US20040073312A1 - Intervertebral prosthetic joint - Google Patents

Abstract

An intervertebral prosthetic joint including a first articular component adapted to engage a first vertebra and a second articular component adapted to engage a second vertebra. The articular components include abutting convex and concave articular surfaces that cooperate to permit articulating motion between the articular components. At least one of the convex and concave articular surfaces includes at least one surface depression that is configured to facilitate removal of matter disposed between abutting portions of the articular surfaces. In one embodiment of the prosthetic joint, each of the articular components has a vertebral bearing surface and a flange extending therefrom that is configured to penetrate a corresponding one of the first and second vertebrae, with the flange defining at least one opening extending therethrough to permit bone through-growth.

Description

FIELD OF THE INVENTION
• The present invention relates generally to the field of spinal implants, and more particularly relates to an intervertebral prosthetic joint for use in the total or partial replacement of a natural intervertebral disc.[0001]
BACKGROUND OF THE INVENTION
• In the treatment of diseases, injuries or malformations affecting spinal motion segments, and especially those affecting disc tissue, it has long been known to remove some or all of a degenerated, ruptured or otherwise failing disc. In cases involving intervertebral disc tissue that has been removed or is otherwise absent from a spinal motion segment, corrective measures are indicated to insure the proper spacing of the vertebrae formerly separated by the removed disc tissue.[0002]
• In some instances, the two adjacent vertebrae are fused together using transplanted bone tissue, an artificial fusion component, or other compositions or devices. Spinal fusion procedures, however, have raised concerns in the medical community that the bio-mechanical rigidity of intervertebral fusion may predispose neighboring spinal motion segments to rapid deterioration. More specifically, unlike a natural intervertebral disc, spinal fusion prevents the fused vertebrae from pivoting and rotating with respect to one another. Such lack of mobility tends to increase stresses on adjacent spinal motion segments. Additionally, several conditions may develop within adjacent spinal motion segments, including disc degeneration, disc herniation, instability, spinal stenosis, spondylosis and facet joint arthritis. Consequently, many patients may require additional disc removal and/or another type of surgical procedure as a result of spinal fusion. Alternatives to spinal fusion are therefore desirable.[0003]
• Several different types of intervertebral disc arthroplasty devices have been proposed for preventing the collapse of the intervertebral space between adjacent vertebrae while maintaining a certain degree of stability and range of pivotal and rotational motion therebetween. Such devices typically include two or more articular elements that are attached to respective upper and lower vertebrae. The articular elements are anchored to the upper and lower vertebrae by a number of methods, including the use of bone screws that pass through corresponding openings in each of the elements and thread into vertebral bone, and/or by the inclusion of spikes or teeth that penetrate the vertebral endplates to inhibit migration or expulsion of the device. The articular elements are typically configured to allow the elements, and correspondingly the adjacent vertebrae, to pivot and/or rotate relative to one another.[0004]
• As discussed above, prior intervertebral disc arthroplasty devices are relatively difficult to implant between adjacent vertebrae. To implant such devices, the adjacent vertebrae are spread apart a distance that is somewhat greater than the normal distance separating the vertebrae so that the device can be maneuvered between the vertebrae and the anchors can be engaged to the vertebral endplates. Such an operation presents a risk of injury to the vertebrae caused by misplacement and/or scratching of the vertebral endplates or other tissue by the anchors. Such operation also presents a risk of injury resulting from over-distraction of the intervertebral space. As also discussed above, other types of prior arthroplasty devices require the threading of bone screws or another type of fastener into the adjacent vertebrae. However, this type of anchoring method requires precise placement and orientation of the bone screws to provide adequate anchoring and to avoid injury to adjacent tissue or vertebral structures. Moreover, prior arthroplasty devices are prone to increased wear or possible malfunctioning if debris or particulate matter becomes lodged between the articular elements.[0005]
• Thus, there is a general need in the industry to provide an improved intervertebral prosthetic joint. The present invention satisfies this need and provides other benefits and advantages in a novel and unobvious manner.[0006]
SUMMARY OF THE INVENTION
• The present invention relates generally to an intervertebral prosthetic joint. While the actual nature of the invention covered herein can only be determined with reference to the claims appended hereto, certain forms of the invention that are characteristic of the preferred embodiments disclosed herein are described briefly as follows.[0007]
• One form of the present invention is directed to an intervertebral prosthetic joint, comprising a first component adapted to engage a first vertebra and including a first articular surface, and a second component adapted to engage a second vertebra and including a second articular surface, with the first and second articular surfaces cooperating to permit articulating motion between the first and second components, and with at least one of the first and second articular surfaces including at least one surface depression configured to facilitate removal of matter disposed therebetween.[0008]
• Another form of the present invention is directed to an intervertebral prosthetic joint, comprising a first articular component adapted to engage a first vertebra and including a projection, and a second articular component adapted to engage a second vertebra and including a recess, with at least a portion of the projection being disposed within the recess to permit articulating motion between the first and second components, and with at least one of the projection and the recess defining at least one passage configured to facilitate removal of matter disposed therebetween.[0009]
• Another form of the present invention is directed to an intervertebral prosthetic joint, comprising a first articular component having a bearing surface adapted to engage a first vertebra, and a second articular component having a bearing surface adapted to engage a second vertebra, with each of the first and second articular components including a flange extending from the bearing surface and adapted to penetrate a corresponding one of the first and second vertebrae, and wherein the flange defines at least one opening extending therethrough to permit bone through-growth.[0010]
