Lower Limb Developmental Problems

See also childhood hip disorders (DDH — covered there, not duplicated here).

Bow legs (genu varum)

Outward bowing — intercondylar separation (ICS) >4 cm. Mostly physiological — toddlers are normally bow-legged until age 3; must be symmetrical for this to apply.

• Consider rickets if: recent immigrant, calcium-poor diet, low sun exposure, maternal vitamin D deficiency in pregnancy, dark skin. Rickets presents with limb pain and fractures alongside the bowing, from vitamin D deficiency, severe renal impairment, or hypophosphataemia — blood testing shows low phosphate and/or vitamin D depending on cause.
• History: trauma, infection, other chronic disease; long-term medication/steroid/chemotherapy use.
• Examination: confirm symmetry; look for lower-limb spasticity/ weakness; examine joints for abnormality/pain; measure height/weight/ percentile; monitor ICS — should be <6 cm.
• Investigations: vitamin D, UEC, calcium/magnesium/phosphate ± PTH.
• Red flags for referral: unilateral bowing; short stature (<3rd centile — suggests metabolic bone disease); not resolving by age 3; ICS >6 cm at age 4, or asymmetry, or severe bowing (>6 cm regardless of height).

Knock knees (genu valgum)

Inward “knocking” — intermalleolar separation (IMS) >4 cm. Also mostly physiological, typically age 2–8 (peak 3–4 years), improving with time; gait can look awkward but resolves. No early treatment changes the adult outcome.

• Monitor IMS — refer if >8 cm, not resolving, or asymmetrical (no fixed age cut-off given).
• Rest of assessment/management mirrors bow legs above.

In-toeing (pigeon toes)

Usually painless, doesn’t affect mobility — caused by deviation at the hip, knee, or metatarsals. Ask if the child favours the “W” sitting position (associated, though not necessarily causative) and about birth trauma, breech positioning, DDH or cerebral palsy history; check for a limp.

Three forms:

• Metatarsus adductus — present at birth, associated with DDH; gives a “bean-shaped” foot. Managed with cast or observation; usually resolves by age 3, refer if not resolving 3 months after presentation. Surgery rarely needed, occasionally after age 2.
• Internal tibial torsion — presents as a toddler, thought to reflect intrauterine positioning; usually bilateral; usually spontaneously resolves by age 4. Examine the thigh–foot angle prone (normal range −30° to +20°). Refer at 6 months after presentation if not resolving. Surgical fixation rarely required, usually age 6–8 if it is.
• Medial femoral torsion (femoral anteversion, “inset hips”) — presents >5 years, normal up to age 12; more common in girls; an inset hip causes inward femoral rotation; the classic “W-sitting” position is painless. Examine prone: hip internal rotation should be <70°; external rotation is typically limited (<20°). Usually resolves before 12 years; refer if still present 8 years after presentation (rarely needs surgery).

Tibial torsion normal range: ~5° at birth up to ~15° at maturity.

Investigations: hip X-ray if a limp or reduced ROM; foot X-ray if pain or rigidity.

General in-toeing referral criteria: rigid foot deformity; scoliosis or neurological abnormality (spasticity); abnormal development; family history of persistent in-toeing; cosmetic concern after age 12; ongoing concern after age 10–12. If otherwise healthy with no developmental concerns, observe until age 10. Discourage W-sitting.

Out-toeing

Occurs in infants from restricted hip internal rotation (an external rotation contracture) — the Charlie Chaplin” stance, age 3 months–2 years. The child weight-bears and walks normally. “No treatment needed — spontaneously resolves; if not, referral/surgery may be needed in older children.

Flat feet

A very common parental concern — most children’s feet are normal for age and simply look flat when standing, due to normal joint laxity.

• Examination: the arch is usually visible with the foot hanging free, and more easily visible on tip-toe standing.
• Minimal benefit from intervention unless there are clear symptoms/ pain.

Club foot / talipes

Most children with an abnormal-looking foot have postural talipes, not true club foot.

Postural talipes (the majority): mild, mobile deformities that correct fully with one-finger pressure:

• Talipes calcaneovalgus — excessive dorsiflexion and eversion.
• Metatarsus varus (metatarsus adductus) — forefoot adduction.
• Postural talipes equinovarus — a positional contracture from intrauterine “packaging”; passively correctable.

Usually resolves spontaneously without treatment; a paediatric physiotherapist can provide gentle stretching exercises (RCH has printed handouts).

True club foot (congenital talipes equinovarus): idiopathic; more severe and stiff — foot in equinus, hindfoot in varus, forefoot supinated. Cannot be passively corrected into a normal position.

• Demographics: 1:1000–1:250 births; highest prevalence in Māori and Pacific Islander populations; males 2× more than females.
• Examination: foot cannot be passively pushed into a normal position; small foot and calf; shortened tibia.
• Investigations: not usually required.
• Management: early referral for orthopaedic correction (fixed talipes needs specialist intervention — do not just observe).

When to refer (general)

Red flags across all rotational/torsional problems: asymmetrical deformity; values exceeding the normal range for age; recurrent tripping in a school-aged child affecting activity participation; or a rigid/ progressive deformity.