Bow Legs, Knock Knees and Other Normal Variants

Bow Legs, Knock Knees and

Other Normal Variants

Dr David Bade

Director of Orthopaedics

Lady Cilento Children’s Hospital

Normal Variants

• Symmetrical

• Improve with growth

• Large range of ‘normal’

• Coronal, axial/rotational planes in the lower

limb

• Most common referral to general paediatric

orthopaedic

• PARENTAL ANXIETY

CORONAL PLANE ISSUES

Knee Varus/Valgus

• Femoro-tibial alignment changes with growth

Maximum varus <18mo

Tachdjian’s 5th Ed

Neutral by 2yo

Max valgus

4yo

Adult

alignment by

10 yo

When does femoro-tibial alignment

become pathological?

1. Genu varum

2. Genu valgum

1. Genu Varum

• Pathologic if:

– >18mo without signs of resolution

– Unilateral

– Progressive

– Pain

– Underlying medical diagnoses

• Rickets

• Renal failure

1. Genu Varum

• What not to miss?

1. Infantile tibia vara (progressive proximal tibial

varus deformity)

• Treatment should begin <4yo

2. Underlying medical diagnoses

• Rickets

• Renal failure

2. Genu Valgum

• Pathologic if:

– Intermalleolar distance >8cm >10yo

– Unilateral

– Progressive

– Underlying medical diagnosis

• Rickets

• Renal failure

2. Genu Valgum

• What not to miss?

– Cozen phenomenon

• Progressive (and generally self-limiting) genu valgum

after proximal tibial metaphyseal greenstick with intact

lateral cortex

Treatment

• 8 plates

– Require referral prior to 12 F or 14 M (guided

growth requires >/= 2 years of growth remaining

for maximal effectiveness)

• Osteotomies

– Generally reserved for skeletally mature patients

ROTATIONAL ISSUES

“Intoer/Outtoer”

• Foot progression angle refers to angle foot

makes with straight line on floor

– Intoers have an internal foot progression angle

– Outtoers have an external foot progression angle

Why does a patient in- or outtoe?

Rotational Profile

• Method of determining the cause for in- or

outtoeing

• Three components

1. Comparison of internal and external rotation

(hip)

2. Thigh-foot angle (or transmalleolar axis)

3. Heel bisector

Rotational Profile

• Place patient prone, knees flexed to 90

• Check:

1. Heel Bisector (N = 2/3)

2. Thigh-foot Angle (N -5 IR – 20 ER)

2. Transmalleolar Axis (N -10 IR – 15 ER)

3. Hip Rotation (compare IR with ER)

Intoeing

• Three etiologies:

1. Femur

2. Tibia

3. Foot

Femur

• Femoral anteversion

– IR > ER

– Pathologic if persists >10yo

• Normal adult anteversion ~15 degrees

Tibia

• Internal tibial torsion

– Thigh-foot angle < -15

– Pathologic if persists >8yo

• Normal adult torsion -5 IR – 30 ER

Foot

• Metatarsus adductus

– Heel bisector > 3

– Pathological

• Associated with DDH

• Screen for DDH with U/S if <6mo and XR if > 6mo

Outtoeing

• Three etiologies:

1. Femur

2. Tibia

3. Foot

Femur

• Femoral retroversion

– ER > IR

– Normal adult anteversion 15

– Pathologic if

• Unilateral

• Progressive

• Associated with groin/thigh/knee pain (SUFE)

Tibia

• External tibial torsion

– Thigh-foot angle > 30 ER

– The most common normal variant not to correct

– Pathologic if

• Unilateral

• Progressive

Foot

• Forefoot abduction

– Heel bisector intersects medial to 2/3

– Pathologic if

• Progressive

• Associated with rigid flatfoot

What needs treatment?

• Controversial!

• Considerations

– Functional limitations

– Pain/ Falls

– Cosmesis

– MTA

• straight- or reverse-last boots (non-operative, low risk)

What treatment is available?

• No successful non-operative therapy

• Operative

– Femoral or tibial derotation osteotomies

PESKY FEET

Flatfeet

• Arch develops until 8yo

• Two varieties

1. Flexible

2. Rigid

Which is it, flexible or rigid?

• Heel rise

• Jack’s test

Normal hindfoot valgus ~5-10 degrees

Flexible flatfeet regain arch and

convert to heel varus with heel rise

Flexible flatfeet regain arch with first toe

dorsiflexion (Jack’s test)

Flexible Flatfeet

• Treatment

– ONLY if painful

• Semirigid medial longitudinal arch support orthotic

What if the arch does not

reconstitute?

• Rigid flatfeet

Rigid Flatfeet

• Differential diagnosis

1. Tarsal coalition

2. Congenital vertical talus

1. Tarsal Coalition

• Abnormal connection between two tarsal

bones

– Fibrous/cartilagenous/bony

• Investigations:

– XR

– +/- CT or MRI

Treatment

• Immobilization

• Orthotic

• Surgical excision

2. Congenital Vertical Talus

• Dorsal dislocation of navicular onto talar head

– “rocker bottom” foot

Summary

1. Genu Varum – Beware >2yo progressive +/- unilateral

2. Genu Valgum – Beware intramalleolar distance >8cm at 10yo

3. Intoeing – Beware DDH in MTA

4. Outtoeing – Beware SUFE

5. Flatfeet – Beware the rigid flatfoot

OPSC at LCCH

• Orthopaedic Physiotherapy Screening Clinic

• Review all normal variant referrals to LCCH

• Doesn’t delay orthopaedic review or

intervention

• Allows earlier review in less hectic clinics

Simple Fracture Management