Prosthetic knee

Abstract: The present invention relates to a prosthetic knee. In one embodiment of the present invention, the knee has a femoral body (20) and meniscal body (40). The femoral body has a femoral alignment member (28), and the meniscal body has a femoral side (42). Extending from the femoral side are at least two guiding protrusions (44) that extend along the longitudinal axis of the meniscal body and define at least two sides of an alignment groove (46). The alignment groove slippingly receives the femoral alignment member. The femoral alignment is able to move within the alignment groove and slip over the alignment groove when a force of sufficient magnitude is applied to the prosthetic and revert into the alignment groove. In another embodiment of the present invention, the groove and the alignment components are reversed on the respective femoral and meniscal bodies.

Description: The human knee is a complex arrangement of ligaments, cartilages, and bone surfaces. The human knee is a versatile component that when properly operating can withstand various loads and forces being applied to it. When such various forces are applied, the knee adapts and moves in relation to those forces. However, because the knee is subjected to great loads and tremendous use, the knee is subject to a host of different ailments, all of which result in discomfort and pain. Osteoarthritis, for example, commonly occurs in older people, and is typically found in the weight bearing joints of a human body, such as the knee and the hip. When osteoarthritis effects a knee, the articular cartilage of the knee degenerates, and the femur and tibia typically begin to wear against one another. This results in pain and stiffness in the joint, and makes flexion and extension of the knee difficult. People suffering this condition are often unable to partake in even the simplest physical activities. Also, injuries to the articular cartilages of the knee often may arise from any of a plurality of sporting activities, like jogging and skiing, that exert substantial forces on the knee. Additionally, accidents and falls apply substantial forces to a knee. Such substantial forces may result in the damage or destruction of the articular cartilages in the knee. Several prosthetic devices are presently available to assist individuals with knee ailments. These devices, however, have shortcomings, such as when loads and forces are applied to the components of the prosthetic some of the components slip away from each other. When such slippage occurs, the conventional prosthetic knee has difficulty joining the components together. For example, in one embodiment of a prosthetic knee the components lock together by a tongue and groove system. In another embodiment of a prosthetic knee, the components contact each other on curved and/or flat surfaces. When these components disengage from each other, they are difficult to mate together. The present invention allows some slippage and simultaneously corrects the slippage. US 6004351 describes a prosthetic knee joint enabling high-angle flexion includes the following members (a)-(c). (a) a femoral component which is adapted to be secured to a distal femur, consists of implant metal, has a concave portion with a depth of 10 mm or more on the lower central surface thereof, adapted to be in slidable contact with the patella or a patellar component, and has a pair of spaced bearing surfaces spaced by the concave portion, consisting of an anterior erect portion, a lower portion and a posterior erect portion, which portions form a smoothly curved surface; (b) a tibial component adapted to be secured to a proximal tibia, consists of implant metal and has an upper convex surface; (c) a unitary bearing insert which consists of polyethylene, is situated slidably between the femoral component and the tibial component in use, has an upper concave surface for supporting the spaced bearing surfaces of the femoral component, defined between an anterior end and a posterior end and having a curvature radius within the range of from 20 mm to 1000 mm on the entire surface between the anterior and posterior ends, and also has a convex lower surface. SUMMARY OF THE INVENTION The present invention relates to a prosthetic knee. In one embodiment of the present invention, there is provided a prosthetic device for a knee comprising a femoral body; a meniscal body having a femoral side; the femoral body or the meniscal body at said femoral side has an alignment groove, the alignment groove is defined by at least two guides from the body on at least two sides of the alignment groove, the alignment groove receives an alignment member that extends from the other body; the alignment member has a stem section and a bearing surface, the stem section extends from the alignment member and the bearing surface extends from the stem section, the bearing surface (a) is capable of contacting the alignment groove and (b) has a greater width than the stem section; the alignment groove is able to slippingly receive and release the alignment member so the alignment member (a) can move within the alignment groove and (b) is able to (i) slip out of the alignment groove, (ii) on to at least one guide when a force of sufficient magnitude is applied to the prosthetic and (iii) revert into the alignment groove. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a front elevational view of the femoral body of the prosthetic knee. Fig. 2 shows a front elevational view of the meniscal body of the prosthetic knee. Fig. 3 shows a front elevational view of the tibial body of the prosthetic knee. Fig. 4 shows a side elevational view of the femoral body of the prosthetic knee. Fig. 5 shows a side elevational view of the meniscal body of the prosthetic knee. Fig. 6 shows a side elevational view of the tibial body of the prosthetic knee. Fig. 7 shows a front elevational view of an alternate embodiment of the femoral body of the prosthetic knee. Fig. 8 shows a front elevational view of an alternative embodiment of the meniscal body of the prosthetic knee. Fig. 9 shows a front elevational view of an alternative embodiment of the tibial body of the prosthetic knee. Fig. 10 shows a side elevational view of an alternative embodiment of the femoral body of the prosthetic knee. Fig. 11 shows a side elevational view of an alternative embodiment of the meniscal body of the prosthetic knee. Fig. 12 shows a side elevational view of an alternative embodiment of the tibial body of the prosthetic knee. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION. The present invention relates to a prosthetic half knee 15, which is embodied in Figs. 1-6. The knee 15 comprises three major components: a femoral body 20, a meniscal body 40, and a tibial body 70. The femoral body 20 is attached to the femur 16 by at least one femur anchor post 24 as shown in Fig. 4. The femur anchor post 24 may be cemented to or driven into the femur 16 using processes and materials well known to those skilled in the art. Similarly, as illustrated in Figs. 3 and 6, the tibial body 70 is attached to the tibia 18 by at least one tibia anchor post 76. This may be accomplished by cementing or driving the anchor posts 76 to the tibia 18, or by other processes well known to those skilled in the art. Interposed between the femoral body 20 and the tibial body 70 is the meniscal body 40, illustrated in Figs. 2 and 5. The femoral body 20 is constructed in an convex arcuate shape such that it is in the condylic shape of a natural femur bone. It may be made of durable plastic or metal, but in either case, materials with low coefficients of friction will prolong the useful life of the prosthetic knee, and facilitate walking and other endeavors. The selection of such materials for such purposes are well known to those skilled in the art. Protruding from the femoral body contact surface 26 is the at least one femur anchor post 24, which anchors the femoral body 20 to the femur 16 as described above. In other embodiments of the present invention, the femoral body 20 may be attached to the femoral bone by making a plurality of holes (not shown) in the contact surface 26 and allowing the bone of the femur 16 to grow therein. The femoral body 20 has a convex arcuate surface 22 spanning its longitudinal axis, this being a load bearing surface supporting loads transmitted from the femur 16. The femoral body 20 has mergedly rising from its convex arcuate surface 22 and spanning a portion thereof designated by line segment A-A in Fig. 4, the femoral alignment member 28, shown in Fig. 1. The femoral alignment member 28 has a sliding surface 29. The femoral alignment member 28 is shaped such that the span of its narrowest width, designated by line segment B-B in Fig. 1, is less than the span of its greatest width, designated by line segment C-C in Fig. 1. This configuration is further described below. Turning now to Figs. 2 and 5, shown therein are front and side elevational views of the meniscal body 40. The meniscal body has a femoral side 42, a tibial side 50, and guiding protrusions 44. The guiding protrusions 44 extend from the femoral side 42 of the meniscal body 40. The guiding protrusions 44 have tapered, rounded, or beveled end portions 45. Defined between the guiding protrusions 44 is the alignment groove 46, shown in Figs. 2 and 5. The alignment groove 46 spans the meniscal body 40 along the longitudinal X axis direction, as shown in Fig. 2. The meniscal body 40 is embodied between the guiding protrusions, and is less than the distance between the guiding protrusions 44, designated by line segment E-E in Fig. 2. As shown, the protrusions can have extensions that secure, with some slippage movement allowed between the meniscal body and the alignment groove. Alternatively, there could be no extensions which also allow the meniscal body and alignment groove to move within. The alignment groove 46 may be embodied to span the length of the meniscal body 40, and be further embodied such that the depth 49 of the alignment groove 46 varies along the longitudinal X axis thereof. In such an embodiment, as shown in Fig. 4, the depth 49 of the alignment groove 46 is, in the preferred embodiment, greater at the center portion 54 of the meniscal body 40, than the depth 49 at the ends 52 of the meniscal body 40. In such an embodiment, the alignment groove 46 may have a generally concave curvature 47 along the longitudinal X axis of the meniscal body 40. The meniscal body 40 itself is embodied to have a concave shape along its longitudinal X axis, shown in Fig. 5. The meniscal