Chapter 48- Limb Length Inequality

Question 1

Describe the short leg limp

Answer 1

Shoulders dip parallel to the floor in stance on the affected side

Question 2

Congenital causes of leg length inequality

Answer 2

• DDH, congenital coxa vara
• congenital short femur/ proximal focal femoral deficiency
• fibula hemimelia
• posteromedial bowing of the tibia
• congenital pseudosrthrosis of tibia
• congenital heniatrophy
• congenital hemihypertrophy
• other causes of soft tissue overgrowth: haemangioma, venous abnormalities, neurofibromatosis

Question 3

Acquired causes of leg length inequality?

Answer 3

• paralytic-polio
• physeal damage: traumatic injury, especially distal femoral growth; infection (osteomyelitis or meningococcemia)
• overgrowth- chronic osteitis or healing fractures

Question 4

What are the Supra pelvic and infrapelvic effects of pelvic obliquity resulting from leg length inequality

Answer 4

Suprapelvic : postural scoliosis

Infrapelvic: long leg is adducted –>hip joint wear and tear in the long term

Question 5

Which tests will help to determine where he length discrepancy lies in leg length inequality

Answer 5

Galeazzi test: flex both knees to 90 with patient lying supine. To assess whether shortening above or below the knee
Bryant’s triangle: assess whether the shortening is above or below the greater trochanter.

Question 6

How to measure for true shortening

Answer 6

Measure from anterior superior illiac spine to the bottom of medial malleolus

Question 7

How to measure for apparent shortening

Answer 7

Measure from a fixed point in the midline above the pelvis to the bottom of the medial malleolus

Question 8

Causes of apparent leg shortening

Answer 8

Suprapelvic: e.g. Scoliosis
Infrapelvic: hip addiction, abduction or flexion deformity or flexion deformity of the knee
Pelvic deformity: pelvic obliquity

Question 9

How to test for functional shortening of legs?

Answer 9

Patient stands on calibrated wood blocks until both iliac crests are felt to be parallel to the floor

Question 10

Radiological investigations for leg length inequality

Answer 10

• leg length views with radio opaque ruler
• Ct scanning
• orthorentogram

Question 11

Conservative management of leg length inequality

Answer 11

Shoe raise p

Question 12

How can leg length equality be achieved

Answer 12

• stop growth on long side: epiphysiodesis
• lengthening the short side: callotasis
• shortening of the long side (may be used in conjunction with the above)

Question 13

Name the methods used to calculate the anticipated leg length discrepancy at maturity

Answer 13

• Moseley straight line graph method

- menelaus growth remaining method

Question 14

At what age do boys and girls stop growing

Answer 14

Boys stop growing at skeletal age of 16, girls at 14 years

Question 15

What is the annual growth at each of the growth plates

Answer 15

Proximal femur/ hip: 0.4 cm
Distal femur: 1.0 cm 
Proximal tibia: 0.6 cm 
Distal tibia 0.4 cm
Foot: 0.4 cm 
Total: 2.4 cm

Question 16

How does one plan treatment based on expected leg length discrepancy?

Answer 16

• less than 2 cm: no treatment as patient compensates with pelvic tilt or heel raise
• 2-5 cm: epiphysiodesis of long leg
• > 5 cm: leg lengthening of short leg +- epiphysiodesis of long leg

Question 17

At what rate is the callus (formed after a controlled fracture) distracted in a callotasis?

Answer 17

1mm/ day

Question 18

What is the healing in callotasis

Answer 18

One month per cm of lengthening

Question 19

Complications of callotasis

Answer 19

Joint contracture
Pin site infection
Neuropraxia
Refracture of the new bone