Gait performance after spinal cord injury

Physiologic and mechanical gait parameters were measured in 36 spinal cord injury (SCI) patients to quantify gait impairment. Average age of the 30 males and six females was 29.0 +/- 10.1 years. Patients were tested at the time of discharge from initial rehabilitation (mean, 0.5 +/- 0.7 years postinjury). Compared with able-bodied subjects tested in the same laboratory, the SCI patients walked 52% slower (41.1 m/minute versus 79.8 m/minute, respectively), the rate of oxygen consumption was 23% higher (14.9 ml/kg.minute versus 12.1 ml/kg.minute), and the oxygen cost per meter was 240% higher (0.52 ml/kg.m versus 0.15 ml/kg.m). Peak axial load on upper extremity walking aids averaged 21.7% of body weight, and the ambulatory motor index (AMI), derived from lower limb strength grades, was 52% of normal strength. The AMI closely correlated with the peak axial load and the percent increase in the oxygen rate above normal. Differences in the AMI among patients accounted for changes in physiologic parameters; therefore, the AMI can be used as a clinical predictor of functional mobility. Annual follow-up studies were performed on ten of the 36 patients. Compared with the initial testing, these patients walked faster (59.9 m/minute versus 40.4 m/minute), more efficiently (0.26 ml/kg.m versus 0.40 ml/kg.m), with slower heart rates (115 beats/minute versus 133 beats/minute), and the peak axial load was less (18% of body weight versus 26% of body weight).