• It is one object of the present invention to provide an improved intervertebral prosthetic joint. Further objects, features, advantages, benefits, and aspects of the present invention will become apparent from the drawings and description contained herein.[0011]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of an intervertebral prosthetic joint according to one form of the present invention.[0012]
• FIG. 2 is a sectional view of the intervertebral prosthetic joint illustrated in FIG. 1.[0013]
• FIG. 3 is a front view of a ball component according to one embodiment of the present invention for use with the intervertebral prosthetic joint illustrated in FIG. 1.[0014]
• FIG. 4 is a side view of the ball component illustrated in FIG. 3.[0015]
• FIG. 5 is a top view of the ball component illustrated in FIG. 3.[0016]
• FIG. 6 is a bottom view of the ball component illustrated in FIG. 3.[0017]
• FIG. 7 is a sectional view of the ball component illustrated in FIG. 5, taken along line-[0018]7-7 of FIG. 5.
• FIG. 8 is a sectional view of the ball component illustrated in FIG. 5, taken along line[0019]8-8 of FIG. 5.
• FIG. 9 is a front view of a socket component according to one embodiment of the present invention for use with the intervertebral prosthetic joint illustrated in FIG. 1.[0020]
• FIG. 10 is a side view of the socket component illustrated in FIG. 9.[0021]
• FIG. 11 is a top view of the socket component illustrated in FIG. 9.[0022]
• FIG. 12 is a bottom view of the socket component illustrated in FIG. 9.[0023]
• FIG. 13 is a sectional view of the socket component illustrated in FIG. 12, taken along line[0024]13-13 of FIG. 12.
• FIG. 14 is a top view of,a ball component according to another embodiment of the present invention.[0025]
• FIG. 15 is a sectional view of an intervertebral prosthetic joint according to another embodiment of the present invention.[0026]
• FIG. 16 is a sectional view of an intervertebral prosthetic joint according to a further embodiment of the present invention.[0027]
• FIG. 17 is a lateral view of a portion of the spinal column, illustrating a pair of adjacent upper and lower vertebrae separated by a natural intervertebral disc.[0028]
• FIG. 18 is an anterior view of the portion of the spinal column shown in FIG. 17, illustrating the removal of portions of the upper and lower vertebrae to accommodate insertion of the intervertebral prosthetic joint illustrated in FIG. 1 therebetween.[0029]
• FIG. 19 is a lateral view of the portion of the spinal column shown in FIG. 18.[0030]
• FIG. 20 is an anterior view of the portion of the spinal column shown in FIG. 18, illustrating implantation of the intervertebral prosthetic joint between the upper and lower vertebrae.[0031]
• FIG. 21 is a partial sectional view of the portion of the spinal column shown in FIG. 18, illustrating implantation of the intervertebral prosthetic joint between the upper and lower vertebrae.[0032]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is hereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates.[0033]
• Referring to FIGS.[0034]1-2, shown therein is an intervertebralprosthetic joint30 according to one form of the present invention. The articulatingjoint30 extends generally along a longitudinal axis L and includes a firstarticular component32 and a secondarticular component34. Thearticular components32,34 cooperate to form the articulatingjoint30 which is sized and configured for disposition within an intervertebral space between adjacent vertebral bodies.
• The articulating[0035]joint30 provides relative pivotal and rotational movement between the adjacent vertebral bodies to maintain or restore motion substantially similar to the normal bio-mechanical motion provided by a natural intervertebral disc. More specifically, thearticular components32,34 are permitted to pivot relative to one another about a number of axes, including lateral or side-to-side pivotal movement about longitudinal axis L and anterior-posterior pivotal movement about a transverse axis T. It should be understood that in a preferred embodiment of the invention, thearticular components32,34 are permitted to pivot relative to one another about any axes that lies in a plane that intersects longitudinal axis L and transverse axis T. Additionally, thearticular components32,34 are preferably permitted to rotate relative to one another about a rotational axis R. Although the articulatingjoint30 has been illustrated and described as providing a specific combination of articulating motion, it should be understood that other combinations of articulating movement are also possible and are contemplated as falling within the scope of the present invention. It should also be understood that other types of articulating movement are also contemplated, such as, for example, relative translational or linear motion.
• Although the[0036]articular components32,34 ofprosthetic joint30 may be formed from a wide variety of materials, in one embodiment of the invention, thearticular components32,34 are formed of a cobalt-chrome-molybdenum metallic alloy (ASTM F-799 or F-75). However, in alternative embodiments of the invention, thearticular components32,34 may be formed of other metallic materials such as titanium or stainless steel, a polymeric material such as polyethylene, or any other biocompatible material that would be apparent to one of ordinary skill in the art. The surfaces of thearticular components32,34 that are positioned in direct contact with vertebral bone are preferably coated with a bone-growth promoting substance, such as, for example, a hydroxyapatite coating formed of calcium phosphate. Additionally, the surface of thearticular components32,34 that are positioned in direct contact with vertebral bone are preferably roughened prior to being coated with the bone-growth promoting substance to further enhance bone on-growth. Such surface roughening may be accomplished by way of, for example, acid etching, knurling, application of a bead coating, or other methods of roughening that would occur to one of ordinary skill in the art.
• Referring to FIGS.[0037]3-8, shown therein are various details regarding thearticular component32.Articular component32 includes asupport plate50 having anarticular surface52 and anopposite bearing surface54.Support plate50 is preferably sized and shaped to substantially correspond to the size and shape of the vertebral endplate of an adjacent vertebra. Thearticular surface52 and the bearingsurface54 are separated by a pair of laterally facingsurfaces56a,56band a pair of axially facingsurfaces58a,58b.The laterally facingsurfaces56a,56b.each preferably define achannel57 extending along at least a portion of the length of thesupport plate50. Thechannels57 are configured to engage a corresponding portion of a surgical instrument (not shown) to aid in the manipulation and insertion of the prosthetic joint30 within an intervertebral space between adjacent vertebrae. The surgical instrument (not shown) is preferably configured to hold thearticular components32,34 at a predetermined orientation and spatial relationship relative to one another during manipulation and insertion of the prosthetic joint30, and to release thearticular components32,34 once properly positioned between the adjacent vertebrae.
