Current concepts in the development of heterotopic ossification.

©2004 British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.86B6. 15356 $2.00 J Bone Joint Surg [Br] 2004;86-B:783-7. Heterotopic ossification can be defined as the formation of bone in tissues which normally exhibit no properties of ossification. It is characterised by the rapid development of calcified bone in soft tissues. Ectopic bone can develop from immature osteoid in a matter of weeks. The development of heterotopic ossification has been shown to be associated with many predisposing factors including neurological injury, both to the spinal cord and the brain, major joint surgery and burns.1-4 Marked variation can occur in the incidence and location of bone formed and in the resulting complications. The first description of heterotopic ossification after neurological injury was by Dejerne and Ceiller1 who detailed the clinical, anatomical and histological features of ectopic bone formation in soldiers who sustained spinal injuries during the First World War. Heterotopic ossification after traumatic brain injury was first reported by Roberts2 who described involvement of the elbow in patients with cerebral injury and a prolonged period of coma. The incidence following brain injury has been reported to vary between 11% and 22%.5,6 The most common joints to be affected are the hip, elbow and shoulder. After such injury an accelerated rate of fracture healing has also been reported with the formation of exuberant callus at fracture sites.7,8 Since the original report of heterotopic ossification after traumatic brain injury,2 there have been a number of papers describing the incidence, location and management. This review provides an analysis of the papers on this topic published previously and discusses the aetiology, pathophysiology and the current concepts of treatment.