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Coxa vara is a deformity of the proximal femur in which the femoral neck-shaft angle is reduced to less than 120° (normal: ~125°–135°), resulting in limb shortening, altered biomechanics, and gait abnormalities.
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Comparison: Coxa Valga vs Coxa Vara
| Feature | ‣ | Coxa vara |
|---|---|---|
| Neck–shaft angle | >135° | <120° |
| Leg length | Apparent lengthening | Apparent shortening |
| Common causes | Neuromuscular disorders, DDH | Rickets, trauma, fibrous dysplasia |
| Clinical gait | Waddling gait, Trendelenburg | Antalgic or Trendelenburg gait |
| Surgical correction | Varus osteotomy | Valgus osteotomy |
| Type | Description | Etiology |
|---|---|---|
| Congenital coxa vara | Present at birth | Developmental failure of medial femoral neck ossification |
| Developmental coxa vara | Arises in early childhood; idiopathic or associated with skeletal dysplasias | May relate to mechanical stress or physeal abnormalities |
| Acquired coxa vara | Due to trauma, infection, rickets, or bone disorders | - Trauma (e.g., proximal femoral fracture) |
| Feature | Description |
|---|---|
| Limping | Trendelenburg or antalgic gait |
| Hip pain | Especially during activity or prolonged standing |
| Limited hip motion | Particularly abduction and internal rotation |
| Leg length discrepancy | Shortening of affected limb |
| Waddling gait | In bilateral cases |
| Complication | Description |
|---|---|
| Progressive deformity | Worsening varus, gait dysfunction |
| Hip instability | Due to disrupted biomechanics |
| Secondary osteoarthritis | Joint malalignment → early degenerative changes |
| Limb length discrepancy | Shortening due to vertical neck orientation |
Plain Radiography: AP pelvis + frog-leg lateral
| Finding | Description |
|---|---|
| Neck-shaft angle <120° | Diagnostic of coxa vara |
| Inverted Y or “shepherd’s crook” deformity | Seen in progressive cases, especially fibrous dysplasia |
| Vertical physis | Sloping proximal femoral growth plate |
| Shortened femoral neck | Broad and thickened appearance |
| Triangular fragment | Seen at inferior femoral neck in congenital cases (Fairbank’s triangle) |
Measurement indices:
| Angle | Normal Value | Significance |
|---|---|---|
| Neck–shaft angle | 125–135° | <120° indicates coxa vara |
| Hilgenreiner epiphyseal (HE) angle | <25° | >60° indicates severe deformity |