjacent vertebrae bodies. The outer convex surfaces of the two body members conform anatomically to the shape of the disc space contacting the endplates. The implant has two body members that are movable relative to one another so as to vary the space between the members. With the implant so positioned and oriented, the implant and thus the disc space may be then distracted and a spacer of a desired, predetermined thickness may be inserted within the space between the body members so as to maintain a desired amount of distraction.
• Still further, the present disclosure relates to such an expandable (variable height) or non-expandable (fixed height) disc prosthesis that may have angled upper and lower surfaces engageable with the adjacent vertebrae bodies so as to introduce a predetermined degree of lordosis thereby to better reconstruct the spine by introducing segmental lordosis and improving regional lordosis and global sagittal balance. It is also understood that 0° or parallel surfaced implants maybe an appropriate choice dictated by intraoperative findings and surgical anatomy.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a lateral view of a series of lumbar vertebrae (or vertebrae bodies) illustrating intervertebral cartilage discs between adjacent vertebrae, and further illustrating an opening in a posterior lateral quadrant of the annulus for the insertion of an expandable lumbar disc replacement implant or prosthesis of the present disclosure within the disc space between adjacent vertebrae so as to maintain the adjacent vertebrae in a desired distracted position;
• FIG. 2 is a median sagittal cross section of one of two adjacent lumbar vertebrae and the annulus between such adjacent vertebrae illustrating the desired position of the lumbar disc replacement implant within the disc space;
• FIG. 3 is a side elevational view of a lumbar vertebrae illustrating the lateral placement of the implant on the upper surface of the cortical rim of the lower vertebrae body;
• FIG. 4 is an axial inferior view of a lumbar vertebrae (e.g., L4) illustrating the implant of the present disclosure which is initially inserted obliquely through an incision in the annulus and received in a first opening generally opposite the incision and in a second opening generally across from the first opening with the implant oriented to extend across the vertebrae bodies and to span from one side to the other of the vertebrae bodies and to bear against the cortical rims of the upper and lower vertebrae bodies and contacting the interposed endplate, where this view further illustrates an oblique slot in the inner faces of the upper and lower implant body members so as to permit a surgical instrument (e.g., a parallel distractor, such as shown inFIGS. 66-70) to be inserted in these slots to distract the expandable implant and the disc space;
• FIG. 4A is a view similar toFIG. 4 of the spine illustrating a minimally invasive TLIF exposure dissecting between the fascial planes of the multifidus and longisimus muscles with an operative tube seated on the bony anatomy of the spine;
• FIG. 4B illustrates lumbar vertebrae L3, L4 and L5 with a unilateral exposure of the operating site between vertebrae L3 and L4;
• FIG. 4C is a posterior view of the operating site on a somewhat enlarged scale;
• FIG. 4D is a view similar toFIG. 4 illustrating the incision and the first and second openings in the annulus without the implant of this disclosure installed;
• FIG. 4E is a view similar toFIG. 4D, but where the incision and the second opening are, respectively, posterior and anterior portions of a single elongate annulotomy and where the first opening is the anterior portion of another elongate annulotomy, where the elongate annulotomies help relax the annulus;
• FIG. 4F is a diagrammatic axial depiction of a vertebrae (or vertebrae body), the annulus, the disc space, and other major anatomical features of the vertebrae illustrating the location of the incision and the openings made in the annulus in accordance with the procedure shown inFIGS. 4 and 4D;
• FIG. 4G is a view similar toFIG. 4F illustrating the location of the openings made in the annulus in accordance with the procedure of this disclosure, as shown inFIG. 4E, such that there is sufficient room to insert an endoscopic light delivery system and lens viewing system and also to accommodate surgical instruments for performing endoscopic discectomy;
• FIG. 4H is a view if a vertebrae and the annulus illustrating an annulotomy in the annulus in a posterior lateral quadrant of the annulus which is somewhat shorter than the elongate incision shown inFIG. 4G such that the annulus is relaxed and such that there is sufficient room to insert an endoscopic light delivery system and lens viewing system and also to accommodate surgical instruments for performing endoscopic discectomy;
• FIG. 4I is a diagrammatic view similar toFIG. 4F illustrating the elongate incision ofFIG. 4H;
• FIG. 4J is a view similar toFIG. 4H illustrating an implant of the present disclosure installed within the disc space, but where the implant is somewhat shorter than the implant shown inFIG. 4, where this implant does not bear on the cortical rim, but is supported by the endplates of the vertebra bodies;
• FIG. 4K is a view similar toFIG. 4J, where the implant is somewhat longer than the implant ofFIG. 4J and where one end of the implant partially extends through the elongate incision and bears at least in part on the cortical rim;
• FIG. 4L is a view similar toFIG. 4E with an implant in accordance with the present disclosure extending across the anterior portion of the disc space and bearing on the cortical rim of the vertebrae bodies;
• FIG. 4M illustrates a typical endoscopic system that may be used in conjunction with the present disclosure where an endoscopic camera and light source may be inserted into the disc space through an elongate incision in the annulus so as to enable the surgeon to perform discectomy of the disc space with endoscopic viewing;
• FIG. 4N is a view similar toFIG. 4M illustrating the insertion of endoscopic apparatus and surgical instruments into the disc space;
• FIG. 4O is a view similar toFIG. 4K illustrating the placement of the implant across the anterior of the disc space and illustrating the insertion of endoscopic and surgical instruments into the disc space;
• FIG. 5 is a posterior perspective view on an enlarged scale of the implant of the present disclosure, as viewed from above, having an upper and a lower body member with a space between the inner faces of these upper and lower body members and with a spacer of predetermined thickness inserted within the space between the body members so that when the disc space is retracted, the body members and the spacer maintain a desired distraction between the adjacent vertebrae bodies and bear normal spinal biomechanical loads until solid spinal fusion is achieved;
• FIG. 6 is a posterior perspective view of the implant shown inFIG. 5, as viewed from below;
• FIG. 7 is an anterior perspective view of the implant shown inFIG. 6, as viewed from above;
• FIG. 8 is another anterior perspective view of the implant, as viewed from below;
• FIG. 9 is a posterior elevational view of the implant illustrating oblique slots in the inner faces of the upper and lower body members with a spacer inserted between the inner faces of the upper and lower body members;
• FIG. 10 is a vertical cross sectional view of the implant taken along line10-10 ofFIG. 9;
• FIG. 11 is anterior view of the implant shown inFIG. 9;
• FIG. 12 is a top plan view of the implant;
• FIG. 13 is a lengthwise vertical cross sectional view taken along line13-13 ofFIG. 12;
• FIG. 14 is a bottom plan view of the implant;
• FIG. 15 is a right side elevational view of the implant as shown inFIG. 12;
• FIG. 16 is a left side elevational view of the implant as shown inFIG. 12;
• FIG. 17 is a bottom perspective exploded view of the implant;
• FIG. 18 is a top perspective exploded view of the implant;
• FIG. 19 is an anterior perspective view of a second embodiment of the implant of the present disclosure illustrating a tab extending upwardly from the anterior end of the lower body member with the tab being adapted to fit within a corresponding recess in the anterior face of the upper member so that upon distraction of the space between the body members and with a spacer disposed within the space between the upper and lower body member, the tab prevents anterior displacement of the spacer from between the body members;
• FIG. 20 is a bottom perspective view of the implant shown inFIG. 19;
• FIG. 21 is a top plan view of the implant shown inFIGS. 19 and 20, with a spacer (shown in dotted lines) positioned between the upper and lower body members;
• FIG. 22 is a vertical section view taken along line22-22 ofFIG. 21 illustrating a first or anterior detent protuberance projecting downwardly from the bottom face of the spacer with this first detent protuberance being received in a corresponding first enlarged recess in the top face of the lower body so as to aid in locating the spacer relative to the lower body member and so as to prevent displacement of the spacer relative to the lower body member upon retraction of the space between the upper and lower body members and upon application of compression and in normal use;
• FIG. 23 is a vertical section view taken along line23-23 ofFIG. 21 illustrating a second or posterior detent protuberance projecting downwardly from the bottom face of the spacer with this second detent protuberance being received in a corresponding second enlarged recess in the top face of the lower body so as to aid in locating the spacer relative to the lower body member and so as to prevent displacement of the spacer relative to the lower body member upon compression of the space between the upper and lower body members;
• FIG. 24 is an exploded perspective view of the implant shown inFIGS. 19-23, as viewed from above;
• FIG. 25 is an exploded perspective view of the implant shown inFIGS. 19-24, as viewed from below, illustrating a pair of spaced detent protuberances on the bottom face of the spacer;
• FIG. 26 is an anterior exploded perspective view, as viewed from above, of the implant illustrating the location of the first and second protuberance receiving recesses formed in the upper face of the lower body, as these recesses are positioned relative to the diagonal slot provided in the lower body for receiving the lower blade of a parallel distractor used to expand the space between the upper and lower body members;
• FIG. 27 is a top plan view of the lower implant body member shown inFIGS. 19-26 in which the spacer is substantially centered between the stabilizing posts and in which the anterior and posterior detent protuberances (as shown in dotted lines) are substantially centered relative to their respective recesses (also shown in dotted lines);
• FIG. 28 is a posterior side elevational view of the implant shown inFIG. 27 with the space between the upper and lower body members distracted and with a spacer interposed between the upper and lower body members with the lateral ends of the spacer substantially centered between the stabilizing posts;
• FIG. 29 is a top plan view of the lower implant body with the spacer being offset within the space between the stabilizing posts toward and bearing against the left-hand post such that both the left-hand post and the detent protuberances are received in their respective recess so as to positively prevent lateral movement of the spacer, and such that the protuberances cooperating with their respective recesses positively prevent movement of the spacer relative to the implant bodies;
• FIG. 30 is a posterior side elevational view of the implant shown inFIG. 29 with the spacer located in the position shown inFIG. 29 with the space between the implant bodies members distracted a distance greater than the thickness of the spacer;
