BALL AND SHAFT OF JOINT PROTHESIS
A prosthesis for replacement of a ball and socket joint in the human body. The prosthetic components comprise a plurality of separate parts which may be inserted through a hole in the femur of the patient and assembled and attached to the prepared acetabulum of the hip bone to form a cup-shaped first shell in a minimally invasive surgical procedure. A cup may be passed through the hole in the femur and attached to the first shell to form a socket portion of the joint. The prosthesis may comprise a shaft having a first end with a ball formed thereon that is inserted in the hole through the femur so that the ball engages the cup for movement therein.
This application is a continuation-in-part of application Ser. No. 10/799,192, filed Mar. 12, 2004, which is a division of application Ser. No. 09/961,662, filed Sep. 24, 2001, now U.S. Pat. No. 6,755,865, the specification and drawings of application Ser. Nos. 10/799,192 and 09/961,662 are incorporated herein their entirety.
FIELD OF THE INVENTIONThe field relates to devices for joint replacement, especially hip and shoulder joint prosthetics and procedures.
BACKGROUND OF THE INVENTIONArthroplasty, the restoration of normal joint motion, is frequently done by the insertion of a prosthetic joint replacement. Implant technology has improved over the last number of years and provides solutions to problems caused by injury, arthritis and other joint diseases. Frequently, the damage is sufficiently severe to require a total joint replacement. The prior art discloses numerous designs for total hip joint prosthetic devices.
Total hip joint replacements require interactive prosthetic femoral and acetabular components to emulate the ball-socket mechanism of a natural hip joint. When the supporting structure is weakened, particularly the femoral head and neck, a prosthetic femoral component with an extended shaft is implanted within the medullary cavity of the femur. Examples of this type total hip replacement prosthetic device are disclosed in U.S. Pat. No. 6,093,208 issued to Enrico Tian and U.S. Pat. No. 5,807,407 issued to England, et al. Many surgeons take this route, even when the underlying bone structure of the femoral head and neck is strong, under the theory that implantation of the shaft within the medullary cavity of the femur is required to obtain the necessary support for the prosthetic femoral head, as the femoral implant is under high stresses that can cause failure of “surface replacement” devices. Such failures frequently occur early in the patient's recovery, before the bonding of the bone to the metal surfaces of the prosthetic implant has occurred. However, the insertion of the prosthetic device with a long femoral shaft requires the resection of the femoral head and neck to obtain access to the longitudinal cavity within the femur. Such surgery is very stressful to the patient and increases the risk of infection. If the device fails, any further implantation of prosthetic devices becomes exceedingly difficult, as the supporting bone structure has already been appreciably reduced.
U.S. Pat. No. 5, 800,558 to Gerald A. LaHaise, Sr., U.S. Pat. No. 5,133,764 to Pappas et al., and U. S. Pat. No. 4,846,841 to Indong Oh, disclose the “surface replacement” technique of a total replacement of a hip joint. “Surface replacement” is aimed at primarily providing replacement of the joint surfaces while preserving as much of the supporting bone structure as possible and preserving the integrity of the medullary cavity. Pappas et al. '764 and Oh '841 each disclose a version of a cap that is implanted over the resected head of the femur. LaHaise '558 discloses a more complex means for attaching the ball to the resected head of a femur. One advantage to the surface replacement type of total hip replacement, is that much of the femur is left intact, so that if the surface replacement method fails, it may be replaced with an intramedullary canal prosthetic component.
Each of the above patents disclose a generally solid metal acetabular cup that is fixed, usually by screws, to a prepared surface of the hip bone. An insert, a layer of plastic or metal is frequently attached to the acetabular cup, the insert being sized to receive the ball portion of the prosthetic joint that is attached to the femur.
Each of these prostheses mentioned above, are installed during lengthy, invasive, major surgery that requires surgically opening the hip area for full exposure and direct access to the hip joint. During surgery the head of the femur must be removed from the acetabular cup, for resection of the femur head or complete removal of the femur head and neck. This surgery comes at a high cost as it is complex, requiring extensive surgical support staff and operating room equipment.
Not withstanding the existence of such prior art prosthetic components and methods for attachment to the human body, it remains clear that there is a need for prosthetic components that may be inserted into the human body without a major incision to gain direct access to the femur and hip bone.