• In a preferred embodiment of the invention, the[0038]articular surface52 includes aprojection60 surrounded by a substantiallyplanar surface62. In one embodiment of the invention, theprojection60 has a convex shape and is preferably configured as a spherical-shaped ball. In another embodiment of the invention, the spherical-shaped surface of the projection has a large enough radius of curvature such that the axis about which thearticular components32,34 pivot relative to one another is located at or below the planar surface62 (i.e., the center of curvature is located at or below planar surface62). However, it should be understood that the pivot axis may alternatively be positioned above theplanar surface62. It should also be understood that other configurations of theprojection60 are also contemplated, such as, for example, cylindrical, elliptical or other arcuate configurations or possibly non-arcuate configurations. It should also be understood that theplanar surface62 may take on non-planar configurations, such as, for example, an angular or conical configuration extending about theprojection60.
• In a preferred embodiment of the invention, the convex articular surface of the[0039]projection60 is interrupted by a surface depression orcavity70 extending along theprojection60. In one embodiment of the invention, thesurface depression70 is configured as a groove. However, as will be discussed in further detail below, it should be understood that other types of surface depressions are also contemplated. One purpose of thegroove70 is to facilitate the removal of matter disposed between abutting portions of thearticular components32,34. More specifically, thegroove70 provides a means for clearing out matter such as, for example, particulate material, that is disposed between the abutting articular surfaces ofcomponents32,34.
• In one embodiment of the invention, the[0040]groove70 extends along the convex surface of the spherical-shapedball60 in such a manner as to divide theball60 into two substantiallysymmetrical portions60a,60b,with each portion extending about approximately 180° of the overall circumference or periphery of theball60. However, it should be understood that thegroove70 may take on other configurations as well. For example, thegroove70 need not necessarily uniformly divide theball60 into symmetrical halves, but may alternatively be positioned at other locations alongball60 and arranged at other angular orientations relative toball60. It should further be understood that thegroove70 need not necessarily extend entirely across theball60, but may alternatively extend across only a portion of theball60. For example, thegroove70 may extend across theball60 in such a manner that only a portion of thegroove70 extends beyond abutting portions of thearticular components32,34 at some point during the articulating motion of joint30. Additionally, it should be understood that thegroove70 need not necessarily have a linear-configuration, but may alternatively take on angular configurations or non-linear configurations, such as, for example, the curvilinear configuration illustrated in FIG. 14. It should also be understood that any number ofgrooves70 may be defined along the periphery of theball60, such as two ormore grooves70 arranged in a uniform manner or alternatively in a random or semi-random pattern, as also illustrated in FIG. 14. In one specific embodiment of the invention, thegroove70 is approximately 0.75 mm deep and approximately 0.4 mm wide and has a radiused bottom surface. However, it should be understood that other sizes and configurations of thegroove70 are contemplated as falling within the scope of the present invention.
• In one embodiment of the invention, the bearing[0041]surface54 is substantially planar and is oriented at an angle α relative to theplanar surface62 to define an outward taper extending fromaxial surface58atowardaxial surface58b.In one embodiment, angle α falls within a range of 0 degrees to about 10 degrees. In a specific embodiment, angle α is about 3 degrees. In another specific embodiment, angle α is about 6 degrees. However, it should be understood that angle α may take on other values that correspond to the particular lordotic angle or morphology of the portion of the spinal column in which the prosthetic joint30 is used. It should further be understood that the bearingsurface54 may be configured to accommodate spinal abnormalities such as scoliosis. In such case, the bearingsurface54 may be angled relative to theplanar surface62 to define a taper extending between thelateral surfaces56a,56b.It should also be understood that the bearing-surface54 may take on alternative configurations, such as, for example, a curved or arcuate configuration that corresponds to the particular contour of the adjacent vertebral endplate against which surface54 abuts. It should likewise be understood that bearingsurface54 may be roughened and/or may define a number of surface projections to aid in gripping the vertebral endplate and to inhibit migration of the prosthetic joint30 relative to the adjacent vertebra.
• A flange member or[0042]keel80 extends from the bearingsurface54 and is configured for disposition within a preformed opening in the adjacent vertebral endplate. In one embodiment, thekeel80 extends perpendicularly from the bearingsurface54 and is approximately centrally located along the bearingsurface54. However, it should be understood that other positions and orientations of thekeel80 are also contemplated. It should also be understood that thearticular component32 may include two ormore keels80 extending from the bearingsurface54.
• The[0043]keel80 extends from a location adjacent theaxially facing surface58atoward theaxially facing surface58balong a substantial portion of thesupport plate50. Preferably, thekeel80 extends along substantially the entire length of thesupport plate50. As illustrated in FIG. 6, thekeel80 is preferably wedge-shaped, defining an outward taper as thekeel80 extends from a leading or insertion end80atowards a trailingend80b.In one specific embodiment, the outward taper is about 4 degrees. However, other taper angles are also contemplated. It should also be understood that thekeel80 need not necessarily be tapered along it length. As will become apparent, the outward taper aids in the insertion of thekeel80 within preformed openings in the adjacent vertebrae. Additionally, theinsertion end80aofkeel80 includes abeveled surface82 to further aid in the implantation of the prosthetic joint30.
