Source: http://www.google.com/patents/US4662889?dq=6,183,366
Timestamp: 2017-01-22 05:02:42
Document Index: 380555247

Matched Legal Cases: ['arts 5', 'art 5', 'art 6', 'art 7', 'arts 5', 'art 5', 'art 6', 'art 7', 'arts 5', 'art 5', 'art 6', 'art 5', 'art 5', 'art 7', 'art 24', 'art 5', 'art 6', 'art 6', 'art 5']

Patent US4662889 - Knee joint prosthesis - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA knee joint prosthesis includes a C-shaped femur cap to be fitted onto a resected femur condyle. The C-shaped femur cap is made up of two arch-shaped parts spaced apart and connected by a relatively flat third part. Each of the arch-shaped parts has a different radius. The arch-shaped part with the...http://www.google.com/patents/US4662889?utm_source=gb-gplus-sharePatent US4662889 - Knee joint prosthesisAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS4662889 APublication typeGrantApplication numberUS 06/603,659Publication dateMay 5, 1987Filing dateApr 26, 1984Priority dateApr 28, 1983Fee statusPaidAlso published asCA1226102A, CA1226102A1, DE3315401A1, EP0126978A1, EP0126978B1Publication number06603659, 603659, US 4662889 A, US 4662889A, US-A-4662889, US4662889 A, US4662889AInventorsLudwig Zichner, Erhard Dorre, Peter Prussner, Horst von BorriesOriginal AssigneeFeldmuhle AktiengesellschaftExport CitationBiBTeX, EndNote, RefManPatent Citations (3), Referenced by (118), Classifications (4), Legal Events (7) External Links: USPTO, USPTO Assignment, EspacenetKnee joint prosthesis
US 4662889 AAbstract
A knee joint prosthesis includes a C-shaped femur cap to be fitted onto a resected femur condyle. The C-shaped femur cap is made up of two arch-shaped parts spaced apart and connected by a relatively flat third part. Each of the arch-shaped parts has a different radius. The arch-shaped part with the larger radius has an oblong hole extending in the circumferential direction of the part. A shaft can be placed through the oblong hole from the femur into the tibia. In addition, a tibia cap can be fitted onto the plateau of the tibia.
1. An implantable knee joint for connecting the femur with the tibia comprising a femoral cap having a C-shaped cross-section for partial enclosure of the resected femoral condyles and for abutment and support on the tibial plateau, said cap having an inner and outer surface; said outer surface shaped to serve as a sliding surface for a corresponding tibial member and said inner surface being mechanically connectable to said resected condyles, wherein the improvement comprises said cap having two arcuate shaped bearing surfaces separated by an oblong cut-out extending in a circumferential direction about said cap wherein said cut-out is in substantially coincidence with a similar shaped slot formed in said resected condyles; and an axially extending cylindrically substantially disc-shaped sliding member disposed in said slot to directly abut the bony tissues of said resected condyles and said disc-shaped sliding member being coupled to a connecting member, said connecting member being an elongated shaft having a first and second ends wherein said first end is arranged to extend into and mechanically anchor within the tibia and the second end extending out of said tibia through said cut-out into a closely fitted engagement with said disc-shaped sliding member thereby actively connecting the femur with the tibia.
2. An implantable knee joint, as set forth in claim 1, wherein said disc-shaped sliding member comprises a cylindrical surface and a pair of spaced end surfaces extending transversely of the cylindrical surface and arranged to abut the bony tissures of said resected condyles, said cylindrical surface being located adjacent the inner surface of said cap with said cylindrical surface extending laterally outwardly from said oblong cut-out on both sides thereof extending in the oblong direction.
3. An implantable knee joint, as set forth in claim 1 or 2, wherein the inner surface of said cap extending along and adjoining said cut-out in the oblong direction thereof. is polished.
4. An implantable knee joint, as set forth in claim 1 or 2, wherein the outer surface of said femoral cap is polished.
5. An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said first end part extends circumferentially for an angular extend in the range of 130° to 190°.
6. An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said second end part extends angularly in the circumferential direction in the range of 120° to 160°.
7. An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said third part in the direction extending between said first and second end parts has an inside radius in the range of 20 to 150 mm.
8. An implantable knee joint, as set forth in claim 1 or 2, wherein the wall thickness of said femoral cap is in the range of 4 to 20 mm.
9. An implantable knee joint, as set forth in claim 5, wherein the inside radius of said first end part is in the range of 8 to 25 mm.
10. An implantable knee joint, as set forth in claim 6, wherein the inside radius of said second end part is in the range 4 to 15 mm.
11. An implantable knee joint, as set forth in claim 5, wherein said oblong cut-out extends angularly in the circumferential direction of said first end part in the range of 90° to 140°.
12. An implantable knee joint, as set forth in claim 1 or 2, wherein a guide sleeve is located around said connecting member in the region where said connecting member extends through said oblong cut-out.
13. An implantable knee joint, as set forth in claim 2, wherein said cylindrical surface of said disc-shaped sliding member is polished.
14. An implantable knee joint, as set forth in claim 13, wherein said end faces of said disc-shaped sliding member are polished.
15. An implantable knee joint, as set forth in claim 12, wherein said disc-shaped sliding has a frusto-conical bore located therein extending inwardly from said cylindrical surface and said connecting member has a complementary frusto-conical surface thereon arranged to engage in said frusto-conical bore in said disc-shaped sliding member.
16. An implantable knee joint, as set forth in claim 1 or 2, wherein said tibial member comprises a tibial cap arranged to cooperate operatively with said femoral cap.
