Severe bilateral hip heterotopic ossification in a pediatric patient with paraplegia following idiopathic myelitis: A case report

Heterotopic ossification (HO) is an uncommon but potentially disabling complication in pediatric patients with neurologic injury, often leading to severe joint stiffness and functional impairment. A 10-year-old boy developed severe bilateral hip ankylosis after idiopathic thoracic myelitis with resultant paraplegia. Progressive hip stiffness compromised sitting balance and self-catheterization. Radiographs and computed tomography demonstrated extensive bilateral HO involving the tensor fascia latae and piriformis muscles. Staged surgical excision of the heterotopic bone followed by rehabilitation improved hip mobility. However, a persistent internal rotation deformity of the right femur, attributed to prolonged immobilization after a prior femoral fracture, continued to impair self-catheterization and required subtrochanteric derotational osteotomy. Postoperatively, stable sitting balance and independent catheterization were achieved. This case underscores the importance of accurate imaging, appropriate surgical timing, and multidisciplinary management in severe pediatric HO.