• In another embodiment of the invention, the[0044]keel80 may alternatively extend between the laterally facingsurface56a,56balong a substantial portion of thesupport plate50. Such an embodiment would accomodate insertion of the prosthetic joint30 using a lateral approach as opposed to the anterior approach illustrated in FIGS. 20 and 21. In a further embodiment of the invention, thekeel80 may be tapered along its height, either tapering inwardly from bearingsurface54 to define a wedge shape or tapering outwardly from bearingsurface54 to define a dove-tail shape. In still another embodiment, thekeel80 may be configured as a winged keel, including a transverse portion extending across the main body portion ofkeel80.
• The[0045]keel80 also includes a pair ofopenings86 extending therethrough to facilitate bone through-growth to enhance fixation to the adjacent vertebra. However, it should be understood that any number ofopenings86 may be defined throughkeel80, including a single opening or three or more openings. It should also be understood that theopenings86 need not necessarily extend entirely through thekeel80, but may alternatively extend partially, therethrough. It should further be understood that thekeel80 need not necessarily define anyopenings86 extending either partially or entirely therethrough. Additionally, although theopenings86 are illustrated as having a circular configuration, it should be understood that other sizes and, configures ofopenings86 are also contemplated. As discussed above, the surfaces of thearticular component32 that are in direct contact with vertebral bone are preferably coated with a bone-growth promoting substance. Specifically, the bearingsurface54 and the surfaces of thekeel80 are preferably coated with hydroxyapatite to promote bony engagement with the adjacent vertebrae. As also discussed above, the bearingsurface54 and the surfaces ofkeel80 are preferably roughened prior to application of the hydroxyapatite coating.
• Referring to FIGS.[0046]9-13, shown therein are various details regarding thearticular component34.Articular component34 includes asupport plate100 having anarticular surface102 and anopposite bearing surface104.Support plate100 is preferably sized and shaped to substantially correspond to the size and shape of the vertebral endplate of an adjacent vertebra. Thearticular surface102 and thebearing surface104 are separated by a pair of laterally facingsurfaces106a,106band a pair of axially facingsurfaces108a,108b.The laterally facingsurfaces106a,106beach preferably define achannel107 extending along at least a portion of the length of thesupport plate100. Similar tochannels57 ofarticular element32,channels107 are configured to engage a corresponding portion of a surgical instrument (not shown) to aid in the manipulation and insertion of the prosthetic joint30.
• In a preferred embodiment of the invention, the[0047]articular surface102 includes arecess110 surrounded by a substantiallyconical surface112. In one embodiment of the invention, therecess110 has a concave shape, and is preferably configured as a spherical-shaped socket. However, it should be understood that other configurations of therecess110 are also contemplated, such as, for example, cylindrical, elliptical or other arcuate configurations or possibly non-arcuate configurations.Conical surface112 is tapered at an angle θ relative to a plane oriented parallel with theplanar surface52 ofarticular component32 in such a manner as to define a uniform taper extending entirely about the concave recess10. In this manner, relative pivotal motion between thearticular components32,34 is limited to approximately ± angle θ. In one embodiment, the angle θ falls within a range of about 10 degrees to about 20 degrees, thereby limiting the overall relative pivotal motion between thearticular components32,34 within a range of just over 20 degrees to just over 40 degrees. In a specific embodiment, angle θ is about 16 degrees, thereby limiting the overall pivotal motion between thearticular components32,34 to just over 32 degrees. As will become apparent, angle θ may take on other values that correspond to the desired amount of relative pivotal movement between thearticular components32,34. It should also be understood that theconical surface112 may take on other configurations, such as, for example, an angular configuration extending about the concave recess10. It should also be understood that thesurface112 could alternatively be configured as a planar surface oriented parallel with the bearingsurface104, and that thesurface52 ofarticular component32 could alternatively be configured as a conical or angled surface tapered at an angle θ, or that both of thesurfaces52,112 could alternatively be configured as conical or angled surfaces tapered at a predetermined angle θ. In an embodiment where both of thesurfaces52,112 are tapered at a predetermined angle θ, the angle θ is preferably about 8 degrees, thereby limiting the overall pivotal motion between thearticular components32,34 to just over 32 degrees.
• Although the[0048]concave recess110 is illustrated as having a generally smooth, uninterrupted articular surface, it should be understood that a surface depression or cavity may be defined along a portion of therecess110 to provide a means for clearing out matter, such as particulate debris, that is disposed between the abutting articular surfaces ofcomponents32,34. In such case, the convex articular surface of theball60 may alternatively define a generally smooth, uninterrupted articular surface. In another embodiment of the invention, each of theconvex projection60 and theconcave recess110 may define a surface depression to facilitate removal of particulate matter disposed between the abutting articular surfaces.
• In one embodiment of the invention, the bearing[0049]surface104 is substantially planar and is oriented at an angle α, similar to that of bearingsurface54 ofarticular component32, to define an outward taper extending fromaxial surface108atowardaxial surface108b.However, it should be understood that bearingsurface104 may take on alternative configurations, such as, for example, a curved or arcuate configuration that corresponds to the particular contour of the adjacent vertebral endplate against which surface104 abuts. It should further be understood that the bearingsurface104 may be configured to accommodate spinal abnormalities such as scoliosis. In such case, the bearingsurface104 may be angled to define a taper extending between thelateral surfaces106a,106b.It should additionally be understood that the bearingsurface104 may be roughened and/or may define a number of surface projections to aid in gripping the vertebral endplate and to inhibit migration of the prosthetic joint30 relative to the adjacent vertebra.
