The GMK Primary patello-femoral joint is designed to mimic the natural anatomy and kinematics of the healthy knee in order to optimise patella tracking, improve articular stability and reduce polyethylene wear. GMK incorporates state of the art design features: Deepened trochlear groove: allowing the patella to articulate at the same height as the normal patella, reducing the occurrence of patella clunk and crepitus. [1] Wide contact area between patella and femoral component: reducing polyethylene stress due to compressive forces. [2,3,4] Higher anterior-lateral wall of the femoral component: guiding and supporting the patella in the initial phases of flexion. 6° oriented sulcus: limiting lateral shear forces on the patella component. [2,6] Asymmetric resurfacing patella with a prolonged lateral flange: providing better contact surface and mimicking the shape of natural patella. [5]