Lower Limb Alignment and Leg Length Discrepancy

Abstract

Leg length discrepancy can be true or apparent and can occur above or below the knee. The body can compensate if the deformity is less than 2 cm. Limb deformities can occur in all planes and persistence of an angular deformity beyond the age of 6 should be treated with suspicion. Causes of limb shortening can be congenital or acquired. It is important to calculate the predicted limb length discrepancy at skeletal maturation to aid with treatment. Many techniques exist to calculate the remaining growth of a bone (e.g. the arithmetic method). Radiography is the key investigation for leg length discrepancy. For treatment a shoe raise can be used to accommodate the discrepancy. Alternatively limb shortening with epiphysiodesis can be used for discrepancies between 2 and 5 cm and limb lengthening with an external fixator or lengthening nail for larger discrepancies.