• FIG. 31 is an exploded perspective view of the implant having an alternative spacer having a “wing” or extension extending laterally from each posterior side of the spacer for cooperating with the stabilizing posts thereby to prevent anterior movement of the spacer beyond a predetermined location for the spacer between the body members;
• FIG. 32 is a posterior exploded perspective view of the implant and spacer illustrated inFIG. 31;
• FIG. 33 is a top plan view of the implant shown inFIGS. 31 and 32 with the alternative spacer positioned between the upper and lower body members with the wings or extensions bearing against their respective posts so as to prevent anterior movement of the spacer beyond the position of the spacer shown;
• FIG. 34 is a posterior side elevational view of the implant shown inFIG. 33;
• FIG. 35 is a top plan view of the lower body member having the alternate spacer positioned thereon with the left lateral side of the spacer bearing against the left post and with the wings or extensions bearing against the respective posterior faces of their respective posts so as to prevent anterior movement of the spacer relative to the lower body member beyond the position shown;
• FIG. 36 is a bottom perspective exploded view of still another embodiment the implant similar to that shown inFIGS. 31-35 in which the spacer has a pair of “wings” or tabs on one end and a single “wing” or tab on the other end with the space between the pair of tabs being spaced as to receive a post such that with the spacer inserted between the implant bodies and rotated such that the spacer is substantially parallel to the implant bodies where the posterior tabs prevent anterior movement of the spacer relative to the posts and the anterior tab prevents posterior movement of the spacer;
• FIG. 37 is a top perspective exploded view of the implant and spacer shown inFIG. 36;
• FIG. 38 is a top plan view of the implant and the spacer showing the spacer prior to being inserted between the implant bodies oriented at an angle with respect to the implant body so as to be inserted between the implant bodies;
• FIG. 39 is a view similar toFIG. 38 with the spacer partially inserted between the upper and lower implant bodies with a stabilizing post received between the pair of spaced wings or tabs;
• FIG. 40 is a view similar toFIG. 39 showing the spacer partially rotated toward its installed position in which the spacer is substantially parallel to the body members;
• FIG. 41 is a view similar toFIG. 40 showing the spacer in its fully installed position;
• FIG. 42 is a perspective view of another embodiment of an expandable or variable height implant of the present disclosure (shown without its spacer positioned between the inner faces of its upper and lower body members) having angled (tapered) upper and lower surfaces for treating or correcting certain lordotic conditions;
• FIG. 43 is a top plan view of the lower body of the implant shown inFIG. 42;
• FIG. 44 is a posterior elevational view of the implant ofFIGS. 42 and 43;
• FIG. 45 is a bottom plan view of the implant ofFIGS. 42-44;
• FIG. 46 is a side elevational view of the implant ofFIGS. 42-45 illustrating the angled upper and lower faces that constitute a lordosis angle for treating or correcting certain lordotic conditions;
• FIG. 47 is a side elevational view of the implant ofFIGS. 42-46 on an enlarged scale illustrating a lordosis angle of both the upper and lower body members;
• FIG. 48 is a perspective view of still another embodiment of the implant of this disclosure where the implant is a one piece non-expandable implant, but rather is of a fixed height, where such implant has angled or tapered upper and lower surfaces and may be readily utilized in accordance with the methods of this disclosure;
• FIG. 49 is a top plan view of the implant ofFIG. 48;
• FIG. 50 is a front elevational view of the implant ofFIGS. 48, 49;
• FIG. 51 is a bottom plan view of the implant ofFIGS. 48-50;
• FIG. 52 is a side elevational view of the implant ofFIGS. 48-51 illustrating the lordosis angles of the upper and lower surfaces of the implant;
• FIG. 53 is a side elevational view of the implant ofFIGS. 48-52 on an enlarged scale illustrating the lordosis angles of the upper and lower surfaces of the implant;
• FIG. 54 is a perspective view of still another non-expandable embodiment of the implant of this disclosure where such implant is fenestrated having openings therein and where such implant may be readily utilized in accordance with the methods of this disclosure;
• FIG. 55 is a top plan view of the implant ofFIG. 54;
• FIG. 56 is a front elevational view of the implant ofFIGS. 54, 55;
• FIG. 57 is a bottom plan view of the implant ofFIGS. 54-57;
• FIG. 58 is a side elevational view of the implant ofFIGS. 54-57 illustrated the angles upper and lower surfaces of the implant;
• FIG. 59 is a side elevational view of the implant ofFIGS. 54-58 on an enlarged scale illustrating a lordosis angle for the upper and lower surfaces of the implant;
• FIG. 60 is posterior top perspective view of still another embodiment of the implant of the present disclosure where the upper and lower body members have a slot in their respective inner faces and where the spacer may have a corresponding slot in register with either the slot in the upper or the lower body member where the posterior ends of these slots may be somewhat wider than the remainder of the slot so as to aid in guiding the operating tips of a distractor or other instrument into the slots;
• FIG. 61 is an exploded perspective view of the implant shown inFIG. 60, as viewed from above;
• FIG. 62 is a posterior bottom perspective view of the implant shown inFIGS. 60 and 61;
• FIG. 63 is an exploded perspective view of the implant shown inFIGS. 60-62 illustrating the slot in the upper face of the spacer;
• FIG. 64 is a top perspective view of another embodiment of the implant of the present disclosure similar to the implant shown inFIGS. 60-63 with the spacer omitted for illustration purposes, but where the bottom body member is split so that it may be assembled around the flanged posts protruding from the bottom of the upper body member and then adhesively joined so posts are captured in the corresponding holes in the bottom body member, with the halves of the bottom body member each having an alignment pin adapted to be received in a corresponding hole in the opposite bottom body member half;
• FIG. 65 is a bottom perspective exploded view of the implant shown inFIG. 64;
• FIG. 66 is an exploded perspective view of a distractor instrument used to distract the implant of this disclosure in situ having operating tips in accordance with the instant disclosure with the distal end of one (or both) of the operating tips having a cleat or hook for engagement with the anterior surface of one of the implant body members when the operating tips are fully inserted into and through the slots in the upper and lower body member such that the cleat engages the implant and allows the implant to be maneuvered within the disc space and allows the implant and the adjacent vertebrae to be distracted without becoming disengaged from the distractor;
• FIG. 67 is a right perspective view of the distractor ofFIG. 66 having the operating tips installed;
• FIG. 68 is a left elevation view of the distractor ofFIG. 66 illustrating a gap between the inner surfaces of the operating tips through which a spacer of the implant of the present disclosure may be inserted into the disc space and inserted between the inner surfaces of the distracted upper and lower body members of the implant;
• FIG. 69 is a top plan view of the distractor and operating tips ofFIG. 68;
• FIG. 70 is a front elevational view of the distractor and operating tips ofFIG. 68;
• FIG. 71 is a view similar toFIG. 4 showing the distractor ofFIGS. 66-70 with its operating tips and operating arms of the distractor inserted through the incision in the posterior lateral quadrant of the annulus with a paddle blade distractor inserted into the gap between the inner faces of the operating arms/tips of the distractor so that upon rotation of the paddle blade distractor about its longitudinal axis by the surgeon the implant of this disclosure and the adjacent vertebrae are distracted a first increment corresponding to the width of the paddle blade distractor so as to insure that the upper and lower implant body members are distracted a first known increment and so as to insure that the operating tips of the distractor are generally parallel;
• FIG. 72 is a perspective view of a paddle blade distractor having a T-handle and a paddle blade having an operating tip or distal end of a predetermined width;
• FIG. 73 is a view somewhat similar toFIG. 4 with the annulus omitted for purposes of clarity illustrating the distraction of two adjacent vertebrae (e.g., L3 and L4) with an implant of the present disclosure inserted in the manner shown inFIG. 4 and with the operating tips of a distractor, such as shown inFIGS. 66-70, positioned between the inner faces of the upper and lower body members of the implant so as to distract the implant and the vertebrae upon actuation of the distractor;
• FIG. 74 is a view similar toFIG. 73 illustrating the insertion of a paddle blade distractor, such as shown inFIGS. 71 and 72, inserted between the inner faces of the operating tips of the distractor so as to distract the implant at least the width of the operating tip of the paddle blade distractor and to return the operating tips to a substantially parallel relation to one another in the event that the thin operating tips have deflected somewhat (from the position that they are shown inFIG. 74) upon operation of the parallel distractor; and
• FIG. 75 is a view similar toFIG. 74 with the paddle blade distractor rotated about 90° from its position shown inFIG. 74, and with portions of the operating tips of the parallel distractor, the operating blade of the paddle blade distractor, and the upper and lower body members of the implant being shown in cross section illustrating how the distal end of the paddle blade distractor distracts the implant (and thus also distracts the disc space) and insures that the operating tips of the parallel distractor are returned to a substantially parallel condition upon the paddle blade distractor being rotated approximately 900.
• Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
DESCRIPTION OF PREFERRED EMBODIMENTS
• Referring now to the drawings and particularly toFIGS. 1-4C, a first embodiment of a lumbar disc implant device of the present disclosure is generally indicated at1 (seeFIG. 2), and is shown in its intended environment installed within the disc space DS between two adjacent human vertebrae to be fused together. Oftentimes theintervertebral disc3 between two adjacent vertebrae (e.g., between lumbar vertebrae L3 and L4, or between lumbar vertebrae L4 and L5) may become degenerated and mechanically incompetent with subsequent loss of height between the adjacent vertebrae with resultant pain and loss of motion. It has become common practice to surgically reconstruct the degenerateddisc3 between the opposing surfaces of the vertebrae bodies and to insert a structural implant within the disc space between the vertebrae so as to space the vertebrae apart a desired distance thus restoring disc space height, and to bear normal biomechanical loads in the spine until a solid spinal fusion occurs. As is conventional, bone graft material (not shown) is introduced into the disc space for fusing the adjacent vertebrae together as the bone graft material grows. Also, such prior disc structural implants are stabilized by known vertebrae fixation devices, such as pedicle screw and rod fixation, which are widely known, but are not shown in the drawings.
