Slipped capital femoral epiphysis: a prospective study of dynamic screw fixation.

Twenty-five consecutive children (29 hips) who had slipped capital femoral epiphysis of a mild degree (slip angle less than 30 degrees) were treated with dynamic screw fixation. The goal of dynamic screw fixation is to achieve physeal stability to prevent additional slippage and to avoid premature physeal closure. Seventeen boys and eight girls were followed up for an average of 7 years (range, 4-13 years). There were 25 chronic slips, three acute slips, and one preslip. The average age at the time of surgery was 11.7 years for the girls (range, 11.1-12.9 years) and 13.9 years for the boys (range, 9.4-16.1 years). The average time to physeal closure was almost the same in both genders (boys, 3.0 years; girls, 3.2 years), ranging from 1.1 years to 6.3 years. No increase in the degree of slippage occurred; there were no perioperative complications, and avascular necrosis and chondrolysis were not apparent. In all 29 hips, no growth disturbance, including greater trochanteric overgrowth, coxa brevis, or coxa vara, was seen. According to the clinical criteria of Heyman and Herndon, 26 hips were rated either excellent or good, and two were rated fair. One was rated poor because of the presence of slight pain after strenuous exercise. The technique of dynamic screw fixation provides sufficient immediate and long-term fixation, does not promote premature physeal closure, and permits normal hip development.