Muscle Force and Gait Performance: Relationships After Spinal Cord Injury

Abstract

Wirz M, van Hedel HJ, Rupp R, Curt A, Dietz V. Muscle force and gait performance: relationships after spinal cord injury. Objectives To relate locomotor function improvement, within the first 6 months after spinal cord injury (SCI), to an increase in Lower Extremity Motor Score (LEMS) and to assess the extent to which the level of lesion influenced the outcome of ambulatory capacity. Design Longitudinal and cross-sectional analyses. Setting Seven SCI rehabilitation centers. Participants Patients (N=178) were analyzed longitudinally (group A, motor complete; group B, motor incomplete; nonwalking or group C, motor incomplete and able to stand). The cross-sectional analysis included 86 patients (paraplegic, n=46; tetraplegic, n=40; group 1 with limited and group 2 with unrestricted walking function 6mo after SCI). Interventions Not applicable. Main Outcome Measures Walking Index for Spinal Cord Injury (WISCI), gait speed, and LEMS. Results For group A, 24.8% of the patients improved in LEMS (median range, 0–10) and 7.7% in walking function (WISCI median range, 0–8; mean gait speed range, 0 to .14±.10m/s). For group B, LEMS improved in 93.5% of the patients (median range, 14–28) and walking function in 84.8% of the patients (WISCI median range, 0–10; mean gait speed range, 0 to .41±.45m/s) ( P<.001). For group C, LEMS and walking function improved in 100% of the patients (LEMS median range, 29–41; WISCI median range, 8–16; mean gait speed range, .36±.29m/s to .88±.44m/s) ( P=.001). In groups B and C, the improvement of walking function was greater than in LEMS. The cross-sectional analysis showed that group 1 patients with tetraplegia had more muscle strength (median LEMS, 31.5), and equal walking function (WISCI, 8; walking speed, 0.4±0.3m/s) compared with patients with paraplegia (LEMS, 23; P<.01; WISCI, 12; P=0.6; speed, 0.4±0.3m/s; P=.68). In group 2, patients with tetraplegia had slightly more strength (LEMS, 48) and equal walking function (WISCI, 20; walking speed, 1.4±0.4m/s) compared with patients with paraplegia (LEMS, 45; P<.05; WISCI, 20; P=1.0; speed, 1.4±0.3m/s; P=.89). Conclusions An improvement in locomotor function does not always reflect an increase in LEMS, and LEMS improvement is not necessarily associated with improved locomotor function. LEMS and ambulatory capacity are differently associated in patients with tetra- and paraplegia. Functional tests seem to complement clinical assessment.