• As shown inFIG. 4A, an approach is made generally in accord with known transforaminal interbody fusion (TLIF) procedures. Specifically, with the patient in a prone position, fluoroscopy localization is used to place an incision at the desired level. Either an open approach or an approach using atubular retractor7, as shown inFIG. 4A, may be used, as is well known in the art. Such a posterolateral TLIF approach is familiar to spine surgeons and does not risk the great vessels and abdominal viscera associated with ALIF (Anterior Lumbar Interbody Fusion) procedures nor does such an approach require an anterior access surgeon. Further, the TLIF approach does not risk injury to the lumbar plexus.
• Further as shown inFIG. 4B, transforaminal access to the disc space DS between the vertebrae is achieved by resection of the inferior facet IF of L3, a portion of the pars interarticularis, and a portion of the superior facet SF of L4. Distraction (i.e., the forcing apart or separation of the vertebrae surfaces) to improve the working corridor may be achieved by using a laminar spreader or pedicle screws, both of which are well-known in the art and which are therefore not shown. Discectomy, a surgical procedure for removal of the disc material from within theannulus9, is performed through an incision orannulotomy11, preferably, but not necessarily, a posterior oblique annulotomy, within the operative field (shown inFIGS. 1 and 4C) made in thewall13 of theannulus9. Endplate preparation follows using standard procedures and instruments including cupped curettes, ring curettes, box curettes, broaches, box chisels, rasps, and pituitary rongers. All of the disc material between the adjacent vertebrae bodies is removed while thewalls13 ofannulus9 are preserved. The cartilaginous endplates of the vertebrae are removed down to bleeding bone, but care is taken to preserve the cortical endplate, especially anteriorly.
• More specifically and as shown inFIG. 4C, incision (annulotomy)11 inannulus9 permits perforations or openings (also referred to as annulotomies)15a,15b, as best shown inFIG. 4, to be made in opposite lateral sides of the anterior annulus such that these openings are generally laterally symmetrical. Those skilled in the art will recognize that a surgeon having access to the interior of the disc space DS viaincision11 will, with proper vision magnification (e.g., a loupe or with endoscopic assistance), be able to make afirst opening15adistal from andopposite incision11. Then, the surgeon can make thesecond opening15bgenerally across the annulus from thefirst opening15aon the opposite anterolateral side of the disc or the annulus (i.e., in the ipsilateral quadrant of the disc relative to incision11). These annulotomies (includingincision11 andopenings15a,15b) also serve as anterior and posterior releases to facilitate disc space DS distraction.
• More specifically, theseanterior annulotomies15a,15bmay be further relaxed using a variety of techniques including the use of so-called “trials” and distractor instruments, as are well known to those skilled in the art. It is common for surgeons to utilize metal trial implants (not shown) for gaging the size of the actual implant to be used where the trial is at least in part shaped like theimplant1 to be used. Such trials are typically provided in a range of widths, lengths and heights. With the disc space DS at least partially distracted, the surgeon will install a first trial, typically of a smaller size, length, width or height than theimplant1 that will be finally installed, through the anterior annulotomies. These trials are used to aid in distracting the vertebrae and to hold the vertebrae in this desired distracted position. After the ligaments and the annulus at least partially relax, further distraction of the disc space may be accomplished by actuation of a parallel distractor applied to the anterior annulotomies bilaterally. Another trial, typically somewhat larger than the first trial, may be inserted if further relaxation of the anterior annulotomies is required. It will be understood that the trials can be used to judge the width and height of the size of theactual implant1 to be employed. Then, with the disc space DS prepared, theimplant1 of the proper height, length, and width will be installed, preferably in the manner discussed below.
• FIG. 4D is a view similar toFIG. 4, but where theimplant1 has been removed from the disc space DS so as to better show theincision11, thefirst opening15a, and thesecond opening15b, as they may be formed inannulus9.
• FIG. 4E is a view similar toFIG. 4D, but where one elongate incision, as indicated at A1, is made inannulus9, where the posterior portion of the elongate incision incorporatesincision11 and where the anterior portion of the elongate incision incorporates thesecond opening15b. Still further, thefirst opening15ais incorporated in an elongate incision A2. These elongate incisions A1 and A2 help relax the annulus. As will be particularly described below in regard toFIGS. 4M-4O, the elongate incision A1 allows for the insertion of endoscopic and surgical instruments so that the surgeon may perform the discectomy of the disc space DS under endoscopic viewing.
• FIG. 4F is a diagrammatic axial illustration of the vertebrae and theannulus9 showing the Sagittal Midline Axis, the Coronal Midline Axis of the Disc, and other prominent anatomical features of the vertebrae and the approximate location ofincision11 andopenings15aand15billustrated inFIGS. 4 and 4D. Alternatively, as shown inFIGS. 4E and 4G, theincision11 and thesecond opening15bmay be formed by a single elongate annulotomy A1 where theincision11 is a posterior portion of the elongate annulotomy A1 and where thesecond opening15bis the anterior portion of the elongate annulotomy A1, and where thefirst opening15amay be the anterior portion of another elongate annulotomy A2 on the opposite side of theannulus9. These elongate annulotomies A1 and A2 relax the annulus and release the disc space to better facilitate the distraction of the adjacent vertebrae. It will be appreciated that the elongate annulotomies A1 and/or A2 serve to maximize the release of the disc space DS and the relaxation ofannulus9 to facilitate distraction. Still further, the elongate annulotomies A1 and/or A2 facilitate discectomy and/or end plate preparation by allowing the surgeon to have a larger field of view of the disc space, either with increased magnification (e.g., a loupe) or with endoscopic assistance (as shown inFIGS. 4M-4O). It will be appreciated that the elongate annulotomies A1 and A3 afford increased room for the insertion of surgical instruments SI (either manual or powered instruments), as shown inFIG. 4N, for performing surgical procedures within the disc space DS, such as discectomy and end plate preparation, and for enhancing the surgeon's field of view of the disc space. Examples of manual surgical instruments may include, but may not be limited to, the above described cupped curettes, ring curettes, broaches, box chisels, rasps, and pituitary rongers. Further, the elongate annulotomy A1 allows an endoscopic light delivery system to illuminate the disc space and an endoscopic lens system to transmit the image to be viewed by the surgeon. Endoscopic apparatus, such as indicated at801 inFIGS. 4M-4O, which is described in detail below, may be used. An advantage to being able to perform the discectomy and/or endplate preparation under endoscopic viewing is that power tools, such as the Midas Rex Spine Shaver Nucleus Removal Set, commercially available from Medtronic, Inc. of Minneapolis, Minn., may be used because the surgeon now has the ability to see and to better control the use of such instruments.
• As shown inFIGS. 4, 4D, and 4F, theincision11 is formed in the posterior lateral quadrant of the disc space DS in the position generally as shown inFIG. 4F. Further, thefirst opening15ais formed in theannulus9 in the generally opposite anterior lateral quadrant of the disc space and thesecond opening15bis formed in the contralateral anterior quadrant (i.e., on the same side as incision as11 or in the ipsilateral anterior lateral quadrant relative to incision11). It will be understood that if it is desired that the approach be from the contralateral side, the openings would be reversed from their position as shown inFIG. 4. Also, the direction of theslots31a,31bin the implant will be reversed.
• More specifically, it will be understood by those of ordinary skill in the art that theincision11 and theopenings15a,15bmay be the mirror image of their locations shown inFIG. 4F, and that the elongate openings or incisions A1 and A2 may be the mirror image of their locations shown inFIG. 4G. It will also be understood by one skilled in the art that the location and the length of the incisions oropenings11,15a,15b, A1 and A2, as shown inFIGS. 4F and 4G, are only the approximate locations of these incisions or openings in theannulus9 and that a surgeon using the implants and methods of this disclosure may vary, at the surgeon's discretion, alter the locations and lengths of these incisions and openings to fit the anatomical features of the particular patient undergoing the operation. It will also be understood that even if the elongate incisions A1 and A2 are not employed, theincision11 and theopenings15a,15bmay be considerably longer than is shown inFIGS. 4D and 4F.
• Referring now toFIGS. 4H-K and FIGS. N-O, it will be noted inFIG. 4H that the incision A3 in the posterior lateral quadrant is considerably longer thanincision11 and that includesincision11. It has been found that such a longer incision relaxes the annulus thereby facilitating discectomy and distraction of the disc space DS. This longer incision A3 is diagrammatically illustrated inFIG. 4I.
• As shown inFIG. 4J, after discectomy of the disc space DS, an implant, as generally indicated in its entirety at I made in accordance with any of the embodiments disclosed herein or any other conventional implant may be inserted into the anterior region of the disc space, where the implant is supported on the end plates of the vertebra. This implant I maintains distraction of the disc space while bone growth or bone graft material (not shown) is packed into the remaining area of the disc space fuses the vertebra.
• As shown inFIG. 4K, an implant I′ may be somewhat longer than implant I shown inFIG. 4J where one end of the implant I′ may partially extend through the anterior portion of incision A3 so that this one end of the implant is supported on the cortical rim CR. Again, implant I′ may be any of the embodiments of the implants disclosed herein or any other conventional implants.
• FIG. 4L is similar toFIGS. 4E and 4G having elongate incisions or annulotomies A1 and A2 inannulus9 with an implant I″ installed within disc space DS extending across the anterior region of the vertebrae bodies VB where the ends of the implant I″ are supported on the cortical rims CR of the vertebrae bodies. Implant I″ may be any of the embodiments of the implants disclosed herein or any other conventional implants.
