Finsbury (instruments) Limited

Michael A Freeman

Michael Antony Tuke

A knee prosthesis comprises (i) a femoral component having a medial condyle and a lateral condyle and (ii) a tibial component. The rolling surface of the medial condyle is part-spherical and the tibial component has a complementary part-spherical depression in its upper surface to receive the medial condyle. The bearing surface of the lateral condyle includes a posterior part which has a curvature in a substantially sagittal plane about a first point on a transverse axis that passes through the center of curvature of the rolling surface of the medial condyle and an anterior part which has a curvature in the same plane about a point that lies on a second transverse axis parallel to, and anterior to, the first transverse axis. The tibial component has an arcuate groove to receive the lateral condyle and to permit, in flexion of the knee after implantation, limited anterior/posterior movement of the lateral side of the tibia relative to the femur. In flexion of the knee the posterior part of the rolling surface of the lateral condyle is received in this arcuate groove but, as the knee straightens and approaches its straightened condition, the anterior part of this rolling surface bears on the anterior end of the groove and thereby forces the lateral side of the tibial component to move anteriorly relative to the lateral condyle by a camming action. In this way anterior/posterior movement of the lateral side of the tibia relative to the femur is hindered in the straightened condition of the knee.

Knee prosthesis

A surgical tool, for use in hip replacement operations comprises a substantially linear stem which in use seats within a preformed femur cavity. A fixed arm extends medially from an upper portion of the stem and terminates in support for a rotatable cutter. One end of the cutter is received in a seating on the stem below the fixed arm. Ancilliary equipment includes a depth locating tool, so correctly positioning the hip implant in relation to the retained femur neck.

Surgical tool

A hip implant has a stem portion with a substantially linear axis and a circular cross-section at least in the region of the bottom end thereof. A wedge-shaped portion extends medially from the stem at or near the top end of the stem. The wedge-shaped portion is surmounted by a ball.

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London, United Kingdom

Michael A Freeman