US20150238317A1 - Joint spacer - Google Patents

Abstract

To change a spatial relationship between two or more bones in a patient's body, a wedge member is moved into a joint between the bones. The wedge member may have a cam-shaped configuration and be rotated through less than a revolution to apply force against the bones. The wedge member may have a porous construction which enables bone to grow through the wedge member and immobilize the joint. The wedge member may be coated with and/or contain bone growth promoting material. The wedge member may be connected to only one of the bones or may be connected to two adjacent bones. If the wedge member is connected to only one bone, the joint may be capable of being flexed after the wedge member is inserted into the joint.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• The present application is a continuation of co-pending U.S. patent application Ser. No. 10/755,996, filed Jan. 13, 2004, which is a continuation of U.S. patent application Ser. No. 10/163,480, filed Jun. 5, 2002, now U.S. Pat. No. 7,780,670, which is a continuation of U.S. patent application Ser. No. 09/569,020, filed May 11, 2000, now U.S. Pat. No. 6,423,063, which is a continuation of U.S. patent application Ser. No. 09/137,443, filed Aug. 20, 1998, now U.S. Pat. No. 6,099,531, the disclosures of which are incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
• The present invention relates to a new and improved method of changing a spatial relationship between bones which are interconnected at a joint in a patient's body.
BACKGROUND OF THE INVENTION
• It has previously been suggested that joints between bones be fused, that is, surgically immobilized, to promote patient comfort. Thus, U.S. Pat. No. 5,026,373 suggests that a fusion cage be positioned between adjacent vertebrae. Perforations are formed in the cage. The cage is packed with a bone-inducing substance. A method for immobilizing vertebrae is also disclosed in U.S. Pat. No. 5,015,255.
• It has previously been suggested that the spatial relationship between portions of a bone in a patient's body be changed to correct deformities. This may be done by removing a wedge-shaped piece of bone in the manner disclosed in U.S. Pat. No. 5,601,565.
• Another method of changing the spatial relationship between portions of a bone in a patient's body includes forming a slot in the bone. A forked wedge tool is inserted into the slot. A plate is then placed in a central opening in the forked wedge tool and positioned against the bone. The plate is secured to the bone. The forked wedge tool is then removed from the opening. This method of changing the spatial relationship between portions of a bone in a patient's body is disclosed in U.S. Pat. No. 5,620,448.
• A method and apparatus for use in changing a spatial relationship between portions of a bone in a patient's body is also disclosed in co-pending U.S. patent application Ser. No. 09/109,126, filed Jun. 30, 1998 by Peter M. Bonutti and entitled Method And Apparatus For Use In Operating On A Bone. This application discloses the use of a wedge member to expand a slot formed in a bone. The wedge member is porous and may be coated with and/or contain bone growth promoting material. The wedge member may have a configuration which corresponds to a configuration of a portion of the bone which is engaged by the wedge member. Alternatively, the wedge member disclosed in the aforementioned application Ser. No. 09/109,126 may have a circular cross sectional configuration with an external thread convolution to enable the wedge member to be moved into an opening in a bone by rotating the wedge member
SUMMARY OF THE INVENTION
• A new and improved method and apparatus is provided to change a spatial relationship between bones which are interconnected at a joint in a patient's body. When this is to be done, an opening is formed in a portion of the patient's body to expose the joint interconnecting the bones. One of the bones is moved relative to the other by expanding at least a portion of the joint with a wedge member. The wedge member is moved into the joint and applies force against the bones. The opening is closed with the wedge member still disposed in the joint between the bones. Force is then transmitted between the bones through the wedge member to maintain the joint in an expanded condition.
• If the joint is to be flexed after being expanded by the wedge member, the wedge member may be connected with only one of the bones. Alternatively, if the joint is to be immobilized (fused) after inserting the wedge member, the wedge member may be fixedly connected with the bones interconnected at the joint. The wedge member may be porous and may be coated with and/or contain bone growth promoting material.
• One embodiment of the wedge member has major side surfaces extending between thick and thin end portions of the wedge member. The wedge member is moved into the joint with the thin end portion leading. As the wedge member is moved into the joint, the thick trailing end portion of the wedge member expands the joint.
• In another embodiment of the invention, the wedge member is rotated relative to the joint to expand the joint. The wedge member may have a circular cross sectional configuration and an external thread convolution which extends from a thin leading end of the wedge member to a thick trailing end of the wedge member. The wedge member is pressed into the joint and rotated to cause the wedge member to expand the joint.
• In another embodiment of the invention, the wedge member has surface areas which are relatively close together and other surface areas which are relatively far apart. The wedge member is moved into the joint with the surface areas which are close together engaging the adjacent bones. The wedge member is then rotated to apply force against the adjacent bones to expand the joint. The wedge member may be rotated about its central axis to apply forced against the bones and expand the joint. Alternatively, the wedge member may be rotated about a location where the wedge member engages one of the bones.
• Regardless of which embodiment of the wedge member is selected, the wedge member may be used with any one of the many different bones and joints in a patient's body. The wedge member may be utilized at joints in a patient's wrist, ankle, hand, foot, back or other portions of the patient's body. The wedge member may be particularly advantageous when a joint between vertebrae in patient's back is to be immobilized. One or more wedge members may be used to expand a joint and transmit force between bones.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing and other features of the present invention will become more apparent from the following description taken in connection with the accompanying drawings wherein:
• FIG. 1 is a schematic illustration depicting the spatial relationship between bones at a joint in a patient's body;
• FIG. 2 is a schematic illustration depicting the manner in which a wedge member is inserted into the joint between the bones ofFIG. 1 to expand a portion of the joint and change the spatial relationship between the bones;
• FIG. 3 is a schematic illustration of another embodiment of the invention in which the joint ofFIG. 1 is flexed after the wedge member has been inserted into the joint and connected with only one of the bones;
• FIG. 4 is a schematic illustration depicting an alternative manner of inserting the wedge member into the joint between the bones ofFIG. 1;
• FIG. 5 is a schematic pictorial illustration of the wedge member ofFIGS. 2 and 3;
• FIG. 6 is a plan view further illustrating the construction of the wedge member ofFIG. 5;
• FIG. 7 is a side view, taken generally along the line7-7 ofFIG. 6, of the wedge member ofFIG. 5;
• FIG. 8 is an enlarged fragmentary schematic sectional view depicting the manner in which the wedge member ofFIGS. 5-7 is positioned, as shown inFIG. 2, in a joint between bones;
• FIG. 9 is a fragmentary schematic sectional view, generally similar toFIG. 8, but on a reduced scale, illustrating an embodiment of the invention in which the wedge member is porous;
• FIG. 10 is a fragmentary schematic sectional view, generally similar toFIG. 9, illustrating an embodiment of the wedge member which is porous and has a chamber which holds bone growth promoting material;
• FIG. 11 is a fragmentary schematic sectional view, generally similar toFIGS. 8-10, illustrating the manner in which the wedge member ofFIG. 3 is connected with only one bone to enable the joint between bones to be flexed;
• FIG. 12 is a schematic illustration depicting the manner in which a rotatable wedge member is moved into a joint between bones;
• FIG. 13 is a schematic illustration depicting the wedge member ofFIG. 12 after the wedge member has been rotated to expand a portion of the joint between the bones;
• FIG. 14 is an enlarged fragmentary schematic sectional view, taken generally along the line14-14 ofFIG. 12, illustrating the relationship of the rotatable wedge member to the bones prior to rotation of the wedge member;
• FIG. 15 is an enlarged fragmentary schematic sectional view, taken generally along the line15-15 ofFIG. 13, illustrating the relationship of the rotatable wedge member ofFIG. 14 to the bones after rotation of the wedge member;
• FIG. 16 is a fragmentary schematic sectional view, taken generally along the line16-16 ofFIG. 15, illustrating the manner in which the rotatable wedge member is connected with the bones;
• FIG. 17 is a fragmentary schematic sectional view, generally similar toFIG. 16, illustrating an embodiment of the rotatable wedge member which is porous;
• FIG. 18 is a fragmentary sectional view, generally similar toFIG. 14, illustrating the relationship between the bones at a joint when another embodiment of the rotatable wedge member is in the initial orientation illustrated inFIG. 12 relative to the bones;
• FIG. 19 is a fragmentary schematic sectional view, generally similar toFIG. 15, illustrating the relationship of the rotatable wedge member ofFIG. 18 to the bones after the wedge member has been rotated;
• FIG. 20 is a fragmentary schematic sectional view, taken generally along the line20-20 ofFIG. 19, further illustrating the construction of the rotatable wedge member;
• FIG. 21 is a schematic illustration, generally similar toFIG. 2, depicting the manner in which another embodiment of the rotatable wedge member is moved into a joint between bones in a patient's body;
• FIG. 22 is an enlarged schematic pictorial illustration of the rotatable wedge member ofFIG. 21;