• FIG. 4M illustrates endoscopicsurgical apparatus801 that may be employed to aid the surgeon in performing the discectomy of the disc space DS thus giving the surgeon the ability to view the disc space while the discectomy is being performed. Heretofore, the surgeon performed the discectomy “blind” and was not able to see into the disc space. In accordance with the present disclosure there is an advantage of performing the discectomy under endoscopic viewing because the surgeon can typically perform the discectomy faster and can visually insure that the discectomy is properly performed such that little or no debris remains in the disc space after discectomy, where such debris may interfere with the growth of the bone growth material packed into the disc space and with the fusing of the vertebra.
• As is conventional, such endoscopicsurgical apparatus801 includes ahousing803 and a fiber opticlight transmitting tube805 that transmits light from803 to a lens in the distal end of the tube to illuminate the disc space. Additionally, the end of thetube805 includes awide angle lens807 which transmits an image of the disc space viatube805 to a wireless transmitter inhousing803 to a wirelessreceiver base station809, which in turn displays the image on amonitor811 to be viewed by the surgeon performing the discectomy. It will be appreciated that, as is conventional, the surgeon may griphousing803 to maneuver the distal end of thelight tube805 in the disc space so as to allow the surgeon to view different areas of the disc space. It is also appreciated that in lieu of wireless coupling of fiber optic endoscope to monitor cables maybe used.
• As shown inFIG. 4N, the elongate incision A3 provides ample room for the insertion of theendoscopic tube805 and thelens807 so that the surgeon may operate surgical instruments SI (either manual or powered) to perform the discectomy under endoscopic viewing.
• FIG. 4O shows that there is ample room within the disc space DS with the elongate incision A3. It will be appreciated that initial endplate preparation may be carried out prior to distraction. However, after the disc space has been distracted and after the implant is in place between the adjacent vertebrae bodies VB, a surgeon may prefer to complete endplate preparation under endoscopic viewing so as to result in better preparation.
• Implants1 are available in a series of various predetermined lengths, widths and heights to best fit particular patients. For example, the length of atypical implant1 may be about 50 mm and about 8.5 mm tall. Calipers or trials (not shown) are used to measure and size the anterior disc space and to determine the length of theimplant1 to be used. Intraoperative fluoroscopy will aid in these measurements.
• With the desired final height, width and length of theimplant1 determined, and with the implant in its collapsed or retracted position (for example, withspacer35 removed from between thebody members17 and19 and with the inner faces of the body members in contact with one another), the implant is inserted into the disc space DS viaincision11 at an oblique angle using the implant applicator (not shown) or other suitable instrument. The implant applicator grasps the implant firmly allowing controlled insertion and positioning of the distal end of the implant thru thecontralateral anterior annulotomy15a. The insertion of the implant is also disclosed in conjunction with thedistractor601, as described hereinafter. Once the proximal end of the implant is within the disc space DS, the applicator is removed. The parallel distractor may be used to maneuver implant into final position with both ends protruding throughanterior annulotomies15a,15b, generally as shown inFIG. 4.
• In this manner, the implant bears against and is supported at least in part by the cortical rim CR of both the upper and lower vertebrae. Fluoroscopic confirmation (as hereinafter described) of optimal positioning utilizing radiographic markers, as indicated at43 inFIGS. 5 and 6, embedded in the implant is carried out. After theimplant1 has been so oriented and positioned within the disc space DS, the blades of a parallel distractor (not shown inFIG. 4, but which distractor may be similar to thedistractor601 hereinafter described) are inserted into the disc space viaincision11 in theannulus9. The disc space and the implant are then further distracted and a spacer, as indicated at35 and as shown below, is installed within the implant in a manner as will appear. Upon removal of the parallel distractor and upon applying compression to the construct, theimplant bodies17,19 and thespacer35 will maintain theimplant1 in its desired height.
• Referring now toFIGS. 5-17, theimplant1 of the present disclosure will now be described in detail. As shown inFIG. 5,implant1 has a pair ofseparate body members17 and19, withbody member17 being referred to as a lower body member and withbody member19 being referred to as an upper body member with aspace21 therebetween. It will be appreciated that with the inner faces of the body members touching one another thespace21 is minimized and the overall height of the implant is minimized. Withimplant1 in this position, it has a low profile that facilitates insertion and final positioning within disc space DS. Further, with thebody members17 and19 spaced apart a maximum distance, the implant is in its fully distracted position. The height ofimplant1 thus may be expanded in situ a desired amount to enable distraction of the degenerateddisc3 to normal anatomic height with appropriate tensioning of theannulus9 and stabilizing ligaments.
• As best shown inFIG. 13, theupper member19 has a pair of spaced stabilizingposts23a,23bextending down intospace21. These stabilizingposts23a,23bare each received in arespective bore25a,25bin thelower member17. As indicated at27, each bore25a,25bhas an inwardly extending flange of somewhat smaller diameter than the remainder of the bore, with the diameter of theflange27 being only somewhat larger than the diameter of the stabilizingposts23a,23b. Further, at the distal end of each of the stabilizing posts, anenlarged head29 is provided with the head being somewhat larger than the diameter of the post and being somewhat larger than the bore inflange27. In this manner, with the posts received in their respective bores, theheads29 on the end of each post cooperates withflange27 so as to prevent thebody members19 and21 from becoming distracted (moved apart) more than a predetermined distance. As best shown inFIG. 17, each of the stabilizingposts23a,23bmay have an optionallongitudinal slot30 which enables the post to be somewhat resiliently compressed so that theflanges29 on the ends of the posts may be inserted through the bores thus allowing the posts to be received in theirrespective bores25a,25b. Once the posts have been inserted in the bores, the posts will spring back to resume their shape and size prior to being compressed. It will be further understood that the bodies ofposts23a,23bpreferably have a sliding close fit within the bores of theirrespective flanges27 such that the posts stabilize the upper and lower body members relative to one another so as to resist the body members from twisting, shearing, or tipping relative to one another in all directions. These stabilizing posts help maintain thebody members17 and19 oriented in a desired parallel relation to one another as theimplant1 is inserted within the disc space DS and distracted, in the manner as will be hereinafter described. Further, the provision offlanges27 and29 provide a tactile feel that prevents over distraction of thebody members17 and19. While the above-described stabilizingposts23a,23bhave been described as havingslots30 therein, it will be understood that the slots may be omitted and that the posts may be solid members.
• As perhaps best shown inFIG. 18, each of thebody members17 and19 has a respective oblique or angledslot31a,31bformed in its inner face. When the body members are assembled as shown inFIG. 13 and with theimplant1 installed as described above with the implant bearing on the cortical rims CR of the vertebrae bodies, theslots31a,31bare oriented so as to be generally in alignment withincision11 inannulus9 so to allow the blades of a distractor instrument (which may be similar todistractor601 hereinafter described) to be inserted in line into these slots. With the operating blades of the distractor received inslots31a,31b, the distractor may then be operated so as to distract thebody members17 and19 and so as to simultaneously distract the vertebrae bodies on opposite sides of the disc space DS a desired amount. The parallel distractor is used to expand thespace21 between thebody members17 and19 using preoperative imagining and intraoperative tactile feedback of annular and ligamentous tensioning. Of course, whenspacer35 of the proper predetermined thickness is inserted inspace21, the desired amount of distraction is maintained. It will be appreciated that theangled slots31a,31bare substantially centered with respect toimplant1 so as to balance the distraction loading and so as to minimize binding of the stabilizingposts23a,23bwithin the openings offlanges27 upon distraction and retraction of the body members relative to one another.
• Aspacer35 of predetermined thickness is insertable within thespace21 betweenbody members17 and19 once the disc space DS and thebody members17 and19 ofimplant1 have been distracted the desired amount. In accordance with this disclosure, a series ofspacers35 of predetermined thicknesses may be provided so that, depending on the amount of distraction needed, and depending on the disc space and the anatomical characteristics of the patient, a spacer is provided for the amount of distraction required. For example, spacers35 may be provided in predetermined thicknesses of, for example, 1 mm, 2 mm, 3 mm, etc. The shape and size ofspacers35 distribute the anatomical spinal loads over a relatively wide surface area of the upper andlower body members17,19. The geometry ofslots31a,31bfacilitates easy withdrawal of the distractor instrument after shim orspacer35 has been properly positioned between theimplant members17 and19. Of course, it will be recognized that the distractor instrument may be used for final positioning and placement ofimplant1 within the disc space.
• As shown inFIG. 4, the length ofimplant1 is sufficient so as to span the disc space DS anteriorly, and to bear on the cortical rims CR of the vertebrae bodies. Theupper face37 ofupper body19 and thelower face39 oflower body17 are preferably of a convex shape so as to generally conform anatomically to the disc space contacting the vertebrae endplates. This anatomic fit of the implant relative to the adjacent vertebrae in addition to the load sharing with the cortical rims of the vertebral bodies will maximize the load bearing capability of the implant. The outer faces37 and39 ofbody members19 and17 may be appropriately textured so as to prevent migration of the implant relative to the vertebrae. Still further, the outer anterior ends of the lower and upper body members are radiused, as indicated at41, so as to generally conform toannulus9 when the implant is positioned bilaterally within the disc space DS with the outer ends of the implant in bearing engagement with the hard cortical rims CR of the upper and lower vertebrae bodies. It will be noted that, as shown inFIG. 4, the ends ofimplant1 may protrude somewhat through the annulotomies oropenings15a,15bin theannulus9. However, it will be understood that the anterior ends41 of the lower and upper body members may be shaped to generally conform to the shape of the disc space DS so that they do not substantially project out beyond the outer surfaces of the vertebrae bodies. Of course, if the lower and upper body members are so shaped to better conform to the vertebrae bodies and to reduce the protrusion of the ends of the body members out beyond thedisc3, the ends ofspacer35 would be similarly shaped.
