Technique of subtrochanteric osteotomy in the surgical management of coxa vara: a novel approach using customized L-plate fixation and biomechanical optimization

BACKGROUND: Developmental coxa vara (DCV) is a rare pediatric deformity caused by defective endochondral ossification of the medial femoral neck, leading to progressive varus angulation, abductor insufficiency, limb-length discrepancy, and gait disturbance. Valgus-producing proximal femoral osteotomy remains the standard surgical intervention; however, debate persists regarding osteotomy level, fixation method, and optimal postoperative management. The aim of this article is to present and evaluate a subtrochanteric valgus osteotomy technique using a customized anatomically contoured L-shaped locking buttress plate, with emphasis on construct stability, reproducibility, and the feasibility of spica-free postoperative management.METHODS: Eighteen consecutive patients (18 hips) with unilateral DCV, diagnosed based on clinical findings and radiographic criteria (femoral neck-shaft angle <110° and Hilgenreiner epiphyseal angle >45°), were prospectively enrolled between January 2020 and December 2023. All patients underwent subtrochanteric closing-wedge osteotomy stabilized with a custom-designed L-shaped plate (UZ Patent FAP No. 00349). Pre- and postoperative radiographic parameters (neck-shaft angle, Hilgenreiner epiphyseal angle, limb-length discrepancy) and functional outcomes (modified Larson Hip Score) were assessed at standardized intervals up to 24-36 months.RESULTS: Radiographic correction was achieved and maintained throughout follow-up. Mean neck-shaft angle improved from 93.7±5.2° preoperatively to 129.9±3.8° at final follow-up (P<0.001). Hilgenreiner epiphyseal angle decreased from 78.2±6.3° to 27.8±3.1° (P<0.001). All osteotomies healed within a mean of 2.4 months, with no cases of nonunion, implant failure, or recurrence. Functional outcomes improved from a mean score of 57.8±4.3 to 97.0±2.8. No patient required hip spica immobilization.CONCLUSIONS: Subtrochanteric valgus osteotomy using a custom L-shaped locking plate provided stable fixation, reliable deformity correction, and favorable functional results in this cohort. These early and midterm outcomes are encouraging; however, given the lack of a control group and limited follow-up duration, further comparative and biomechanical studies are needed to determine the relative advantages and long-term efficacy of this technique.

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