Source: https://patents.justia.com/patent/4662889
Timestamp: 2019-12-07 00:28:58
Document Index: 151085366

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']

US Patent for Knee joint prosthesis Patent (Patent # 4,662,889 issued May 5, 1987) - Justia Patents Search
Justia Patents US Patent for Knee joint prosthesis Patent (Patent # 4,662,889)
Apr 26, 1984 - Feldmuhle Aktiengesellschaft
a density=or >3.92 g/cm.sup.2,
a purity=or >99.7% Al.sub.2 O.sub.3,
a Vickers hardness (P=2M)=or >22000 N/mm.sup.2,
an average grain size=or <10 .mu.m,
an average bending strength=or >320 N/mm.sup.2,
a compression strength=or >4000 N/mm.sup.2, and
a tensile strength=or >160 N/mm.sup.2.
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 .alpha. in the range of 130.degree. to 190.degree.. 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.degree. to 160.degree. 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.
The oblong hole formed in the femur cap extends in an angular range of 90.degree. to 140.degree., accordingly, the shaft guided in the oblong hole can be moved through an angle of at least 90.degree. up to a maximum of 140.degree., in other words, the full motion of the knee joint is possible.
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 R.sub.B of the arch-shaped part 5 is in the range of 8 to 25 mm, while the inside radius R.sub.b 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 R.sub.L 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 .alpha. in the range of 130.degree. to 190.degree. while the smaller radius arch-shaped part 6 has an angular range .beta. in the range of 120.degree. to 160.degree..
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.degree. to 140.degree..
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.degree. to 190.degree..
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.degree. to 160.degree..
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.degree. to 140.degree..
Assignee: Feldmuhle Aktiengesellschaft (Du)
Inventors: Ludwig Zichner (Frankfurt), Erhard Dorre (Plochingen), Peter Prussner (Dietzenbach), Horst von Borries (Krefeld)
Application Number: 6/603,659