Modified Dunn procedure versus percutaneous pinning in moderate/severe stable slipped capital femoral epiphyses.

BACKGROUND The modified Dunn procedure (MDP) has risen enthusiasm in treating slipped capital femoral epiphyses (SCFE) due to the anatomic reduction and high patients' satisfaction rates at long-term follow-up. Main aim of this study is to compare clinical and radiographic outcomes of 2 cohorts with moderate to severe stable SCFE treated by MDP and in situ fixation. METHODS Medical records were analysed to collect demographic data, comorbidities and time from slip to surgery. The collected postoperative data were: avascular necrosis (AVN); complications; progression of osteoarthritis and subsequent procedures. Southwick angles (SA), alpha angles and Klein line were measured on the preoperative x-rays, on the immediate postoperative period and at the latest follow-up. Outcomes scores were recorded by the following questionnaires: the Harris Hip Score, the Hip disability and Osteoarthritis Outcome Score, the Merle d'Aubigne and Postel score and the Western Ontario and McMaster Universities Arthritis Index. Kaplan-Meier survivorship curve was calculated. RESULTS We compared 81 hips treated by MDP with 22 hips treated by in situ pinning (PS) for moderate/severe stable SCFE. No significant differences were found between the 2 groups in terms of age, BMI, comorbidities and preoperative slip angles. At the latest follow-up, postoperative anteroposterior mean slip angles were respectively 6.2 and 19.9° in MDP and PS group (p = 0.3). Slip angles in frog lateral view were 11° in the MDP group and 39.7° in the PS group (p = 0.2). MDP group achieved better correction angles on frog leg view (11° vs. 39.7°; p < 0.001). There was no statistically significant difference in the occurrence of AVN among both groups (19.7% MDP group vs. 31.8% PS group) (p = 0.2). CONCLUSIONS The MDP in treating severe stable SCFE showed the best deformities corrections in conjunction with the highest functional scores at long-term follow-up and similar rates of osteonecrosis compared to in situ fixation.