Knee Deformity

Question 1

Causes of Knock Knee (Genu Valgum)

Answer 1

1. Normal in 2 to 6 years old
2. Rickets
3. Diseases that damage to the outer part of upper tibial epiphysis
   • Trauma
   • Osteomyelitis
   • Bone Tumour
4. Syndromes
   • Marfan’s syndrome
   • MPS
5. Laxity of ligaments

Question 2

Causes of Bow Leg (Genu Varum)

Answer 2

1. Normal before 2 years old
2. Rickets
3. Damage to the inner part of tibial epiphysis
4. Blount’s disease
   • Disease of unknown aetiology
   • Because of tibial torsion (internal)
   • —> Distortion of medial growing plate
   • —> Deformity
   • XR – Hooking of medial upper end of tibia

Question 3

Clinical approach

Answer 3

1. Consider the deformity significant if
   • Genu varum - distance between medial femoral condyles with medial malleoli of ankle together is > 5 cm or asymmetrical bowing (one’s fist can fit into the space in between
   • Genu Valgum - distance between medial malleoli with knees together is >10 cm or 5 to 10 cm but has associated bony abnormalities suggestive of rickets; or asymmetrical bowing
   • However, if:
   • • Family hx of bone disease
   • • Asymmetry of deformity
   • • Associated bone disease or short starture

Must treat as abnormal case and investigate

2. Look for signs of rickets
3. Look for other joint/ limb deformity e.g. flat feet
4. Examine parents or sibling for similar deformity

Question 4

Causes of scars in Lower Limbs

Answer 4

1. Groin cutdown wound
   • Cardiac catherization wound
   • Adductor tenotomy
2. Mid thigh or calf
   • Muscle Bx scar
3. Ankle
   • Archilles tenotomy

Question 5

Causes of Genu Recurvatum

Answer 5

1. Laxity of ligament
2. Neuromuscular disease - weakness, eg poliomyelitis, CP
3. Damage to the tibial tuberosity / anterior part of epiphysis of knee.

After making the diagnosis, demonstrate the relevant physical signs:
• Ataxia
• Romberg sign
• Specific gait

If with spinal scar
• examine the abdomen for kidneys and bladder

Question 6

Charcot Marie Tooth syndrome

Answer 6

• AD or AR
• Onset at adolescent age
• First presented with Claw feet, but no wasting or weakness
• Later with equinus; Varus deformity of foot and foot drop and wasting of peroneal muscle becomes evident followed by wasting of muscles of thigh = ‘Inverted bottle’
• Wasting may involve upper limbs
• Neurological exam reveals objective sensory loss and absent ankle jerk
• Investigation: CSF - Normal; Nerve Conduction Velocity - Decreased