The Relationship between Muscle Activity and Gait Parameters for TKR Patients and Control Subjects

INTRODUCTION: Total knee replacement (TKR) successfully relieves knee joint pain and improves function according to patient reported measures, although recent studies have found that TKR patients do not regain full functional mobility after surgery [1, 2]. Knee kinematics and kinetics measured during gait analysis can be used to assess functional demands, and estimate net muscle activity. However, their relationship to the activity of specific muscles after TKR is unknown. It is also not known if the relationships between knee gait parameters and muscle activity differ between TKR patients and normal control subjects. The purposes of the present study were to compare gait parameters, muscle activity, and the relationship between the two for TKR patients and healthy matched control subjects during level walking. We hypothesized that (1) knee flexion angle and peak external knee moments, (2) the time during stance when functional muscle pairs were both active (co-activated), and (3) the relationship between gait parameters and muscle co-activation times, would be different for the TKR and control subjects.