Disodium etidronate: its role in preventing heterotopic ossification in severe head injury.

Heterotopic ossification (HO) occurs in up to 75% of patients who survive severe head injury and is a major factor in prolonging their rehabilitation. Prevention of HO has not been emphasized in acute care management of patients with head injury. But with spinal cord injuries and total hip arthroplasty, HO has been prevented by use of disodium etidronate (EHDP). This study compares the incidence and severity of HO in 10 patients with severe head injury who were treated with EHDP and 10 matched controls without drug treatment. Patients selected for EHDP treatment were consecutive admissions who had Glasgow Coma Scores (GCS) less than nine. Treatment was begun within two to seven days of injury with 20mg/kg/day via nasogastric tube and was discontinued if the patient awakened within two weeks (low risk of HO). After three months EHDP was given orally at 10mg/kg/day for an additional three months. Ten patients completed the treatment regime and were compared to 10 patients with similar injuries. Of the 10 patients treated with EHDP, two developed HO, while clinically significant HO was found in seven of the 10 nontreated patients (chi square = p less than 0.025). This finding could not be explained on the basis of differences in the two groups; the groups were alike in age, sex, length of coma, extracranial fracture, spasticity, type of head injury, and injury severity (GCS). These data suggest that HO may be prevented by early use of EHDP, and the results warrant further clinical trials.