Risk factors for heterotopic ossification in children and adolescents with severe traumatic brain injury.

Previous reports on the incidence of heterotopic ossification (HO) in children and adolescents with traumatic brain injury (TBI) have ranged from 3% to 20%. These studies mention HO briefly or address patient cohorts with coma more than three months. We reviewed the medical records of 90 children younger than 19 years old, who were comatose more than 24 hours after TBI. Mean followup was 33.1 months (range = 2 to 128 months). Incidence of HO was 14.4% (n = 13). One to five sites were involved, with hip and knee most frequent, followed by shoulder, elbow, and nonjoint sites. Children with HO were older than 11 years (relative risk [RR] = 18.85, confidence interval [CI] = 3.7, 95.7), had a greater length of coma (RR = 7.22, CI = 1.4, 37.1), and had a greater associated risk for poor functional outcome (RR = 2.89, CI = 1.02, 7.9) compared to those without RO. Multiple limb fractures showed a trend toward association with increased incidence of HO. Other factors, including gender, history of skull fracture, brain CAT scan findings, and presence of spasticity, were not predictive of HO. Eleven children were treated with etidronate, four with nonsteroidal antiinflammatory drugs, and one with surgery. Only three children had residual functional impairments attributed to the presence of HO.