<qa>  How many patients will undergo routine hip replacements?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. 