Is Subcapital Realignment for Slipped Capital Femoral Epiphysis a Reproducible Technique? Midterm Results

Area of Science:

• Orthopedic Surgery
• Pediatric Orthopedics
• Skeletal Dysplasias

Background:

• The modified Dunn procedure with an extended retinacular flap aims for anatomic reestablishment in moderate to severe slipped capital femoral epiphysis (SCFE).
• Concerns persist regarding the risk of avascular necrosis (AVN) and other complications associated with this surgical technique.

Purpose of the Study:

• To determine the incidence of symptomatic AVN and other complications after the modified Dunn procedure for moderate to severe SCFE.
• To assess the achieved femoral head-neck alignment and position relative to the greater trochanter.
• To evaluate for radiographic signs of osteoarthritis at a minimum of 4 years post-surgery.

Main Methods:

• Retrospective analysis of 33 patients (33 hips) treated with the modified Dunn procedure for SCFE (slip angle ≥ 30°) between 2006 and 2018.
• Median follow-up of 80 months; additional procedures (periacetabular or femoral osteotomy) were performed in 33% of patients.
• Assessment of symptomatic AVN, further surgeries, complications, and radiographic parameters including osteoarthritis signs.

Main Results:

• Only 3% (1 patient) developed symptomatic AVN and required further surgery; another 3% underwent revision for screw breakage.
• Postoperative restoration of hip morphology was achieved, with normalized alpha angle, anterior head-neck offset, and neck-shaft angle.
• No radiographic signs of osteoarthritis were detected at the minimum 4-year follow-up.

Conclusions:

• The modified Dunn procedure is a reproducible technique for moderate to severe SCFE, yielding few symptomatic AVN cases and complications.
• The procedure successfully restores hip morphology.
• Longer follow-up and multi-center data are needed to fully assess long-term risks of AVN and osteoarthritis progression.