A Rare Presentation of Bilateral Hip Heterotopic Ossification in a Spinal Cord Injury Pediatric Patient: A Case Report

Case Diagnosis: Heterotopic ossification (HO) in a pediatric spinal cord injury (SCI) patient

Case Description or Program Description: A 16-year-old male was found unhelmeted at the scene of an ATV accident. Imaging on arrival to acute care revealed C6-C7 fractures and focal cord contusion. After emergent open reduction and C4-T2 spinal fusion, he was admitted to pediatric inpatient rehabilitation unit (IRU) for traumatic C7 AIS C. Seven weeks from date of SCI, the patient reported progressive hip pain, limited hip flexion impacting function, and worsening spasticity and autonomic dysreflexia. Physical examination revealed palpable bony masses in the hip region, decreased range of motion, and pain exacerbation with passive hip flexion. A magnetic resonance imaging scan showed extensive HO abutting the bilateral inferior iliac bones and proximal femurs. Orthopedic surgery recommended delaying resection for at least 6 months. Treatment with indomethacin and gentle, passive range of motion (ROM) exercises with therapies were initiated.

Setting: Pediatric inpatient rehabilitation

Assessment/Results: Certain therapeutic SCI interventions, such as standing frame trials, were limited throughout inpatient rehabilitation by severe hip stiffness and discomfort. Despite extensive therapy, at discharge the patient remained wheelchair-dependent with minimal voluntary lower extremity movement.

Discussion (relevance): Our case emphasizes the difficulties in diagnosis and management of HO in these rare pediatric SCI cases. Early detection of HO is critical, but challenging due to the non-specificity of early symptoms such as pain and stiffness. Therapeutic challenges include delaying surgery until full ectopic bone maturation to minimize HO recurrence risk, and passive-only ROM preferentially to avoid excessive forces that could exacerbate HO. Notably, available pediatric management guidelines are largely derived from adult studies.

Conclusions: HO is a significant barrier to participation and subsequent functional recovery throughout inpatient rehabilitation. Further research is needed to create pediatric HO management protocols, rather than management derived from adult studies.