Gait variability is affected more by peripheral artery disease than by vascular occlusion

Background Patients with peripheral artery disease (PAD) have altered gait variability from the first step they take, well before the onset of claudication pain. The mechanisms underlying these gait alterations are poorly understood. Aims This study sought to isolate the effect of reduced blood flow on gait variability by comparing healthy older controls and patients with PAD. We also determined the diagnostic value of gait variability parameters to identify the presence of PAD. Methods Thirty healthy older controls and thirty patients with PAD walked on a treadmill at their self-selected speed in rested (normal walking for controls; pain free for PAD) and reduced blood flow (post vascular occlusion with thigh tourniquet for controls; pain for PAD) conditions. Gait variability was assessed using the largest Lyapunov exponent, approximate entropy, standard deviation, and coefficient of variation of ankle, knee, and hip joints range of motion. Receiver operating characteristics curve analyses of the rested condition were performed to determine the optimal cut-off values for separating individuals with PAD from those without PAD. Results and Discussion Patients with PAD have increased amount of variability for knee and hip ranges of motion compared with healthy older group. Comparing for conditions, reduced blood flow demonstrated increased amount of variability compared with rested blood flow. Significant interactions between group and condition occurred at the ankle for Lyapunov exponent, approximate entropy, and coefficient of variation. A combination of gait variability parameters correctly identifies PAD disease 70% of the time or more. Conclusions Gait variability is affected both by PAD and by the mechanical induction of reduced blood flow.