# US 8,540,776 B2 · Total knee prosthesis

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- Number: US 8,540,776 B2
- Document ID: US8540776B2
- Status: Granted
- Kind: B2
- Application number: 12/996,161
- Filed: 2009-06-03
- Published: 2011-05-26
- Granted: 2013-09-24
- Earliest claimed: 2008-06-06
- Applicants: Michel Bercovy; Luc Kerboull; David Bracy
- Inventors: Michel Bercovy; Luc Kerboull; David Bracy
- Web page: https://patentgrep.com/patent/US8540776B2

## CPC

- A61F 2/3868: {with sliding tibial bearing}
- A61F 2002/30934: {Special articulating surfaces}
- A61F 2002/30952: {using CAD-CAM techniques or NC-techniques}
- A61F 2310/00179: Ceramics or ceramic-like structures
- A61F 2310/00203: containing alumina or aluminium oxide
- A61F 2310/00239: containing zirconia or zirconium oxide ZrO2
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

The present invention relates to a total knee prosthesis. This prosthesis includes a femoral implant (2) including two condyles (8, 9) delimiting between them an intercondylar notch (10), a tibial implant (3) intended to rest on the end of the tibia, and an articular insert (4) interposed between the tibial implant and the femoral implant and the upper surface of which (41) includes two glenoid cavities (18, 19) with an external profile (181, 191) congruent with the external profile (81, 91) of the condyles (7, 8) of the femoral implant and connected together through an interglenoidal connecting surface (20). According to the invention, the intercondylar notch (10) and the interglenoidal connecting surface (20) have congruent contact surfaces (101, 201) which are inscribed in two mating hyperbolic paraboloids and the contact surface (181, 191) of the glenoid cavities (18, 19) have in a horizontal section an ovoid shape and its inclined point (P) is located posteriorly to the line of larger width (L) of the insert.

## Claims

### Claim 1

A total knee prosthesis (1) including:
a femoral implant (2) including two condyles (8, 9) delimiting between them an intercondylar notch (10), an external profile (101) of which is convex in a sagittal plane and concave in a frontal plane and is connected in all the planes without any discontinuity with an external profile (81, 91) of the condyles,
a tibial implant (3) including at least one supporting plate (21) intended to rest through a lower surface (212) thereof on the end of the tibia, if necessary after resection, and
an articular insert (4) interposed between the tibial implant and the femoral implant and capable of co-operating with them through lower (44) and upper (41) contact surfaces with shapes respectively mating an upper surface (211) of the supporting plate of the tibial implant and the external profiles (81, 91, 101) of the condyles and the intercondylar notch of the femoral implant,
the upper surface (41) of the articular insert including two glenoid cavities (18, 19) of the external profile (181, 191) congruent with the external profile (81, 91) of the condyles (8, 9) of the femoral implant and connected together through an interglenoidal connecting surface (20), with a shape congruent with the one of the intercondylar notch (10), and of an external profile (201) convex in a frontal plane and concave in a sagittal plane and connecting in all the planes without any discontinuity with the external profile (181, 191) of the glenoid cavities,
characterized in that the intercondylar notch (10) and the interglenoidal connecting surface (20) have congruent contact surfaces (101, 201), the contact surface (101) of the intercondylar notch (10) having a hyperbolic paraboloid shape and the contact surface (201) of the interglenoidal connecting surface (20) having a hyperbolic paraboloid shape mating the one defined by said intercondylar notch 10 and in that the contact surface (181, 191) of the glenoid cavities (18, 19) has in a horizontal section an ovoid shape and an inclined point (P) is located posteriorly to a line of larger width (L) of the insert, the concave external profile (201) in a sagittal plane of the connecting surface (20) defining a first high point at an anterior portion (42) and a second high point at a posterior portion (43), the first high point is higher than the second high point so that a straight line (Δ) passing through the first high point and the second high point, has a slope from the anterior portion (42) towards the posterior portion (43) of the insert and in that this straight line forms an angle α comprised between 1° and 15°.

### Claim 2 (depends on 1)

The prosthesis according to claim 1, characterized in that lowest points of the contact surface (181, 191) of the glenoid cavities (18, 19) of the insert are all located on a same straight line in a median plane of the insert.

### Claim 3 (depends on 1)

The prosthesis according to claim 1, characterized in that ovoid contact surfaces (181, 191) of the glenoid cavities of the insert are connected, at each flexural level through an isthmian surface concave towards a front and rear in the hyperbolic paraboloid of the surface (201) of the interglenoidal connecting surface (20).

### Claim 4 (depends on 1)

The prosthesis according to claim 1, characterized in that the width (Is) of the interglenoidal connecting surface (20), taken in a horizontal plane, is decreasing from an anterior portion (42) towards a posterior portion (43) of the insert.

### Claim 5 (depends on 1)

The prosthesis according to claim 1, characterized in that a radius of curvature R2 of the external profile (201) for connecting the interglenoidal connecting surface (20) with the external profile (181, 191) of the glenoid cavities (18, 19) of the articular insert and the radius of curvature R1 of the external profile (101) for connecting the intercondylar notch (10) are substantially equal in common frontal planes so that the intercondylar notch (10) forms an imprint of the interglenoidal connecting surface (20) between both condyles (8, 9) of the femoral implant (2).

### Claim 6 (depends on 1)

The prosthesis according to claim 1, characterized in that the width (Ii) of the insert, taken in a horizontal section, is decreasing from its posterior portion (43) towards its anterior portion (42), said insert being inscribed in a trapezium.

### Claim 7 (depends on 1)

The prosthesis according to claim 1, characterized in that it includes a patellar implant adapted for co-operating through an articular surface with the femoral implant, the articular surface of said patellar implant being a hyperbolic paraboloid mating the one defined by the intercondylar notch.

### Claim 8 (depends on 1)

The prosthesis according to claim 1, characterized in that the tibial implant (3) includes on its lower face of its plate (21), lateral stabilisation reinforcements oriented towards the base of the area supporting the condyles in the glenoid cavities of the insert when the knee is in a flexure position.

### Claim 9 (depends on 1)

The prosthesis according to claim 1, wherein the angle is between 4° and 10.