• FIG. 23 is a fragmentary schematic illustration, generally similar toFIG. 2, depicting the manner in which another embodiment of the wedge member is moved into a joint between bones in a patient's body; and
• FIG. 24 is an enlarged fragmentary schematic sectional view, taken generally along the line24-24 ofFIG. 23, further illustrating the relationship of the wedge member to the bones.
DETAILED DESCRIPTION OF THE INVENTIONGeneral Description
• An upper orfirst bone30 in a patient's body is illustrated schematically inFIG. 1. A lower orsecond bone32 is connected with theupper bone30 at a joint34. Thebones30 and32 and joint34 have been illustrated schematically to represent any one of many bones and joints in a patient's body. Thus, thebones30 and32 and joint34 may be disposed in a patient's hand, foot, back, or other portion of the patient's body. It should be understood that thebones30 and32 and joint34 have been illustrated schematically inFIG. 1 as being representative of any one of the many joints in a human patient's body and it is not intended to limit the present invention to any particular joint.
• In order to correct deformities, improve patient comfort or other reasons, it may be desired to change the spatial relationship between the upper andlower bones30 and32. Thus, it may be desired to change the angular relationship between longitudinalcentral axes38 and40 from the relationship illustrated schematically inFIG. 1 to the relationship illustrated schematically inFIG. 2.
• In order to change the spatial relationship between the longitudinalcentral axes38 and40 of thebones30 and32, an opening is formed in a portion of the patient's body to expose the joint34. A wedge member44 (FIG. 2) is moved into the exposed joint34 between thebones30 and32. Thewedge member44 applies force against the outer side surfaces of thebones30 and32 at the joint34 to expand a portion of the joint.
• As thewedge member44 is moved into the joint34, in the manner illustrated schematically inFIG. 2, thelower bone32 is pivoted relative to theupper bone30 about an axis extending through the joint34. This changes the angular orientation of thelower bone32 relative to theupper bone30. Thus, the spatial relationship between the upper andlower bones30 and32 is changed from the spatial relationship illustrated inFIG. 1 to the spatial relationship illustrated inFIG. 2 by thewedge member44.
• InFIG. 2, thewedge member44 has been illustrated schematically as having an extent which corresponds to approximately one-half of the extent of the joint34. However, it is contemplated that thewedge member44 could have an extent which is either smaller than or greater than the extent illustrated inFIG. 2. Thus, the distance between the thick and thin end portions of the taperedwedge member44 may be less than one-half of the width of the joint34. Similarly, the distance between the thin leading end portion and thick trailing end portion of thewedge member44 may be greater than one-half of the width of the joint34.
• Thewedge member44 may be relatively narrow, as measured along the thin end portion of the wedge member. This would enable a plurality ofnarrow wedge members44 to be used to expand a single joint34. If thewedge member44 is relatively wide, only a single wedge member may be required to expand a joint34, as shown inFIG. 2.
• In the embodiment of the invention illustrated inFIG. 2, the joint34 is fused after the joint has been expanded by thewedge member44 to change the spatial relationship between thebones30 and32. Thus, after the joint34 has been expanded by thewedge member34, the joint is immobilized with the upper andlower bones30 and32 in the spatial relationship illustrated inFIG. 2. When thewedge member44 is utilized in association with joints between vertebrae in a patient's back, it is believed that it may be particularly advantageous to immobilize the joint34.
• Immobilization of the joint34 may be accomplished by connecting thewedge member44 with both theupper bone30 and thelower bone32. Immobilization of the joint34 may also be accomplished by the growth of bone and/or other body tissue between the twobones30 and32 at the joint34. Known bone growth promoting materials may be provided at the joint34 if desired. The bone growth promoting materials may include bone morphogenic proteins and/or other osteoinductive materials.
• In the embodiment of the invention illustrated inFIG. 3, the joint34 is capable of being flexed after thewedge member44 has been utilized to expand a portion of the joint. Thus, once thewedge member44 has been inserted into the joint34, in the manner illustrated inFIG. 2, the patient may flex the joint under the influence of force transmitted to thebones32 and30 from muscle tissue in the patient's body.
• When the joint34 is flexed, as illustrated schematically inFIG. 3, thebone32 moves away from thewedge member44. Thewedge member44 is fixedly connected to only thebone30. This allows thebone32 to move away from the wedge member. It is believed that it will be particularly advantageous to enable the joint34 to be flexed when the wedge member is utilized to correct deformities occurring in hands, feet, wrists or ankles of a patient. However, it should be understood that the wedge member could be attached to a single bone at any joint in a patient's body which is to be flexed after the wedge member has been used to expand the joint.
• In the embodiment of the invention illustrated inFIGS. 1-3, thewedge member44 has been shown as being moved into the joint34 in a direction which is perpendicular to an axis about which the joint is flexed. Thus, thewedge member44 is moved into the joint34 (FIG. 2) in a direction perpendicular to the axis about which the joint34 is schematically illustrated inFIG. 3 as being flexed.
• In the embodiment of the invention illustrated inFIG. 4, thewedge member44 is inserted into the joint34 in a direction parallel to the axis about which the joint is normally flexed. Thus, thewedge member44 is illustrated inFIG. 4 as being inserted into the joint34 in a direction perpendicular to the plane of the drawing of the joint34 inFIGS. 1 and 3. It should be understood that thewedge member44 could be inserted into a joint, such as the joint34, in any desired direction in order to obtain a desired expansion of the joint. Thus, thewedge member44 could be moved into the joint34 along a path which is neither perpendicular to or parallel to the axis about which the joint is flexed.
• After one ormore wedge members44 have been positioned in a joint34, in the manner previously explained, the opening in the patient's body is closed. When the opening in the patient's body is closed, thewedge member44 remains in the joint34 between thebones30 and32. Thewedge member44 is formed of a rigid material which is capable of transmitting force between thebones30 and32 immediately after being positioned in the joint34. Therefore, thewedge member44 is effective to maintain the changed spatial relationship, such as the spatial relationship illustrated inFIG. 2, between thebones30 and32 during loading of the joint34 immediately after positioning of the wedge member in the joint.
Wedge Member
• The wedge member44 (FIGS. 5-7) tapers from athick end portion50 to athin end portion52. Thewedge member44 has flat upper and lower major side surfaces54 and56 (FIG. 7) which slope toward each other from thethick end portion50 to thethin end portion52. The major side surfaces54 and56 intersect at thethin end portion52. The pointedthin end portion52 of thewedge member44 facilitates moving the wedge member into the joint34 between thebones30 and32 (FIG. 2).
• In the illustrated embodiment of the wedge member44 (FIGS. 5-7), thethick end portion50 has anouter side surface60 which forms a portion of a cylinder. Thethin end portion52 extends diametrically across the cylinder (FIG. 6). Therefore, thewedge member44 has a semi-circular configuration. However, it should be understood that the configuration of the upper and lower major side surfaces54 and56 of thewedge member44 corresponds to the configuration of the joint with which the wedge member is to be associated.
• The semi-circularouter side surface60 will, for many joints at least, have an irregular configuration other than the semi-circular configuration illustrated inFIGS. 5 and 6. This enables theouter side surface60 to be aligned with the outer side surfaces of thebones30 and32 at the joint34. Since most bones do not have outer side surfaces which form portions of a semi-circular, it is believed that in all probability, thewedge member44 will have anouter side surface60 with an irregular configuration rather than the semi-circular configuration illustrated inFIG. 5.
• The extent of thethin end portion52 of thewedge member44 may be substantially less than shown inFIG. 6. Thus, the extent of thethin end portion52 of thewedge member44 may be less than one-half of the extent shown inFIG. 6. This would result in the major side surfaces54 and56 of thewedge member44 having a generally U-shaped configuration. Parallel triangular side surfaces would extend between theouter side surface50 of thewedge member44 and opposite ends of thethin end portion52. These triangular side surfaces would be spaced from opposite sides of the joint34 when thewedge member44 is inserted into the joint.
• When thewedge member44 has a relatively narrow, generally U-shaped configuration, a plurality of the wedge members may be inserted into a single joint34 (FIG. 1). When a plurality ofnarrow wedge members44 are used at one joint34, the wedge members may have different configurations. Thus, thewedge members44 may have different lengths and/or different angles between the upper and lower major side surfaces54 and56 of the wedge members.
• The upper and lower major side surfaces54 and56 of thewedge member44 slope toward each other from thethick end portion50 to thethin end portion52 of the wedge member. It is contemplated that a plurality ofwedge members44 having different acute angles between the upper and lower major side surfaces54 and56 may be provided. This would enable a surgeon to select thewedge member44 having a desired thickness at thethick end portion50. Thus, if a surgeon determines that a joint should be expanded to either a lesser or greater amount than would be accomplished by a wedge member having one angle, the surgeon may select a wedge member having a different angle and thickness to effect the desired expansion of the joint34. It is also contemplated that a plurality ofwedge members44 having different widths, as measured along thethin end portion52, may be provided.
