The effect of load carriage on the gait of girls with adolescent idiopathic scoliosis and normal controls.

Adolescent idiopathic scoliosis (AIS) and load-bearing both appear to place similar demands on gait, but no data regarding the combined effects of load-bearing gait in subjects with AIS could be found. The gait patterns of 22 normal adolescent girls and 28 girls with mild AIS (Cobb angle<25 degrees ) were recorded at backpack loads of 0, 7.5, 10, 12.5 and 15% body weight. Temporal-distance and joint kinematic, moment and power parameters were analyzed by repeated measures ANOVA. Findings showed that backpack carriage places an increased demand on the musculature of the lower limb and results in a gait characterized by reduced pelvic motion and greater hip flexion-extension. AIS has a generally similar effect on gait kinematics as backpack carriage, with AIS subjects having significantly longer double support durations, shorter single support durations and lower knee joint power generation and absorption than normal subjects. No interaction between backpack load and AIS was found however, although investigation of parameters indicating a critical response to load showed that this typically occurred at lower backpack loads (7.5% body weight) in the AIS group. Overall, both AIS and load-bearing place increased demands on gait, but carriage of a loaded backpack does not appear to cause any greater demand on subjects with AIS than normal controls.