Prophylaxis of HO targets the biochemical mechanisms of heterotopic bone formation by: 1) Disrupting inductive signaling pathways, 2) Altering osteoprogenitor cells in target tissues, and 3) Modifying the environment conductive to formation of heteroptic bone. The two mainstays of therapy are low dose radiation treatment and non-steroidal anti-inflammatory medications (NSAIDs). The efficacies of these treatments were found to be equivalent by Burd et al in 166 randomized patients. However, NSAID therapy was shown to be considerably more cost effective with lower rates of morbidity. Large randomized studies have subsequently shown large reductions in the incidence of HO using NSAID therapy in the perioperative period. The Cochrane review of 16 randomized trials in 5000 patients found one-half to two-thirds reduction in HO with indomethacin.Even less potent NSAID therapy has been effective in reducing rates of HO. Fransen et al reported a 30% reduction in HO during the HIPAID trial comparing perioperative ibuprofen with placebo in nearly 1000 patients. The two groups had no statistical difference in functional outcome despite the higher incidence of HO in the prophylaxed group.