SN2 SHORT NOTE 5M

Describe Genu Varum & Genu Valgum in detail.

General Surgery · Final Professional

Definitions

Genu varum (‘bow legs’) is outward bowing of the legs so the knees are apart when the ankles touch; genu valgum (‘knock knees’) is the opposite — the knees touch and the ankles are apart. Both are often physiological and part of normal development, but may occasionally be pathological.

Physiological Development

There is a normal, well-recognised sequence: infants are mildly bow-legged (varum) up to about 2 years, swing to knock-knees (valgum) that is maximal around 3–4 years, and then settle to the adult alignment by about 6–7 years. This physiological pattern is symmetrical, painless and resolves spontaneously, needing only reassurance and observation.

DANGER / REMEMBER

Suspect a pathological cause if the deformity is severe, progressive, asymmetrical, painful, outside the expected age range, or associated with short stature. Causes include rickets, Blount’s disease (tibia vara), skeletal dysplasias, and physeal injury.

Assessment & Management

Measure the intercondylar (in varum) or intermalleolar (in valgum) distance and observe over time; investigate atypical cases (radiographs, and biochemistry for rickets). Physiological deformity needs only reassurance; pathological deformity is treated by addressing the underlying cause and, if severe or persistent, by guided growth (hemiepiphysiodesis) or corrective osteotomy.

Blount’s Disease

Blount’s disease (tibia vara) is an important pathological cause of genu varum: a growth disorder of the posteromedial proximal tibial physis producing a sharp, progressive varus angulation localised to the upper tibia (unlike the smooth, generalised bowing of physiological varum). It occurs in an infantile form (often bilateral, associated with early walking and obesity) and an adolescent form, and is confirmed radiographically by the abnormal medial physis and metaphyseal beaking. Treatment is by bracing in early cases and guided growth or osteotomy for progressive deformity.

CLINICAL PEARL

The reassuring rule: symmetrical, painless bowing or knock-knee that fits the normal age pattern needs only observation; asymmetry, pain, progression, short stature or deformity outside the expected age demands investigation for rickets, Blount’s disease or a dysplasia.

Physiological variation follows a predictable age pattern.

KEY POINT

Key points TO remember

Varum = bow legs (knees apart); valgum = knock knees (ankles apart).
Normal sequence: varum <2 y → valgum ~3–4 y → adult alignment by ~7 y.
Red flags: severe, progressive, asymmetrical, painful, short stature.
Pathological causes: rickets, Blount’s disease, dysplasias; treat cause ± guided growth/osteotomy.

EXAM TIP

Sources: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.

All questions in Paediatric Orthopaedics

Every General Surgery chapter →