Intermediate follow-up of a simple method of hip arthrodesis in adolescent patients

Thirteen male patients (average age, 15.6 years) underwent intraarticular hip arthrodesis for unilateral disabling hip disease. Follow-up averaged 6.6 years. Seven patients had excellent or good Harris hip scores. Ten patients had low back pain, and seven patients had knee pain on the side of the fused hip. Limb-length discrepancy averaged 3.7 cm. A progressive hip adduction drift (average, 7 degrees) occurred during follow-up. Patients whose hips were fused in a position of 20-25 degrees flexion and whose limb-length discrepancies were < 2 cm had significantly lower incidences of back pain. Cybex muscle testing revealed significantly decreased quadriceps strength (29%) on the hip-fusion side. Gait laboratory analysis demonstrated decreased velocity, stride length, and cadence. There were two mildly symptomatic nonunions. Based on these results, we recommend that the hip fusion be positioned in 20 degrees flexion and 0 degree abduction. The joint must be completely debrided down to viable bone to maximize chances for union. Maintaining a limb-length discrepancy of < 2 cm is essential to minimize the incidence of low back pain, quadriceps deficiency, and abnormal gait parameters.