17. An implantable knee joint, as set forth in claim 16, wherein said tibial cap is C-shaped in cross-section.
18. An implantable knee joint, as set forth in claim 16, wherein said tibial cap has a region thereon corresponding to the eminentia intercondylaris, and said tibial cap has a bore extending through the region corresponding to the eminential intercondylaris for receiving said connecting member.
The present invention is directed to a knee joint prosthesis for the connection of the femur with the tibia and it includes a femur cap with a hook-shaped cross-section for partially enclosing the prepared femur condyles and simultaneous support on the tibia plateau along with a connecting member which can be implanted into the tibia.
Knee joint prostheses which replace the entire joint, require a resection of the entire joint and are known, for instance, from German Offenlegungsschrift No. 29 06 458 and German Offenlegungsschrift No. 25 49 819. In the design of a prosthesis, it is the goal to replace, if possible, only the sliding surfaces and still provide a firm guidance of the bony joint parts, even when there is ligament instability.
Therefore, it has been suggested in German Offenlegungsschrift No. 30 39 392 to resect the condylar area so that a femur cap can be attached with bone cement. Such a femur cap encloses the peripheral end of the resected femur and has as an outer surface two spherical areas which correspond to the condyles. These spherical areas are connected with a cup which replaces the tibia plateau and in which a pin attachment connects the two spherical segment-shaped areas. The cup is secured onto the tibia with bone cement. During hardening of the bond cement, however, a relatively high temperature develops so that temporary damage to the bone structure occurs. Further, antibody reactions and biomechanical factors, particularly in younger patients, argue against the use of bone cement. Accordingly, if possible, the use of bone cement should be avoided.
Therefore, it is the primary object of the present invention to provide an implantable joint which does not have the disadvantages experienced in the past and, while maintaining the physiological motion of the joint, that is the bending of the leg, even when the ligaments are damaged, assures a safe connection between the femur and tibia. In addition, the placement of the prosthesis should require as little bone resection as possible so that the option of a second operation is available. The so-called primary fixation is particularly important. In implants secured with bone cement, it is difficult to determine any difference between primary and secondary fixation, because the absolute anchoring effect takes place by means of the bone cement. As a result, the joint can be stressed after the hardening of the cement. If another type of attachment of the joint prosthesis is selected, such as screwing or nailing, the joint does not reach its full carrying capacity immediately. While it is fixed in the bone, that is the primary fixation, the final anchoring or securement takes place only as the bone grows in, and the prosthesis must first heal in place. The healing process takes longer when the primary fixation is weaker, because any movement between the bones and the implant disturbs the healing process. When the primary fixation is weak, the extremeties must be immobilized which is a considerable problem for the patient and there is also the danger of impairing the movement of the extremities when the healing period is overly long. Under such circumstances, thromboses and embolisms frequently occur.
Therefore, a preferred feature of the invention is to afford a knee joint prosthesis with very good primary fixation so that the healing process is shortened and an early stressing of the prosthesis can take place.
In accordance with the present invention, a knee joint prosthesis is connected to the femur and the tibia and includes a hook-shaped cross-section femur cap which partially encloses the resected femur condyles and is at the same time supported on the tibia plateau, and a connecting member implanted into the tibia and extending into the femur cap. The prosthesis is characterized by the following combination of features:
(a) the cross-section of the femur cap is C-shaped;
(b) the C-shaped cross-section of the femur cap is formed by two arches each having a different radius and connected to one another by a relatively flat surface member; and
(c) in the portion of the femur cap having the larger radius arch, a hole, oblong in the circumferential direction, is arranged to receive a shaft which can be implanted into the tibia.
The C-shaped cross-section of the femur cap with its two arch-shaped parts permits a firm anchoring on the femur without using bone cement on the resected femur condyles. The primary fixation is achieved by the fit between the inner surface of the femur cap and the outer surface of the resected femur condyles. Due to the manner in which the cap is placed on the femur, a movement of the cap is possible in the direction of the axes of the arch-shaped parts. To prevent such movement, the femur cap is nailed or screwed to the femur or, according to a preferred embodiment of the invention, by engaging the shaft into a cylinder rotatably arranged within the femur cap in the region bounded by the larger radius arch-shaped part with the cylinder extending laterally beyond the opposite circumferential extending sides of the oblong hole. The cylinder is placed, practically without any play, between the two resected femur condyles and the cylinder has a bore arranged to receive the shaft. The shaft is anchored in the tibia. From the tibia, the shaft extends through the oblong hole in the region of the larger radius arch-shaped part of the femur cap for preventing any movement of the femur cap in the direction of the axis of the larger radius arch-shaped part.
Accordingly, a primary fixation of the femur cap is obtained in a practically ideal manner without the use of bone cement and this fixation has the further considerable advantage that the bone requires only minimum resecting.
The outer shape of the femur cap corresponds basically to the natural shape of the joint and is polished in accordance with an advantageous embodiment of the invention.
The tibia is supported twice. It is supported during compressive load on the outer periphery of the femur cap where an implant is used as replacement of the tibia plateau and, secondly, the tibia is connected by the shaft with the cylinder so that during the application of tensile stress, the sliding motion is displaced into the larger radius arch-shaped part of the femur cap, that is, between the surface of the cylinder and the inner surface of the femur cap. In an advantageous embodiment of the invention, the inner surface of the femur cap in the region of the larger radius arch-shaped part which adjoins the oblong hole, is polished.
To afford a further reduction in friction, the end faces of the cylinder which slide during movement of the knee on the resected sides of the femur condyles, can be polished. It is advantageous to polish the surface of the cylinder to assure that the friction between the cylinder and femur cap is maintained as low as possible.