• A flange member or[0050]keel120, configured similar to thekeel80 ofarticular component32, extends from the bearingsurface104. In one embodiment, thekeel120 extends perpendicularly from the bearingsurface104 and is approximately centrally located along bearingsurface104. However, it should be understood that other positions and orientations of thekeel120 are also contemplated. It should also be understood that thearticular component34 may include two ormore keels120 extending from the bearingsurface104.
• The[0051]keel120 extends from a location adjacent axially facingsurface108atoward axially facingsurface108b,preferably along a substantial portion of thesupport plate100. As illustrated in FIG. 11, thekeel120 is preferably wedge-shaped, defining an outward taper as thekeel100 extends from a leading orinsertion end120ato trailingend120b.Additionally, theinsertion end120aofkeel120 includes abeveled surface122 to further aid in the implantation of the prosthetic joint30. In another embodiment of the invention, thekeel120 may alternatively extend between the laterally facingsurface106a,106balong a substantial portion of thesupport plate100 to accommodate for insertion of the prosthetic joint30 between adjacent vertebral bodies using a lateral approach. In a further embodiment of the invention, thekeel120 may be tapered along its height, either tapering inwardly from the bearingsurface104 to define a wedge shape or tapering outwardly from bearingsurface104 to define a dove-tail shape. In still another embodiment, thekeel120 may be, configured as a winged keel, including a transverse portion extending across the main body portion ofkeel120.
• [0052]Keel120 includes a pair ofopenings126 extending therethrough to facilitate bone through-growth to enhance fixation to the adjacent vertebra. However, it should be understood that any number ofopenings126 may be defined through thekeel120, including a single opening or three or more openings. It should also be understood that theopenings126 need not necessarily extend entirely throughkeel120, but may alternatively extend partially therethrough. It should further be understood that thekeel120 need not necessarily define anyopenings126 extending either partially or entirely therethrough. As discussed above, the surfaces of thearticular component34 that are in direct contact with vertebral bone are preferably coated with a bone-growth promoting substance, such as, for example, a hydroxyapatite coating. As also discussed above, the surfaces of thearticular component34 that are in direct contact with vertebral bone are preferably roughened prior to application of the bone-growth promoting substance.
• Referring once again to FIG. 2, the projection or[0053]ball60 ofarticular component32 is at least partially disposed within the recess orsocket110 ofarticular component34. The convex and concave articular surfaces ofball60arid socket110 abut one another in such a manner as to provide relative articulating motion between thearticular components32,34. Specifically, thearticular components32,34 are allowed to pivot and rotate relative to one another to maintain or restore motion substantially similar to the normal biomechanical motion provided by a natural intervertebral disc. The relative pivotal motion between thearticular components32,34 is limited by the abutment of theconical surface112 ofcomponent34 against theplanar surface62 ofcomponent32. During the articulating motion, thegroove70 formed along theball60 provides a passage for removing any matter, such as particulate debris, that may become lodged between the abutting articular surfaces of thecomponents32,34. Thegroove70 channels any such debris clear from the interfacing articular surfaces of the prosthetic joint30 to prevent or at least reduce wear which otherwise might occur if foreign particles and/or built-up wear debris were to remain between the abutting portions of the articular surfaces.
• Referring to FIGS. 15 and 16, shown therein are intervertebral prosthetic joints according to other embodiments of the present invention. With regard to FIG. 15, shown therein is a prosthetic joint[0054]130 including a firstarticular element132 and a secondarticular element134.Articular elements132,134 are similar toarticular components32,34 in many respects except that theconvex ball160 ofarticular component132 includes a flattenedportion170 extending along a portion ofball160. The flattenedportion170 serves substantially the same purpose as thegroove70 extending along theball60; namely, to provide a means for removing any particulate debris that may become lodged between the abutting articular surfaces ofcomponents132,134. Although the flattenedportion170 is located at the approximate center ofball160, it should be understood that the flattenedportion170 may be located anywhere alongball160. It should also be understood that any number of flattenedportions170 may be formed along theball160, and that theball160 may include a combination ofgrooves70 and flattenedportions170 to facilitate the removal of matter disposed between the abutting articular surfaces.
• With regard to FIG. 16, shown therein is a prosthetic joint[0055]230 including a firstarticular element232 and a secondarticular element234.Articular elements232,234 are similar toarticular components32,34 in many respects except that theconcave recess240 ofarticular component234 includes anopening270 formed therein. Theopening270 serves substantially the same purpose as thegroove70 extending along theball60; namely, to provide a means for removing any particulate debris that may become lodged between the abutting articular surfaces ofcomponents232,234. Preferably, theopening270 extends through thesupport plate100 of thearticular component234 to channel any particulate debris that may become lodged between the abutting articular surfaces away from the ball-and-socket joint. Theopening270 may also extend through thekeel120 of thearticular component234. Although theopening270 is illustrated as being located at the approximate center of thesocket240, it should be understood that theopening270 may be located anywhere alongsocket240 and at any orientation relative tosocket240. It should also be understood that any number ofopenings270 may be formed alongsocket240, and that thesocket240 may include a combination ofgrooves70 andopenings270 to facilitate the removal of matter disposed between the abutting articular surfaces.
• In further embodiments of the invention, either or both of the convex and concave articular surfaces of the[0056]components32,34 may define other types and configurations of surface depressions. For example, the surface depressions may be configured as multiple indentations or dimpling extending along one or both of the articular surfaces. In one specific embodiment, the convex articular surface may include multiple surface depressions such as may be found on the outer surface of a golf ball. However, it should be understood that many types and configurations of surface depressions may be used.
