Frequency-of-occurrence of myoelectric patterns to evaluate gait motor control strategies after hip replacement surgery.

Gait alterations are observed even years after hip replacement surgery. Such long-lasting alterations may arise from a global change of the motor control strategies. The aim of this work is to investigate the changes in gait motor control strategies of patients after hip replacement surgery by analyzing the frequency of occurrence (OF) of myoelectric activation patterns. We studied five lower limb muscles during gait, in hip prosthesis patients and controls. We found that patients adopt a motor control strategy that tends to prefer "simplified" myoelectric patterns, showing a smaller number of activations within the gait cycle. This altered motor control was present both on the prosthesis and the sound side, and did not improve during the 12-month follow-up. The reduced number of activations is even more evident in lateral hamstrings and gluteus medius, which are the muscles more affected by hip replacement surgery. Furthermore, this study demonstrated that the OF is a sensitive parameter able to discover subtle changes in motor control strategies. Its use can be extended to other studies involving motor coordination, motor learning and motor control adaptations.