• The acute angle between the flat upper and lower major side surfaces54 and56 is determined by the extent to which the joint34 is to be expanded, that is, the extent to which the spatial relationship between thebones30 and32 is to be changed by insertion of thewedge member44. Of course, the specific angle provided between the upper and lower major side surfaces54 and56 of thewedge member44 will vary depending upon the size of the joint with which the wedge member is used and the extent to which the spatial relationship between thebones30 and32 is to be changed by use of the wedge member. In addition, the length and width of thewedge member44 inserted into a particular joint will be determined by the extent to which the joint is to be expanded and the total number of wedge members to be inserted into the joint.
• It is believed that it may be desired to have the acute angle between the upper and lower major side surfaces54 and56 (FIG. 6) of thewedge member44 within a range between one and thirty degrees. Although it is difficult to be certain, it is believed that it may be preferred to have the acute angle between the upper and lower major side surfaces54 and56 of thewedge member44 vary within a range of five degrees to twenty degrees. It should be understood that the foregoing specific ranges of sizes for the angle between the upper and lower major side surfaces54 and56 of thewedge member44 have been set forth herein for purposes of clarity of description and it is contemplated that the angle between the upper and lower major side surfaces54 and56 may be any one of many angles other than these specific angles.
• The size of the wedge member relative to a specific joint34 may vary depending upon the deformity to be corrected. Thus, anarrow wedge member44 may have a thin end portion52 (FIG. 6) with a length which is relatively small compared to the width of a joint. Thethin end portion52 of thenarrow wedge member44 could have a length of less than one fourth the distance across the joint. This would result in opposite ends of thethin end portion52 being spaced from the periphery of the joint. It is contemplated that a plurality ofnarrow wedge members44 could be used to expand a single joint.
• Thewedge member44 may be formed of any one of many different known materials which are compatible with a patient's body. For example, the wedge member may be formed of human or animal bone, stainless steel, tantalum, a porous ceramic, or a polymeric material. If desired, the wedge member may be formed of a biodegradable material. However, it is preferred to have thewedge member44 formed of a rigid material which is capable of enabling force to be transmitted through the joint34 between thebones30 and32 immediately after installation of the wedge member in the joint.
• In the embodiment of the invention illustrated inFIG. 2, the joint34 is immobilized. To facilitate immobilization of the joint34, thewedge member44 is fixedly connected with thebone30 and with thebone32. To facilitate fixedly connecting thewedge member44 with thebones30 and32, a pair ofpassages64 and66 are formed in the wedge member44 (FIGS. 6 and 7). When thewedge member44 is positioned in the joint34 (FIG. 2), suitable fasteners, that is screws70 and72 extend through thepassages64 and66 into thebones30 and32 in the manner indicated schematically inFIG. 8. Thescrews70 and72 engage hard corticalouter layers76 and78 of thebones30 and32. If desired, thescrews70 and72 could extend into the relatively softcancellous bone80 and82.
• Although thewedge member44 has been illustrated inFIG. 8 as being connected with thebones30 and32 by a pair ofscrews70 and72, it should be understood that thewedge member44 may be connected with only one of thebones30 or32 by only one of thescrews70 or72 if desired. For example, if thewedge member44 is connected with thebone30 by thescrew70, the joint34 could be flexed in the manner illustrated schematically inFIG. 3, after thewedge member44 has been moved into the joint.
Positioning of Wedge Member
• When thewedge member44 is to be inserted in to the joint34 to change the spatial relationship between thebones30 and32 in the manner illustrated schematically inFIG. 2, a location for insertion of the wedge member into the joint34 is selected by a surgeon. The specific location at which thewedge member44 is inserted into the joint34 to expand the joint will be selected by the surgeon as a function of the desired result from a particular operation. In addition, the size of thewedge member44 will be selected by the surgeon as a function of the joint and the result to be obtained from a particular operation.
• The configuration of thewedge member44 will be selected by the surgeon as a function of the location where the wedge member is to be inserted into the joint34. Thewedge member44 may be relatively wide and have a longthin end portion52, as shown inFIG. 6, to enable the thin end portion to extend between opposite sides of the joint. Alternatively, thewedge member44 may be relatively narrow and have athin end portion52 which is short. If this is done, thethin end portion52 would not extend between opposite sides of the joint34. A plurality of thenarrow wedge members44 may be inserted into a single joint34 to expand the joint and transmit force between thebones30 and32.
• The surgeon makes an incision in soft body tissue surrounding the joint34 to expose the joint. Once the joint34 has been exposed, the thin end portion52 (FIGS. 5 and 6) of thewedge member44 is moved into the joint34. When thewedge member44 is to be inserted into a joint in the manner illustrated schematically inFIG. 2, the longitudinal central axis of thethin end portion52 of the wedge member is aligned with an axis about which the joint pivots. The wedge member is then moved into the joint34 along a linear path which extends perpendicular to the axis about which the joint pivots. Thewedge member44 is moved into the joint34 by applying force against the trailingthick end portion50 of the wedge member.
• As thewedge member44 is moved into the joint34, the upper major side surface54 (FIGS. 5 and 7) of the wedge member slides along an outer side surface88 (FIG. 8) of theouter layer76 of hard cortical bone. The lowermajor side surface56 of thewedge member44 slides along anouter side surface90 of theouter layer78 of hard cortical bone.
• The outer side surfaces88 and90 of thebones30 and32 are in their naturally occurring conditions. Thus, the outer side surfaces88 and90 of thebones30 and32 are not cut away to prepare for insertion of thewedge member44 into the joint34. However, it should be understood that under certain circumstances that it may be necessary to abrade or otherwise cut the outer side surfaces88 and90 of theouter layers76 and78 of hard cortical bone to prepare the joint34 for insertion of thewedge member44.
• As the thin leading end portion52 (FIG. 8) of thewedge member44 moves into the joint34, the upper and lower major side surfaces54 and56 apply force against the outer side surfaces88 and90 on thebones30 and32. As this occurs, the joint34 is expanded. As the joint34 is expanded, thebone32 is pivoted, relative to thebone30, from the initial orientation, shown inFIG. 1, to the improved orientation shown inFIG. 2. As this occurs, the longitudinalcentral axis40 of thebone32 moves relative to the longitudinalcentral axis38 of thebone30. Therefore, the angular relationship between thebones30 and32 is changed by expansion of a portion of the joint34 by insertion of thewedge member44 into the joint.
• When thewedge member44 has been pressed the desired distance into the joint34, by the application of force against thethick end portion50 of thewedge member44, theouter side surface60 on the wedge member moves slightly inward of the outer side surfaces on thebones30 and32 (FIG. 8). Theouter side surface60 on thewedge member44 has a configuration which corresponds to the configurations of the outer side surfaces on thebones30 and32 adjacent to the joint34. Therefore, thewedge member44 does not project outward from the joint. This minimizes any tendency of the wedge member to subsequently abrade body tissue adjacent to the joint34.
• Once thewedge member44 has been moved into the desired orientation relative to thebones30 and32, as illustrated schematically inFIG. 8, thewedge member44 is fixedly connected with thebones30 and32 by thescrews70 and72 to immobilize the joint. The area surrounding and directly adjacent to thewedge member44 is packed with bone growth promoting material and/or bone chips. The bone growth promoting materials may include bone morphogenic proteins and/or other osteoinductive materials. This promotes fusion of thebones30 and32 for remedial immobilization of the joint34.
• Since thewedge member44 is rigid, it can immediately transmit loads between thebones30 and32. Therefore, after the incision which exposed the joint34 has been closed, the patient can begin to load the joint34. Thewedge member44 is effective to maintain the joint34 in an expanded condition during loading of the joint. Therefore, thebones30 and32 remain in the improved spatial relationship illustrated inFIG. 2 during loading of the joint34.
Wedge MemberSecond Embodiment
• In the embodiment of the invention illustrated inFIGS. 1-8, a solid wedge member has been utilized to expand the joint34. In the embodiment of the invention illustrated inFIG. 9, a porous wedge member is utilized to expand a joint. Since the embodiment of the invention illustrated inFIG. 9 is generally similar to the embodiment of the invention illustrated inFIGS. 1-8, similar numerals will be utilized to designate similar components, the suffix letter “a” being associated with the numerals ofFIG. 9 in order to avoid confusion.
• Awedge member44ais positioned in a joint34abetweenbones30aand32a. Thewedge member44aengages outer side surfaces88aand90aonlayers76aand78aof hard cortical bone. The outer side surfaces88aand90aare in their naturally occurring conditions.
• As thewedge member44ais moved into the joint34a, flat upper and lower major side surfaces54aand56aon thewedge member44aslide along the outer side surfaces88aand90aon thebones30aand32a. The upper and lower major side surfaces54aand56aof thewedge44aapply force against the outer side surfaces88aand90aof thebones30aand32ato expand the joint34aas the wedge member is moved into the joint. Thewedge member44ais moved into the joint34aunder the influence of force applied against an outer side surface60aon a trailingthick end portion50aof thewedge member44a.
• Once the joint34ahas been expanded to change the spatial relationship between thebones30aand32a, suitable fasteners (screws)70aand72aare inserted through passages in thewedge member44a. Thescrews70aand72aengage the hard corticalouter layers76aand78aof bone to fixedly secure thewedge member44awith thebones30aand32a.