• After the implant has been inserted in the disc space DS and oriented and positioned as above described with the ends of the implant supported at least in part by the cortical rims CR of the upper and lower vertebrae bodies and after the implant has been distracted as described and the desiredthickness spacer35 has been inserted between the lower andupper bodies17 and19, bone graft material may be packed between the implant and the posterior annulus filling the disc space. Of course, depending on the height of the cortical rim and the depth of the end plate after preparation for receiving bone graft material, the implant may also be supported at least in part by the end plates of the adjacent vertebrae bodies. It will also be understood that vertebrae fixation will be used in conjunction withimplant1. The fixation system used in conjunction withimplant1 is conventional and no particular system is preferred. It will be understood that as the bone graft material grows within and substantially fills the disc space DS, the vertebrae will be fused by this bone growth.
• It will be understood that the lower andupper bodies17 and19 ofimplant1 andspacer35 may be made of any suitable material such as surgical stainless steel, titanium, polyetheretherketone (PEEK), or carbon fiber reinforced PEEK, other surgical grade polymer or other material. Of course, theimplant1 and the spacers are delivered to the operating room in a sterile condition, and are available in a variety of lengths and profiles to as optimize patient fit. It may be preferable thatimplant1 be made of PEEK because the modulus of elasticity of PEEK is similar to the modulus of elasticity of bone. However, PEEK is substantially radiolucent and thus is not readily viewable in radiographs. If PEEK is used for the implant, it is preferable that radio opaque markers, as indicated at43 (as shown inFIGS. 5 and 6), be inserted within the implant so that the position and orientation of the implant may be fluoroscopically verified once the implant has been inserted in the disc space DS. Preferably,markers43 are made of tantalum or other suitable metal so as to show more clearly on radiographic images.
• Withimplant1 properly positioned between the vertebrae, with the implant properly distracted, withspacer35 of the proper thickness inserted betweenbody members17 and19, and with the afore-mentioned bone graft material packed between the implant and the posterior annulus, conventional posterior spinal fixation appliances (not shown), such as pedicle screws, are applied. Compression is applied to the entire construct so as to restore or maintain sagittal alignment, so as to fixate thestructural implant1 within the disc space DS between adjacent vertebrae, and so as to provide the optimal environment for bone fusion of the vertebrae.
• Referring now toFIGS. 19-41, a second embodiment of the implant of this disclosure is indicated in its entirety byreference character101. The “primed” reference characters shown inFIGS. 19-30 ranging between1 and43 indicate parts having substantially the same construction and function as the parts identified by these reference characters1-43 inFIGS. 1-18. However, some of these components have been modified to carry out a somewhat different function, as will be described.
• As shown inFIG. 19,lower body member17′ has atab103 extending upwardly from the inner surface of one of the body members, for example, the lower body member along the anterior end thereof. Thistab103 extends up from the upper surface of the lower body member a distance sufficient so as to be at least partially slidingly received in acorresponding groove105 formed in theanterior wall107 of the other body member, for example,upper body member19′ when aspacer35′ is received withinspace21′ between the upper and lower body members and when the upper and lower body members are at least partially retracted withspacer35′ disposed therebetween. In this manner,tab103 prevents movement of the spacer beyond the anterior end of the body members and thus self-locates the spacer in anterior/posterior direction. The tab further prevents anterior migration of thespacer35′ beyond the anterior edge oflower body member17′ during normal use of the implant by the patient. Whiletab103 is shown to be an elongate single tab extending along the anterior edge of thespacer35′, it will be understood that the tab may actually be two or more spaced tabs extending upwardly from the spacer.
• Referring now toFIGS. 21-30, the bottom face ofspacer35′ is shown to have a pair of downwardly projecting male protuberances, as indicated at109a,109b. Each of these protuberances has a generally part-spherical convex outer surface for purposes as will be described. Further, the upper surface oflower body member17′ has a corresponding pair of female recesses, as indicated at111a,111b, positioned to receive a respective protuberance. Each of these female recesses has a generally part-spherical concave surface that is engaged by its respective male protuberance. As shown best inFIGS. 22-28, eachrecess111a,111bis larger in diameter than itsrespective protuberances109a,109bfor purposes as will appear. As shown inFIG. 24, recesses111a,111bare spaced on opposite sides ofslot31b′ in areas of the upper surface oflower body member17′ large enough to accommodate the recesses. As further shown inFIG. 21,protuberances109a,109bare preferably spaced on opposite sides of a first centerline CL1 (as shown inFIG. 21) ofspacer35′ an equidistant amount. Therespective recesses111a,111bare also preferably equidistantly spaced on opposite side of a second centerline CL2 (as shown inFIG. 27) diametrically extending throughbores25a′,25b′ inlower body member17′. However, those skilled in the art will recognize that the location of the protuberances and the recesses may be at any desired location. It will be further understood that while two protuberances and two recesses are shown, that other numbers of and shapes of the protuberances and recesses may be utilized.
• It will be appreciated by those skilled in the art that instead ofprotuberances109a,109bbeing provided on the bottom face ofspacer35′, they may instead (or may in addition) be provided on the upper face of the spacer and therecesses111a,111bmay be provided on the lower face of theupper body member19′. Further, it will be understood that the recesses may be provided on the spacer and the protuberances may be provided on a cooperating inner face of an adjacent body member.
• It will also be appreciated that becauserecesses111a,111bare of larger diameter than theirrespective protuberance109a,109b, and because the generally part-spherical surfaces of the convex male protuberances engage the generally part-spherical female concave surfaces of their respective recesses, the mating convex surface of the protuberance acts like a cam follower and concave surfaces of the recesses act as a cam so that upon the application of compressive loads to theimplant101, the cooperating and complimentary protuberances and recesses will guide or force the protuberances to move downwardly toward the bottom of the concave recesses so as to self-position and/or to self-center the spacer relative to the body members. While the shape of the protuberances are recesses have been described as being preferably part-spherical, it will be understood that, in accordance with this disclosure, that other rounded shapes may be employed.
• In use, as the distractor instrument (not shown) is withdrawn fromslots31a′,31b′, as the disc space DS is retracted, and as compression is applied to the spinal column, this compression will tend to effect the above-described camming action that will self-center (or self-align) thespacer35′ in proper position within thespace21′ between the upper andlower body members19′ and17′. Further, with such compression loads applied to implant101,protuberances109a,109bwill interfere with (bear against) the sides of therecesses111a,111bthereby to securely hold or retainspacer35′ in its desired position withinspace21′. Further, the complimentary protuberances and recesses, when under compression loading, cooperate with one another so as to resist migration of the spacer relative to the body members during normal use by the patient. It will also be appreciated that the height of the protuberances and the depth of the recesses are such that with the protuberances received within their respective recesses, the protuberances may carry at least some of the compression load applied to spacer35′ by the upper andlower body members17′,19′ ofimplant101. Still further, with theprotuberances109a,109bpositioned in the bottom of theirrespective recesses111a,111b, respectively, the protuberances and the recesses prevent or resist movement (migration) and pull-out of the spacer relative to thebody members17′,19′ in all directions. Also, theposts23a,23bwill prevent lateral displacement of the spacer within theimplant101.
• It will be further noted inFIGS. 27 and 28 that with the spacer in its desired position, theprotuberances109a,109bare substantially centered relative to theirrespective recesses111a,111bso thatspacer35′ is substantially centered betweenposts23a′23b′. It will be appreciated that so long as each of said protuberances are received anywhere within its respective recess,spacer35′ will be properly positioned in a desired general location betweenbody members17′,19′. It will be understood that with each of the protuberances substantially centered with respect to its respective recess, that the spacer will be located or positioned in a nominal position relative to the body members, as illustrated inFIGS. 27 and 28.
• Further, it will be noted that the anterior end of thespacer35′ abuts against (or is in relatively close proximity to) the inner or posterior face oftab103. In this manner,tab103 cooperates with the anterior face ofspacer35′ to as to prevent anterior displacement of the spacer from its desired general position between thebody members17′,19′. Because of the interaction of the generally convex surfaces of the protuberances and the concave surfaces of their respective recesses,spacer35′ is effectively constrained against anterior, posterior, lateral, and angled movement relative to the upper and lower body members.
• Further, as previously described, bone graft material (not shown) is typically packed between the posterior face ofimplant101 and the inner face of the posterior annulus substantially filling the disc space DS such that bone graft material also aids in preventing posterior movement of thespacer35′ relative to the body members. Thus, it will be appreciated thattab103, and the cooperating generally rounded or part-spherical surfaces ofprotuberances109a,109band recesses111a,111b, and the bone graft material prevent migration of thespacer35′ relative to theimplant body members17′,19′ not only immediately following surgery, but also during normal use by the patient as the bone graft material fuses the vertebrae together.
• Referring now toFIGS. 29 and 30, thebody members17′ and19′ are shown withspacer35′ laterally offset to the left such that the left end of the spacer is in contact with stabilizingpost23a′ and such that theprotuberances109a,109bare disposed above the extreme left-hand reaches of theirrespective recesses111a,111b. Upon retraction of the disc space DS and upon the application of compression loads to the construct, the previously described camming action of the convex protuberances engaging the concave recesses cause the spacer to move or shift relative to the body members and to be at least partially self-aligned and self-centered with respect to the lower body members so as to be closer to its nominal desired general location, as shown inFIGS. 27 and 29. However, those skilled in the art will recognize that so long as the protuberances are received within their respective recesses, the spacer will be located within its desired general location and that such location results in an acceptable insertion and location of the spacer inimplant101.
• This self-centering, self-aligning feature of thespacer35′ means that upon installation ofspacer35′ during the surgical procedure, the surgeon need only place theimplant101 within the disc space DS (as described above in regard to implant1). With theimplant101 so positioned, the surgeon then, using the above-described distractor instrument, distractsbody members17′ and19′ and insertsspacer35′ withinspace21′ between the body members. It will be appreciated that due totab103, the stabilizingposts23a′,23b′, and the length of the spacer, the spacer need only be positioned between the posts and somewhat to the posterior oftab103 such that upon removal of the distractor instrument (which will allow retraction of the vertebrae) and upon the application of a compressive load to the spinal column, the above-described self-centering and self-aligning features of theprotuberances109a,109band recesses111a,111bwill move the spacer from the position as shown inFIGS. 29 and 30 to the substantially centered position of the spacer shown inFIGS. 27 and 28. Of course, if the spacer is shifted to the right, retraction and the application of compressive loads will also self-center and self-align the spacer. Additionally, if there is some angular displacement of the spacer, the protuberances and recesses will straighten the spacer relative to the body members in the same manner.
