The main goal is to prospectively evaluate bone mineral density adjacent to the femoral component and femoral bone remodeling of two different designs: CORAIL impaction broach titanium stem compared to a modular titanium femoral stem (Tri-lock). Patients will be randomized to one of the two treatment groups prior to surgery. Each patient will be evaluated at their regularly scheduled 10-14 days, 3, 6, 12 and 24 month visits following surgery. Patients will be asked to have bilateral DEXA bone mineral density tests (10-14 days post-surgery, and 6, 12 and 24 months post-operatively). Urine and serum samples (measures of bone turnover) will be collected at 3, 6 and 12 months post-operatively after an overnight fast. Patient reported questionnaires will be completed preoperatively and at the 3, 6, 12, and 24 month visits.

The main goal is to prospectively evaluate bone mineral density adjacent to the femoral component and femoral bone remodeling of two different designs: CORAIL impaction broach titanium stem compared to a modular titanium femoral stem (Tri-lock). The investigators expect the CORAIL femoral stem group to show significantly less bone loss on the femoral side as compared to the Tri-lock group. The primary outcome is percent change in bone mineral density (BMD) (g/cm2) from baseline (10-14 days post-op) to the two year post-operative interval, as measured radiographically in zones 1 and 7.

Patients will be randomized to one of the two treatment groups prior to surgery. Each patient will be evaluated at their regularly scheduled 10-14 days, 3, 6, 12 and 24 month visits following surgery.

Bilateral DXA bone mineral density tests will be performed at 10-14 days following surgery (baseline assessment) and at 6, 12, and 24 months post-operatively.

Urine and serum samples (measures of bone turnover) will be collected at 3, 6 and 12 months post-operatively after an overnight fast.

The Harris Hip Score will be completed at each post-operative visit except the immediate (10-14 days), when risk of dislocation precludes a determination of range of motion. At the 3, 6, 12 and 24 month post-operative visits, the patient will complete the SF-36 Item Health Survey, WOMAC and UCLA activity scale.

Inclusion Criteria:

• Patients who are undergoing primary hip surgery for osteo/degenerative arthritis (does not include traumatic arthritis, congenital hip dysplasia, or avascular necrosis).
• Patients who are skeletally mature, as determined by Risser sign or at least 18 years of age
• Patients under 75 years of age
• Patients for whom there is a reasonable expectation that they will be available for each examination scheduled over a two year post-operative follow-up period.

Exclusion Criteria:

• Patients with previous fusions, acute femoral neck fractures and above knee amputations.
• Patients with evidence of active local infection
• Patients with neurologic or musculoskeletal disease that may adversely affect gait or weight-bearing.
• Patients who have previously undergone an ipsilateral hemi resurfacing, total resurfacing, total bipolar, unipolar or total hip replacement device, or any prior hip surgery or retained internal fixation.
• Patients who are anticipated to require contralateral hip surgery in the next year
• Patients with known disorders of bone metabolism, systemic inflammatory disorders, and use of drug medications, including oral steroids, HRT, Tamoxifen, calcium, or vitamin D in the past year, and any past bisphosphonate therapy.
• Patients with a Body Mass Index (BMI) > 35
• Patients with neuropathic joints
• Patients with severe documented psychiatric disease
• Patients requiring structural bone grafts
• Patients with an ipsilateral girdlestone
• Patients with sickle cell disease
• Patients with major acetabular bone stock deficiency