Instance of Peak Knee Flexion and Adduction Moment During Deep-Squat

People with knee osteoarthritis present with difficulty in performing high flexion activities that load the knee. Information on peak external knee adduction-moment (KAM) and knee flexion moment (KFM), which are established biomechanical markers of tibio-femoral joint loading. during activities of daily living such as squat, is not known. Hence, the present study explored instance of peak KAM and KFM during deep-squat in people with varying squat exposure to enable guiding of therapeutic interventions for optimal knee function. Thirty healthy adults, aged 30–45 years, were categorized based on daily squat exposure as non-squatters (nil squat exposure), ADL-Squatters (squat exposure<60 min) and occupational-squatters (squat exposure>60 min). 3D motion capture of deep-squat was performed at a Human Movement Science laboratory. Knee flexion angle during deep-squat increased with quantum of daily squat exposure. KAM and KFM were observed to increase with knee flexion angle during squat descent. Knee moments peaked at 109.8±48.2°, 123.5±37.8° and 135.7±30.9° of knee flexion in the 3 groups, respectively. During ascent, knee moments peaked at 136.1±21.5°, 122.9±42.9° and 149.5±21.9° respectively. Peak KFM decreased linearly with increase in squat exposure, however KAM did not show similar trend. These findings indicated that instance of peak loading varies in people with daily squat exposure. Lack of adequate knee motion and muscle control required to maintain knee stability during high flexion activities can result in higher knee joint moments. Therefore, rehabilitation programs need to account for lifestyle behaviors and focus on prescription of appropriate exercises to develop mobility and muscle control for greater knee stability.