• Referring to FIG. 17, shown therein is a lateral view of a portion of the spinal column, illustrating a pair of adjacent upper and lower vertebrae V[0057]_U, V_Lseparated by a natural intervertebral disc D. As discussed above, in cases where the natural intervertebral disc D is diseased or degenerated, the natural disc D is typically removed via a discectomy or a similar surgical procedure, the details of which would be known to one of ordinary skill in the art.
• As illustrated in FIGS. 18 and 19, removal of the-diseased or degenerated disc D results in the formation of an intervertebral space S between the upper and lower vertebrae V[0058]_U, V_L. To accommodate insertion of the prosthetic joint30 within the intervertebral space S, preparation of the upper and lower vertebrae V_U, V_Lis required to accept the prosthetic joint30 therebetween. Specifically, elongate openings orslots300 are formed along the vertebral endplates of the upper and lower vertebrae V_U, V_Lat a predetermined width w and to a predetermined depth d. In one embodiment of the invention, theelongate slots300 are rectangular-shaped and extend from ananterior side302 of the vertebrae V_U, V_Ltoward aposterior side304 of the vertebrae V_U, V_L. In a specific embodiment, theslots300 are formed by chiseling or curetting. However, other methods of formingslots300 are also contemplated as would occur to one of ordinary skill in the art, such as, for example, by drilling or reaming. In a preferred embodiment of the invention, the width w of theslots300 is equal to or somewhat less than the corresponding width of thekeels80,120 ofarticular components32,34. Additionally, the depth d of theslots300 is preferably approximately equal to or slightly greater than the length of thekeels80,120.
• Referring to FIGS. 20 and 21, following preparation of the intervertebral space S, the[0059]articular components32,34 are inserted between the upper and lower vertebrae V_U, V_L. First, thearticular components32,34 are placed in a predetermined relationship with respect to one another, preferably by an insertion instrument (not shown) or an equivalent tool that is adapted to engage thechannels57,107 formed along a length of thesupport plates50,100. The insertion instrument (not shown) holds thearticular components32,34 in a predetermined spatial relationship and at a predetermined orientation with respect to one another. The prosthetic joint30 is inserted between the upper and lower vertebrae V_U, V_Lin a direction generally along the longitudinal axis L, with thekeels80,120 ofcomponents32,34 being axially displaced along theslots300. Notably, since thekeels80,120 are axially displaced through the preformedslots300, distraction of the upper and lower vertebrae V_U, V_Lto accommodate insertion of the prosthetic joint30 is minimized, if not eliminated entirely.
• As discussed above, the[0060]keels80,120 are tapered or wedge-shaped to facilitate insertion within theslots300. The taper angle defined by each of thesupport plates50,100 also facilitates insertion of the prosthetic joint30 within the intervertebral space S. Since the width w of theslots300 is equal to or somewhat less than the corresponding width of thekeels80,120, thekeels80,120 are effectively wedged within theslots300. The depth d of theslots300 formed in the upper and lower vertebrae V_U, V_Lcorrespondingly controls the positioning of the prosthetic joint30 within the intervertebral space S. Specifically, proper positioning of the prosthetic joint30 is accomplished when the insertion ends80a,120aof thekeels80,120 bottom out against the end surfaces ofslots300. Controlling the insertion depth of the prosthetic joint30 results in more precise positioning to avoid over-insertion or under-insertion of prosthetic joint30. As discussed above, the angular positioning of thearticular components32,34 relative to one another is dictated by the geometry of the upper and lower vertebrae V_U, V_Land the particular location within the spinal column. As should be apparent, the distance between thesupport plates50,100 should be approximately equal to the height of the removed disc D, and the angular disposition of thesupport plates50,100 is dictated by the particular curvature or lordosis of the spinal column.
• In the illustrated embodiment of the invention, the prosthetic joint[0061]30 is implanted in the intervertebral space S via an anterior approach. However, it should be understood that theslots300 may alternatively extend from theposterior side304 of the vertebrae. V_U, V_Ltoward theanterior side302 at a depth d, and the prosthetic joint30 may alternatively be implanted in the intervertebral space S via a posterior approach. It should also understood that theslots300 may alternatively extend from a first lateral side of the vertebrae V_U, V_Ltoward the opposite lateral side of the vertebrae at a depth d, and the prosthetic joint30 may alternatively be implanted in the intervertebral space S via a lateral approach.
• Once the[0062]prosthetic Joint30 is inserted within the intervertebral space S, thearticular components32,34 are initially secured to the upper and lower vertebrae V_U, V_Lvia the disposition of thekeels80,120 within theslots300 formed in the vertebrae V_u, V_Land by the compression forces exerted upon the bearing surfaces54,104 of thearticular components32,34 by the adjacent vertebral endplates. The keels80,120 thus serve to resist migration or displacement of the prosthetic joint30 relative to the adjacent vertebrae V_U, V_L. Subsequent to the implantation of prosthetic joint30, thearticular components32,34 are further secured to the upper and lower vertebrae V_U, V_Lvia bone growth through theopenings86,126 inkeels80,120 and/or by bone on-growth onto the surfaces of thearticular components32,34 that are in direct contact with vertebral bone. The bone through-growth and bone on-growth provide further resistance to the migration or displacement of the prosthetic joint30 and prevent expulsion of the prosthetic joint30 from the intervertebral space S. It should be understood that other means of engaging the prosthetic joint30 to the upper and lower vertebrae V_U, V_Lare also contemplated, such as, for example, by bone screws, staples, an adhesive, or by other methods of engagement as would occur to one of ordinary skill in the art.
• In use, the[0063]articular components32,34 cooperate with one another to provide a ball-and-socket type joint that permits relative pivotal and rotational movement therebetween, which correspondingly permits relative pivotal and rotational movement between the upper and lower vertebrae V_U, V_L. As a result, substantially normal biomechanical motion is restored to the portion of the spinal column being treated. Although the devices and methods of the present invention are particularly applicable to the lumbar region of the spine, it should nevertheless be understood that the present invention is also applicable to other portions of the spine, including the cervical or thoracic regions of the spine.
• While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.[0064]

