Mid-term outcomes of the modified Dunn procedure for slipped capital femoral epiphysis: results from a north African pediatric hip unit

Background: Slipped Capital Femoral Epiphysis (SCFE) is a prevalent pediatric orthopedic condition. Treatment options range from in situ pinning to various osteotomies, with the Modified Dunn procedure gaining significant attention over the past two decades. However, the suitability of this procedure for different SCFE subtypes and the risk of avascular necrosis (AVN), particularly in moderate and severe cases, remains controversial. This study aims to report the midterm clinical and radiographic outcomes of the Modified Dunn procedure in treating SCFE, emphasizing the factors contributing to AVN development.

Patients and methods: We conducted a prospective case series between 2014 and 2022, enrolling patients with moderate and severe SCFE who were treated using the Modified Dunn procedure by a single experienced hip surgeon. Patients were followed up clinically and radiologically for a minimum of two years.

Results: Thirty-six patients (29 males, 7 females) with moderate and severe SCFE were included, with an average age of 14 years and a mean follow-up of 49.28 months (range: 24-118 months). Statistically significant improvements were observed in clinical and radiographic parameters at the final follow-up compared to pre-operative data. Five patients developed AVN, though no specific risk factor reached statistical significance regarding AVN development. While most AVN cases occurred early in the learning curve, this trend was not statistically significant.

Conclusion: Modified Dunn is a safe and effective option for treating moderate to severe SCFE, offering superior femoral head realignment and patient-reported outcomes. When performed by experienced surgeons, it results in acceptable complication rates, including AVN.

Level of evidence: Level IV Prospective Case series.