• Asingle wedge member44ais used to expand the joint34a. However, a plurality ofnarrow wedge members44amay be inserted into the joint at spaced apart locations about the periphery of the joint if desired.
• In accordance with a feature of this embodiment of the invention, thewedge member44ais porous so that bone can grow through the wedge member. It is contemplated that the wedge member could be provided with a porous construction by having passages extend through the wedge member between the upper and lower major side surfaces54aand56aof the wedge member. The open ends of the passages would enable bone to grow through thewedge member44a.
• In the embodiment of thewedge member44aillustrated inFIG. 9, the wedge member is formed of a rigid open cell material. The open cell material provides cavities in which bone can grow through thewedge member44a. Thus, thewedge member44a(FIG. 9) has a cellular construction similar to coral.
• It is contemplated that thewedge member44amay be coated with a material which promotes the growth of bone. The cells in thewedge member44amay be at least partially filled with bone growth promoting material. The bone growth promoting materials may be bone morphogenic proteins and other osteoinductive materials. In addition to bone growth promoting material associated with thewedge member44a, the space around and adjacent to thewedge member44ain the joint34amay be packed with bone growth promoting material and/or bone chips.
• Thewedge member44ais rigid and can be subject to normal loading immediately after being positioned in the joint34a. This enables the patient to subject thebones30aand32ato normal loading without waiting for fusion to occur through and around thewedge member44a. Of course, with the passage of time, the growth of bone through thewedge member44aand around the wedge member will strengthen the immobilization of the joint34a.
• In the embodiment of the invention illustrated inFIG. 9, the passages through thewedge member44aare formed by the open cell structure of the wedge member This results in the passages through thewedge member44ahaving an irregular configuration. If desired, linear passages could be formed in thewedge member44a. The linear passages may be drilled, cast, or formed in other ways in thewedge member44a.
Hollow Wedge Member
• In the embodiment of the invention illustrated inFIGS. 1-8, thewedge member44 is formed by a solid piece of material. In the embodiment of the invention illustrated inFIG. 9, thewedge member44ais formed by a continuous piece of porous material. In the embodiment of the invention illustrated inFIG. 10, the wedge member is formed by a hollow piece of porous material. Since the embodiment of the invention illustrated inFIG. 10 is generally similar to the embodiments of the invention illustrated inFIGS. 1-9, similar numerals will be utilized to designate similar components, the suffix letter “b” being associated with the numerals ofFIG. 10 to avoid confusion.
• In the embodiment of the invention illustrated inFIG. 10, awedge member44bis inserted into a joint34bbetweenbones30band32bto expand the joint. Expansion of the joint34bby thewedge member44bchanges the spatial relationship between thebones30band32b. Thewedge member44bis held against movement relative to thebones30band32bby fasteners (screws)70band72b. Thefasteners70band72bextend through passages in thewedge member44bintolayers76band78bof hard cortical bone onbones30b,32b. Thelayers76band78bare in their naturally occurring condition.
• When thewedge member44bis to be moved into the joint, athin end portion52bof thewedge member44bis pressed into the joint34bby applying force against anouter side surface60bat athick end portion50bof thewedge member44b. The force applied against the trailingthick end portion50bof thewedge member44bcauses flat upper and lower major side surfaces54band56bto slide along outer side surfaces88band90b. As the upper and lower major side surfaces54band56bon thewedge member44bslide along the outer side surfaces88band90bof thebones30band32b, the wedge member applies force against the bones to expand the joint34bin the manner previously explained.
• In accordance with a feature of this embodiment of the invention, thewedge member44b(FIG. 10) is hollow. Therefore, a compartment orcavity100 is formed in thewedge member44b. Thecompartment100 has upper and lower inner side surfaces102 and104 which are smaller than the upper and lower major side surfaces54band56bof thewedge member44b. However, the inner side surfaces102 and104 of thecompartment100 have the same general configuration as the upper and lower major side surfaces54band56bof thewedge member44b.
• Thecompartment100 is filled with bonegrowth inducing material110. The bonegrowth inducing material110 is positioned in thecompartment100 through a suitable opening (not shown) formed in either the upper major side surface54bor the lower major side surface56bof thewedge member44b. Once thecompartment100 has been filled with bonegrowth inducing material110, the opening to the compartment is closed. However, thewedge member44bis formed of a porous material which enables bone to grow through the wedge member.
• The growth of bone through thewedge member44bis promoted by the bonegrowth inducing material110 in thecompartment100. The bonegrowth inducing material110 in thecompartment100 may be any of many known bone morphogenic proteins and osteoinductive materials. For example, apatite compositions with collagen may be utilized. Demineralized bone powder may also be utilized. Regardless of which of the known bone growth inducing materials are selected, the presence of the bonegrowth promoting material110 in thecompartment100 will promote a growth of bone through openings in theporous wedge member44b.
• Thewedge member44bmay, itself, be formed of a suitable rigid material, such as tantalum, stainless steel, or ceramic materials. In addition to the bonegrowth inducing material110, the surfaces of thewedge member44band openings in the porous material of the wedge member may be coated with suitable bone growth promoting materials.
• Thewedge member44bis porous so that bone can grow through the wedge member. In the embodiment of the invention illustrated inFIG. 10, the wedge member is formed of an open cell material having a construction similar to coral. The open cell material provides irregular passages which extend through thewedge member44band enable the bone to grow through the wedge member. However, it should be understood that thewedge member44bcould be formed of a solid material with passages drilled or cast in the wedge member. Regardless of which of the materials the wedge member is formed, it is believed that it will be advantageous to have the material be sufficiently rigid to enable the joint44bto be load bearing immediately after an operation installing the wedge member in the joint.
Single Connection for Wedge Member
• In the embodiments of the invention illustrated inFIGS. 8-10, thewedge members44,44a, and44bare connected with bones on opposite sides of a joint by suitable fasteners (screws). In the embodiment of the invention illustrated inFIG. 11, the wedge member is connected with only one of the bones. Since the embodiment of the invention illustrated inFIG. 11 is generally similar to the embodiments of the invention illustrated inFIGS. 1-10, similar numerals will be utilized to designate similar components, the suffix letter “c” being associated with the numerals ofFIG. 11 to avoid confusion.
• A wedge member44cis inserted into a joint34cbetween upper andlower bones30cand32c. The wedge member44chas the same general configuration and construction as thewedge member44 ofFIGS. 5-8. However, the wedge member44cis connected with only one of thebones30cand32c. Thus, rather than utilizing a pair of fasteners to secure the wedge member44cto the upper andlower bones30cand32c, only asingle fastener70cis utilized to connect the wedge member44cwith theupper bone30c. Therefore, installation of the wedge member44cin the joint34cdoes not result in immobilization of the joint.
• Since the wedge member44cis connected with thebone30cby thefastener70c, thebone32cmay be moved away from the wedge member during flexing of the joint34c. This may result in the upper major side surface54con the wedge member54cremaining in engagement with theouter side surface88con thebone30cwhile theouter side surface90con thebone32cmoves away from the lowermajor side surface56con the wedge member44c. Of course, asingle fastener70cmay be utilized to hold the wedge member in the joint34cwhere the outer side surfaces88cand90con the upper andlower bones30cand32cremain in engagement with the upper and lower major side surfaces54cand56cof the wedge member44c.
• In the embodiment of the wedge member44cillustrated inFIG. 11, the wedge member is formed of a solid material through which bone does not grow. However, it is contemplated that a single fastener, corresponding to thefastener70cofFIG. 11, may be used to connect a porous wedge member with a bone. Of course, bone may grow through the porous wedge member. The porous wedge member may have the same construction as shown inFIGS. 9 and 10, with the exception of being held in place by only asingle fastener70c.
Rotatable Wedge Member
• In the embodiment of the invention illustrated inFIGS. 1-11, thewedge member44 is moved into the joint34 between the upper andlower bones30 and32 along a linear path. Thewedge member44 is moved into the joint34 with thethin end portion52 of the wedge member leading and thethick end portion50 of the wedge member trailing. The tapered configuration of the wedge member results in the application of force against the upper andlower bones30 and32 to expand the joint34 in the manner previously explained.
• In the embodiment of the invention illustrated inFIGS. 12-16, the wedge member is moved into the joint between the upper and lower bones and then rotated. During initial movement of the wedge member into the joint between the bones, there may be some expansion of the joint. During rotation of the wedge member in the joint, there is further expansion of the joint. Since the embodiment of the invention illustrated inFIGS. 12-15 is generally similar to the embodiments of the invention illustrated inFIGS. 1-11, similar numerals will be utilized to designate similar components, the suffix letter “d” being associated with the numerals ofFIGS. 12-15 to avoid confusion.
