Heterotopic ossification after hip surgery in cerebral palsy.

Heterotopic ossification is a post-surgery complication occasionally observed in patients with infantile cerebral palsy. In the majority of the cases such lesions are found at the hip after surgery on the skeleton and the soft tissues. At our Institute in the last five years, this complication has been observed four times, in 39 patients, who underwent mainly soft tissue releases because of flexion and adduction contracture of the hip. In these cases, as in a further patient with myelomeningocele, the periarticular heterotopic ossification appeared in the hip after tenotomy of the ilio-psoas at the lesser tronchater associated to other surgical procedures. Conversely, no cases of ossification have been found after tenotomy of the adductors or the gracilis or selective tenotomy of the psoas at the pelvic brim. The exact causes of this complication are still unclear, but after an analysis of the literature and patient history it can be hypothesised that it may be related to the surgical procedures carried out.