Impairment variables predicting activity limitation in individuals with lower limb amputation.

The purpose of this study was to determine whether measures of impairment (i.e., muscle strength, balance), personal factors (i.e., comorbidities, demographic information) and amputation specific variables (i.e., time since amputation, cause of amputation, level of amputation) were able to predict performance on the six-minute walk test, a measure of activity limitation, in individuals with lower limb amputation. A total of 72 individuals with lower limb amputation ranging in age from 21-83 were tested for balance, limb muscle strength and function. Medical comorbidities were recorded and activity limitation was measured using the six-minute walk test. Data were analyzed and multivariate relationships were examined using multiple linear regression. Impairment variables of strength, balance, subject demographics, time since amputation, cause of amputation and level of amputation were all significant predictors and explained 72% of the variance in the outcome variable. Strength of the hip extensors was the strongest predictor, accounting for 30.9% of the total variance. Multiple factors impact six minute walk scores in individuals with lower limb amputation. Impairments in hip strength and balance appear to be the two most significant. The findings of this study support the use of the six-minute walk test to underscore impairments of the musculoskeletal system that can affect ambulation ability in the amputee.