Forces and impulses during aided gait

Walking aids stabilize, support, and restrain/propel the locomotion of a body with functional deficits due to musculoskeletal and neuromuscular disorders. The relative contribution of limbs and aids in these functions was quantified in three patient groups: those with postoperative total hip replacement (THR), tibial fracture, and paraplegia. Aid forces were recorded and resolved into three components. Floor-to-foot forces were measured anterior-posteriorly and vertically. Results were interpreted by temporal relationships between aids and limb, symmetry of restraining/propelling forces, and peak forces during limb and aid loading phases. Impulse values (area under the force-time curve), presented as histograms, readily demonstrated the contribution of aids and limbs to locomotion. Results showed (1) variability in aid loadings among THR subjects, and between ipsilateral and contralateral sticks; (2) symmetrical restraining and propelling aid loadings of fracture subjects; and (3) that aid impulses directed medially were greater than the combined anterior-posterior direction amounts in four of seven subjects performing three-point gait. It is suggested that this technique of quantifying aid usage by impulse histograms be used to evaluate and prescription and sizing, gait training, and crutch design.