• Further, those skilled in the art will recognize that upon application of compression loads (as herein described) and/or upon the application of repeated micro-motion compressive spinal column loads by the patient, as during sitting or walking, the cooperatingprotuberances109a,109band recesses111a,111bmaintain the self-alignment and self-centering of the spacer relative to the upper and lower body members and prevent migration of the spacer relative to the body members.
• It will be further appreciated by those skilled in the art that if during the surgical procedure a first spacer is inserted withinspace21′ between thebody members17′ and19′ and if it is determined that the first spacer should be removed, the surgeon need only insert the distractor blades of the distractor instrument (not shown) intoslots31a′,31b′ of the body members so as to distract or expandspace21′. Then, thefirst spacer31′ may be readily removed by gripping the spacer with a clamp and removing it from between the body members and to withdraw the spacer through the above-describedincision11 in theannulus9, as shown inFIG. 4C. Then, a second spacer of, for example, a different (greater) thickness, may be readily inserted.
• As indicated at113a,113binFIGS. 19-30, a pair of holes is provided inspacer35′ so as to more readily permit the surgeon to grasp the spacer by means of a clamp or other instrument so as to enable the surgeon to maneuver the spacer withinspace21′ between thebody members17′,19′, or to remove the spacer.
• It will be further appreciated that with the expandable lumbar interbody orimplant1 of the present disclosure in its collapsed height condition withoutspacer35 installed between the upper andlower body members17,19, it is easier for the surgeon to insert the interbody into the disc space DS through theannulotomy11, and the interbody is more readily maneuverable by the surgeon within the disc space so that the interbody spans the apophyseal ring and so that the ends of the interbody are properly inserted in theanterolateral annulotomies15a.15b, as generally shown inFIG. 4. It will also be appreciated that with theinterbody1 in its collapsed condition, it is much easier to remove the interbody from the disc space.
• Referring now toFIGS. 31-35, an alternative embodiment ofspacer35′ is shown and is indicated in its entirety at35″. Thisspacer35″ is shown to have a pair of wings orextensions115a,115b, one on each end of the spacer, extending laterally from the posterior side of the spacer. The anterior faces of these wings or extensions bear against the posterior faces ofrespective posts23a′,23b′ so as to prevent anterior movement of thespacer35″ beyond its predetermined position, as shown inFIGS. 33 and 35. These wings are an alternative structure to or in addition totab103 for locating the spacer in anterior/posterior position relative to the body member and for preventing anterior movement of the spacer beyond a desired location. It will be further appreciated that the length of eachwing115a,115bis such that with the spacer positioned withinspace21′ (as shown inFIG. 35) such that one lateral side of the spacer bears against itsrespective post23a′ or23b′, the wing on the opposite lateral side of the spacer still engages the posterior face of its respective post such that both of the wings bear against their respective posts and thus positively prevent insertion of the space in anterior direction beyond a desired anterior position relative to thebody members17′,19′.
• Thus, upon installation of thespacer35″, the spacer need only be oriented itsprotuberances109a,109bfacingbody member17′, with thewings115a,115bfacing toward the posterior of theimplant101, with the body of the spacer positioned between theposts23a,23b′. Then upon retraction of the vertebrae spacing and upon the application of compression loading to theimplant101, the protuberances and the recesses will cooperate, as previously described, so as to self-center and to self-align the spacer relative to the body members. Further, with the protuberances received in their respective recesses and with such normal compression loads applied to the implant, the protuberances and recesses will effectively prevent movement or migration of the spacer relative to the body members. Still further, with bone graft material (not shown) packed within the disc space DS on the posterior side ofimplant101, the bone graft material will also aid the protuberances and recesses in preventing movement or migration of the space from between the body members.
• As shown best inFIG. 33,spacer35″ has an oblique slot117 extending part way through the upper or lower (or both) faces of the spacer. This slot provides clearance for an operating blade of a distractor to be inserted within the slot to aid in positioning the spacer between the inner faces of the body members of the implant. The slot117 in the spacer is generally in register with theslot31a′ or31b′ in its proximate body member.
• Referring now toFIGS. 36-41, an alternative embodiment ofspacer35′ is shown and is indicated in its entirety at35′″. Thisspacer35′″ is shown to have a pair of wings orextensions115a′″,115b′″, one on each lateral end of the spacer, extending laterally from the posterior side of the spacer. In addition, on the right-hand end of the spacer (as shown inFIG. 36) has anotherwing115c′″ spaced fromwing115b′″ with the space therebetween being sufficient so as to readily receive stabilizingpost23b′. The anterior faces of wings orextensions115a′″,115b′″ bear against the posterior faces ofposts23a′,23b′ so as to prevent anterior movement of thespacer35′″ beyond its predetermined position, as shown inFIG. 4I. In addition the inner or posterior face ofwing115c′″ is positioned to engage againstpost23b′ so as to prevent posterior movement of thespacer35′″. It will be further appreciated that the length of eachwing115a′″,115b′″, and115c′″ is such that with thespacer35′″ positioned withinspace21′ (as shown inFIG. 4I) such that one lateral side of the spacer bears against itsrespective post23a′ or23b′, thewing115a′″ or115b′″ on the opposite lateral side of the spacer still engages the posterior face of its respective post such that both of the wings bear against their respective posts and thus positively prevent insertion of the spacer in anterior direction beyond a desired anterior position relative to thebody members17′,19′.
• As shown inFIG. 38, upon installation ofspacer35′″, the spacer is oriented at an oblique angle with respect to theimplant bodies17′,19′ when the implant bodies are positioned between adjacent vertebrae and with the implant bodies distracted (as generally shown inFIG. 4) so as to receive that spacer inserted through anannulotomy11 on the opposite side from that shown inFIG. 4. As shown inFIG. 39, the spacer is moved diagonally betweenbody members17′,19′ untilpost23b′ is received betweenwings115b′″,115c′″. Then, as shown inFIG. 4O, the spacer is rotated so that thespacer35′″ is rotated clockwise aboutpost23b′ (as shown inFIG. 4O) untilwing115a′″ bears against the posterior surface ofpost23a′. In this position, post23b′ is received betweenwings115b′″ and115c′″ and wing115′″ bears against the posterior surface ofpost23a′.
• It will be appreciated that ifspacer35′″ is to be inserted through anannulotomy11 of the opposite side of the disc from that shown inFIG. 4, thespacer35′″ would be oriented to be a mirror image of thespacer35′″ shown inFIG. 38.
• Withspacer35′″ in the position shown in dotted lines inFIG. 4I, theprotuberances109a,109bare received inrecesses111a,111band the body of the spacer is positioned between theposts23a,23b′. Then upon retraction of the vertebrae spacing and upon the application of compression loading to theimplant101, the protuberances and the recesses will cooperate, as previously described, so as to self-center and to self-align the spacer relative to the body members. Further, with the protuberances received in their respective recesses and with such normal compression loads applied to the implant, the protuberances and recesses will effectively prevent movement or migration of the spacer relative to the body members. Still further, with bone graft material (not shown) packed within the disc space DS on the posterior side ofimplant101, the bone graft material will also aid the protuberances and recesses in preventing movement or migration of the space from between the body members. As noted, the spacedwings115b′″,115c′″ substantially prevent both anterior and posterior movement of the spacer relative to thebody members17′,19′ beyond a predetermined limited amount of movement.
• It will be further appreciated thatimplants1 and101 may be provided in a range of widths, thicknesses, and lengths to readily accommodate taller disc spaces DS and different vertebrae sizes. For example,implants1,101 may have heights ranging between 8.5 mm-10.0 mm, to accommodate taller or shorter disc spaces DS and may have widths ranging between about 11-13 mm., and lengths ranging between about 40-60 mm. to accommodate vertebrae having a larger vertebrae footprint.
• Referring now toFIGS. 42-59, three additional embodiments of the implant of the present disclosure are illustrated in which the upper and lower surfaces of the implant are angled (tapered from rear to front) so as to provide options for encountered or desired disc space lordosis. Specifically referring to the embodiment shown inFIGS. 42-47, this is an expandable interbody or implant, as indicated in its entirety byreference character201. The construction of this interbody orimplant201 is similar to the embodiments discussed above andreference characters217,219, etc. indicate parts having a similar construction and operation as similar parts identified bysimilar reference characters17,19 etc. of the embodiment illustrated inFIGS. 1-41. Accordingly, only the primary differences betweenimplant201 and the above-described embodiments will be described in detail. InFIGS. 42-47, the implant is shown in its collapsed or retracted condition with nospacer35 installed between the inner surfaces of the lower andupper body members217 and219. However, it will be understood that with theimplant201 inserted in disc space DS, as described above, and with the lower and upper body members distracted, aspacer35,35′,35″, or35′″ may be inserted withinspace221 between the body members in the manner described above.
• As perhaps best shown inFIG. 47, theupper face237 ofupper body member219 and thelower face239 oflower body member217 are angled or tapered from rear to front at a lordotic angle LA. The lordotic angles ofvarious implants201 may range between about 0° and about 12°. It will be appreciated that the lordotic angles of the upper and lower body members may be different. Thus, upon encountering a patient having disc space lordosis,implants201 having the desired lordotic angles LA, as chosen by the surgeon, may be used so as to reconstruct the spine by maintaining segmental lordosis, regional lordosis, and global sagittal balance. More specifically, upon encountering a need to improve the segmental or disc space lordosis, animplant201 having a desired predetermined lordosis angle LA may be installed in disc space DS so that with the implant distracted, with anappropriate spacer35,35′,35″, or35′″ installed inspace21 between the lower and upper body members, with upper andlower faces237,239 of the implant engaging the cortical rims CR of the adjacent vertebrae bodies, and with the angled, convex shape of the upper and lower faces of the implant generally conforming to the disc space and contacting the vertebrae endplates, upon distracting the adjacent vertebrae bodies, the desired amount of lordotic correction may be introduced in the reconstructed disc space. It will be also appreciated that because theimplant201 is supported by the cortical rims CR of the vertebrae bodies, there is less of a tendency for subsidence to occur with a consequent loss of disc space height to preoperative levels.
