A scoping review of non-linear analysis approaches measuring variability in gait due to lower body injury or dysfunction

The aim of this review is to evaluate and summarize existing literature using non-linear analysis methodology to consider variability of human movement due to lower limb injury or dysfunction. Scoping review. An electronic keyword search was performed on three databases to identify appropriate research. This research was then examined for details of measures and methodology, use of control groups and general study characteristics to identify related themes. Fifteen papers were reviewed and synthesized. A range of conditions were studied, mainly affecting knee and ankle joints, and each using different non-linear methods and different equipment (motion capture, accelerometry, and muscle activation) to evaluate the mathematically chaotic nature of the movement and assess the variability in gait. Sample sizes and effect sizes are commonly small in these studies. Non-linear analysis is a potentially useful tool in both diagnosis and evaluation of injury, and this should inform future clinical processes when dealing with injury and movement variability. Despite numerous studies evaluating neurological conditions and ageing, focus on injury is limited, with notable gaps in terms of considering other joints and joint actions, so this should be a promising area of research to develop our understanding of injury and rehabilitation and how this affects gait variability. •Chronic injury results in a more rigid gait, and also increased local dynamic stability.•Research is limited when considering injury and dysfunction, and future studies should consider other joints and planes.•Non-linear analysis can inform future clinical processes when dealing with injury rehabilitation and movement variability.