Modified Dunn Technique for Unstable Slipped Capital Femoral Epiphysis: A Midterm Single Center Experience.

To evaluate the safety and reproducibility of the surgery for unstable slipped capital femoral epiphysis (SCFE) through the modified Dunn technique in a single center cohort from Brazil.  We retrospectively analyzed a cohort of patients submitted to this procedure by a single surgeon who was a hip preservation specialist. Demographic data and radiographic angles were evaluated for the relative risk (RR) of avascular necrosis (AVN) using a log-binomial regression model with simple and random effects.  Among the 30 patients (30 hips) with a mean age of 11.79 years at the time of the operation, there were 17 boys and 18 left hips, which were operated on in a mean of 11.5 days after the slip. The mean follow-up was of 38 months. The preoperative Southwick angle averaged 60.69° against 4.52° postoperatively (  < 0.001). A larger preoperative slip angle was associated with the development of AVN (RR: 1.05; 95% confidence interval [95%CI]: 1.02-1.07;  < 0.01). The overall AVN rate was of 26.7%. Function was good or excellent in 86% of uncomplicated hips, and poor in 87.5% of the partients who developed AVN, as graded by the Harris Hip Score. There was no statistical relationship between epiphyseal bleeding and AVN development (  = 0.82).  The modified Dunn technique is associated with restoration of the femoral alignment and function after unstable SCFE, when uncomplicated. Moreover, it was shown to be reproducible in our population, with a rate of 26% of femoral head necrosis.