Is there a role for controlled repositioning and mini-open primary osteoplasty in the management of unstable slipped capital femoral epiphysis?

Abstract

The management of unstable slipped capital femoral epiphysis is controversial with variable rates of avascular necrosis (AVN). Treatment options include in-situ stabilization, gentle/positional reduction and screw fixation and modified Dunn's procedure (MDP). We present a technique of controlled repositioning (CRP) of the epiphysis to pre-acute slip stage, screw fixation and primary osteoplasty. Between 2015 and 2020, 38 unstable slips were treated in our institution. Of these, 14 underwent successful CRP and the rest were treated with MDP. All the 14 patients who had CRP and completed 1-year follow-up were included for this study. The head-neck angle (HNA) was measured at presentation and alpha angle, head-neck offset and AVN were assessed during follow-up. The average age was 14 years (9-18) and mean follow-up was 17.7 months (12-43). The average intraoperative flexion internal rotation before osteoplasty was -18.5° (-40° to -5°) which improved to +22.1° (+15° to +30°). The average preoperative HNA was 48.7° (34.1° to 70.7°) which improved to 18.4° (1.8° to 35.7°) post-operatively. At final follow-up, the average alpha angle and head-neck offset were 46.4° (30.9° to 64.6°) and 0.22 (0.09 to 0.96), respectively. The AVN rate in the CRP group was 7.1% compared with 20.8% in the MDP group, which was not significant (P = 0.383). Two patients had screw breakage. CRP, screw fixation and mini-open primary osteoplasty is a feasible treatment option in a subgroup of patients with unstable SCFEs. The limitation with this technique is that the final decision is made intraoperatively, and hence the patient and parents need to be counselled and consented appropriately. Level of evidence: Level IV-Case series.

Fig. 1.

Institutional treatment flow chart for unstable SCFEs.

Fig. 2.

The rationale of controlled repositioning and osteoplasty for unstable SCFEs. (A) Pictorial representation of a mild stable SCFE with new bone formation on the posterior aspect. (B) Diagrammatic representation of an acute-on-chronic unstable SCFE. (C) Pictorial representation of CRP, screw fixation and primary osteoplasty.

Fig. 3.

(A) Patient positioned on a radiolucent table; note the external rotation position of the left lower limb. (B, C) Image intensifier view of the affected hip in anteroposterior and cross-table lateral projection showing severe slip. (D) The clinical picture following controlled repositioning (CRP). Note the neutral position of the limb with the patella and foot pointing upwards. (E) Image intensifier view of the affected hip in cross-table lateral projection after CRP showing mild slip. The residual slip, potential to cause impingement, is marked with a black dotted line. (F) Image intensifier view of the affected hip in cross-table lateral projection after screw fixation and anterior osteoplasty, AP view shown in the inset.

Fig. 4.

(A) Intraoperative picture showing the exposure of hip through Heuter approach. (B) Closer look at the head–neck junction showing the torn anterior retinacular flap and the prominent metaphysis off the epiphysis. (C) Intraoperative picture after osteoplasty showing the head–neck offset.

Fig. 5.

(A) Measurement of α-angle in the frog-leg lateral view (40° in this example). (B) Measurement of the head–neck offset in the lateral view.

Fig. 6.

(A) Radiograph of the pelvis with both hips in AP projection showing an acute SCFE on the right hip. (B) AP view of the right hip in AP projection at 12 months follow-up following CRP and osteoplasty showing normal hip joint with no evidence of AVN. (C) Frog-leg lateral view of the pelvis with both hips at 12 months follow-up following CRP and osteoplasty showing α-angle of 31.7° and head–neck offset ratio of 0.15.