Practically all biocompatible materials which have the necessary strength can be used for forming the prosthesis. Care must be taken, however, that the materials used do not cause abrasion when they move relative to one another. As an example, the femur cap can be formed of ceramic oxides or metal with the cylinder being made of HD-polyethylene. Combinations of ceramic oxides and metal or metal and metal cannot be used because there is the danger of metal abrasion due to movement. It is preferable if ceramic oxides are used for both the femur cap and the cylinder, because they have extremely low abrasion values which are practically zero and excellent compatability with the body. The term ceramic oxides is defined more precisely as sintered ceramic oxides of high purity, where the term "high purity" means that the sintered ceramic oxide has a purity exceeding 95%. Sintered metal oxides of zirconium, titanium and particularly aluminum, as well as mixtures thereof, are included under the term "sintered ceramic oxides" in view of the above explanation. It is preferable to use a sintered aluminum oxide having the following characteristics:
a density=or >3.92 g/cm2,
a porosity=or <2%,
a water absorption=or <0.01%,
a purity=or >99.7% Al2 O3,
a Vickers hardness (P=2M)=or >22000 N/mm2,
an average grain size=or <10 μm,
an average bending strength=or >320 N/mm2,
a compression strength=or >4000 N/mm2, and
a tensile strength=or >160 N/mm2.
Such a material affords the required high safety for a prosthesis over several decades, and due to the combination of the high density with the low average grain size and the high purity of the sintered aluminum oxide, excellent characteristics are attained. With regard to purity it is to be understood that in aluminum oxide there are as few foreign substances as additional components which could lead to a glassy intermediate or transition phase. It would not be contradictory of this requirement if the starting material, that is aluminum oxide, contained certain additives, for instance, magnesium oxide may be added as a grain growth inhibitor.
It is possible to polish a material so that it has very high values of smoothness and consequently extremely low friction is present as is necessary in a prosthesis, that is, the friction between the cylinder and the inner surface of the femur cap is very low as well as the friction between the end faces of the cylinder and the resected condyle surfaces contacted by the cylinder.
For the primary fixation of the femur cap, it is important that the measurements of the resected condyle surfaces exactly coincide with the inside measurements of the femur cap, so that the cap can be secured to the femur by a press fit. With a press fit connection, the use of bone cement is unnecessary. Further, with such a connection, an excellent primary fixation is achieved immediately. It is a prerequisite that the narrow tolerances are maintained during implantation and also during the manufacture of the femur cap. Therefore, the resection is carried out advantageously by means of a template-guided end milling cutter or plane milling cutter guided according to the inside shape of the femur cap. In an additional surgical step, the surfaces of the condyles are resected so that these spaced surfaces in the assembled joint form the contact with the end faces of the cylinder.
The cylinder is supported in the region of the larger radius arch-shaped part of the femur cap and this arch-shaped part extends through an angle α in the range of 130° to 190°. Accordingly, this arch-shaped part provides a good support for the cylinder within the femur cap and also makes it possible to provide a solid attachment of the femur cap to the femur.
The angular extent of the smaller radius arch-shaped part, in accordance with the present invention, is in the range of 120° to 160° so that in the normal case it encloses only a small partial area of the facies patellaris, if a larger resection of the femur part was necessary, the arch-shaped part can be extended higher for completely replacing the facies patellaris and, if necessary, also the patella.
In a preferred embodiment of the present invention, the inner radius of the larger radius arch-shaped part is in the range of 8 to 25 mm, the inside radius of the smaller radius arch-shaped part is in the range of 4 to 15 mm and the surface extending between the two arch-shaped parts has a relatively flat configuration with a radius in the range of 20 to 150 mm. The selection of the radii depends on the condition of the bone structure, that is, the size of the joint to be replaced and the amount of the bone substance to be resected, and it also depends on the material used for the femur cap. The basic prerequisite is that the least amount of bone structure is to be removed as can be justified. This requirement provides the opportunity to afford the possibility of a second operation at a point in time significantly later and also that, in the event the implantation of the prosthesis is no longer possible, a joint stiffening can be undertaken without any considerable shortening of the leg. Shortening results primarily from the thickness of the implant materials used and, according to a preferred embodiment of the invention, the thickness of the femur cap should not be less than 4 mm and not exceed 20 mm. The lower limit of 4 mm permits the safe use of a metal implant though in a femur cap formed of ceramic oxide the thickness would be greater, preferably not less than 6 mm. As already mentioned, the upper limit of 20 mm is the result of a shortening which occurs during stiffening of the joint by a second operation which also should be as minor as possible.
When using ceramic oxides which are preferred because of their greater hardness and thus low susceptibility to wear, it is possible to select the radii so that they are not too small because the processing step, such as grinding and polishing can be better controlled. Furthermore, during the pressing of the ceramic oxide powder in a mold, a more uniform material flow, and as a result, a more uniform distribution of strength results. It is preferable to maintain the radius above its lower limit, that is, for the inside radius of the smaller radius arch-shaped part of 4 mm.
The oblong hole formed in the femur cap extends in an angular range of 90° to 140°, accordingly, the shaft guided in the oblong hole can be moved through an angle of at least 90° up to a maximum of 140°, in other words, the full motion of the knee joint is possible.
In a preferred embodiment of the invention, in the region of the oblong hole, the shaft is provided with a guide sleeve. The guide sleeve is made of the same ceramics material as the femur cap and surrounds the metallic shaft in the region of the oblong hole so that during movement of the joint, that is, during bending of the knee, the ceramic oxide material slides on ceramic oxide material and no metal abrasion can take place.
