Complete knee prosthesis
OwnerJacques Afriatinventor
Life of this patent
Estimating the term…
Abstract
A prosthesis whose condyles (3) have a spiral form, viewed in the saggital plane and the femoral element (1) has a medial lobe (6) with a curved surface. The medial plateau (2) has glenoid cavities (2b) for the condyles (3) and a medial prominence (5) which forms a posterior support surface (5a) against which the lobe (6) is supported in the course of movement of the joint. The glenoid cavities (2b) on the medial plateau (2) and the condyles (3) are congruent in extension and in the first part of the flexion movement of the joint. The posterior sections of the condyles (3) and the medial lobe (6) inscribe circles with the same centres and the medial lobe (6) contacts against the posterior support surface (5a) at the end of the first part of movement and then rests against the posterior support surface (5a) to perform a “roll-back”.
Claims3
Complete knee prosthesis, comprising:
- a femoral element (1) with femoral condyles (3) having, seen in the sagittal plane, a spiral form corresponding substantially to a form of natural condyles, with gradual reduction of their radii towards posterior sectors, and comprising a medial lobe (6) with a curved surface;
- a tibial seat forming an upper support plate, and
- a medial plateau (2) intended for resting against said upper support plate of the tibial seat and comprising glenoid cavities (2b) receiving the condyles (3) of the femoral element (1), said medial plateau (2) having a medial prominence (5) which forms a posterior support surface (5a), against which said lobe (6) is capable of resting during the movement of the joint, wherein,
- the glenoid cavities (2b) of the medial plateau (2) and the condyles (3) of the femoral element (1) are formed to be congruent when the prosthesis is in extension and on a first part of the flexion movement of the joint extending between this extension position and the angle of flexion between about 30 to 80° from which the congruence of the condyles (3) with the glenoid surfaces is lost due to the spiral form of the condyles (3),
- the posterior sectors of the condyles (3) and of the medial lobe (6) inscribe circles of same centers,
- the medial lobe (6) is formed so as not to contact said posterior support surface (5a) during said first part of movement, but to contact said posterior support surface (5a) when said flexion angle is reached and then to carry the joint against this posterior support surface (5a) over the remainder of the flexion travel, while performing a rolling movement of the femoral condyles (3) with respect to the tibial seat in the posterior direction, called “roll-back”, and
- said posterior support surface (5a) has a curved shape corresponding to the curved shape of said medial lobe (6), so that this lobe rests against this posterior support surface (5a) over a wide surface throughout the second part of movement, consecutive to said first part of movement.
Dependencies are inferred from the claim text.