body 40 may be constructed of durable plastic, metal, or other materials well known to those skilled in the art. Figs. 3 and 6 show the tibial body 70, which has a support surface 72 that supports the meniscal body 40. The tibial body 70 also has a support surface 74 which rests on the tibia 18. The tibial body 70 is anchored to the tibia 18 by the tibial body anchor posts 76. The tibial body 70 may be constructed of hard durable plastic, metal, or other materials well known to those skilled in the art. The tibial body 70 may be cemented to the tibia 18 with adhesives and cements known to those skilled in the art. The tibial body 70 may also be constructed with a plurality of holes (not shown), such that the tibia 18 bone grows into the holes and attaches itself to the tibial body 70 in that manner. The femoral body 20, the meniscal body 40, and the tibial body 70 are constructed as described above and are inserted into a patient by procedures well known to those skilled in the art. The femur 16 and the tibia 18 are prepared for receiving the prosthetic 15. This process typically entails shaping the femur 16 and tibia 18 such that they are altered, for example flattened in some embodiments or rounded in other embodiments (not shown), to receive the femur anchor posts 24 and the tibial body anchor posts 76. The femur anchor posts 24 and tibial body anchor posts 76 are driven into the femur 16 and tibia 18 respectively. The meniscal body 40 is slid over the femoral alignment member 28 along the sliding surface 29. In this position, the femoral alignment member 28 occupies and is received in the alignment groove 46 in the meniscal body 40. The femoral alignment member 28 is captured in the alignment groove 46. Thus, as the prosthetic knee 15 articulates back and forth in the X axis direction, shown in Figs. 4-6, the femoral alignment member 28 slides back and forth along the alignment groove 46. The lack of any extensions from the guiding extensions allow the femoral body 20 to slip out of the alignment groove 40 and on to a wall of the guiding extension in such a way that the femoral body 20 is able to revert into the alignment groove 40 without difficulty, and, hopefully, naturally. As stated previously, forces are applied to a knee. The present invention allows the knee to receive forces and loads from various angles. And when the knee receives a force or load other than one at 0° relative to the femur and/or the tibia, the present invention allows the prosthetic knee to accommodate and adapt to those forces and/or loads without having the knee being damaged. This arrangement allows the user maximum possible flexion and extension capabilities in the knee, without problems of the meniscal body 40 undesirably and permanently slipping and sliding out of the X axis direction of travel without extraordinary forces being applied thereon. To achieve the proper tension in the prosthetic knee 15 during flexion and extension thereof, the meniscal body 40 thickness may need to be adjusted. For each differently sized individual, a meniscal body 40 of different thickness may be selected. Such sizing of prosthetics to patients is well known to those skilled in the art. Another embodiment of the prosthetic knee 15, illustrated in Figs. 7-12, comprises three major components: a femoral body 106, a meniscal body 120, and a tibial body 140. The femoral body 106 is attached to the femur 102 by at least one femur anchor post 110, extending from the femoral body bone contact surface 114, as shown in Figs. 7 and 10. The femur anchor posts 110 may be cemented to or driven into the femur 102 using processes and materials well known to those skilled in the art. Similarly, as illustrated in Figs. 9 and 12, the tibial body 140 is attached to the tibia 104 by at least one tibia anchor post 146. This may be accomplished by cementing the tibia anchor posts 146 to the tibia 104 or by other processes well known to those skilled in the art. Interposed between the femoral body 106 and the tibial body 140 is the meniscal body 120, as illustrated in Figs. 7-9. Referring to Figs. 7 and 10, the femoral body 106 is shown, having a convex arcuate surface 108 spanning its longitudinal axis in the X direction, this being a load bearing surface. The convex arcuate surface 108 has a femoral body alignment cutout 112 extending along a portion of the longitudinal axis thereof, illustrated in Figs. 7 and 10. The femoral body alignment cutout 112 is defined by the femoral guides 116. The femoral alignment cutout 112 being shaped such that the distance between the distance between the femoral guides 116, indicated by line segment F-F in Fig. 7, is equivalent to or less than the width of the sliding surface 117 of the femoral body 106, indicated by line segment G-G. The depth 127 of the femoral alignment cutout 112, may be embodied to vary along the longitudinal X axis of the femoral body 106, such that at the ends of the cutout 118, the depth 127, is less than at the center portion 119, of the femoral body 106, as seen in Figs. 7 and 10. The femoral alignment cutout 112 also may be embodied to have a convex curvature along its longitudinal X axis. Referring to Figs. 8 and 11, the meniscal body 120 has an alignment side 122, and extending from the alignment side 122 a meniscal alignment