The Medacta International GMK Sphere Cementless Post-Marketing Surveillance Study

Inclusion Criteria: * A disabled or severely disabled joint as a result of arthritis, traumatic arthritis, rheumatoid arthritis, poly-arthritis or avascular necrosis * Patients between the age of 18 and 80 at the time of consent * Listed for total knee replacement surgery. * Patients who are willing and able to give informed written consent Exclusion Criteria: * Progressive local or systemic infection * Muscular loss, neuromuscular disease or vascular deficiency of the affected limb, making the operation unjustifiable * Severe instability secondary to advance destruction of condralar structures or loss of integrity of the medial or lateral ligament * Those whose prospects for a recovery to independent mobility would be compromised by known coexistent, medical problems * Patient whose BMI exceeds 40 * Any case not described in the inclusion criteria