• Upper andlower bones30dand32dare interconnected at a joint34d(FIG. 12). Prior to insertion of awedge member44d, the upper andlower bones30dand32dare in the same spatial orientation relative to each other as is illustrated inFIG. 1. Upon insertion of thewedge member44dinto the joint34d, in the manner illustrated inFIG. 12, there may be a slight expansion of the joint34dand a slight change in the orientation of theupper bone30drelative to thelower bone32d. There is a relatively small change in the spatial relationship between theupper bone30dand thelower bone32dbecause thewedge member44dis inserted into the joint34din an orientation in which thewedge member44dis relatively thin as viewed inFIG. 12, that is, in a direction transverse to the joint34d.
• After thewedge member44dhas been inserted into the joint34din the manner indicated schematically inFIG. 12, thewedge member44dis rotated, through less than one revolution, about anaxis120 in the manner indicated schematically by anarrow122 inFIG. 13. As thewedge member44dis rotated through approximately ninety degrees about theaxis120, the wedge member applies force against the upper andlower bones30dand32dto expand the joint34d. As the joint34dis expanded by rotation of thewedge member44d, the spatial relationship between the upper andlower bones30dand32dchanges from the spatial relationship illustrated schematically inFIG. 12 to the spatial relationship illustrated schematically inFIG. 13. Thus, by the combined effect of insertion of thewedge member44dinto the joint34dand rotation of the wedge member in the joint, the spatial relationship of the upper andlower bones30dand32dwas changed from the spatial relationship illustrated inFIG. 1 for thebones30 and32 to the spatial relationship illustrated inFIG. 13 for the upper andlower bones30dand32d.
• Thebones30dand32dillustrated schematically inFIGS. 12 and 13 should be considered as being representative of bones at many different locations in a patient's body. Thus, thebones30dand32dmay be any of the many bones in a patient's wrist, ankle, hand, foot, back, or other portion of a patient's body. Thebones30dand32dmay be vertebrae in a patient's back. It should be understood that thewedge member44dmay be used with any one of the many different types of joints in a patient's body.
• Thewedge member44dhas a generally oval, cross-sectional configuration (FIGS. 14 and 15), as viewed in a plane perpendicular to a longitudinal central axis of the wedge member. Thus, thewedge member44dhas an outer side surface126 (FIG. 14) with a pair ofarcuate nose portions128 and130. Thearcuate nose portions128 and130 of theouter side surface126 are interconnected by a pair ofarcuate side portions134 and136.
• The arcuateouter side surface126 tapers from athick end portion50d(FIG. 16) to athin end portion52d. In the illustrated embodiment of thewedge member44d, thethin end portion52dis blunt or truncated. Thus, thethin end portion52dof thewedge member44ddoes not come to a sharp point as does the thin end portions of thewedge members44,44a,44band44c.
• It should be understood that thewedge members44a,44band44c(FIGS. 5-11) could be constructed with a blunt thin end portion corresponding to the bluntthin end portion52d(FIG. 16) on thewedge member44dif desired. However, it is believed that by having the thin end portion of the wedge members ofFIGS. 5-11 taper to a sharp point, insertion of the wedge members into a joint is facilitated. Similarly, if desired, thewedge member44dcould be provided with athin end portion52d(FIG. 16) which comes to a sharp point in the same manner as thewedge members44,44a,44band44c.
• When thewedge member44dis inserted into the joint34d(FIG. 14), thearcuate side portion134 engages theouter side surface88dof theupper bone30dand thearcuate side portion136 engages theouter side surface90dof thelower bone32d. Thearcuate side portions134 and136 are relatively close together so that minimal expansion of the joint34doccurs when thewedge member44dis inserted into the joint. As thewedge member44dis inserted into the joint34d, thearcuate side portions134 and136 slide along and are effective to apply force against the outer side surfaces88dand90dof the upper andlower bones30dand32dto effect some expansion of the joint34d. The outer side surfaces88dand90dof thebones30dand32dare in their naturally occurring conditions.
• After thewedge member44dhas been inserted into the joint34d, in the manner shown inFIGS. 12 and 14, a suitable tool is inserted into a hexagonal socket140 (FIG. 14) in thewedge member44d. Torque is transmitted from the tool to thewedge member44dto rotate the wedge member through less than one revolution in the direction indicated by thearrow122 inFIGS. 13 and 15. This results in thewedge member44dbeing rotated through approximately ninety degrees in a clockwise direction from the position shown inFIG. 14 to the position shown inFIG. 15. As thewedge member44dis rotated, the wedge member applies force against the upper andlower bones30dand32dand expands the joint34d.
• Upon initiation of rotation of thewedge member44dfrom the position shown inFIG. 14 toward the position shown inFIG. 15, thearcuate side portions134 and136 slide along the outer side surfaces88dand90don the bones. As the rotation of thewedge member44dcontinues, thearcuate nose portions128 and130 of thewedge member44dapproach the outer side surfaces88dand90dof the upper andlower bones30dand32d. As this is occurring, the joint34dis expanded by the force applied against the upper andlower bones30dand32dby thewedge member44d. When thewedge member44dreaches the position shown inFIG. 15, thearcuate nose portions128 and130 engage the outer side surfaces88dand90don the upper andlower bones30dand32dto hold the joint34din the expanded condition illustrated inFIGS. 15 and 16.
• A pair of mountingtabs144 and146 (FIG. 16) are integrally formed with thewedge member44d. The mountingtabs144 and146 project outwardly from theend portion50dof thewedge member44d. The mountingtabs144 and146 are aligned with thearcuate nose portions128 and130 of theouter side surface126 on thewedge member44d. Therefore, the mountingtabs144 and146 are disposed adjacent to thebones30dand32din the manner illustrated schematically inFIG. 16.
• A pair of retainingscrews70dand72dextend through the mountingtabs144 and146 into theouter layers76dand78dof hard cancellous bone on the upper andlower bones30dand32d. The mounting screws orfasteners70dand72dare effective to hold thewedge member44dagainst rotation relative to the upper andlower bones30dand32d. Bone growth promoting material and/or bone chips may be packed in the joint34daround thewedge member44d. Thewedge member44dis rigid and can transmit force between thebones30dand32das soon as it is rotated to the position shown inFIGS. 15 and 16.
• As is perhaps best seen inFIG. 15, thewedge member44dis narrower than the distance across the joint34d. Therefore, a plurality ofwedge members44dmay be utilized to hold the joint34din the expanded condition ofFIGS. 15 and 16. The plurality ofwedge members44dcould be positioned in the joint34dwith their rotational axes120 (FIG. 16) in a parallel relationship or with theirrotational axes120 skewed relative to each other. If a plurality ofwedge members44dare utilized, they could be of different sizes or have different angles of taper along theaxis120.
• It should be understood that thewedge members44,44a,44band44cofFIGS. 5-11 could also be relatively narrow. A plurality of wedge members ofFIGS. 5-11 could be positioned in a joint with their longitudinal axes either parallel or skewed relative to each other.
Porous Rotatable Wedge Member
• In the embodiment of the invention illustrated inFIGS. 12-16, thewedge member44dis formed as a solid body of rigid material, such as stainless steel. The wedge member in the embodiment of the invention illustrated inFIG. 17 is formed of a rigid porous material. Since the embodiment of the invention illustrated inFIG. 17 is generally similar to the embodiments of the invention illustrated inFIGS. 1-16, similar numerals will be utilized to designate similar components, the suffix letter “e” being associated with the numerals ofFIG. 17 to avoid confusion.
• Thewedge member44eis disposed in a joint34ebetween upper andlower bones30eand32e. Thewedge member44eapplies force against the outer side surfaces88eand90eof the upper andlower bones30eand32eto expand the joint34eand change the orientation of the upper and lower bones relative to each other. In the embodiment of the invention illustrated inFIG. 17, thewedge member44etapers from athick end portion50eto athin end portion52e. In the illustrated embodiment of the invention, thethin end portion52eof thewedge member44ehas a pointed configuration rather than the blunt configuration of thewedge member44dofFIG. 16. However, thewedge member44ecould have the same configuration as thewedge member44dif desired.
• Thewedge member44e(FIG. 17) has an oval cross sectional configuration, as viewed on a plane extending perpendicular to acentral axis120eof thewedge member44e. Thus, thewedge ember44ehas anouter side surface126ewitharcuate nose portions128eand130e. Thearcuate nose portions128eand130 are interconnected by arcuate side portions corresponding to thearcuate side portions134 and136 of thewedge member44d(FIGS. 14 and 15). Asocket140e(FIG. 17) is provided in thewedge member44eto facilitate the application of torque to the wedge member.
• In accordance with a feature of the embodiment of the invention illustrated inFIG. 17, thewedge member44eis formed of a rigid porous material having an open cell construction. The porous open cell construction of thewedge member44eenables bone to grow through the wedge member. Thewedge member44emay have an open cell construction similar to the construction of coral.
• Thewedge member44emay be coated with bone growth promoting materials to promote the growth of bone through the wedge member. The open cells in theporous wedge member44ecould be at least partially filled with the bone growth promoting material. In addition, bone growth materials and/or bone chips may be packed in the joint34earound thewedge member44e. The bone growth promoting materials may include bone morphogenic proteins and/or other osteoinductive materials.
• A pair offasteners70eand72eare provided to connect thewedge member44ewith the upper andlower bones30eand32e. Thus, thefasteners70eextends into theouter layer76eof hard cortical bone on theupper bone30e. Similarly, thefastener72eextends into theouter layer78eof hard cortical bone on thelower bone32e. In the illustrated embodiment of the invention, thefasteners70eand72eextend through passages in thewedge member44einto the upper andlower bones30eand32e. However, if desired, thewedge member44ecould be provided with mounting tabs, similar to the mountingtabs144 and146 ofFIG. 16.