• Referring now toFIGS. 49-53, still another embodiment of a non-expandable or fixed height interbody implant in accordance with the present disclosure is shown. This implant is indicated in its entirety byreference character301. As noted,implant301 is non-expandable or of fixed height and thus has a one-piece body303 having anupper surface305 and alower surface307. The rear face ofbody303 has aslot309 therein similar to slot31 of the above embodiments so that the implant maybe inserted into the disc space DS throughannulotomy11 and maneuvered within the disc space by the surgeon so that the ends of the implant bear on the cortical rims CR of the adjacent vertebrae bodies and such that the implant is positioned generally similar toimplant1, as illustrated inFIG. 4. It is also understood theslot309 may be replaced by another modification (not shown) of the fixed height implant interbody implant that would allow a surgeon to use a tool to grasp and maneuver the implant in the disc space. The upper andlower faces305 and305 are angled or tapered in a manner similar toimplant201 such that these upper and lower faces have a lordotic angle LA, which may range from about 0° to about 12°. Of course, the lordotic angles LA ofimplant301 may be used to maintain or correct disc space lordosis in the same manner as described in regard toimplant201.
• Turning now toFIGS. 54-59, still another embodiment of the present disclosure is illustrated in its entirety at301′. Thisimplant301′ is similar toimplant301, as above described, except that it has openings orfenestrations311 formed therein that may be packed with bone growth material so as to promote bone growth and to aid in fusing the adjacent vertebrae. This augments the bone graft material the surgeon places posterior to the implant for fusing or permanently joining the vertebrae bodies above and below the disc space. It will be understood that such fenestrations may be incorporated in any of the embodiments of the implants of this disclosure.
• Referring now to the embodiment of the implant of the present disclosure shown inFIGS. 60-65, this is essentially the same as the implant shown inFIGS. 42-47 and this new embodiment is indicated in its entirety byreference character401. The various features and parts ofimplant401 correspond generally to the corresponding to the features and parts of the body members and spacers shown inFIGS. 42-47, except as particularly pointed out and described below. Theimplant401 has alower body member417 and anupper body member419 with aspacer435 positioned between the inner faces of the upper and lower body members.Spacer435 is similar tospacer35″ shown inFIGS. 33-36, except that it has an oblique slot436 (as best shown inFIG. 61) in one face of the spacer that extends through the spacer from its posterior to its anterior edge. Likewise, the lower body member and the upper body member each have arespective oblique slot431a,431bin the inner face of each body member that extends through the body from the posterior to the anterior edge of the body member, with these slots being generally in register with one another. As indicated at421 for each of theslots436,431a, and431b, the posterior portion of these slots is preferably somewhat wider than the anterior portion of the slot so as to aid in guiding a respective operating blade of a distractor or other instrument into the slot, as will be more particularly described below. It will be appreciated that theslot436 inspacer435 may be in the bottom face of the spacer, or slots similar to slot436 may be provided in both the upper and lower faces of the spacer. It will also be appreciated that the slots shown inFIGS. 60-63 are used when the incision11 (as shown inFIG. 4) is in the posterolateral portion of theannulus9. However, the angle of the oblique slots may be reversed if theincision11 is on the contralateral side of the disc space. It will also be appreciated that the lower andupper body members417,419 ofimplant401 may have their upper and lower faces formed to have the lordotic angles LA, as shown inFIG. 47.
• Further,spacer435 may be provided with wings or extensions, as indicated at415a,415band415c, to be similar in construction and operation towings115a′″.115b′″, and115c′″ heretofore described in relation to the embodiment shown inFIGS. 36-41.
• Referring now toFIGS. 64 and 65, thelower body member417 ofimplant401 has been modified so as to facilitate capture ofposts423a,423bof theupper body member419 by forming thelower body member417 in two pieces, as indicated at417a,417b. Each of these body pieces has analignment pin451 extending from its inner face to be received in arespective bore453 in the opposite body piece such that the twobody pieces417a,417bcan be fitted together around posts423a,423bwith theflange429 on the outermost end of the posts received inbores425a,425bwith theflange429 positioned below the inwardly extendingflange427. With each of the alignment pins451 received in itsrespective bore453, the body pieces are in alignment with one another. A suitable adhesive or the like may be used to permanently join the body pieces once they are assembled.
• Referring now toFIGS. 66-70, a distractor instrument, as indicated in its entirety at601, is illustrated having upper and lower arms, as generally indicated at603 and605, made in accordance with this disclosure. It will be appreciated that the distractor is conventional and it has a parallelogram linkage, as indicated generally at607, such that upon compressing thehandles609,611 toward one another, the operating arms orblades603,605 are distracted (moved apart) relative to one another and are maintained in generally parallel relation. As is conventional,distractor601 has areturn spring610 to bias the handles apart from one another and acurved rack613 pivotally attached to one of the handles and extending through an opening in the other handle with the rack having a plurality ofteeth615 that cooperate with a spring biased pawl617 (as best shown inFIG. 68) carried by the other handle such that the distractor will automatically lock each time the handles are compressed a distance corresponding to the pitch of the teeth on the rack. In this manner, when the surgeon releases the handles, the distractor will be locked and the desired distraction will be maintained. Of course, thepawl617 may be disengaged so as to allow retraction.
• As best shown inFIGS. 66-70, the operatingarms603 and605 angle obliquely relative to thehandles609,611 at generally the same oblique angle as theannulotomy incision11 is positioned within the annulus, as shown inFIG. 4. It will be appreciated that such oblique angle of the operating arm positions the handles of thedistractor601 out of the surgeon's field of view of the operating site. The operatingarms603,605 each have a respective operating tip, as indicated at621,622, on their outer ends and these operating tips are relatively thin and are generally parallel to one another with a space or a gap619 (as best shown inFIG. 68) between the inner faces of the operating blades. In this disclosure, the term “operating members” may refer to either operatingarms603,605 and/or to the operatingtips621,622. With the operating blades inserted into and throughslots431a,431bof animplant401 positioned generally in the disc space DS (as shown inFIG. 4),distractor601 may be operated to distract bothimplant401 and the disc space. With the implant and the disc space so distracted, the obliquely oriented operatingarms603,605 present an opening formed by gap619 (as best shown inFIGS. 68 and 70) so as to receive thespacer435. The spacer is guided by the inner faces of the operatingarms603,605 and by the inner faces of operatingblades621,622 as the spacer is moved into position between the upper andlower implant bodies419,417, so that the spacer may assume its position as generally shown inFIG. 4.
• As shown best inFIG. 68, one of the thin operating blades ortips621 or622 may have on its distal end a cleat or hook623 on its distal end. This cleat may be on either the lower or the upper operating tip, or such cleats may be provided on both the upper and lower operating tips. With thedistractor tips621,622 inserted throughslots431aand431bof the lower and upperimplant body members417 and419, thecleat623, which as shown inFIG. 68 is on thelower operating tip622, engages the anterior face of thelower body member417 and the sides of the operating tips engage the sides of theslots431a.431band thus enable the surgeon to engage the anterior face of the lower body member and the sides of the upper and lower body members so that the implant may be readily positioned between the vertebrae in a desired anterior-to-posterior relation and in a desired lateral position generally corresponding to the position ofimplant1, as shown inFIG. 4, so that the implant is at least in part supported on the cortical rim CR of the vertebrae. It will be understood that because theposts423a,423bare received in theirrespective bores425a,425bof thelower body member417 such that the upper and lower body members are readily moved as a unit upon moving the distractor so as to position the implant within the disc space DS. It will be also understood that withcleat623 on thelower operating tip622, theslot431ain the lower body member may be somewhat deeper than theslot431bin the upper body member so as to accommodatecleat623.
• It will be further understood that as thedistractor601 is operated so as to distract the implant and the adjacent vertebrae, a considerable distraction force is applied to the operatingarms603,605 andtips621,622 such that the operating arms and tips may deflect and such that deflection may cause the implant to become displaced from the operating tips. Thecleat623, however, prevents the implant from moving toward the anterior relative to the distractor and thus the cleat aids in keeping the implant in its desired position as the implant and the disc space are distracted. Further, the cleat and the fact that the operating arms have a relatively good fit withinslots431a,431b, allow the surgeon to maneuver the implant within the disc space DS to the position shown inFIG. 4. Further, it will be appreciated that the upper and lower faces oftips621 and622 of operating arms orblades603,605 engage their respective upper andlower body members419 and417. Upon operation ofdistractor601 by the surgeon, bothimplant401 and the disc space DS are distracted. While the operatingtips621,623 ofdistractor601 may be used by the surgeon to maneuver or position theimplant1 within the disc space DS, it will be understood that within the scope of this disclosure, the surgeon may usedistractor601 to distract the adjacent vertebrae and the expandable implant and the surgeon may use another instrument that hooks onto the implant so that it may be readily maneuvered and positioned within the disc space.
• As noted, the flared or enlarged ends421 ofslots431a,431band436 aid in guiding the operating blades into the slots. It will be appreciated that theupper operating tip621 may also have a cleat similar to clear623 (not shown) that extends upwardly. It will be also realized that the thickness of the slots in the spacer and in the upper and lower body members ofimplant401 may be appropriately sized to accommodate such upwardly facing cleat.
