Delayed Onset Time of Gluteus Medius Muscle and Frontal Mechanics of Trunk and Pelvis in Individuals with Medial Knee Osteoarthritis

Objective: An increased strengthening of hip abductor muscles helps to improve pain and functional activity in medial knee osteoarthritis (OA). However, the mechanism analysis of the functional benefits is still incomplete. The objective was to compare the function of the gluteus medius (GMed) muscle, the contralateral pelvic drop, and ipsilateral trunk lean between the with and without knee OA groups. Material and Methods: Twenty individuals participated in the study. Kinematics and kinetics were recorded during level walking using a 10-camera ViconTMNexus system and a force plate. GMed activity was recorded using a Delsys Trigno system. The data of 2 participants were excluded because they were incomplete. Finally, 18 data (9 knee OA and 9 asymptomatic) were reported. Independent T-test and the Mann-Whitney U test were used for statistical analysis. Results: A delayed time of GMed muscle (32.73±30.42 ms) was significantly (p-value=0.006) exhibited in individuals with knee OA after foot contact. A lower knee injury and OA outcome score was noted in individuals with knee OA. No significant difference in manual muscle strength test, contralateral pelvic drop, lateral trunk lean, and average GMed muscle activity was observed between the groups. Conclusion: A significant delay of GMed activation was noted in individuals with knee OA who had moderate severity in the current study, and it might be a sensitive indicator for the observation of neuromuscular deficits. In future studies, interventions aimed at improving the onset time of GMed should be investigated in individuals with knee OA in order to assess the clinical implications.