• When thewedge member44eis to be used to change the spatial relationship between the upper andlower bones30eand32e, the wedge member is inserted into the joint34ewith thearcuate nose portions128eand130eof the wedge member spaced from the outer side surfaces88eand90eon the upper andlower bones30eand32e. At this time, thewedge member44eis in the same orientation as is illustrated inFIG. 14 for thewedge member44d. Arcuate side portions of the arcuateouter side surface126eon thewedge member44eengage the outer side surfaces88eand90eon the upper andlower bones30eand32ein the same manner as is illustrated for thewedge member44dinFIG. 14.
• Although inserting thewedge member44einto the joint32emay effect an initial, relatively small expansion of the joint, the majority of the expansion of the joint34eis obtained by rotating thewedge member44eabout itscentral axis120e. To rotate thewedge member44eabout itscentral axis120e, a suitable tool is inserted into thesocket140e. Force is transmitted from the tool to thewedge member44eto rotate the wedge member. As the wedge member is rotated relative to the upper andlower bones30eand32e, the wedge member further expands the joint34eand effects further change in the spatial relationship between the upper andlower bones30eand32e.
• Once thewedge member44ehas been moved to the position illustrated inFIG. 17, that is, to a position corresponding to the position of thewedge member44dinFIG. 15, the wedge member is connected to the upper andlower bones30eand32e. To connect the wedge member with the upper andlower bones30eand32e, thescrews70eand72eare inserted through passages in the wedge member into the bone. Bone growth promoting material and/or bone chips may be packed in the joint34earound thewedge member44e.
• Although asingle wedge member44eis utilized to expand the joint34e, a plurality of wedge members could be utilized if desired. When a plurality ofwedge members34eare held to expand the joint34e, the wedge members may all be of the same size and configuration or may have different sizes and configurations.
Rotatable Wedge Member AlternativeEmbodiment
• Thewedge members44dand44eare rotated about theircentral axes120dand120e(FIGS. 16 and 17) to effect expansion of thejoints34dand34e. In the embodiment of the invention illustrated inFIGS. 18 through 20, the wedge member is rotated about a location where the wedge member engages one of the bones. Since the embodiment of the invention illustrated inFIGS. 18-20 is generally similar to the embodiments of the invention illustrated inFIGS. 1-17, similar numerals will be utilized to designate similar components, the suffix letter “ft being associated with the numerals ofFIGS. 18-20 to avoid confusion.
• Upper andlower bones30fand32fare interconnected at a joint34f. Awedge member44fis illustrated inserted into the joint34fbetween the upper andlower bones30fand32. Thewedge member44fis positioned in the joint34f(FIG. 18) with a relatively narrow width of the wedge member between outer side surfaces88fand90fon hard corticalouter layers76fand78fof the upper andlower bones30fand32f. Although the outer side surfaces88fand90fof the upper andlower bones30fand32fare in their naturally occurring conditions, it is contemplated that a surgeon may want to prepare the surfaces of the bone for thewedge member44fby cutting away extraneous material to promote seating of thewedge member44fon the upper andlower bones30fand32f.
• Thewedge member44fhas anarcuate nose portion128fand apivot end portion150f. Thenose portion128fand pivotend portion150fare interconnected byside portions134fand136f. Theside portion134fhas a continuously curving arcuate configuration. Theside portion136fmay have a linear configuration.
• Theside portion136fhas a relatively flat area which engages theouter side surface90fon thelower bone32fwhen thewedge member44fis oriented as illustrated inFIG. 18 If desired, theside portion136fcould have an arcuate configuration corresponding to the arcuate configuration of theside portion134f. If theside portion136fhad the same configuration as theside portion134f, thewedge member44fwould have a symmetrical configuration about an axis extending through the relatively sharply defined pivot end portion150c.
• Thewedge member44fhas the same size and configuration throughout its length. Thus, theend portion150fof the wedge member is the same size as theend portion52f(FIG. 20). However, if desired, thewedge member44fcould taper from a relativelythick end portion50fto a relatively thin orsmall end portion52fin the manner illustrated inFIGS. 16 and 17 for thewedge members44dand44e. It should be understood that any one of the wedge members illustrated inFIGS. 1 through 17 could be formed with the same configuration as thewedge member44fif desired. However, it is believed that in most instances it will probably be preferred to provide the wedge members ofFIGS. 1-17 with an axially tapered configuration to facilitate insertion of the wedge members into the joint between the upper and lower bones.
• Thewedge member44f(FIGS. 18,19 and20) is formed of a rigid porous open cell material. The rigid porous open cell material of thewedge member44fhas a construction generally similar to coral. However, thewedge member44fcould be formed of a nonporous material if desired.
• It is contemplated that thewedge member44f, like the wedge members illustrated inFIGS. 1-17, may be formed of human or animal bone, metal, ceramic, or a polymeric material. While it may be preferred to form thewedge member44fof a porous material to enable bone to grow through the wedge member, thewedge member44fmay be formed of a solid material through which bone can not grow.
• Thewedge member44fmay be coated with or packed with bone growth promoting materials. The bone growth promoting materials may be bone morphogenic proteins and/or other osteoinductive materials. Bone chips may be included with the bone morphogenic proteins and/or other osteoinductive materials packed around thewedge member44f.
• Of course, thewedge member44fmay be provided with a tapered configuration to facilitate insertion into the joint34f. When thewedge member44fis to be utilized to change the spatial relationship between the upper andlower bones30fand32f, the wedge member is inserted into the joint34f. The illustrated embodiment of thewedge member44fhas the same size and configuration throughout its length. Therefore, thewedge member44fdoes not taper to a thin end portion to facilitate insertion of the wedge member into the joint34f. Therefore, the joint34fmay be initially expanded with a suitable tool to enable thewedge member44fto be inserted into the joint, in the orientation illustrated inFIG. 18.
• When thewedge member44fis inserted into the joint34f, there will be a slight initial expansion of the joint. As was previously mentioned, thewedge member44fmay have an axially tapered configuration, similar to the configuration of thewedge members44dand44e(FIGS. 16 and 17), to facilitate insertion of thewedge member44finto the joint34f.
• As thewedge member44fis initially inserted into the joint34f, theside portions134fand136fon thewedge member44fslide along the outer side surfaces88fand90fon the upper andlower bones30fand32f. At this time, thearcuate nose portion128fof thewedge member44fis spaced from the outer side surface surfaces88fand90fof the upper andlower bones30fand32f.
• To further change the spatial relationship between the upper andlower bones30fand32f, thewedge member44fis rotated about an axis extending through a location where thepivot end portion150fof thewedge member44fengages theouter side surface90fof thelower bone32f. To effect rotation of thewedge member44f, a suitable tool is inserted into asocket140f. Force is transmitted through the tool to thewedge member44furging thewedge member44fto rotate in a clockwise direction from the position shown inFIG. 18 to the position shown inFIG. 19.
• Upon initial application of the force to thewedge member44furging the wedge member to rotate in a clockwise direction (as viewed inFIG. 18), thepivot end portion150fof thewedge member44fis pressed against theouter side surface90fof thelower bone32f. At the same time, theside portion134fof thewedge member44fbegins to slide along theouter side surface88fon theupper bone30f.
• Continued application of force (torque) to thewedge member44fresults in the wedge member pivoting about an axis which extends through a location where theend portion150fof thewedge member44fengages theouter side surface90fon thelower bone32f. As thewedge member44fpivots about theend portion150f, thearcuate nose portion128fmoves into engagement with and slides along theouter side surface88fon theupper bone30f. As thewedge member44fapproaches the orientation shown inFIG. 19, the joint34fis expanded and the spatial relationship between the upper andlower bones30fand32fis changed with a resulting change in the angular orientation of the upper and lower bones relative to each other.
• When thewedge member44freaches the orientation shown inFIG. 19, the joint34fhas been expanded to the maximum extent possible by the wedge member. Thewedge member44fis then connected with the upper andlower bones30fand32fby suitable fasteners. The fasteners may extend through mounting tabs, similar to the mountingtabs144 and146 illustrated inFIG. 16 or the fasteners may extend through the wedge member in the manner illustrated schematically inFIG. 17. Of course, thewedge member44fcould be held in the upright (as viewed inFIG. 19) orientation in any one of many different manners by a suitable fastener arrangement.
• Although only asingle wedge member44fhas been shown inFIGS. 18-20, a plurality of thewedge members44fcould be used to expand the joint34fand to transmit force between thebones30fand32f. Whether asingle wedge member44for a plurality ofwedge members44fare used to expand the joint, the joint may be packed with bone growth promoting material.
Screw Type Wedge Member
• In the embodiment of the invention illustrated inFIGS. 12-16, thewedge member44dhas a relatively smoothouter side surface126. In the embodiment of the invention illustrated inFIGS. 21 and 22, the wedge member has a configuration similar to the configuration of a screw and has a irregular outer side surface. Since the embodiment of the invention illustrated inFIGS. 21 and 22 is generally similar to the embodiments of the invention illustrated inFIGS. 12-20, similar numerals will be utilized to designate similar components, the suffix letter “g” being associated with the numerals ofFIGS. 21 and 22 to avoid confusion.
