June 20, 2024

Congenital coxa vara is a condition seen in a child when the neck-shaft angle of the proximal femur is below 110°

Pathology

Due to defect in disturbance in endochondral ossification and growth originating in the medial part of proximal femur epiphysis plate

Increases shear force on physis due to decrease in the neck-shaft angle which causes lower limb proximally shortened

Vertically displaced epiphysis plate is medial to the defect in osteoporotic with a triangular piece of bone separated from the inferior aspect of neck: Fairbanks triangle

Features of Congenital coxa vara

Congenital coxa vara radiology
Features of congenital coxa vara

Verticle epiphysis plate

Inverted V shape defect

Short femoral neck

Decrease Neck-shaft Angle

Etiology

Unknown

Postulates

  1. The primary defect in the femoral Neck ( endochondral ossification defect in the inferior femoral neck)
  2. Vascular insult during the intrauterine period

Classifications

Congenital Coxa-vara

Developmental Coxa-vara (detected while child begins to walk)

Acquired Coxa-vara

The child presents with a Painless limb

Waddling gait in Bilateral cases

Short limb and weak hip abductors

Physical signs

GT elevated

Trendelenburg test (+)

Limb shortened by >2.5 cm

ROM is restricted in Internal rotation and Abduction

See also: Gait analysis

X-ray features

Neck shaft angle <110°

Inverted V defect in femoral neck

Osteoporotic metaphysic with Fairbanks triangle

The shallow and deformed acetabulum

Short neck, concave inferior border forming down hanging lip

Head, epiphyseal cartilage and triangular fragment seems slipping

GT- beak-shaped, over grows proximally and touches acetabulum.

Developmental coxa-vara vs congenital coxa-vara

Absent in developmental coxa-vara:

  • The short femur (shortening is a 1° defect)
  • Thickening of calcar in the femoral shaft with hypoplastic or absent Lesser trochanter

Classification

Hilgenreiner’s epiphyseal (HE) angle

Hilgenreiner’s epiphyseal (HE) angle
Hilgenreiner’s epiphyseal (HE) angle

HE angle > 60° and gradually increasing then the progression of coxa vara can be anticipated

HE angle < 60° but >45° Gray Zone , should be observed

HE angle < 45° which signifies that gradually corrects spontaneously without operative intervention

Treatment

Goals

  • Restore Neck – Shaft angle (around 140°)
  • Reduce shortening
  • Reduce abductor lurch

Mainly surgical

  • Conservative treatment has little or no value
  • If left untreated:- pseudoarthosis develops at defect

Indications

  • HE angle >45-60°
  • Progressively decreasing proximal femoral shaft angle or equal / less than 90-100°

Osteotomies types

1. Subtrochanteric Valgus Osteotomy

Subtrochanteric Valgus Osteotomy
Subtrochanteric Valgus Osteotomy
  • A small wedge is removed from proximal fragment and osteotomy fixed with plates/pins fixation
  • Restore Neck-shaft angle
  • Provides Virtual lengthening to limb
  • Disadvantages includes: premature epiphyseal closure in majority even without direct physeal injury

2. Pauwel devised Y-shaped Intertrochanteric osteotomy

  • Closing wedge composed of  Y
Dickson’s geometric osteotomy
Pauwel devised Y-shaped Intertrochanteric osteotomy

3. Dickson’s geometric osteotomy

  • Changes femoral alignment, places vertical defect into a horizontal position and abducted shaft of the femur, it supports the head and increases the length
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