If the femur cap is a metal implant then, to prevent metallic abrasion, the sliding cylinder within the cap is formed of HD-polyethylene, that is, a plastics material. In such an arrangement, the guide sleeve would not be made of a ceramic oxide, because it would lead to metallic abrasion in the region of the oblong hole in the femur cap. Accordingly, the guide sleeve is preferably made of the same plastics material as the cylinder.
The shaft is formed of a material usually employed for metal implants, such as an alloy containing chromium, nickel, molybdenum and cobalt or titanium. If the cylinder into which the shaft is to be attached is formed of high pressure polyethylene, the shaft may be connected with the cylinder by means of a snap-in connection. In such a connection, the shaft is provided in the engagement region within the cylinder with an annular groove and the cylinder has an annular protuberance corresponding to the groove. The shaft can be attached within the cylinder by pressing it into the bore formed in the cylinder so that the annular protuberance seats within the annular groove.
In another preferred arrangement of the invention the cylinder has a frusto-conical bore and the shaft is provided with a frusto-conical section for engagement within the bore. In this arrangement, the cylinder containing the frusto-conical bore is formed of a sintered ceramic oxide material and the shaft with a corresponding frusto-conical section has a deformable surface. Due to the interaction of the two frusto-conical surfaces, an automatic locking effect is achieved so that the shaft is firmly secured within the cylinder.
The invention also includes a tibia cap arranged to be used with the femur cap. Direct action of the femur cap on the cartilage of the tibia plateau leads to a punctiform and linear stress on the cartilage and consequently to its regression. This occurs because the outer shape of the femur cap is selected to correspond to the shape of the natural bone structure, however, it is not possible to achieve a complete adaptation, since the dimensions of the condyles change and as a result the tibia plateau, in engagement with the condyles, is differently formed. The punctiform and/or linear stress caused by the femur cap and causing the regression of the cartilage, then acts directly on the tibia plateau whereby bone regression takes place, accordingly, the coordination of the tibia cap to the femur cap is particularly important.
The tibia cap in this embodiment of the invention has a C-shaped cross-section and is provided in the region of the eminentia intercondylaris with a bore to receive the shaft. A plastics material, preferably HD-polyethylene, is the preferred material for the interaction with the femur cap whether it is formed of metal or of ceramic oxide. In either case, the damping action during sudden movement is very advantageous, however, it is also important that in the combination of a ceramic oxide femur cap with a HD-polyethylene tibia cap that excellent low friction values are achieved. The outer configuration of the tibia cap is selected based on the natural shape of the tibia plateau, that is, it has at both sides of the eminentia intercondylaris one cap to hold the femur condyles. Due to its C-shaped cross-section, the tibia cap can be pushed onto the tibia after the completed resection of the tibia plateau, so that the securement of the tibia cap is effected without the use of bone cement. The primary fixation can also be effected by means of screws or nails. It is more advantageous, however, to insert the shaft into the tibia through a bore in the tibia cap in the region of the eminentia intercondylaris.
In any case, it is necessary to place the shaft in the tibia when a femur cap is to be implanted. If a tibia cap is also to be implanted, then the same shaft can be used to fix both the femur cap and the tibia cap in position and such an arrangement represents a considerable improvement over the art.
FIG. 1 is an exploded perspective view of a prosthesis embodying the present invention;
FIG. 2 is a side view, partly in section, of another implanted prosthesis;
FIG. 3 is a rear view of the implanted prosthesis in FIG. 2;
FIG. 4 is a front view of the implanted prosthesis in FIG. 2;
FIG. 5 is a side view partially in section of the prosthesis embodying the present invention showing another embodiment of the shaft;
FIG. 6 is a rear view of the prosthesis shown in FIG. 5;
FIG. 7 is a front view of the prosthesis shown in FIG. 5;
FIG. 8 is another arrangement of the embodiment shown in FIG. 5 in which a cylinder is not inserted into the condyle region of the femur; and
FIG. 9 is a side view of a prosthesis exemplary of the state of the art.
In FIG. 1, femur 15 is resected in the region of the condyles 19 in the circumferential direction so that a femur cap 4 can be slid onto the end of the femur. Perpendicularly to the circumferentially extending surfaces, the condyles 19 are resected on the adjacent sides so that generally parallel surfaces 21 are formed in the region of the fossa intercondylaris 20. During the assembly of the prosthesis, a cylinder 10 is placed between the surfaces 21 so that its end faces 12, extending transversely of the circumferentially extending cylindrical surface 11, contact the surfaces 21 of the condyles. In the assembled position, the cylinder 10 has a frusto-conical bore 13 directed toward the tibia 3. Further, the cylindrical surface 11 of the cylinder 10 bears against the fossa intercondylaris 20.
As can be seen in FIG. 1 and FIG. 2 the femur cap 4 is formed by two oppositely arranged arch-shaped parts 5, 6, the arch-shaped part 5 has a larger radius than the arch-shaped part 6. A relatively flat surface part 7 extends between the two arch-shaped parts 5, 6. The inside radius RB of the arch-shaped part 5 is in the range of 8 to 25 mm, while the inside radius Rb of the arch-shaped part 6 is in the range of 4 to 15 mm. The part 7 extending between the two arch-shaped parts 5, 6 has a slight curvature as compared to these arch-shaped parts with inside radius RL in the range of 20 to 150 mm. Further, as is also shown in FIG. 2, the larger radius arch-shaped part 5 has an angular range α in the range of 130° to 190° while the smaller radius arch-shaped part 6 has an angular range β in the range of 120° to 160°.
