Association between muscle trauma and heterotopic ossification in spinal cord injured patients: reflections on their causal relationship and the diagnostic value of ultrasonography.

Paraplegic patients presenting with a subacute limitation of hip joint mobility were subjected to serial sonographic examinations. In four patients the initial sonographic study disclosed discontinuity with fluid collection in the psoas muscle, which was diagnostic of a traumatic muscle rupture. All four patients subsequently developed sonographic and radiographic evidence of heterotopic ossification. Our findings confirm that ultrasonography is an easy and inexpensive screening method for the early diagnosis of heterotopic ossification. The sonographic results obtained in these four paraplegic patients are indicative of a possible traumatic origin of heterotopic ossification around the hip.