SUMMARY OF THE INVENTIONThe present invention relates to a prosthesis and method for implantation of that prosthesis within the human body as the replacement for a ball joint. Reduced or minimally invasive procedures secure a ball and shaft in the femur and a shell and cup in the acetabulum, for example. A segmented shell may comprise a plurality of separate segments which may be inserted minimally invasively into the patient and assembled and may be attached to the hip bone to form a socket.
One advantage is that a shell and cup and a shaft and ball may be implanted without fully opening or exposing the hip joint, directly.
An expandable drill bit is disclosed that is capable of removing a portion of the head of the femur and a thin portion of the outer layer of the acetabulum, for example, through a hole bored at an angle through the femur.
Another advantage is that the implant may be removed an a traditional implant may be inserted without causing damage or weakness that impairs the subsequent implant.
BRIEF DESCRIPTION OF THE DRAWINGSFor a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawings, in which:
The examples described and drawings rendered are illustrative and are not to be read as limiting the scope of the invention as it is defined by the appended claims
DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of a ball and shaft joint prosthesis is illustrated in
For a total hip joint replacement, the acetabulum of the patient is prepared for receipt of the socket implant 12 and the femur is prepared for receipt of the ball implant and shaft combination 114. For a total shoulder joint replacement, the glenoid cavity of the scapula is prepared for receipt of a socket implant 12 and the humorous bone is prepared for receipt of the ball implant and shaft combination 114. In the case of a shoulder joint, the portion of the socket implant that is attached directly to bone may be solid or segmented, as the shoulder socket implant is much smaller than the hip socket implant, and the size of the humorous bone in comparison with the femur supports a larger access bore for passing a solid shoulder socket implant therethrough, although use of separate segments has the advantage of reducing the size of the borehole needed for inserting the socket 12.
For purposes of illustration, the hip joint will be used to illustrate the apparatus and method of implantation. A socket implant 12 comprises a first segmented shell 16 made of material, such as biocompatible metal, a second segmented shell 70 made from a material, such as a synthetic resin, and a cup 106, which may be made of any material having a hard surface capable of sustaining wear from a ball, such as a metal or cross-linked, high density polyethylene.
Another example is illustrated in
Yet another example is illustrated in
Now referring to the examples in
Each segment 20a-j has an inner surface 32, having a concave curvature, an outer surface 34, having a convex curvature, a first longitudinal side 36, a second longitudinal side 38, a first end 40 and a second end 42. The outer surface 34 of each segment 20 may longitudinally and transversely arcuate, with a curvature that will mount to the curvature of the prepared surface of the hip. Each segment has a groove 44 formed in the outer surface 34 proximal the first end 40, as seen in
Also, the example illustrated in
As seen most clearly in
For example, the segmented shell 16 may be constructed of titanium or cobalt chrome alloys. However, other materials that are resistant to wear, tough, and stiff may be suitable for the purpose.
The segmented shell 16 may be received by the surgeon in disassembled form for thorough disinfecting prior to assembly in the patient by the surgeon or may be packaged in a sterile pack in an assembly or pre-assembled state. During assembly of the segmented shell 16, each of the segments may be mounted on a respective secondary guide wire 30 and advanced along the wire until the groove 44 engages the ridge 22 on the base 18 as best represented by
As shown in
A portion of the sides 84 and 86 of each of the parts 72a-d, that is proximal the outer rim 104 of the shell 70 extend radially toward the central axis D. When the parts 74a-e are being assembled to form the cup shaped shell 70, the last part 72e is tapered outwardly such that the sides 84 and 86 are angled toward one another. The horizontal arc of the second face 82 is smaller than the horizontal arc of the first face 80. To ensure that all sides fit tightly, the sides of the adjacent parts, 72a and 72d, are tapered inwardly to match the taper of part 72e such that the sides fit tightly when the parts are fully assembled.
The sides 84 and 86 of each of the parts 74a-d are tapered outwardly so that the first face 92 is much larger than the second face 94. The transverse dimensions of the second face 94 of the parts 74a-d vary along the longitudinal axis C between the first end 88 and the second end 90. The horizontal width of the second face 94 varies from a sharp edge (where the cross-section of the part would be triangular) proximal the first end 88 to a greater cross-section as seen in
The second shell 70 may be constructed from a synthetic resin or a suitable metal. In one example, the second shell is formed in place by injecting a polymer resin, which hardens when cured, as a alternative to a second segmented shell. The second segmented shell 70 may be made using the same material used for the first segmented shell. The second segmented shell may be comprised of interlocking segments and a base similar to the first segmented shell 16, as an alternative to the structure illustrated in
As shown in
The cup 106 may be retained in the second shell 70 by a snap ring, press fit, adhesive bond or other retainer. The shells and the cup may be attached to one another in a number of different ways. Snap rings or drop rings operate simply. Snap ring or drop ring 145, as seen in
A ball implant and shaft combination 114, as shown in
A groove 140 may be formed in the side wall 137 adjacent the bottom 128 to receive a U-shaped shield 142 that has a pair of legs 144 that extend outwardly from the groove. This shield is curved to fit the body 120 so that the legs will engage the comer of the cortical bone along the superior portion of the hole through the femur to reduce the risk that the bone will fail due to stresses applied by the body 120 of the shaft 114.
When the patient's bone structure is large enough or the prosthesis small enough,
A compound shell 610, illustrated in
An advantage of this apparatus and method is that the surgery is much less invasive, takes much less time, requires much less surgical support in the operating room, and is much less expensive. In addition, if these components were to fail, a full hip joint replacement, done in accordance with current practice, is still available, as more than enough of the femur remains and only a small portion of the acetabulum was removed. The steps for implantation of these prosthetic components are discussed below. Thus, the examples are suitable for use as a temporary prosthetic device, for example.
The patient is suitably prepared for surgery in accordance with known practice. In an example of a method of using a prosthetic device in a minimally invasive surgery, the patient's body is aligned so that a longitudinal axis D extending from and neck and head of the femur of the patient passes through the geometric center of the acetabulum of the patient, such as illustrated in
The hole 158 for example, does not remove the interior of the subchondral plate. To ensure that the bore does not extend beyond the planned depth into the acetabulum, such as 2 mm, the cannulated drill bit and drill ride the guide wire 152 to a stop 153, as seen in
As seen in
Once debris is removed, a socket implant may be attached to the hipbone of the patient. A ball 110 is sized to be inserted through the hole 158, and the acetabulum site on the hipbone has been enlarged by the expandable drill bit 166. Therefore, the cup 106 is sized to receive the ball and the cup 106 is supported by one or more shells attached to the hip bone. The larger the cross-section of the neck of the femur the larger the hole 158 that can be bored through the femur, without damage to the subchondral plate, through which the socket implant is passed. The surgeon, based upon measurements of the patient's bone structure, may determine the particular size and structure of the socket implant.
In one example, prosthetic component 10 comprises a segmented first shell 16, a segmented second shell 70, a cup 106, and a shaft 114 of
In one example, the surgeon selects the example using two segmented shells. The next step is to implant the first segmented shell 16. The base 18 having the cannulated screw 178 inserted therein, is mounted on the guide wire 152 so that the cannulated screw and base 18 passes along the guide wire 152 and is therefore centered in the acetabulum . With the base 18 centered by the guide wire the self-tapping cannulated screw 29 is driven into the bone of the acetabulum of the patient by a cannulated screw driver. The ends of the plurality of flexible wires 30 attached to the base 18 may extend outwardly through and beyond the sleeve 160. First a segment having two male arms 52, which in
After positioning of segment 20h, segment 20g is then mounted on its corresponding flexible secondary guide wire 30 and installed so that the female land 56 engages the groove 58 of the segment 20h. The next segments are inserted in the same manner until the next to last segment 20j is in place. The last segment, segment 20i, has two female arms 54 that engage with the male arms 52 on segments 20h and 20j interlocking the segments 20a-j of the segmented first shell 16 in place. In addition, as discussed previously, the segment 20i is tapered so that it may be inserted in place from the inside of the first shell 16. A surgical nail is driven through the hole 48 of segment 20i to secure the segments. As seen in
A second segmented shell 70 is likewise positioned within the first shell 16.
As shown in
Alternatively, if the second segmented shell 70 has a similar interlocking arm structure as the first segmented shell 16, the segments are inserted through the sleeve 160 and assembled in the first segmented shell 16 in the same manner that the first segmented shell 16 was inserted through the sleeve 160 and assembled in the acetabulum. Of course, the first and last segments of the second shell may be attached or bound to the first shell 16 by heat and pressure or using a snap ring, for example.