The arch-shaped part 5 is provided with an oblong hole 8 extending in the circumferential or curved direction of the arch-shaped part. The oblong hole has an angular extent in the range of 90° to 140°.
By pressing the C-shaped femur cap 4 onto the resected condyles 19, note the direction of the arrows showing the movement of the cap in FIG. 1, and with the cylinder 10 fitted into the space between the surfaces 21 on the condyles 19, the cylinder 10 is located within the arch-shaped part 5 of the femur cap and the oblong hole 8 affords access to the frusto-conical bore 13, note FIG. 2, within the cylinder 10. Note that the bore 13 is located eccentric to the center of the cylinder 10 and extends chordally of the cylinder. In the assembled position, the cylindrical surface 11 of the cylinder 10 rests against the fossa intercondylares 20.
As can be seen in FIG. 1, the plateau of the tibia 3 is resected to receive the tibia cap 1. As can be seen in FIGS. 1 and 2, the tibia cap 1 has a pair of opposite arch-shaped parts each with a different radius similar to the arrangement of the femur cap 4. Tibia cap 1 is provided with a bore 2 in the region of the eminentia intercondylaris 16. After fitting the tibia cap 1 on the tibia 3, a bore is formed in the tibia 3 for receiving the shaft 9. The shaft 9 is driven through the bore 2 into the bore formed in the tibia 3. As indicated in FIG. 1, the portion of the shaft 9 to be inserted into the bore in the tibia is provided with outwardly projecting support ribs 18 so that a secure attachment is effected in the tibia 3. At the end of the support ribs 18 closer to the femur 15, the shaft has a cylindrical area 22 which serves to hold a guide sleeve 17. Extending from the cylindrical section 22 as viewed in FIG. 1 toward the femur there is a frusto-conical section 14 which has a taper angle in the range of 1:10 to 1:20 and it engages into the frusto-conical bore 13 in the cylinder 10. The tibia cap 1 is designed so that the fibula 23 usually does not have to be resected.
In FIGS. 2, 3 and 4 and also in FIG. 8 another embodiment of the shaft is illustrated. In these figures, the shaft 9 is provided with a threaded insert 31 which is placed within an expansion dowel sleeve 30. By rotating the threaded insert 31, the expansion dowel sleeve 30 is pressed against the wall in the bore of the tibia 3 and fixes the tibia cap in position on the end of the tibia 3.
In FIG. 5, a variation of the shaft 9 shown in FIG. 1 is provided with the end of the shaft inserted into the cylinder 10 being bent angularly relative to the remainder of the shaft extending through the femur cap 4 and the tibia cap 1 into the tibia 3. The bent section of the shaft 9 within the cylinder 10 is in the form of a cylindrical pin 32. Adjacent the end of the shaft 9, the cylindrical pin 32 has an annular groove 33 extending around the pin and an annular protuberance 34 formed by the material of the cylinder and extending into the bore in the cylinder engages within the annular groove. In this embodiment, the cylinder is formed of HD-polyethylene and the end of the cylinder pin 32, first inserted into the bore 13 in the cylinder, is frusto-conically chamfered so that it can be inserted into the bore 13. As the pin is driven into the bore 13, it presses the annular protuberance 34 outwardly due to the elasticity of the material forming the cylinder until the end of the pin reaches the inner end of the bore and the annular protuberance 34 rebounds inwardly and engages within the annular groove 33. As a result, the shaft 9 is firmly anchored within the cylinder 10.
As viewed in FIG. 5, with the leg in the straightened or extended position, the part 7 of the femur cap 4 is located practically horizontally, that is, perpendicular to the axis of the femur 15. The condyle reconstruction part 24 of the femur cap 5, that is, the outside surface of the arch-shaped part 5 is approximately barrel-shaped and rests in the complementary shaped cups 25 of the tibia cap, note FIGS. 2 to 4.
In FIGS. 2 to 8 an implanted femur cap 8 is shown in direct engagement with the tibia cap 1. In the embodiments illustrated in FIGS. 2 to 7, similar to that displayed in FIG. 1, the engagement of the shaft 9 in the cylinder 10 is shown and while it is extremely advantageous, it is not required in each operation. FIG. 8 displays the femur cap 4 fixed in place by a screw attachment so that it is not necessary to resection the region of the fossa intercondylaris 20. In this embodiment, however, the shaft is still required for guidance, however, it is of a shorter construction, that is, it only projects through the oblong hole 8 of the femur cap. It does not project to any significant amount into the region of the fossa intercondylaris 20. Further, the shaft 9 extends through a guide sleeve 17 held on the shaft by means of the head 35 on the end of the shaft 9 projecting through the oblong hole 8.
In FIG. 5 the smaller radius arch-shaped part 6 of the femur cap 4 extends upwardly further into the femur 15 and this arrangement is required when the patella must be replaced. This extended portion of the arch-shaped part 6 serves as a guide for the artificial patella.
In FIG. 9 the state of the art is displayed with the femur 15 being resected to a greater degree in the region of the condyles 19 and this region is surrounded by a hook-shaped implant 27. The hook-shaped implant 27 is secured by cement and a holding pin 25. Further, the implant 27 rests on a support plate 29 secured by cement into the tibia 3.