member 124. Opposite the alignment side 122 is the tibial side of meniscal body 126. The alignment member 124 has bearing surface 128 having a first width 134, indicated by line segment H-H in Fig. 8, which is greater than second width 136, designated line segment I-I in Fig. 8. Bearing surface 128 is in a sliding relationship with sliding surface 117 of the femoral body 106. The thickness of the meniscal body 120 may be embodied such that the thickness is greater at the end portions 130 of the meniscal body, than at the center portion 132, as shown in Fig. 11. This gives the meniscal body 120 a concave curvature along the longitudinal X axis direction, as depicted in Fig. 11. The tibial body 140 shown in Figs. 9 and 12, has on one side a support surface 142 for supporting the meniscal body 120, and on the other side a support surface 144 for resting on the tibia 104. The tibial body 140 may be constructed of hard durable plastic, metal, or other materials known to those skilled in the art. The tibial body 140 may be cemented to the tibia 104 with adhesives and cements known to those skilled in the art. The tibial body 140 may also be constructed with a plurality of holes such that the tibia bone 104 grows into the holes and attaches itself to the tibial body 140 in that manner. The femoral body 106, the meniscal body 120, and the tibial body 140 are constructed as described above, and are inserted into a patient by procedures well known to those skilled in the art. The femur 102 and the tibia 104 are prepared for receiving the prosthetic. This process typically entails shaping the femur 102 and tibia 104 such that they are flattened to receive the femoral body anchor posts 110 and the tibial body anchor posts 146. Then, the femoral anchor posts and tibial body anchor posts 146 are driven into the femur 102 and tibia 104 respectively. The meniscal alignment member 124 of the meniscal body 120 is slid into the femoral alignment cutout 112, and captured therein by the femoral guides 116. The meniscal body 120 and the femoral body 106 are thus able to slide relative to one another along the X axis direction, as shown in Figs. 10-12. Further, since the alignment member 124 occupies the femoral alignment cutout 112, and is thus limited to motion in the X axis direction, the prosthetic knee 100 is stable during flexion and extension thereof. Additionally, either embodiment of the prosthetic knee described herein may be used in conjunction with the medial condyle of the femur 16a and 102a, or the lateral condyle of the femur 16b and 102b, or both. Such procedures for implanting a prosthetic knee are well known to those skilled in the art. The present invention can be distributed to medical practitioners through a kit. The kit contains the present invention in a sterile environment so the medical practitioner can open the kit in the operating room and use the prosthetic knee. The prosthetic knee, as stated earlier, is inserted into a patient through conventional methods known to those skilled in the art. In particular, a method of inserting a prosthetic knee into a mammal may comprise the steps of: placing a femoral body having a femoral alignment member onto a predetermined portion of a femur; and inserting a meniscal body having a femoral side over a predetermined portion of a tibia, wherein the meniscal body further comprises at least two guiding protrusions extending from the femoral side that extend along the longitudinal axis of the meniscal body and defines at least two sides of an alignment groove; and wherein the alignment groove slippingly receives the femoral alignment member so the femoral alignment moves within the alignment groove and is also able to slip on to the alignment groove when a force of sufficient magnitude is applied to the prosthetic and revert into the alignment groove. In an alternative embodiment, a method of inserting a prosthetic knee into a mammal may comprise the steps of: inserting a femoral body defining a femoral alignment cutout defined by at least two femoral guides from the femoral body on at least two sides of the femoral alignment on a predetermined portion of a femur; placing a meniscal body having an alignment side having a meniscal alignment member extending therefrom on a predetermined portion of a tibia, wherein the prosthetic further has the femoral alignment cutout slippingly receiving the meniscal alignment member so the meniscal alignment member moves within the femoral alignment cutout and is also able to slip on to the femoral guides when a force of sufficient magnitude is applied to the prosthetic and reverts into the femoral alignment cutout. It will be understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to describe the nature of the artificial knee, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. For example, any of a plurality of differently shaped femoral alignment members 28 (rounded, squared, or beveled), and corresponding alignment grooves 46 (rounded, squared, or beveled) and guiding protrusions 44 are within the ambit of the prosthetic knee and appended claims. Additionally, any of a plurality of differently shaped femoral alignment cutouts 112, and corresponding meniscal alignment members 124 are within the ambit of the present prosthetic knee and appended claims.

