Evaluating Improved Knee-Save device in Deep Squatting Tasks

Osteoarthritis (OA) is a chronic disease that affects 32.5 million people in the US. The prevalence of knee OA among adults over 60 years is approximately 10% (men) and 13% (women). Epidemiological studies showed that the prevalence of knee OA among workers is associated with their occupational activities. In many occupational activities, such as floor installation, electrical repairs and installations, roofing, retail stocking, gardening, and construction repairs, workers need to perform high knee-flexion tasks. