# Congenital Coxa Vara

> Congenital coxa vara with neck-shaft angle, Hilgenreiner-epiphyseal angle, inverted-V defect and valgus osteotomy criteria for NEET-PG Orthopaedics.

- Canonical URL: https://prepelephant.com/topics/neet-pg/orthopaedics/congenital-coxa-vara
- Exam / course: NEET-PG · Subject: Orthopaedics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Campbell's Operative Orthopaedics; Maheshwari's Essential Orthopaedics
- How to cite: "Congenital Coxa Vara", PrepElephant, https://prepelephant.com/topics/neet-pg/orthopaedics/congenital-coxa-vara

## Direct answer

Congenital coxa vara is a developmental deformity of the proximal femur in which the neck-shaft angle is reduced, usually to below about 120 degrees, producing a varus and often shortened limb. The radiological clues are a widened Hilgenreiner-epiphyseal angle and an inverted-V defect, a radiolucent area with a triangular metaphyseal fragment in the inferomedial femoral neck. It presents as a limp or short limb, and a valgus osteotomy is needed when the deformity progresses.

## What you must remember

- **Neck-shaft angle:** about 150 degrees at birth, falling to roughly 125 degrees in adults; congenital coxa vara is a reduced angle well below the age-appropriate norm.
- **Hilgenreiner-epiphyseal angle:** measured between the Hilgenreiner line and a line along the physis; a widened angle signals a more severe deformity.
- **Inverted-V defect:** an inverted-Y radiolucent area in the inferomedial femoral neck, with a triangular metaphyseal fragment, associated with a poorer prognosis.
- **Presentation:** a limp, a short limb, a waddling gait and an abductor lurch, noticed in early childhood.
- **Associations:** fibrous dysplasia, including the McCune-Albright pattern, and cleidocranial dysplasia are recognised causes of a varus proximal femur.
- **Valgus osteotomy:** the standard correction for a progressive or functionally limiting deformity, aiming to restore the neck-shaft angle and the mechanical axis.
- **Differentials:** developmental dysplasia of the hip, Perthes disease and slipped capital femoral epiphysis must be excluded before the diagnosis is accepted.

## Measuring the deformity and choosing when to operate

A two-year-old presents with a short, varus limb and a waddling gait, and the pelvis radiograph shows a low neck-shaft angle. The steps below turn these measurements into a decision about surgery.

1. **Confirm the angle:** an anteroposterior pelvis radiograph measures the neck-shaft angle on each side, and an angle well below the age norm, sustained over serial films, establishes coxa vara.
2. **Measure the Hilgenreiner-epiphyseal angle:** draw the Hilgenreiner line through the triradiate cartilages and a line along the physis of the affected femur; a widened angle indicates a more severe deformity.
3. **Look for the inverted-V defect:** an inverted-Y radiolucency at the inferomedial neck suggests a poorer prognosis and supports the congenital diagnosis.
4. **Assess function:** a limp, limb shortening, abductor weakness on examination and serial radiographs showing progressive varus define whether the deformity is limiting.
5. **Plan a valgus osteotomy:** when the deformity is progressive or functionally limiting, a valgus intertrochanteric osteotomy is planned to restore the neck-shaft angle and the mechanical axis.
6. **Follow the hip after correction:** serial review checks for recurrence, leg-length change and complications such as nonunion or avascular necrosis.

## Where the exam tries to catch you

Examiners test the measurements, the prognostic signs and the reason an osteotomy is needed.

- **Trap:** calling every low neck-shaft angle congenital coxa vara. — **Correct:** the angle must be read against age-based norms, and coxa vara has to be separated from Perthes disease, dysplasia of the hip and skeletal causes.
- **Trap:** operating on a mild, stable varus. — **Correct:** observation is reasonable when the deformity is not progressing, with surgery reserved for progressive or functionally limiting cases.
- **Trap:** ignoring fibrous dysplasia in a varus hip. — **Correct:** fibrous dysplasia is a recognised cause of coxa vara and must be excluded before the diagnosis of congenital deformity is accepted.

## Frequently asked questions

### What is the normal neck-shaft angle at different ages?

The femoral neck-shaft angle is about 150 degrees at birth and gradually falls to roughly 125 degrees in adulthood. Congenital coxa vara is diagnosed when the neck-shaft angle is reduced well below the age-appropriate norm, typically below about 120 degrees.

### Which radiological signs predict a poor outcome in congenital coxa vara?

The Hilgenreiner-epiphyseal angle and the inverted-V defect are the main radiological predictors of outcome in congenital coxa vara. A widened Hilgenreiner-epiphyseal angle and an inverted-Y radiolucent defect in the femoral neck both indicate a more severe and progressive deformity.

### When is valgus osteotomy indicated in congenital coxa vara?

Valgus osteotomy is indicated in congenital coxa vara when the varus deformity is progressive, causes a limp or significant limb shortening, or is unlikely to remodel. Criteria and timing differ between textbooks, so the decision is individualised to the child's radiographs and function.

### Which conditions must be excluded in a child with a varus hip?

Developmental dysplasia of the hip, Perthes disease, slipped capital femoral epiphysis, fibrous dysplasia and skeletal dysplasias must be excluded in a child with a varus hip. Congenital coxa vara is therefore a diagnosis confirmed only after these differentials are considered on the radiographs.