Source: https://patents.google.com/patent/US7364590B2/en
Timestamp: 2019-11-17 18:58:41
Document Index: 295334216

Matched Legal Cases: ['arts 13', 'art 14', 'art 13', 'art 13', 'art 14', 'art 13', 'art 14']

US7364590B2 - Anatomical knee prosthesis - Google Patents
Anatomical knee prosthesis Download PDF
US7364590B2
US7364590B2 US10/409,356 US40935603A US7364590B2 US 7364590 B2 US7364590 B2 US 7364590B2 US 40935603 A US40935603 A US 40935603A US 7364590 B2 US7364590 B2 US 7364590B2
US10/409,356
US20040204766A1 (en
2003-04-08 Application filed by Thomas Siebel filed Critical Thomas Siebel
2003-04-08 Priority to US10/409,356 priority Critical patent/US7364590B2/en
2004-10-14 Publication of US20040204766A1 publication Critical patent/US20040204766A1/en
2008-04-29 Publication of US7364590B2 publication Critical patent/US7364590B2/en
According to FIG. 1, previous knee prosthesis are oriented on the so-called mechanical axis δ1 with respect to its joint line 2′. The mechanical axis δ1 is the line that runs vertically from the center 1 of the head of the femur through the knee joint 3 to the ankle 4. The joint lines 2′ and 5′ of previous knee prosthesis implants were implanted at an angle of (β1) 90° to this mechanical axis. The medial and lateral condyles of the femur were equally large in regard to their polycentric radius.
In reality, it is now the case that the joint line 5 of the upper ankle joint 4 to the axis δ1 forms an angle (α1) of 85°±5° ascending medially and descending laterally. Furthermore, in the region of the knee joint line 2, the anatomical healthy knee joint also does not form a right angle with the mechanical axis δ1 that was assumed at that time, but rather the tibial plateau descends medially by an angle (β2) of about 3°±x or ascends laterally by 3°±x relative to the mechanical axis δ1. The consequence of this is that the condyles of the femur have different radii. Laterally, the polycentric radii are somewhat smaller in the side view, while the medial condyle of the femur is distinctively larger with polycentric radii, as far as the radial diameter is concerned. The bearing surface in the a.p. plane is somewhat narrower in the case of the medial condyle of the femur, compared to the lateral condylar part. In addition, it should be noted that the tibial plateau drops by 3-7° in the dorsal direction.
FIG. 1 is a side view of the tibia, knee joint and the femur;
FIGS. 13 a and 13 b show front views of the femur implants of FIGS. 12 a and 12 b.
The tibial implant shown in FIG. 2 has a stepped tibial plateau 6 that descends, due to the step which is oriented to the axis of a shaft 9, centrally from the lateral side 7 to the medial side 8. The tibial plateau 6 is formed by a layer 10 of polyethylene. The remainder of the tibial implant is made of metal.
The tibial implant shown in FIG. 3 has a polyethylene layer 10 that forms a tibial plateau 6 with treads 11, 12. The tibial plateau 6 is at an angle α<90° to the axis of the shaft 9 so that the tibial plateau 6 descends from the lateral side 7 to the medial side 8.
The femoral implant shown in FIG. 4 has two condylar parts 13, 14, whereby the condylar part 14 is offset relative to the condylar part 13 in a proximal (towards the head) and ventral (towards the front) direction. Due to the offset the joint line 2 is at an angle α<90° to the mechanical axis δ1. The joint line 2 descends from the lateral side 7 to the medial side 8.
FIG. 11 a shows a lateral side view in the medial direction of a femur implant. FIG. 11 b is a medial side view in the opposite direction. FIG. 11 a shows a lateral condylar part 13 a and FIG. 11 b shows a medial condylar part 14 a. The condylar part 13 a has smaller polycentric radii 21 than the condylar part 14 a.
FIG. 12 a is a perspective view of a femoral implant corresponding to the femoral implant of FIG. 11 a. FIG. 12 b is a perspective view of a femoral implant corresponding to the femoral implant of FIG. 4. FIGS. 13 a and 13 b show the implants of FIGS. 12 a and 12 b in a front view.
LIST OF REFERENCE NUMBERS FIG. 1: 1 = mechanical axis δ1 2 = anatomical line of the interarticular space of the knee FIG. 2: 1 = lateral 2 = medial 3 = polyethylene 4 = metal 5 = stem FIG. 3: 1 = lateral 2 = medial 3 = angle < 90° FIG. 4: 1 = lateral 2 = medial 3 = bearing surface = width greater medially than laterally 4 = angle < 90° FIG. 5: 1 = lateral 2 = medial FIG. 6: 1 = lateral 2 = medial 3 = polyethylene inlays with different heights FIG. 8: 1 = lateral 2 = medial FIG. 9: 1 = lateral 2 = medial FIG. 10: 1 = lateral 2 = medial FIG. 12 a: 1 = lateral 2 = medial FIG. 12 b: 1 = lateral 2 = medial FIG. 13 a: 1 = lateral 2 = medial FIG. 13 b: 1 = lateral 2 = medial
3. The anatomical knee prosthesis according to claim 2, wherein the implants are configured so that, after implantation, the femur shaft and the tibia shaft form an angle of 5-7° valgus.
5. The anatomical knee prosthesis according to claim 2, wherein the femur has condyles with differently sized polycentric condylar parts including a medial condylar part with a different polycentric radius from a lateral condylar part, so that, with respect to a joint bearing surface, a medially descending angle of 3°±x to the mechanical axis is achieved.
8. The anatomical knee prosthesis according to claim 6, wherein the joint surface is constructed by medial and lateral bearing surfaces with different height levels, each of which forms a 90° angle to the bearing axis.
9. The anatomical knee prosthesis according to claim 2, wherein the tibial implant has a tibial plateau anatomically implanted so as to generate a medially descending angle of 3°±x.
10. The anatomical knee prosthesis according to claim 9, wherein the tibial implant is implanted to descend dorsally by 3-10°, descend medially by 3°±x**, and, with respect to the bearing surface, more pronounced medially than laterally.
13. The anatomical knee prosthesis according to claim 12, wherein the tibial plateau is provided with a stem, which forms an angle of 87°±x in the medial direction.
14. The anatomical knee prosthesis according to claim 12, wherein the tibial plateau has a stem fixed at right angles on the tibial plateau implant that is inserted in the bone only at a medially descending angle of 3°±x.
US10/409,356 2003-04-08 2003-04-08 Anatomical knee prosthesis Active US7364590B2 (en)
US10/409,356 US7364590B2 (en) 2003-04-08 2003-04-08 Anatomical knee prosthesis
US20040204766A1 US20040204766A1 (en) 2004-10-14
US7364590B2 true US7364590B2 (en) 2008-04-29
US10/409,356 Active US7364590B2 (en) 2003-04-08 2003-04-08 Anatomical knee prosthesis
2003-04-08 US US10/409,356 patent/US7364590B2/en active Active
US20040204766A1 (en) 2004-10-14