Genu Valgum (Pediatric)

INTRODUCTION

Definition

Condition in which the knees angle in and touch each other when the legs are straightened. Might be uni- och bilateral. 

Epidemiology

Bilateral angular deformity is common and is most often physiologic.

Physiology

  • Normal knee alignment progresses from 10-15° of varus at birth to maximal valgus angulation of up to 20° at age of 3-4 years. Genu valgum should not increase after 7 years of age. After age 7 years, valgus should not exceed 12°, and the intermalleolar distance should be less than 8 cm.
  • Neutral femoral-tibial alignment occurs at 12-14 months old.

Pathoanatomy

The deformity is usually localized in the distal femur but it may also arise in the proximal tibia.

Etiology

Bilateral
  • Physiologic genu valgum (most often)
  • Rickets, renal osteodystrophy
  • Skeletal dysplasia: E.g. chondroctodermal dysplasia, spondyloepiphyseal, Morquio syndrome
Unilateral: Bilateral genu valgum often occurs from pathological conditions.
  • Physeal injury (trauma, infection, or vascular)
  • Proximal tibial metaphyseal (Cozen) fracture
  • Benign tumors: E.g. fibrous dysplasia, Ollier disease, osteochondroma

CLINICAL FEATURES

Symptoms

The child usually doesn’t have any symptoms.

DIAGNOSIS

X-ray

Will show the genu valgum. 

TREATMENT

Overview

Pathologic genu valgum should generally be treated with surgery. Patients within this physiologic range do not require treatment.

Nonoperative Treatment

Orthotics/bracing is not effective in genu valgum. If genu valgum occurs after proximal tibial metaphyseal fracture (Cozen phenomenon) it will typically remodel spontaneously and should be observed.

Operative Treatment

Indication: If the mechanical axis falls in the outer quadrant of the tibial plateau (or beyond) in children older than 10 years, i.e. in children older than 10 years with > 10 cm between the medial malleoli or > 15° of valgus angulation. 
  • Mechanical axis is represented by a line drawn from the center of the femoral head to the center of the distal tibial plafond.
Method:
  • Hemiepiphysiodesis or temporary physeal tethering with staples, transphyseal screws, or plate/screw devices of the medial side is effective before the end of growth for severe deformities.
  • Varus-producing osteotomies could be necessary when insufficient growth remains or the site of the deformity is away from the physis. 

Table of Contents

1. Miller, M. and Thompson, S. (2016). Miller’s review of orthopaedics. 7th ed. Philadelphia, PA: Elsevier.
2. Boyer, M. (2014). AAOS comprehensive orthopaedic review 2. 2nd ed. Rosemont: American Academy of Orthopaedic Surgeons.