Claims: A prosthetic device for a knee comprising a femoral body (20, 106); a meniscal body (40, 120) having a femoral side; the femoral body (20, 106) or the meniscal body (40, 120) at said femoral side has an alignment groove (46), the alignment groove (46) is defined by at least two guides from the body on at least two sides of the alignment groove (46), the alignment groove (46) receives an alignment member (28) that extends from the other body; the alignment member (28) has a stem section and a bearing surface, the stem section extends from the alignment member (28) and the bearing surface extends from the stem section, the bearing surface (a) is capable of contacting the alignment groove (46) and (b) has a greater width than the stem section; the alignment groove is able to slippingly receive and release the alignment member (28) so the alignment member (28) (a) can move within the alignment groove (46) and (b) is able to (i) slip out of the alignment groove (46), (ii) on to at least one guide when a force of sufficient magnitude is applied to the prosthetic and (iii) revert into the alignment groove (46). A prosthetic device according to Claim 1, wherein the femoral body (20, 106) has a femoral alignment member (28); the meniscal body (40, 120) has a femoral side (42) and at least two guiding protrusions (44) extending from the femoral side that extend along the longitudinal axis of the meniscal body and define at least two sides of an alignment groove (46). A prosthetic device according to Claim 1, wherein the femoral body (20, 106) has a femoral alignment member (28); the device additionally comprises a tibial body (70, 140) having a support surface (72); the meniscal body (40, 120) has a femur side having a femur alignment groove (46) for accommodating the femoral alignment member (28), the meniscal body being interposed between the femoral body (20) and the support surface(72) of the tibial body (70); and at least two guiding protrusions extending from the femoral side that extend along the longitudinal axis of the meniscal body and defines at least two sides of the alignment groove. The prosthetic device of Claim 3, wherein the femoral alignment member (28) has a sliding surface for sliding in the femur alignment groove (46). The prosthetic device of any one of Claims 2 to 4, wherein the femoral body (20, 106) has a convex shape and the femoral alignment member (28) has a convex shape. The prosthetic device of any one of Claims 2 to 5, wherein the alignment groove (46) has a concave curvature extending along the longitudinal axis of the meniscal body (40, 120). The prosthetic device of any one of Claims 2 to 6, wherein the femoral alignment member (28) spans a portion of the longitudinal axis of the femoral body (20, 106). The prosthetic device of any one of Claims 2 to 7, wherein the femoral alignment member (28) mergedly rises from the femoral body (20, 106) and wherein the span of the femoral alignment member at its narrowest width is less than the span of the femoral alignment member at its greatest width. The prosthetic device according to Claim 1, wherein the device comprises: a femoral body (20, 106) defining a femoral alignment cutout (112) defined by at least two femoral guides (116) from the femoral body on at least two sides of the femoral alignment; a meniscal body (40, 120) having an alignment side (122) having a meniscal alignment member (124) extending therefrom; and the femoral alignment cutout (112) slippingly receives the meniscal alignment member so the meniscal alignment member moves within the femoral alignment cutout and is also able to slip cut of the femoral guides (116) when a force of sufficient magnitude is applied to the prosthetic and reverts into the femoral alignment cutout. The prosthetic device according to Claim 1, wherein the device comprises: a femoral body (20, 106) defining a femoral alignment cutout (112) defined by at least two femoral guides (116) from the femoral body on at least two sides of the femoral alignment; a tibial body (70) having a surface for support; and a meniscal body (40, 120) interposed between the tibial body and femoral body and situated on the surface for support, the meniscal body having an alignment side having a meniscal alignment member extending therefrom, the femoral alignment cutout slippingly receives the meniscal alignment member so the meniscal alignment member moves within the femoral alignment cutout and is also able to slip out of the femoral guides when a force of sufficient magnitude is applied to the prosthetic and reverts into the femoral alignment cutout. The prosthetic device of Claim 9 or 10, wherein the femoral body (20, 106) has a sliding surface having a width, such that the distance between the femoral guides is less than the width of the sliding surface of the femoral body. The prosthetic device of Claim 11, wherein the meniscal body (40, 120) has a bearing surface (128) in a slidable relationship with the sliding surface of the femoral body. The prosthetic device of Claim 12, wherein the bearing surface (128) and the sliding surface are constructed of materials having low coefficients of friction.

Inventors: REPICCI JOHN A, REPICCI, JOHN A.
Applicants: REPICCI JOHN A, REPICCI, JOHN A.
Application year: 2001
Main classification: A61F2
IPC codes: A61F2