Abstract

Developmental coxa vara (DCV) is a rare paediatric hip deformity characterized by a progressive reduction in the femoral neck-shaft angle (NSA) and marked verticalization of the proximal femoral physis. Accurately differentiating DCV from traumatic physeal injuries or neglected femoral neck fractures is critical in toddlers presenting with an isolated, unilateral limp to avoid irreversible bio-mechanical failure. We present the case of a 3-yearold female who presented with a four-month history of a painless limp and 1.5 cm of left lower limb shortening. Radiographic evaluation revealed a reduced left femoral neck-shaft angle and a pathognomonic Hilgenreiner-Epiphyseal (H-E) angle of 86°, accompanied by a characteristic inverted Y-shaped radio-lucency and an inferior-medial triangular bone fragment. The absolute absence of trauma combined with these distinct, chronic structural changes definitively excluded an acute or neglected fracture mal-union. Given that an H-E angle of 86° represents extreme biomechanical shear instability; representing abnormal abductor mechanism. This serves as an absolute indication for surgical correction via valgus proximal femoral osteotomy to restore tension to the abductor mechanism, improve hip stability, and prevent progressive limb shortening and early joint degeneration.

Keywords

developmental coxa vara, femoral neck-shaft angle, hilgenreiner-epiphyseal angle, growth plate, vertical physis, abductor mechanism, limb length discrepancy