Various surfaces of the prosthesis are polished to limit friction during use of the prosthesis. For example, the inside surface of the femur cap in the region of the oblong hole 8, located in the larger radius arch-shaped part 5, is polished. Further, the outer surface of the femur cap is also polished. When the embodiment as illustrated in FIG. 1 is used, both the cylindrical surface 11 and the end faces 12 of the cylinder are polished.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4136405 *Apr 29, 1977Jan 30, 1979Zimmer U.S.A.Rotational offset knee prosthesisUS4262368 *Sep 24, 1979Apr 21, 1981Wright Manufacturing CompanyRotating and hinged knee prosthesisUS4538306 *Jun 22, 1983Sep 3, 1985Feldmuhle AktiengesellschaftImplantable elbow joint* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS4822366 *Oct 16, 1986Apr 18, 1989Boehringer Mannheim CorporationModular knee prosthesisUS5133759 *May 24, 1991Jul 28, 1992Turner Richard HAsymmetrical femoral condye total knee arthroplasty prosthesisUS5330532 *Nov 9, 1990Jul 19, 1994Chitranjan RanawatKnee joint prosthesisUS5397360 *Feb 11, 1993Mar 14, 1995Osteonics Corp.Modular components for prosthetic implantsUS5755800 *Dec 23, 1996May 26, 1998Johnson & Johnson Professional, Inc.Modular joint prosthesis augmentation systemUS5755803 *May 17, 1996May 26, 1998Hudson Surgical DesignProsthetic implantUS5755804 *Feb 21, 1997May 26, 1998Plus Endoprothetik AgEndoprosthetic knee jointUS5766257 *Jan 28, 1997Jun 16, 1998Implant Manufacturing And Testing CorporationArtificial joint having natural load transferUS5879354 *Jul 14, 1997Mar 9, 1999Hudson Surgical Design, Inc.Prosthetic implantUS5954770 *Feb 21, 1997Sep 21, 1999Plus Endoprothetik AgEndoprosthetic knee jointUS6117175 *Aug 29, 1997Sep 12, 2000Bosredon; JeanSpherical knee joint prosthesisUS6168629 *Oct 14, 1998Jan 2, 2001Tornier S.A.Femoral component for knee prosthesisUS6197064Mar 3, 1999Mar 6, 2001Hudson Surgical Design, Inc.Prosthetic implantUS6485519Jan 29, 2001Nov 26, 2002Bristol-Myers Squibb CompanyConstrained prosthetic knee with rotating bearingUS6719800Nov 2, 2001Apr 13, 2004Zimmer Technology, Inc.Constrained prosthetic knee with rotating bearingUS6773461Sep 4, 2002Aug 10, 2004Zimmer Technology, Inc.Constrained prosthetic knee with rotating bearingUS7255712Apr 15, 1997Aug 14, 2007Active Implants CorporationBone growth promoting implantUS7326252Dec 22, 2003Feb 5, 2008Smith & Nephew, Inc.High performance knee prosthesesUS7344541Jan 13, 2004Mar 18, 2008Hudson Surgical Design, Inc.Methods and apparatus for femoral and tibial resectionUS7572295Dec 3, 2002Aug 11, 2009Active Implants CorporationCushion bearing implants for load bearing applicationsUS7615081May 23, 2003Nov 10, 2009Zimmer, Inc.Femoral components for knee arthroplastyUS7758653May 21, 2003Jul 20, 2010Active Implants CorporationImplantsUS7803193Dec 3, 2004Sep 28, 2010Active Implants CorporationKnee prosthesis having a deformable articulation surfaceUS7815645Jan 14, 2005Oct 19, 2010Hudson Surgical Design, Inc.Methods and apparatus for pinplasty bone resectionUS7857814Mar 8, 2005Dec 28, 2010Hudson Surgical Design, Inc.Methods and apparatus for minimally invasive arthroplastyUS7922771Jan 31, 2008Apr 12, 2011Smith & Nephew, Inc.High performance knee prosthesesUS7935151Apr 9, 2010May 3, 2011Hudson Surgical Design, Inc.Femoral prosthetic implantUS7967822Oct 29, 2004Jun 28, 2011Hudson Surgical Design, Inc.Methods and apparatus for orthopedic implantsUS8021368Mar 8, 2005Sep 20, 2011Hudson Surgical Design, Inc.Methods and apparatus for improved cutting tools for resectionUS8062377Oct 31, 2007Nov 22, 2011Hudson Surgical Design, Inc.Methods and apparatus for knee arthroplastyUS8088167Dec 15, 2009Jan 3, 2012Hudson Surgical Design, Inc.Femoral prosthetic implantUS8114083Mar 8, 2005Feb 14, 2012Hudson Surgical Design, Inc.Methods and apparatus for improved drilling and milling tools for resectionUS8268006May 28, 2010Sep 18, 2012Zimmer, Inc.Constrained prosthetic knee with rotating bearingUS8287545Mar 8, 2005Oct 16, 2012Hudson Surgical Design, Inc.Methods and apparatus for enhanced retention of prosthetic implantsUS8298238Aug 6, 2008Oct 30, 2012Hudson Surgical Design, Inc.Methods and apparatus for pivotable guide surfaces for arthroplastyUS8353914Jul 9, 2007Jan 15, 2013Hudson Surgical Design, Inc.Methods and apparatus for improved profile based resectionUS8394147Nov 23, 2010Mar 12, 2013Smith & Nephew, Inc.High performance femoral knee prosthesesUS8394148Nov 23, 2010Mar 12, 2013Smith & Nephew, Inc.Tibial component of high