The primary aim of this randomised trial is to determine the effects of a short peri-operative course of treatment with a non-steroidal anti-inflammatory drug (NSAID), ibuprofen, on the long-term consequences of ectopic bone formation in patients undergoing elective total hip replacement surgery. The specific hypotheses to be tested at that 6 to 12 months after surgery, patients assigned post-operative ibuprofen will have less self-reported pain and physical disability, greater health-related quality of life and reduced ectopic bone formation compared with those assigned placebo.