A Blog by Antoni Caserta
Children use a vast combination of compensatory mechanisms in order for their gait to appear as normal as possible. However length lengths over 3.7% of total height have been shown to have visual, centre of gravity and mechanical compensations. So when a kindergarten teacher referred a nearly 5 year old child into our clinic for gait and running pattern concerns it wasn’t a surprise to see that this young little trooper had a leg length discrepancy (LLD).
This child had a history of lone tone, hypermobility and hip dysplasisa of the left hip which was treated with a pavlik harness shortly after birth.
Today’s assessment indicated a positive galeazzi sign for LLD, asymmetry in hip range of motion, low tone and a high beighton score. Gait appeared asymmetrical, with a trendleburg and early heel rise on the short side and circumduction, rearfoot valgus and external angle of gait on the longer side.
When the LLD was picked up, the family raced off to their GP for a second opinion. Long leg xrays were ordered and a 0.7mm LLD was measured. Given the history of hip dysplasia the GP referred to orthopaedics for a review. But what does this measure really mean?
The child has been doing a strength program over the last year and the conpensation for the LLD is hardly noticeable. The mother presented to us yesterday with a follow up imaging report from the GP, that shows an increase in LLD by 3mm through femur, which is now a 10mm LLD.
Going forward from here?
There are four techniques for predicting LLD at the maturity of growth. These include the arithmetic method, the growth-remaining method, the Mosely straight line method and the Paley multiplier method.
Using the Paley leg length multipliers at 5 yrs of age the LLD at the completion of growth was to be 1.274cm, however now at 6 years of age this has increased to 1.67cm. Using the multiplier you would expect a consistent end result at any stage, however given the change in outcome measures this suggests it the leg length may be progressive in nature.
At the time we only used the one method. What we should have done was organise a number of measurements and used a number of the four techniques used for predicting LLD at maturity as “one measurement may be an error, two measurements give a trend and three measurements allow a curve to be drawn” [Kelly 2008]
Monitor, wait, address what is in front of you but most of all, open communication with the care team. A child wiht a LLD may need nothing, a simple heel raise or something more interventional from your orthopaedic colleagues.
Kelly PM, Diméglio A. Lower-limb growth: how predictable are predictions? J Child Orthop. 2008;2:407–415.
Moseley CF (1977) A straight-line graph for leg-length discrep- ancies. J Bone Joint Surg 59(2):174–179
Paley D, Bhave A, Herzenberg JE, Bowen JR. Multiplier method for predicting limb-length discrepancy. J Bone Joint Surg Am 2000; 82:1432–1446.
Friend L, Widmann RF. Advances in mangement of limb length discrepancy and lower limb deformity. Curr Opin Pediatr 2008; 20: 46-51