The anatomical reduction of a moderate or severe stable slipped capital femoral epiphysis by modified Dunn subcapital osteotomy using the Ganz approach FUNCTIONAL AND RADIOLOGICAL OUTCOMES

Aims This study analysed the clinical and radiological outcome of anatomical reduction of a moderate or severe stable slipped capital femoral epiphysis (SCFE) treated by subcapital osteotomy (a modified Dunn osteotomy) through the surgical approach described by Ganz. Patients and Methods We prospectively studied 31 patients (32 hips; 16 females and five males; mean age 14.3 years) with SCFE. On the Southwick classification, ten were of moderate severity (head shaft angle > 30 degrees to 60 degrees) and 22 were severe (head-shaft angle > 60 degrees). Each underwent open reduction and internal fixation using an intracapsular osteotomy through the physeal growth plate after safe surgical hip dislocation. Unlike the conventional procedure, 25 hips did not need an osteotomy of the apophysis of the great trochanter and were managed using an extended retinacular posterior flap. Results Clinical outcome was assessed using the range of movement and the Harris Hip (HHS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC), and Merle d'Aubigne scores, while radiological measurements included slip and alpha angles. The mean duration of follow-up was 24.1 months (12 to 40). There was a significant improvement in all clinical and radiological measurements after treatment (p < 0.001). Post-operative major complications were one deep infection and one case of femoral head collapse. Conclusion These findings suggest that a modified Dunn osteotomy carried out through Ganz approach is a safe and effective method of treating the stable SCFE with a high degree of slip.