Abstract: A tool for driving a screw having two threaded shanks separated by an intermediate portion. The tool includes a rod having a tapped end portion adapted to engage one of the threaded shanks. The tool also includes a cage adapted to receive the intermediate portion of the screw therein. The cage is provided with at least one opening containing a rolling member configured to be applied against a surface of the intermediate portion of the screw. The tool additionally includes a tube surrounding the rod and the cage. The tube includes an inner wall having a profile configured such that as the tube is rotated about the longitudinal axis, the inner surface applies a radial force to the rolling member, causing the rolling member to be radially displaced through the opening in the cage and placing it in abutment with the intermediate portion of the screw.

Abstract: A trochlea implant for a femoro-patellar prosthesis, the implant being L-shaped, comprising a trochlea branch and an inter-condyle branch, the posterior face of the implant including a rectangular longitudinal rib designed to be engaged in a groove of corresponding shape machined in the anterior face of the trochlea to improve the stability of the prosthesis.