Claims (40)

What is claimed is:

1. An intervertebral prosthetic joint, comprising:

a first component adapted to engage a first vertebra and including a first articular surface; and

a second component adapted to engage a second vertebra and including a second articular surface, said first and second articular surfaces cooperating,to permit articulating motion between said first and second components; and

wherein at least one of said first and second articular surfaces includes at least one surface depression configured to facilitate removal of matter disposed between abutting portions of said first and second articular surfaces.

2. The intervertebral prosthetic joint ofclaim 1, wherein said surface depression comprises a groove extending beyond abutting portions of said first and second articular surfaces at some point during said articulating motion.

3. The intervertebral prosthetic joint ofclaim 1, wherein said surface depression comprises an opening in communication between said at least one of said first and second articular surfaces and a surface remote from abutting portions of said first and second articular surfaces.

4. The intervertebral prosthetic joint ofclaim 1, wherein one of said first and second articular surfaces comprises a convex surface, another of said first and second articular surfaces comprises a concave surface, at least a portion of said convex surface abutting at least a portion of said concave surface to permit said articulating motion.

5. The intervertebral prosthetic joint ofclaim 4, wherein said convex and concave surfaces are substantially spherical-shaped.

6. The intervertebral prosthetic joint ofclaim 5, wherein said surface depression comprises a groove extending inwardly from a circumference of at least one of said convex and concave surfaces.

7. The intervertebral prosthetic joint ofclaim 4, wherein said surface depression comprises a groove extending along at least a portion of said at least one of said convex and concave surfaces.

8. The intervertebral prosthetic joint ofclaim 7, wherein said groove extends inwardly from a periphery of said at least one of said convex and concave surfaces.

9. The intervertebral prosthetic joint ofclaim 7, wherein said groove extends beyond abutting portions of said convex and concave surfaces at some point during said articulating motion.

10. The intervertebral prosthetic joint ofclaim 7, wherein said groove extends across said at least one of said convex and concave surfaces to divide said at least one of said convex and concave surfaces into two distinct portions.

11. The intervertebral prosthetic joint ofclaim 10, wherein said distinct portions are substantially symmetrical.

12. The intervertebral prosthetic joint ofclaim 7, wherein said groove extends along said at least one of said convex and concave surfaces in a non-linear configuration.

13. The intervertebral prosthetic joint ofclaim 12, wherein said non-linear configuration is a curvilinear configuration.