The next step is to insert a cup 106 through the sleeve 160 and fit it to the second shell 70 such as by using a snap ring 188 that is inserted in the groove 190 in the parts 72a-e. As the cup is pushed into the interior cavity of the first shell 16, the exterior sides of the cup 106 engage the snap ring 188 pushing it into the groove 190 until the groove 190 aligns with the groove 182 in the cup 106, at which time the snap ring 188 expands outwardly and engages the groove 182 locking the cup 106 within the second shell 70, as seen in
The sleeve 160 may be removed from the hole 158 prior to inserting the ball and shaft assembly 114. As illustrated in
The shaft 114 may be cannulated by at least one tube 124 which permits flushing and suctioning of the hip joint site prior to closing the incision and at a later date, if infection or other difficulties occur. At this time, the surgeon may attach and implant a drainage bag constructed from a formulation of silicon and rubber, not shown, to catch any drainage after the incision is closed. The incision may now be closed. At a later date it may be necessary to remove and replace the drainage bag.
If the surgeon determines, through measurements of the patient's bone structure and other factors such as age, athleticism and purpose of the prosthetic, that the bone structure can support an alternative prosthetic component 310, the surgeon may select a prosthetic component 310 having fewer parts, reducing the complexity of the procedure. The steps for implantation of the prosthetic component 310 will largely be the same as the previous procedure, except a second segment shell is not inserted. All the steps leading up to and for installing the first segment 316 are the same as described above.
The next step is to insert a cup 406 through the sleeve 460, the cup being sized and configured to be received into the interior cavity of the segmented shell 316. The steps for attachment of the cup 406 to the shell 316, by snap ring 445 are the same as discussed above for attaching the cup 106 to the second shell 70, except the snap ring 445 is positioned in the segmented shell 316.
The surgeon may determine that a second shell or shell liner may be formed as a single piece, as shown in
The surgeon may determine that none of the segmented acetabulums will be appropriate and may insert any of the well known acetabulums directly into the prepared hip socket. These acetabulums may be selected that have a cup sized to receive the ball 110, 710. The surgeon may determine that minimally invasive surgery is not preferred, but the surgeon may use a reduced invasiveness, as previously discussed. For example, the femoral head may be partially resected and the neck and head portion may be extended through an incision without fully and directly exposing the joint.
In
In
Annular plate 202, as shown in
The hollow shaft 192 provides a means for delivering a flushing fluid to the cutting site through the port 216, which is connected to a pressurized water supply, (not shown). The port 216 is connected to a fixed annular ring 218, as seen in detail FIG. 29, that is sealingly attached to an annular cavity 217 that extends about the body 190 so that the body 190 may rotate inside the ring and maintain the port 216 in fluid flow communication with annular cavity 217 and the hollow shaft 192. A water source is attached to the port 216 by any well known means. Suction may be applied to port 220 by any well known suction device (not shown). Port 220 is connected in fluid flow communication with the interior of the body 190 through a fixed annular ring 224, for rotation of the body 190 therein, and an annular cavity 222. This permits suctioning the flush water and debris from the hip joint site through the plurality of holds 226 through the end plate 208 and the hollow body 190.
As the body 190 is free to slide longitudinally on the shaft 192, it is also free to rotate about the longitudinal axis of the shaft 192. During a cutting operation the body 190 must rotate with the shaft 192 to maintain the wires 204 in proper orientation. Therefore, thumbscrew 228 is tightened to rotate the body 190 with the shaft 192 and is loosened when adjustments are made to the angle of the blades 168. For adjustments to be made to the blades 168, the drilling must be stopped, the thumb screw 228 loosened, and the body moved along the shaft 192.
As discussed previously, each blade 168 has an outer cutting edge 170 and an inner cutting edge 172. The outer cutting edge is used primarily for cutting through the head of the femur and cutting the acetabulum to its predetermined curvature. The inner cutting edge is used to further trim the neck and head of the femur to ensure adequate clearance for free movement of the prosthetic joint.
In
The foregoing examples are not limiting and should not be used to limit the claims. Instead, the claims should be read in light of the specification as a whole according to their plain meaning to a person of ordinary skill in the field.
Claims
1. A joint prosthesis, comprising:
- An implant comprising a neck joining a ball to a body of the implant and a flange extending spirally from an outer cylindrical surface of the body such that the spiral flange extends into a bone and increases the contact area between the implant and the bone, when the implant is threaded into the bone, wherein the implant has a cylindrical axis extending along the cylindrical axis of the outer cylindrical surface and through the ball of the implant.
2. The joint prosthesis of claim 1, wherein a plurality of channels are formed in the implant such that holes on the outer cylindrical surface are in the fluid communication with a channel capable of delivering a cement between the outer cylindrical surface and the bone.
3. The joint prosthesis of claim 1, wherein an end of the implant opposite of the ball is dome-shaped.
4. The joint prosthesis of claim 1, further comprising a socket capable of receiving the ball of the implant in a cup of the socket.
