Measurement of Paretic–Lower-Extremity Loading and Weight Transfer After Stroke

Abstract

Background Weight bearing through, or “loading” of, the paretic lower extremity and transfer of weight from one lower extremity to the other are important impairment-level goals of stroke rehabilitation. Improvements in these limb-loading and weight-transfer abilities have been shown to relate to improved performance of many functional activities. Unfortunately, valid and practical clinical measures of paretic–lower-extremity loading and weight transfer have not been identified. Objective The purpose of this study was to assess convergent validity of the Step Test (ST) and the knee extension component of the Upright Motor Control Test (UMCe) as measures of paretic-limb loading and of the Repetitive Reach Test (RR) as a measure of weight transfer in the first 6 months after stroke. Design This was a prospective cohort study of 33 adults with lower-extremity motor impairment following unilateral, noncerebellar stroke. Participants were tested one time per month from 1 to 6 months poststroke. Results Scores on the ST (performed with the nonparetic leg as the stepping leg) and UMCe were positively correlated with peak vertical ground reaction forces (GRFs) beneath the paretic limb during functional tasks (R2=.35–.76 for the ST, pseudo R2=.21–.34 for the UMCe). Scores on the RR were positively correlated with change in vertical GRF beneath the paretic limb during the diagonal reach task (R2=.45) and with weight-transfer time during stepping with the nonparetic limb (R2=.15). Conclusions The ST, performed with the nonparetic leg as the stepping leg, is a valid measure of paretic-limb loading during stroke recovery. Of the clinical measures tested, the ST correlated most strongly with the force platform measures.