The modified Dunn procedure for slipped capital femoral epiphysis does not reduce the length of the femoral neck

Objective: The treatment of slipped capital femoral epiphysis (SCFE) is evolving, with the development of new surgical techniques. We wanted to study if modified Dunn procedure restores the normal alignment of the proximal femur and the risk of avascular necrosis is increased. Methods: This is a single centre, retrospective study, comparing the outcomes of in situ pinning and modified Dunn procedure. Between 2001 and 2014, 7 children (7 hips) underwent the modified Dunn procedure and 10 children (10 hips) pinning in situ for stable and unstable SCFE. Mean age of the patients was 12.7 years with a median follow-up of 18 months. Results: The radiological parameters improved in the modified Dunn procedure group, while the length of the femoral neck didn’t change significantly (p=0.09). Postoperative clinical outcomes were slightly better in the modified Dunn procedure group (6 hips out of 7 had good and excellent results) compared to the pinning in situ group (8 good and excellent results out of 10 hips) (p=0.04). No avascular necrosis was found and there were no cases of chondrolysis. Conclusion: Radiographic parameters of the proximal femur assessed in our study improved in all hips that underwent modified Dunn procedure, without the creation of secondary deformities.