Total hip replacement is a common procedure for the treatment of osteoarthrosis of the hips, the aims of this study are to determine the effect of implant stem design on bone quality surrounding the implant using three stem designs that are routinely implanted at this hospital.

120 patients will undergo routine hip replacements using either the C-Stem, Exeter Stem or Charnley stem implants. Patients will be clinically evaluated pre-operatively and randomised to one of the three implants. Post-operatively, patients will be clinically reviewed for 2 years using bone mineral density scans, radiological review, blood and urine analysis for bone markers and validated questionnaires to assess clinical data (Oxford Hip and Harries Hip). Patients will be assessed for prothesis migration using the EBRA methods.

Inclusion Criteria:

• patients must be aged 60 yrs or more uncomplicated primary or secondary osteoarthritis of the hip undergoing unilateral cemented total hip arthroplasty using a metal on polyethylene bearing couple.

Exclusion Criteria:

• metabolic bone disorders, systemic disorders such as rheumatoid arthritis and patients who have taken pharmacological doses of oral steroids, hormone replacement therapy, tamoxifen, calcium or vitamin D supplements within the last year. Patients with a prior history of bisphosphonates and women of child bearing age.

Pre-assessment clinics at Sheffield Hospitals, patients booked for hip replacements.