5. The joint prosthesis of claim 4, wherein the socket comprises a shell and the cup is fixedly supported by the shell, and the shell is capable of being fixed to a bone structure in the body of a patient undergoing joint replacement surgery without fully opening and exposing the hip joint.
6. The joint prosthesis of claim 5, wherein the shell is comprised of a plurality of separate segments, each having a concave arcuate surface such that the concave surface for supporting the cup is assembled by joining the concave arcuate surfaces of each of the plurality of separate segments.
7. The joint prosthesis of claim 6, wherein a plurality of the plurality of separate segments have an interlocking member capable of interlocking with an interlocking member of a neighboring interlocking member, when assembled to form the shell.
8. The joint prosthesis of claim 7, wherein a key segment has a wedge and two femal interlocking members each of the two femal interlocking members being capable of engaging a male interlocking member of each of its two nearest neighboring segments, and the wedge locks the plurality of segments together.
9. The joint prosthesis of claim 6, further comprising a base having at least one ridge extending from the base and a fastener for fastening the base to the bone structure in the body of the patient, and a plurality of the plurality of segments each have a groove capable of pivotally engaging the at least one ridge of the base during assembly of the shell.
10. The joint prosthesis of claim 5, wherein the ball and the shell, when assembled to form the socket, define an outwardly facing surface opposite of a surface of the socket facing the bone structure, and the outwardly facing surface is nonplanar.
11. The joint prosthesis of claim 10, wherein the nonplanar outwardly facing surface is arranged such that the implant has a range of motion greater than the range of motion of an implant having a planar outwardly facing surface.
12. A joint prosthesis comprising:
- a segmented shell having an interior surface,
- a second shell fixedly retained within said interior surface of said segmented shell;
- a cup, said cup having an exterior surface and an interior surface, said exterior surface of said cup being sized and configured to be fixedly retained in said second shell, and
- a shaft having a first end and a second end, said first end of said shaft having a ball formed thereon that is received by said cup for movement therein, wherein the segmented shell comprises:
- a base; and
- a plurality of segments, each segment, of said plurality of segments, having a first end, a second end and a pair of opposing sides extending therebetween, each first end of each said segment, of said plurality of segments, pivotally engaging said base such that each side of each said segment, of said plurality of segments, is adjacent one of said sides of another one of said plurality of segments, each segment, of said plurality of segments, being longitudinally and transversely arcuate, such that when each segment, of said plurality of segments, is aligned with adjacent segments thereto, said plurality of segments form a cup-shaped shell.
13. A joint prosthesis as in claim 12, wherein said base has a ridge formed thereon and each segment, of said plurality of segments, has a groove proximal one end of each segment capable of pivotally engaging said base.
14. A joint prosthesis as in claim 12, wherein said second shell is formed from a polymer and the polymer adheres to the surface of the segmented shell.
15. A joint prosthesis comprising:
- a first segmented shell having an interior surface comprised of a plurality of separate segments;
- a second segmented shell supported by the first segmented shell, the second shell being comprised of another plurality of separate segments;
- a cup, the cup having an exterior surface and an interior surface, said exterior surface of said cup being sized and configured to be fixedly retained in the second segmented shell, and a shaft having a first end and a second end, the first end of the shaft having a ball that is received by the cup.
16. A joint prosthesis as in claim 15, wherein the shaft has at least one channel passing through a body of the shaft such that the at least one channel extends from an opening in the second end of the shaft through the body to an opening in the neck.
17. A joint prosthesis as in claim 16, wherein the shaft has a plurality of channels, and at least two channels are in fluid flow communication.
18. A joint prosthesis as in claim 15, wherein the shaft has at least one longitudinally extending side wall and a groove formed in said side wall proximal the second end of the shaft, and a U-shaped shield has a bottom and a pair of legs extending outwardly from the bottom, the bottom being received in the groove such that the pair of legs extend outwardly form the shaft.
19. A joint prosthesis as in claim 15, wherein the shaft has a flange extending spirally from an outer cylindrical surface of the shaft.
20. A joint prosthesis as in claim 12, wherein the shaft has a flange extending spirally from an outer cylindrical surface of the shaft.
Type: Application
Filed: Jan 12, 2007
Publication Date: May 17, 2007
Inventor: Imad Tarabishy (Brooksville, FL)
Application Number: 11/622,887
International Classification: A61F 2/36 (20060101);