Capital Realignment for Moderate and Severe SCFE Using a Modified Dunn Procedure

Abstract

Moderate to severe slipped capital femoral epiphysis leads to premature osteoarthritis resulting from femoroacetabular impingement. We believe surgical correction at the site of deformity through capital reorientation is the best procedure to fully correct the deformity but has traditionally been associated with high rates of osteonecrosis. We describe a modified capital reorientation procedure performed through a surgical dislocation approach. We followed 40 patients for a minimum of 1 year and 3 years from two institutions. No patient developed osteonecrosis or chondrolysis. Slip angle was corrected to 4°to 8°and the mean alpha angle after correction was 40.6°. Articular cartilage damage, full-thickness loss, and delamination were observed at the time of surgery, especially in the stable slips. This technique appears to have an acceptable complication rate and appears reproducible for full correction of moderate to severe slipped capital femoral epiphyses with open physes.

Hip impingement in slipped capital femoral epiphysis: A changing perspective

“…Although common in severe slips, this can be seen in mild slips as well [20][21][22]. In addition, posteromedial callus formation, as a part of the chronic reactive healing process of SCFE, places tension on the posterosuperior retinaculum, which contains the blood supply to the femoral head, complicating potential corrective surgical options [12,13,22].…”

“…As a result, this technique has been modified and combined with an open surgical dislocation approach with a greater focus on protecting the blood supply to the epiphysis via developing an extended posterosuperior retinacular flap with subperiosteal exposure of the femur [12,22]. The combination of this Dunn osteotomy with the open surgical dislocation approach has been coined the ''modified'' Dunn procedure by Ganz [12].…”

“…The combination of this Dunn osteotomy with the open surgical dislocation approach has been coined the ''modified'' Dunn procedure by Ganz [12].…”

“…Ziebarth et al [12] reported their results utilizing the modified Dunn procedure in 40 patients with no cases of AVN. Slongo et al reported on 23 cases treated with the modified Dunn procedure and reported two cases with either AVN or severe osteoarthritis [47].…”

Is Assessment of Femoral Head Perfusion During Modified Dunn for Unstable Slipped Capital Femoral Epiphysis an Accurate Indicator of Osteonecrosis?

“…One of the benefits of the subcapital realignment through the surgical dislocation approach (modified Dunn procedure) is visualization and protection of the vascular retinaculum and direct assessment of perfusion of the femoral head during surgery. Femoral head perfusion may be assessed by evaluating bleeding after creating a 2-mm drill hole [9,24,30,31], by laser-Doppler flowmetry [9,30], and/or by intracranial pressure probe monitoring [24]. Assessment of perfusion during surgery may allow for adjustments of positioning the femoral head if blood flow decreases after the femoral head is reduced.…”