This study evaluates femoral head resurfacing versus a large femoral head (Durom®) total hip system. This is a prospective randomized trial.

Inclusion Criteria:

1. Indication for hip resurfacing because of osteoarthritis or avascular necrosis
2. Aged 19 to 65 years old
3. Ability to give informed consent

Exclusion Criteria:

1. Previous fracture requiring internal fixation of the hip
2. Previous hip osteotomy (pelvic or femoral)
3. Dysplasia requiring structural bone graft
4. Inability to respond to questionnaires in English (or French, Montreal centre only)
5. The presence of osteopenia or osteoporosis
6. Evidence of hepatic/renal insufficiency or failure from medical history or laboratory assessment