EFFECTS OF LEG LENGTH DISCREPANCIES ON THE FORCES AT THE HIP-JOINT

The authors questioned whether leg length discrepancies of the magnitu de ordinarily seen after total hip reconstruction (<2 cm) would substa ntially alter hip joint forces, Using conventional gait analysis techn iques to ascertain intersegmental resultant hip forces and moments, th e authors used lifts to simulate leg length discrepancies of 2.3, 3.5, and 6.5 cm in 7 normal subjects, The 2.3-cm lift produced no changes, On the side of the lift (long limb), the 3.5- and 6,5-cm lifts modest ly decreased mean peak intersegmental resultant hip forces by 6% and 1 2%, respectively, but not moments, The changes were, however, variable , with a few subjects showing increases and the rest showing decreases in selected forces or moments, On the side opposite to the lift (shor t limb), the 3.5- and 6,5-cm Lifts increased mean peak intersegmental resultant hip forces by 2% to 12%, but not moments except in 1 case (8 %), It is concluded that leg length discrepancies of the sort commonly seen after total hip reconstruction would likely cause no substantial changes in hip forces.