This study compares the change in bone density which occurs after hip replacement with different femoral stem devices.

Inclusion Criteria:

• Minimum age 20 years, maximum age 80 years
• Osteoarthritis of the hip
• Elective THA
• Signed Informed Consent

Exclusion Criteria:

• Osteoporosis
• Revisions
• Clinically obese (>40 body mass index [BMI])
• Femoral dysplasia
• Trochanteric osteotomy
• Inflammatory arthritis
• Breast-feeding, pregnancy, or women of childbearing potential without documentation of a negative pregnancy test and not utilizing contraception
• Patients with a history of having taken or currently taking bisphosphonates, PTH, fluoride therapy or strontium ranelate or patients taking other chronic medications that in the investigator's opinion are known to affect bone mineral density in a substantial way
• Patients with severe medical condition(s) that in the view of the investigator prohibits participation in the study
• Use of other investigational agent in the last 30 days
• Unable to sign Informed Consent

Adult patients undergoing elective total hip arthroplasty