summary Developmental Coxa Vara is a rare condition that causes a decreased neck-shaft angle that is associated with an ossification defect in inferior femoral neck. Diagnosis can be confirmed with plain radiographs of the hip. Treatment can be nonoperative or surgical corrective valgus derotation osteotomy depending on patient symptoms, the severity of varus deformity, and degree of angle progression. Epidemiology Incidence 1 in 25,000 live births in the US Demographics males and females affected equally presents between age of ambulation and 6 years of age Anatomic location bilateral in 1 in 3 cases Risk factors congenital defects differential diagnosis trauma SCFE Legg-Calve-Perthes Etiology Pathophysiology proximal femoral cartilaginous physis or ossification center defects lead to decreased proximal femoral neck-shaft angle vertical position of the proximal femoral physis and varus pathomechanics coxa vara and vertical physis increases physeal sheering forces inferior medial neck compressive forces Genetics no clear inheritance pattern Associated conditions femoral neck stress fractures decreased limb length early hip osteoarthritis Classification Etiologies of Coxa Vara developmental congenital (e.g. congenital short femur, PFFD) acquired (e.g. SCFE, infection, Perthes) dysplasia (e.g OI, Jansen, Schmid, SED) cretinism Presentation History previous hip trauma or infection associated skeletal abnormalities prenatal and developmental history family history of similar deformity Symptoms usually painless gait abnormality waddling or limp (trendelenburg gait) caused by abductor weakness from tension abnormality Physical exam inspection leg length discrepancy high riding greater trochanter limb shortening excessive lumbar lordosis motion restricted hip range of motion in all planes that is usually non-tender Imaging Radiographs recommended views: AP hip with limb internally rotated + lateral hip findings varus neck shaft angle <120 degrees short femoral neck, vertical physis increased Hilgenreiner's epiphyseal angle (normal <25 degrees) determined on AP as angle between Hilgenreiner's line and a line through the proximal femoral physis triangular metaphyseal fragment in inferior femoral neck (looks like inverted-Y radiolucency) decreased femoral anteversion CT indications surgical planning delineate proximal femur defects orientation of deformity views consider all views including 3D reconstructions findings deformity configuration bone stock physeal widening Treatment Nonoperative observation alone indications Hilgenreiner-ephyseal angle (normal <25 degrees) <45 degrees – unlikely to progress 45-60 – may progress will require close follow-up if non-symptomatic Operative corrective valgus derotation osteotomy (VDRO) indications Hilgenreiner's physeal angle > 60° Hilgenreiner's physeal angle between 45-60° if symptomatic (e.g. limp & progression of varus) progressive decrease in neck shaft angle < 110 ° aftercare hip-spica or abduction pillow x 4-6 weeks depending on fixation and healing Technique Corrective valgus derotation osteotomy (VDRO) goals over-correct neck shaft angle (literature suggests to reduce Hilgenreiner's physeal angle < 38°) correct leg length discrepancy correct hip anteversion/retroversion re-establish abductor muscle tensioning approach typically a hip direct lateral approach is used procedure(s) valgus trochanteric osteotomy – may fix with blade plate supine with bump perform adductor tenotomy direct lateral approach valgus osteotomy as template overcorrect to place physis in horizontal position (to decrease shear stress) derotation to antevert neck as neck hip cast post-op for 6 weeks greater trochanter epiphyseodesis to prevent GT overgrowth in vascular coxa vara lateral approach fluoro to determine position of physis curette or drill physis greater trochanter transfer lateral approach free GT fragment of soft tissues transfer distal and lateral freshen lateral femoral recipient bed cortex with osteotomy place GT fragment so that tip is at level of femoral head Complications Loss of correction Premature closure of the proximal femoral physis Overgrowth of proximal femur Dysplasia of acetabulum