Characteristics of functional gait among people with and without peripheral neuropathy

It is advantageous from a rehabilitation standpoint to determine physiological factors associated with functional gait. These factors may be fundamentally different in those with peripheral neuropathy (PN) compared to age-matched healthy individuals. The purpose of this investigation was to examine associations between functional gait and measures of leg strength, standing balance, and locomotor kinematics in people with and without PN. Methods: Individuals with PN and age-matched controls were assessed for functional gait by the 6-min walk and timed Up-and-go tests. Leg strength was measured as isokinetic peak torque of the knee extensors. Standing balance was assessed by center-of-pressure sway velocity and area during quiet stance. Locomotor kinematics from treadmill walking were used to compute stride duration variability and local instability (i.e., finite-time Lyapunov exponents), which estimate kinematic divergence caused by small-scale perturbations. Results: Leg strength and locomotor kinematics - in particular local instability - correlated with functional gait performance in controls. Conversely, reduced functional gait performance in the PN group was primarily mediated by impaired standing balance control. Discussion: Locomotor kinematics predicts functional gait, and the magnitude of variability and local instability should be calculated to fully evaluate locomotor system health. The observation that different factors associated with functional gait between groups speaks to the uniqueness of the PN-related movement disorder. Functional gait-related rehabilitation programs for PN patients should be tailored toward this uniqueness. (C) 2009 Elsevier B.V. All rights reserved.