Nerve palsy after hamstring lengthening in patients with cerebral palsy.

BACKGROUND: The purpose of this study was to assess the incidence of, risk factors for, and treatment of nerve palsy after hamstring lengthening in children with cerebral palsy.

METHODS: A medical record review of patients with cerebral palsy who had hamstring lengthening between 1994 and 2005 was performed. Data included the preoperative popliteal angle, the presence of a knee flexion contracture, postoperative pain management, and type of immobilization. The presence of postoperative nerve palsy was established based on the recording of numbness, loss of motor function in the foot, or hypersensitivity of the foot in the inpatient record or the postoperative clinic notes. The need for medical management and time to resolution of symptoms were noted.

RESULTS: A total of 292 children underwent 329 hamstring lengthening surgeries. The mean age at surgery was 9.5 years (range, 2.5-18 years). Twenty-eight patients (9.6%) experienced postoperative nerve palsy. Time to recognition of the palsy ranged from 4 hours to 72 days. Patients diagnosed within 24 hours had loss of motor function and/or lack of sensation of the toes. Patients diagnosed from 8 to 72 days postoperatively had dysesthesias of the feet. Treatment of early palsies consisted of the removal of immobilization, bivalving of casts, or wedging casts into flexion. Fourteen of 28 patients were treated with Neurontin. Twenty-two of 25 patients with adequate follow-up recovered nerve function. Older children, noncommunicative patients, nonambulatory patients, and those who had epidural pain management were at statistically significant higher risk for postoperative palsy. The trend for palsies in spastic quadriplegic patients and after repeat lengthening procedures did not reach significance. There was no significant relationship between popliteal angle or the presence of a knee flexion contracture and development of nerve palsy.

CONCLUSIONS: Nerve palsy occurred in 9.6% of patients undergoing hamstring lengthening. Although the greatest risk was in noncommunicative adolescents who were nonambulatory, a small number of younger ambulatory patients developed palsies as well, so that all patients must be considered at risk. Vigilance in patients with epidural pain control to avoid excessive hip flexion and/or knee extension is warranted. Treatment is immediate knee flexion. Resolution of symptoms occurred in 82.1% of patients.