• Anupper bone30gis connected with a lower bone32gin a patient's body at a joint34g. It should be understood that the joint34ghas been illustrated schematically inFIG. 21 and may be any joint in a patient's body. Arigid wedge member44gis utilized to change the spatial relationship between the upper andlower bones30gand32g. Thewedge member44gis effective to expand at least a portion of the joint34gwhen thewedge member44gis inserted into the joint34g.
• Thewedge member44ghas athick end portion50gand a thin end portion52g. Thewedge member44ghas an overall conical configuration. Anexternal thread convolution160 is formed on thewedge member44g. Theexternal thread convolution160 has a spiral configuration and extends from thethick end portion50gto the thin end portion52gof thewedge member44g.
• Although theexternal thread convolution160 could have many different configurations, the illustrated thread convolution has generally V-shaped crests and roots. The general configuration of theexternal thread convolution160 is an American National Form Screw Thread and has a pitch cone with an angle of between five degrees and twenty degrees. Although one specific external thread convolution has been illustrated and described herein, it should be understood that theexternal thread convolution160 could have a configuration of any one of many different known thread convolutions. It is believed that it may be desired to use known bone screw thread configurations for the configuration of theexternal thread convolution160.
• Therigid wedge member44gmay be formed of metal, ceramic, human or animal bone, or suitable polymeric materials. It is believed that it will be desirable to form thewedge member44gof a material which is sufficiently rigid to withstand the forces transmitted between the upper andlower bones30gand32g. If desired, thewedge member44gmay be formed of a porous material having openings through which bone may grow. It is believed that it may be desired to coat thewedge member44gwith a bone growth promoting material.
• When thewedge member44gis to be utilized to change the spatial relationship between the upper andlower bones30gand32g, the thin end portion52gof thewedge member44gis pressed into the joint34gbetween the upper andlower bones30gand32g. Thewedge member44gis then rotated about its longitudinalcentral axis120g. Ahexagonal recess140gis provided in thewedge member44gto facilitate the transmission of force from a suitable tool to thewedge member44g.
• As thewedge member44gis rotated through a plurality of revolutions about its longitudinalcentral axis120g, the external thread convolution160gengages the upper andlower bones30gand32g. As thewedge member44gis rotated about its longitudinal central120g, theexternal thread convolution160 engages the upper andlower bones30gand32gand pulls the wedge member into the joint34g. As this occurs, the joint34gis expanded and the spatial relationship between the upper andlower bones30gand32gis changed.
• Once thewedge member44ghas moved into the joint34gand the spatial relationship between the upper andlower bones30gand32ghas been changed, the joint34gmay be packed with bone growth promoting materials and/or bone chips. It is contemplated that various known bone morphogenic proteins may be used with other osteoinductive materials to induce bone growth in the joint34g. Although only asingle wedge member44gis illustrated inFIG. 21, a plurality of wedge members may be used if desired.
Bone Fitting Wedge Member
• In the embodiments of the invention illustrated inFIGS. 1-11, the wedge members have flat upper and lower major side surfaces54 and56 (FIG. 6). In the embodiment of the invention illustrated inFIGS. 23 and 24, the wedge member has nonlinear side surfaces which have been shaped to correspond to the configuration of end portions of the bone at a joint between the bones. Since the embodiment of the invention illustrated inFIGS. 23 and 24 is generally similar to the embodiments of the invention illustrated inFIGS. 1-11, similar numerals will be utilized to designate similar components, the suffix letter “h” being associated with the numerals ofFIG. 9 to avoid confusion.
• Upper andlower bones30hand32hare interconnected at a joint34h. The joint34his a schematic representation of any one of many joints in a patient's body. The joint34hmay be in a patient's wrist, ankle, hand, foot, back, or other portion of the patient's body.
• When the spatial relationship between the upper andlower bones30hand32his to be changed, awedge member44his moved into the joint34h. Thewedge member44his moved into the joint with athick end portion50hof the wedge member trailing and athin end portion52hof the wedge member leading. As thewedge member44his pressed into the joint34h, upper and lower major side surfaces54hand56hare pressed against outer side surfaces88hand90hon the upper andlower bones30hand32h. This results in expansion of the joint34hin the manner previously described in conjunction with the embodiments of the invention illustrated inFIGS. 1-11.
• In accordance with a feature of this embodiment of the invention, the upper and lower major side surfaces54hand56hon thewedge member44hare configured to match the configuration of the outer side surfaces88hand90hon the upper andlower bones30hand32h, in the manner illustrated schematically inFIG. 24. By having the upper and lower major side surfaces54hand56hconfigured to match the configuration of the outer side surfaces88hand90hon the upper andlower bones30hand32h, thewedge member44his firmly seated against the bone and held against sidewise (as viewed inFIG. 24) movement relative to the bones. The arcuate configuration of the upper and lower major side surfaces54hand56hon thewedge member44hextends from thethick end50hof thewedge member44hto thethin end52hof the wedge member.
• In the embodiment of the invention illustrated inFIG. 24, thewedge member44his formed of a rigid porous material having an open cell construction. A compartment orcavity100hin thewedge member44hholds bonegrowth inducing materials110h. The bonegrowth inducing materials110hmay include bone morphogenic proteins and other osteoinductive materials. The joint34hmay be packed with bone growth promoting materials and/or bone chips.
• Thewedge member44his fixedly connected to the upper andlower bones30hand32hby suitable fasteners (not shown). Thewedge member44hmay be connected with the upper andlower bones30hand32hby screws corresponding to thescrews70 and72 ofFIG. 8. Alternatively, thewedge member44hmay be connected with the upper andlower bone30hand32hby screws which extends through mounting tabs, corresponding to the mountingtabs144 and146 ofFIG. 16. If desired, thewedge member44hmay be connected with only theupper bone30hor only thelower bone32h.
• It is believed that by having the side surfaces54hand56hconfigured to correspond to the configuration of thesurfaces88hand090hon thebones30hand32h, the joint34hwill be particularly stable when the joint has been immobilized by connecting thewedge member44hto the bones. Although only asingle wedge member34hhas been illustrated inFIGS. 22 and 24, a plurality of wedge members could be used to expand the joint. It is believed that thewedge member44hmay be particularly advantageous when vertebrae in a patient's back are to be interconnected.
CONCLUSION
• In view of the foregoing description it is apparent that a new and improved method and apparatus is provided to change a spatial relationship betweenbones30 and32 which are interconnected at a joint34 in a patient's body. When this is to be done, an opening is formed in a portion of the patient's body to expose the joint34 interconnecting thebones30 and32. One of thebones30 and32 is moved relative to the other by expanding at least a portion of the joint34 with awedge member44. Thewedge member44 is moved into the joint and applies force against thebones30 and32. The opening is closed with thewedge member44 still disposed in the joint between the bones. Force is then transmitted between thebones30 and32 through thewedge member44 to maintain the joint34 in an expanded condition.
• If the joint34 is to be flexed after being expanded by thewedge member44, the wedge member may be connected with only one of thebones30 and32. Alternatively, if the joint34 is to be immobilized (fused) after inserting thewedge member44, the wedge member may be fixedly connected with thebones30 and32 interconnected at the joint. Thewedge member44 may be porous and may be coated with and/or contain bone growth promoting material.
• One embodiment of thewedge member44 has major side surfaces54 and56 extending between thick andthin end portions50 and52 of the wedge member. Thewedge member44 is moved into the joint34 with thethin edge portion52 leading. As thewedge member44 is moved into the joint34, the thick trailingend portion50 of the wedge member expands the joint.
• In another embodiment of the invention, thewedge member44d,44e,44f, or44gmay be rotated relative to the joint. In one embodiment of the invention, thewedge member44ghas a circular cross sectional configuration and has anexternal thread convolution160 which extends from a thin leading end52gof the wedge member to a thick trailingend50gof the wedge member. Thewedge member44gis pressed into the joint34gand rotated to cause the wedge member to expand the joint.
• In another embodiment of the invention, thewedge member44d,44eor44fhassurface areas134 and136 which are relatively close together andother surface areas128 and130 which are relatively far apart. Thewedge member44d,44e, or44fis moved into the joint34 with thesurface areas134 and136 which are close together engaging theadjacent bones30 and32. Thewedge member44d,44eor44fis then rotated to apply force against the adjacent bones to expand the joint. Thewedge member44dor44emay be rotated about itscentral axis120 to apply forced against thebones30 and32 and expand the joint. Alternatively, thewedge member44fmay be rotated about a location where the wedge member engages one of the bones.
• Regardless of which embodiment of thewedge members44,44a,44b,44c,44d,44e,44f,44gor44his selected, the wedge member may be used with any one of the many different bones and joints in a patient's body. The wedge member may be utilized at joints in a patient's wrist, ankle, hand, foot, back, or other portions of the patient's body. The use of the wedge member may be particularly advantageous when a joint between vertebrae in a patient's back is to be immobilized. One or more wedge members may be used to expand a joint to transmit force between bones.