performance knee prosthesisUS8398715Oct 20, 2009Mar 19, 2013Smith & Nephew, Inc.High performance knee prostheses with converging anterior and posterior portionsUS8398716Nov 23, 2010Mar 19, 2013Smith & Nephew, Inc.High performance knee prostheses with posterior camUS8403992Nov 23, 2010Mar 26, 2013Smith & Nephew, Inc.High performance knee prosthesesUS8425617Nov 23, 2010Apr 23, 2013Smith & Nephew, Inc.Knee prostheses with convex slope on portion of tibial articular surfaceUS8430932Dec 6, 2011Apr 30, 2013Puget Bio Ventures LLCFemoral prosthetic implantUS8449618Nov 23, 2010May 28, 2013Smith & Nephew, Inc.High performance knee prosthesesUS8460391Sep 25, 2009Jun 11, 2013Zimmer, Inc.Modular femoral components for knee arthroplastyUS8523950Jun 30, 2007Sep 3, 2013Smith & Nephew, Inc.Anatomical motion hinged prosthesisUS8545570Jan 14, 2009Oct 1, 2013Smith & Nephew, Inc.Hinged joint systemUS8545571Jul 30, 2010Oct 1, 2013Howmedica Osteonics Corp.Stabilized knee prosthesisUS8603095Nov 8, 2011Dec 10, 2013Puget Bio Ventures LLCApparatuses for femoral and tibial resectionUS8603178Nov 23, 2010Dec 10, 2013Smith & Nephew, Inc.Knee prostheses with convex portion on tibial lateral articular surfaceUS8647389Dec 17, 2010Feb 11, 2014Smith & Nephew, Inc.High performance knee prosthesesUS8652210Nov 23, 2010Feb 18, 2014Smith & Nephew, Inc.Femoral prostheses with lateral buttress for patellaUS8740906Jul 11, 2008Jun 3, 2014Hudson Surgical Design, Inc.Method and apparatus for wireplasty bone resectionUS8768028May 11, 2010Jul 1, 2014Conformis, Inc.Methods and compositions for articular repairUS8814946Jul 17, 2009Aug 26, 2014Active Implants CorporationCushion bearing implants for load bearing applicationsUS8852195Jan 21, 2005Oct 7, 2014Zimmer, Inc.Guide templates for surgical implants and related methodsUS8862202Sep 10, 2012Oct 14, 2014The Board Of Trustees Of The Leland Stanford Junior UniversityAssessing the condition of a joint and preventing damageUS8882847Nov 24, 2004Nov 11, 2014Conformis, Inc.Patient selectable knee joint arthroplasty devicesUS8888857Sep 5, 2012Nov 18, 2014Zimmer, Inc.Constrained prosthetic knee with rotating bearingUS8926706 *Nov 11, 2011Jan 6, 2015Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS8926709 *Aug 11, 2011Jan 6, 2015Smith & Nephew, Inc.Structures for use in orthopaedic implant fixation and methods of installation onto a boneUS8932363Nov 7, 2003Jan 13, 2015Conformis, Inc.Methods for determining meniscal size and shape and for devising treatmentUS8945230May 12, 2010Feb 3, 2015Conformis, Inc.Patient selectable knee joint arthroplasty devicesUS8965088Jan 17, 2014Feb 24, 2015Conformis, Inc.Methods for determining meniscal size and shape and for devising treatmentUS8974539Nov 11, 2011Mar 10, 2015Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS9020788Feb 15, 2012Apr 28, 2015Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS9055953May 11, 2010Jun 16, 2015Conformis, Inc.Methods and compositions for articular repairUS9056012Aug 9, 2013Jun 16, 2015Smith & Nephew, Inc.Hinged joint systemUS9066804Jun 27, 2011Jun 30, 2015Puget Bioventures LlcMethod and apparatus for femoral and tibial resectionUS9155626Sep 10, 2013Oct 13, 2015Acumed LlcRadial head prosthesis with floating articular memberUS9173744Sep 9, 2011Nov 3, 2015Zimmer GmbhFemoral prosthesis with medialized patellar grooveUS9180015Mar 24, 2014Nov 10, 2015Conformis, Inc.Implants for altering wear patterns of articular surfacesUS9192391Jun 29, 2015Nov 24, 2015Puget Bioventures LlcMethod for minimally invasive total knee arthroplastyUS9301845Jun 15, 2006Apr 5, 2016P Tech, LlcImplant for knee replacementUS9308091May 12, 2009Apr 12, 2016Conformis, Inc.Devices and methods for treatment of facet and other jointsUS9308095Apr 27, 2012Apr 12, 2016Zimmer, Inc.Femoral component for a knee prosthesis with improved articular characteristicsUS9320605Oct 24, 2012Apr 26, 2016Smith & Nephew, Inc.High performance knee prosthesesUS9320620Jul 9, 2013Apr 26, 2016Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS9333085Sep 30, 2013May 10, 2016Conformis, Inc.Patient selectable knee arthroplasty devicesUS9381087May 18, 2015Jul 5, 2016Smith & Nephew, Inc.Hinged joint systemUS9387079Oct 10, 2013Jul 12, 2016Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS9402729Mar 9, 2015Aug 2, 2016Smith & Nephew, Inc.High performance knee prosthesesUS9421022Nov 23, 2015Aug 23, 2016Puget Bioventures LlcMethod and apparatus for total knee arthroplastyUS9439767Oct 10, 2013Sep 13, 2016Conformis, Inc.Patient-adapted and improved articular implants, designs