• It will be appreciated that due to the length of the operatingarms603,605 and the relative thinness of the operatingtips621,622, and due to the relatively high forces necessary to distract the vertebrae, it is preferable that the operating blades and tips be made of a suitable high strength, high modulus of elasticity material, such as a suitable stainless steel alloy, such as Carpenter 465SS, so as to resist deflection. However, other suitable materials may be used.
• As described above,annulotomy incision11 may be formed in the contralateral posterolateral quadrant of theannulus9. In such case, theslots436,431a, and431binimplant401 would be reversed from their positions shown inFIGS. 60-65 so that the slots are generally along the axis of theannulotomy11. In such case, thedistractor601 would have the angle of its operatingarms603,605 reversed from the angle shown inFIGS. 66-70. As shown inFIG. 66, thearms603 and605 are removably secured to the parallelogram linkage so that they may be installed and removed without the use of tools (e.g., they may be snapped into position). Thus, if it is desired to change thearms603,605 for other arms that angle in the opposite direction from the position shown inFIGS. 66-70, the new arms may be readily installed.
• Referring now toFIGS. 71-75, after the surgeon has installed an implant of the present disclosure, such as indicated at401, and after the surgeon has operateddistractor601 so as to distract the disc space DS a first amount, a series of paddle blade distractors of different widths, one of which is shown inFIG. 72 and which is generally indicated in its entirety at701, may be used to insure that the disc space DS and the upper andlower body members417,419 of theimplant401 of this disclosure are progressively distracted predetermined amounts corresponding to the width of the particular paddle blade distractor being used until the desired distraction is achieved and so that the operatingarms603,605 andtips621 and622 ofdistractor601 are maintained in a generally parallel relation. For example, a set of four (4)paddle blade distractors701 may be used with each of the paddle blade distractors having apaddle blade703 with the width of the distal end or operatingtip705 of each of thepaddle blades703 being progressively wider, for example, 3 mm., 5 mm., 7 mm., and 9 mm. Except for the width of the distal ends705, these paddle blade distractors are generally the same and thus only one will be described in detail. Thepaddle blades703 of each of thepaddle blade distractors701 are of the same thickness (e.g., 2 mm.). However, as noted above, the width of thedistal end705 of the paddle blade constituting its operating end has a width corresponding to one of the above-mentioned series widths. A T-handle707 is affixed to theproximal end709 of thepaddle blade703. Theproximal end709 of each of the paddle blades has a width greater than the width of its respective distal end or operatingtip705 to provide maximum strength (resistance to torsion or twisting) when thehandle707 is rotated by the surgeon. The sides of thedistal end705 of the operating blade may either be parallel (as shown inFIG. 72), or the sides may have a slight taper.
• As shown best inFIG. 73,implant401 without itsspacer435 installed is positioned in the disc space DS similar to its position as shown inFIGS. 4 and 71. The operatingarms603,605 and theircorresponding operating tips621,622 of distractor601 (as shown by bold lines) are inserted between the inner faces of the upper andlower body members419 and417 ofimplant401 of the present disclosure. Thedistractor601 is then operated so as to distract (force apart) the lower andupper body members417 and419 and to distract the disc space DS between adjacent vertebrae (e.g., L3 and L4) a first increment. Then, as shown inFIG. 74, a firstpaddle blade distractor701 having the narrowest width (e.g., 3 mm.)operating blade705 may be inserted intogap619 between the operatingblades603,605 and theircorresponding operating tips621,622 ofdistractor601. The surgeon then rotates the T-handle707 approximately 90° (as shown inFIG. 75) so that the edges of the operating tip orblade705 bear against the inner faces of the operatingtips621,622 ofdistractor601 thereby to force the operating tips apart at least the width of operating blade705 (e.g., 3 mm.). As shown best inFIG. 75, because the edges of theoperating blade705 are substantially parallel (or may have a slight taper), as thepaddle blade distractor701 is rotated about the longitudinal axis ofblade703, the side edges of theoperating tip705 insure that the operatingarms603,605 and the relativelythin tips621,622 ofdistractor601 are returned to a parallel (or nearly parallel) condition if they deflected as thedistractor601 was actuated. Those skilled in the art will appreciate that when it is stated that theoperating blade705 is inserted withingap619 and when theoperating blade705 is rotated about its longitudinal axis, the edges of the operating blade may contact the inner surfaces of the operatingarms603,605, or the edges may or may not also contact the inner surfaces of operatingtips621,622. Likewise, if the edges of the operating blade bear against the inner faces of the operatingtips621,622, the edges may or may not engage the inner surfaces of the operatingarms630,605.
• Then, the surgeon may further operatedistractor601 to further distract the disc space and the upper and lower body members of the implant an additional amount. The firstpaddle blade distractor701 is removed from between the upper andlower body members419 and417 of implant410 and a next widerpaddle blade distractor701 having an operating blade somewhat wider (e.g., 5 mm.) may be inserted between the inner faces of operatingarms603 and605 ofdistractor601. As shown best inFIG. 75, this secondpaddle blade distractor701 is then rotated about 90° so as to insure that the upper and lower body members and the disc space are distracted an amount at least as wide as the width of the next wider paddle blade (e.g., 5 mm.) and to return the operatingtips621,622 to a parallel relation. This process may be repeated until the disc space has been sufficiently distracted to allow the insertion of theappropriate spacer435 ofimplant401 of the present disclosure. It will be understood that theoperating tip705 of the set of paddle blade retractors may have widths different from the 3 mm., 5 mm., 7 mm., and 9 mm widths described above and more or fewerpaddle blade distractors701 may be used in accordance with this disclosure.
• In accordance with the present disclosure, a method of distracting and fusing a disc space between two adjacent vertebrae bodies is described including the steps of making an incision in the annulus at the desired level to access a disc space between the adjacent vertebrae to be fused, where the incision is in a posterior lateral quadrant of the annulus and the incision is of sufficient length so as to permit the accommodate surgical instrumentation for performing surgical procedures within the disc space and so as to accommodate endoscopic instrumentation in the disc space so as to enable visualization of the disc space for the surgeon performing the surgical procedures. A discectomy of the disc material is performed within the annulus via the incision in the annulus under endoscopic viewing of the disc space. The endplates of the adjacent vertebrae bodies are prepared under endoscopic viewing of the disc space. It is understood that in accordance with the present disclosure, the surgeon may elect to perform surgical procedures within the disc space without endoscopic visualization. The implant is inserted into the disc space via the incision so as to extend substantially across the vertebrae bodies in the anterior region of the vertebrae bodies. And, the implant and the disc space are distracted a desired amount. It will be understood that the order of the steps of the above method (or any method described in the present disclosure) may not be critical, but as the steps are described in this disclosure, it is necessary to list one step before the other, but in the performance of the method, it is not necessary that the steps be performed in the order described.
• As various changes could be made in the above constructions and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims (6)

1. An expandable spinal implant for insertion in a disc space between two adjacent vertebrae bodies to be fused together by bone graft material placed in said disc space, said vertebrae bodies each having a cortical rim and an end plate within said cortical rim, said disc space being substantially defined by an annulus attached to said adjacent vertebrae bodies and by the endplates of said adjacent vertebrae bodies, said implant comprising an elongate body having a height and a width such that said implant may be inserted into the disc space through an incision in a posterior portion of the annulus, said implant having a length such that with said implant positioned within said disc space the implant may be oriented to extend across the disc space so that said implant is at least in part supported on said cortical rim of at least one of said vertebrae bodies, said implant having a lower body member and an upper body member each of which is adapted to be cooperable with a distractor for distraction of said body members while said implant is within said disc space so as to effect distraction of said disc space, said implant further comprising a spacer insertable into said disc space through said incision in said annulus and to be positioned between said upper and lower body members while the upper and lower body members are distracted within said disc space such that said implant with said spacer installed between said upper and lower body members is configured to maintain distraction of said disc space a desired amount.

2. An implant as set forth inclaim 1 wherein said implant has a first end and a second end, and wherein said implant is of such a length that with its first end at least partially received in a first opening in an anterior portion of said annulus generally opposite said incision, and with said implant oriented to extend across said vertebrae bodies and with the second end of said implant at least partially received in a second opening in an anterior portion of said annulus generally opposite said first opening, said implant is at least in part supported on at least one of said cortical rims.

3. An implant as set forth inclaim 1 wherein one of said body members has an inner surface and a pair of stabilizing posts extending from said inner surface and the other of said body members has a pair of bores for receiving said stabilizing posts, said posts and said bores being configured to maintain said body members in desired relation to one another and yet permitting distraction and retraction of the body members relative to one another.

4. An implant as set forth inclaim 3 wherein each said bore has a sliding axial fit relative to its respective said post so as to aid in stabilizing said body members relative to one another and so as to permit distraction and retraction of said body members relative to one another.

5. An implant as set forth inclaim 1 wherein said implant is configured to be supported on said one cortical rim at two or more locations spaced from one another.

6. A spinal implant for insertion in a disc space between two adjacent vertebrae bodies, said disc space being defined by an annulus attached to said adjacent vertebrae bodies, each of said vertebrae bodies having a cortical rim and an endplate within its cortical rim, said implant comprising an elongate body configured to be inserted within the disc space through an incision in a posterolateral portion of said annulus, said implant having a length, a first end, and a second end such that with said first end of the implant being at least partially received in a first opening formed in an anterior portion of the annulus, said implant may be oriented within said disc space so that with said first end received in said first opening said first end is supported on one of said cortical rims proximate said first opening and so that with said implant extending generally laterally of said vertebrae bodies with its second end being at least partially received within a second opening in said annulus generally opposite said first opening said implant being least in part supported on the one cortical rim, said implant having a lower body member and an upper body member, each of said body members being configured to be cooperable with a distractor so that upon operation of said distractor said body members are forced apart so as to in turn distract the disc space, said implant further comprising a spacer of a predetermined thickness adapted to be inserted through said incision into said disc space and positioned between said upper and lower body members while said body members are distracted so as to substantially maintain a desired amount of distraction of said disc space.

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