Claims (20)

I claim:

1. An implantable device for maintaining a spatial relationship between a first bone and a second bone of a joint, the implantable device comprising:

a body formed of a polymeric material having a trailing end, a leading end, an upper surface and a lower surface, the upper and lower surfaces configured such that the body is thicker at the trailing end than at the leading end, a tooling socket extending into the trailing end, an upper mounting tab integrally formed with the body and extending upwardly from the upper surface, a lower mounting tab integrally formed with the body and extending downwardly from the lower surface, an upper fastener hole in the upper mounting tab and a lower fastener hole in the lower mounting tab, the tooling socket positioned between the upper and lower fastener holes;

an upper fastener having a head and a threaded shaft, the upper fastener configured for positioning in the upper fastener hole and for positioning in the first bone in a mounted configuration; and

a lower fastener having a head and a threaded shaft, the lower fastener configured for positioning in the lower fastener hole and for positioning in the second bone in the mounted configuration.

2. The implantable device ofclaim 1, wherein the heads of the upper and lower fasteners are positionable in engagement with the trailing end in the mounted configuration.

3. The implantable device ofclaim 1, wherein the upper fastener hole defines an upper longitudinal axis and the lower fastener hole defines a lower longitudinal axis, the upper and lower longitudinal axes oriented generally perpendicular to the trailing end.

4. The implantable device ofclaim 1, wherein the body further includes a first side portion and a second side portion, the first and second side portions extending between the upper and lower surfaces.

5. The implantable device ofclaim 4, wherein the first and second side portions taper from the trailing end toward the leading end.

6. The implantable device ofclaim 1, wherein the tooling socket is comprised of a hexagonal socket, the hexagonal socket generally centered on a longitudinal central axis of the body, the hexagonal socket configured to receive a suitable tool to rotate the body through less than one revolution.

7. The implantable device ofclaim 1, wherein the upper and lower surfaces are substantially flat.

8. The implantable device ofclaim 7, wherein the upper and lower surfaces are generally smooth.

9. The implantable device ofclaim 1, wherein the leading end has a blunt end portion.

10. The implantable device ofclaim 1, wherein the leading end tapers to a sharp leading edge.

11. The implantable device ofclaim 1, wherein the body further includes a bone growth passage formed therein, the bone growth passage extending between the upper surface and the lower surface, the bone growth passage configured to facilitate bone growth through the body between the first bone and the second bone in a mounted configuration.

12. The implantable device ofclaim 11, wherein the bone growth passage is packable with bone growth material.

13. The implantable device ofclaim 11, wherein the body includes a longitudinal central axis, the bone growth passage is substantially linear and oriented substantially perpendicular to the longitudinal central axis.

14. The implantable device ofclaim 11, wherein the bone growth passage is comprised of a first passage and a second passage, the first and second passages being substantially linear, the first passage extending between the upper and lower surfaces and the second passage extending between the upper and lower surfaces.

15. The implantable device ofclaim 1, wherein shapes of the upper and lower surfaces of the body are configured to correspond to the first and second bones, the first and second bones being comprised of a superior vertebra and an inferior vertebra, respectively.

16. The implantable device ofclaim 1, wherein the body is coated with a material that promotes bone growth.

17. The implantable device ofclaim 1, wherein the body includes a compartment formed therein, the compartment configured for packing with bone growth inducing material, the compartment defining upper and lower inner side surfaces, the upper and lower inner side surfaces being smaller than the upper and lower surfaces, respectively.

18. The implantable device ofclaim 1, wherein the body tapers from the trailing end toward the leading end, the taper being configured to facilitate insertion of the body into the joint, the joint being comprised of a vertebral joint between a superior vertebra and an inferior vertebra.

19. The implantable device ofclaim 1, wherein the body includes a first side surface and a second side surface extending between the trailing end and the leading end, the first and second side surfaces having an irregular configuration such that the first and second side surfaces are configured to be aligned with outer surfaces of the first and second bones, wherein the first bone is a superior vertebra and the second bone is an inferior vertebra.

20. The implantable device ofclaim 1, wherein the body includes a first side surface and a second side surface extending between the trailing end and the leading end, the first and second side surfaces being nonlinear and shaped to correspond to the configuration of the joint, wherein the joint is between vertebrae.

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