PARETIC LOWER EXTREMITY LOADING and WEIGHT TRANSFER FOLLOWING STROKE.
Vicki S. Mercer, Shuo‐Hsiu Chang, Jama L. Purser, Janet K. Freburger · Neurology Report · 2005
Purpose/Hypothesis: Improved ability to bear weight on or load the paretic lower extremity (LE) and to transfer weight from one LE to the other is one of the main goals of stroke rehabilitation. Although this goal appears theoretically sound, the functional significance of these abilities has not been addressed empirically. The purpose of this project was to determine how impairment-level measures of paretic LE loading and weight transfer relate to clinical and/or self-report measures of physical function and disability during early recovery from mild to moderate stroke. Number of Subjects: Twenty-five subjects (12 men, 13 women; mean age = 60.5 ± 17.2 years) with a diagnosis of a single, unilateral stroke participated in the study. Materials/Methods: Subjects were tested at 1, 2, and 3 months post stroke. The Step Test (ST) and the Repetitive Reach (RR) test were used as measures of LE loading and weight transfer, respectively. A third impairment-level measure, paretic hip abductor muscle torque, was examined because of the important role of the hip abductors in both loading and weight transfer. Self-selected gait speed (GS) and the MOS Short Form-36 Physical Functioning Index (PFI) were used to assess physical function. Three domains (mobility, ADL/IADL, participation) of the Stroke Impact Scale (SIS) were used to assess self-reported disability. Regression analyses were conducted to examine the bivariate associations between each impairment and physical function measure and between each impairment and disability measure for each time point (1, 2, 3 months). Results: All of the impairment measures were positively associated with all of the physical function measures. These associations generally got stronger over time (i.e., from 1 to 3 months). The associations were stronger for self-selected gait speeds (R2 values 0.30 – 0.79) than for the PFI scores (R2 values 0.15–0.63). Both ST and RR scores were strongly associated with gait speed at all 3 time points. At 3 months, each additional step on the ST corresponded to a 0.08 m/sec increase in gait speed (95% CI=0.06–0.10, p<0.001), and each additional reach during RR was associated with a 0.03 m/sec gait speed increment (95% CI=0.02–0.04, p=<0.001). The impairment-disability associations were weaker than the impairment-physical function associations, with only some reaching statistical significance. ST scores and RR scores were positively associated with SIS mobility (R2 values .32-.46) and SIS ADL/IADL (R2 values .16-.37), with RR scores having the strongest associations. Hip abductor torque was positively associated with SIS mobility (R2=.19). The impairment-disability associations also got stronger over time. Conclusions: Impairment in paretic lower extremity loading and weight transfer abilities relates to physical function and disability during the first 3 months following stroke. Clinical Relevance: By use of interventions that promote symmetrical weight bearing and smooth, rapid weight transfer between the lower extremities, physical therapists may be able to help stroke survivors improve function and minimize disability.