14. The intervertebral prosthetic joint ofclaim 7, wherein a plurality of said grooves extends along said at least one of said convex and concave surfaces.

15. The intervertebral prosthetic joint ofclaim 7, wherein said groove extends along an outer contour of said at least one of said convex and concave surfaces.

16. The intervertebral prosthetic joint ofclaim 7, wherein said groove has a length and a width, said length being greater than said width.

17. The intervertebral prosthetic joint ofclaim 4, wherein said surface depression comprises an opening in communication between said one of said convex and concave surfaces and a surface remote from said abutting portions of said first and second convex and concave surfaces.

18. The intervertebral prosthetic joint ofclaim 15, wherein said remote surface is a vertebral bearing surface configured to engage a corresponding one of the first and second vertebrae.

19. The intervertebral prosthetic joint ofclaim 4, wherein a portion of said convex surface is flattened to form said surface depression.

20. The intervertebral prosthetic joint ofclaim 4, wherein at least one of said convex and concave surfaces is at least partially surrounded by a tapered surface to limit said articulating motion within a predetermined range of motion.

21. The intervertebral prosthetic joint ofclaim 20, wherein said tapered surface is a conical surface extending entirely about said at least one of said convex and concave surfaces.

22. The intervertebral prosthetic joint ofclaim 1, wherein each of said first and second components includes at least one channel configured to accept a corresponding portion of an insertion tool therein to maintain said first and second components at a predetermined position and at a predetermined orientation relative to one another during insertion of the prosthetic joint between the first and second vertebrae.

23. The intervertebral prosthetic joint ofclaim 1, wherein each of said first and second components includes a vertebral bearing surface and a flange extending from said vertebral bearing surface, said flange being adapted to penetrate a corresponding one of the first and second vertebrae, said flange defining at least one opening, therethrough to permit bone growth through said flange.

24. The intervertebral prosthetic joint ofclaim 1, wherein the matter comprises particulate material.

25. An intervertebral prosthetic joint, comprising:

a first articular component adapted to engage a first vertebra and including a projection; and

a second articular component adapted to engage a second vertebra and including a recess, at least a portion of said projection being disposed within said recess to permit articulating motion between said first and second components; and

wherein at least one of said projection and said recess defines at least one cavity configured to facilitate removal of matter disposed between said projection and said recess.

26. The intervertebral prosthetic joint ofclaim 25, wherein said projection includes a convex surface, and wherein said recess includes a concave surface, at least a portion of said convex surface abutting at least a portion of said concave recess to permit said articulating motion.

27. The intervertebral prosthetic joint ofclaim 26, wherein said cavity comprises a flattened portion extending along at least a portion of said generally convex surface.

28. The intervertebral prosthetic joint ofclaim 26, wherein said cavity comprises a groove extending along at least a portion of at least one of said convex and concave surfaces.

29. The intervertebral prosthetic joint ofclaim 26, wherein said cavity comprises an opening communicating between said one of said convex and concave surfaces and a surface remote from said at least one of said convex and concave surfaces.

30. An intervertebral prosthetic joint, comprising:

a first articular component having a bearing surface adapted to engage a first vertebra; and

a second articular component having a bearing surface adapted to engage a second vertebra; and

wherein each of said first and second articular components includes a flange extending from said bearing surface and configured to penetrate a corresponding one of the first and second vertebrae, said flange defining at least one opening therethrough to permit bone growth through said flange.

31. The intervertebral prosthetic joint ofclaim 30, wherein said flange is positioned within a preformed opening in said corresponding one of the first and second vertebrae.

32. The intervertebral prosthetic joint ofclaim 31, wherein said flange has a length and is tapered along at least a portion of said length to facilitate insertion of said flange into said preformed opening.

33. The intervertebral prosthetic joint ofclaim 31, wherein said flange has a leading end, said leading end defining a beveled surface to facilitate insertion of said flange into said preformed opening.

34. The intervertebral prosthetic joint ofclaim 30, wherein each of said first and second articular components includes an articular surface disposed generally opposite said bearing surface, said articular surfaces cooperating to permit articulating motion between said first and second components.

35. The intervertebral prosthetic joint ofclaim 34, wherein at least one of said articular surfaces includes at least one surface depression to facilitate removal of matter disposed between said articular surfaces.

36. The intervertebral prosthetic joint ofclaim 35, wherein said surface depression is a groove extending along said at least one of said articular surfaces.

37. The intervertebral prosthetic joint ofclaim 36, wherein one of said first and second articular surfaces comprises a convex surface, another of said first and second articular surfaces comprises a concave surface, at least a portion of said convex surface abutting at least a portion of said concave surface to permit said articulating motion, said groove extending beyond said abutting portions of said convex and concave surfaces at some point during said articulating motion.

38. The intervertebral prosthetic joint ofclaim 30, wherein said flanges are coated with a bone-growth promoting substance to facilitate bone growth onto said flanges.

39. The intervertebral prosthetic joint ofclaim 30, wherein said flange defines a plurality of said openings therethrough.

40. An intervertebral prosthetic joint, comprising:

a first articular component including means for engaging a first vertebra; and

a second articular component including means for engaging a second vertebra; and

wherein said first and second articular components include surface means for permitting articulating motion therebetween, said surface means including means for removing matter disposed between abutting portions of said first and second articular components.

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