Ultrasound in the early diagnosis of heterotopic ossification in patients with spinal injuries.

Heterotopic ossification (HO) is a potentially disabling complication of spinal injuries and other chronic disorders. It is of unknown aetiology and currently there is no easy or convenient diagnostic method that will allow very early confirmation of the inflammatory changes that precede osteoid and, later, true bone formation. Clinical experience, however, indicates that early treatment with radiotherapy, antiinflammatory agents or diphosphonates is needed to control the progression. This study was undertaken to assess the role of ultrasound (US) in the very early diagnosis of HO in patients with spinal injuries. US was found to be very sensitive in detecting focal soft tissue abnormalities around joints and in the muscles of these patients. If combined with a Doppler study to exclude deep venous thrombosis (DVT), and infection or tumour could be excluded clinically, US was extremely accurate in predicting the presence or absence of early HO changes within hours of the clinical manifestation. In 2 patients it successfully predicted HO in the opposite leg before clinical signs were evident. This study also provided supportive evidence of the theory of microtrauma in the aetiology of HO. As ultrasound is portable, safe, cheap, reproducible and accurate, it is the method of choice in the early diagnosis of HO. It allows early treatment to prevent the formation of osteoid and subsequent bone formation.