(5) Patients with neuropathic joints. (6) Patients with severe documented psychiatric disease. (7) Patients requiring structural bone grafts. (8) Patients with a documented allergy to cobalt chromium molybdenum. (9) Patients with an ipsilateral girdlestone. (10) Patients with sickle cell disease. (11) Patients with renal failure as defined by serum creatinine level greater than 180 Fmol/L.