A normal knee is a complex structure: when it bends, the lateral (outer) side rolls back while the medial (inner) side remains stable. The GMK Sphere knee is designed to provide a more natural motion that replicates the movement of the healthy knee: it allows stability in the medial side through a ball-and-socket mechanism and accommodates the natural movement of the lateral side without imposing any constrained motion.

The GMK Sphere medial ball-in-socket mechanism can replicate the function and the stability provided by the natural stabilisers of the knee, most of which are removed during total knee replacement. Stability is important for common activities such as ascending and descending stairs, standing up from a seated position, getting into a car as well as more demanding activities like shopping and gardening. Published studies* actually confirm that patients prefer knees with a medial ball-and-socket compared to other conventional knee designs, as they feel more natural, more stable and stronger during daily activities. * Pritchett JW, “Patients Prefer A Bicruciate-Retaining or the Medial Pivot Total Knee Prosthesis”, J. Arth 2011.