and related guide toolsUS9452051Sep 16, 2013Sep 27, 2016Howmedica Osteonics Corp.Stabilized knee prosthesisUS9495483Jul 30, 2012Nov 15, 2016Conformis, Inc.Automated Systems for manufacturing patient-specific orthopedic implants and instrumentationUS20030225457 *May 23, 2003Dec 4, 2003Justin Daniel F.Femoral components for knee arthroplastyUS20040243244 *Dec 22, 2003Dec 2, 2004Jason OttoHigh performance knee prosthesesUS20040249467 *Mar 19, 2004Dec 9, 2004Meyers John E.Constrained prosthetic knee with rotating bearingUS20050055028 *Jan 13, 2004Mar 10, 2005Hudson Surgical Design, Inc.Methods and apparatus for femoral and tibial resectionUS20050085915 *Dec 3, 2002Apr 21, 2005Amiram SteinbergCushion bearing implants for load bearing applicationsUS20050137710 *Dec 3, 2004Jun 23, 2005Amiram SteinbergOne piece snap fit acetabular cupUS20050143836 *Dec 3, 2004Jun 30, 2005Amiram SteinbergOne piece snap fit acetabular cupUS20050149038 *Oct 4, 2004Jul 7, 2005Hudson Surgical, Inc.Methods and apparatus for orthopedic implant preparation systemsUS20050149039 *Oct 29, 2004Jul 7, 2005Haines Timothy G.Methods and apparatus for orthopedic implantsUS20050149040 *Oct 23, 2004Jul 7, 2005Haines Timothy G.Methods and apparatus for orthopedic surgical navigation and alignmentUS20050149199 *Dec 3, 2004Jul 7, 2005Amiram SteinbergOne piece snap fit acetabular cupUS20050177244 *Dec 3, 2004Aug 11, 2005Amiram SteinbergOne piece snap fit acetabular cupUS20050202371 *May 21, 2003Sep 15, 2005Mcguire JohnImplantsUS20060015117 *Mar 8, 2005Jan 19, 2006Haines Timothy GMethods and apparatus for minimally invasive arthroplastyUS20060030853 *Jan 14, 2005Feb 9, 2006Haines Timothy GMethods and apparatus for pinplasty bone resectionUS20070260323 *Dec 14, 2006Nov 8, 2007Zimmer, Inc.Distal femoral knee prosthesesUS20080000943 *Jun 21, 2007Jan 3, 2008Muller Martini Holding AgStitching device for stitching printed productsUS20080039941 *Jul 27, 2007Feb 14, 2008Active Implants CorporationBone growth promoting implantUS20080119940 *Jan 31, 2008May 22, 2008Otto Jason KHigh performance knee prosthesesUS20090125116 *Jan 14, 2009May 14, 2009Smith & Nephew, Inc.Hinged joint systemUS20100076567 *Sep 25, 2009Mar 25, 2010Zimmer, Inc.Modular femoral components for knee arthroplastyUS20100131070 *Jun 30, 2007May 27, 2010Smith & Nephew, Inc.Anatomical motion hinged prosthesisUS20100172005 *Jan 5, 2010Jul 8, 2010Canon Kabushiki KaishaOptical scanning apparatus and image forming apparatus using the sameUS20100234961 *May 17, 2010Sep 16, 2010Otto Jason KHigh Performance Knee ProsthesesUS20100303324 *May 11, 2010Dec 2, 2010Conformis, Inc.Methods and Compositions for Articular RepairUS20110130842 *Nov 23, 2010Jun 2, 2011Otto Jason KHigh performance knee prosthesesUS20110137427 *Nov 23, 2010Jun 9, 2011Otto Jason KHigh Performance Knee ProsthesesUS20120041566 *Aug 11, 2011Feb 16, 2012Smith & Nephew, Inc.Structures for use in orthopaedic implant fixation and methods of installation onto a boneUS20120232669 *Nov 11, 2011Sep 13, 2012Bojarski Raymond APatient-adapted and improved articular implants, designs and related guide toolsUSRE44476May 7, 2010Sep 3, 2013Zimmer, Inc.Constrained prosthetic knee with rotating bearingEP2145604A1Dec 3, 2002Jan 20, 2010Active Implants CorporationCushion bearing implants for load bearing applicationsWO1997029703A1Feb 20, 1997Aug 21, 1997Hudson Surgical Design, Inc.Prosthetic implant* Cited by examinerClassifications U.S. Classification623/20.26International ClassificationA61F2/38Cooperative ClassificationA61F2/385European ClassificationA61F2/38D2CLegal EventsDateCodeEventDescriptionApr 26, 1984ASAssignmentOwner name: FELDMUHLE AKTIENGESELLSCHAFT, FRITZ-VOMFELDE-PLATZFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:ZICHNER, LUDWIG;DORRE, ERHARD;PRUSSNER, PETER;AND OTHERS;REEL/FRAME:004480/0544Effective date: 19840426Nov 2, 1990FPAYFee paymentYear of fee payment: 4Dec 17, 1992ASAssignmentOwner name: STORA FELDMUHLE AKTIENGESELLSCHAFT, GERMANYFree format text: CHANGE OF NAME;ASSIGNOR:FELDMUHLE AKTIENGESELLSCHAFT;REEL/FRAME:006372/0701Effective date: 19921201Owner name: CERASIV GMBH INNOVATIVES KERAMIK-ENGINEERING, GERMFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:STORA FELDMUHLE AKTIENGESELLSCHAFT;REEL/FRAME:006372/0742Effective date: 19921201Dec 7, 1994SULPSurcharge for late paymentDec 7, 1994FPAYFee paymentYear of fee payment: 8Dec 13, 1994REMIMaintenance fee reminder mailedNov 2, 1998FPAYFee paymentYear of fee payment: 12RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services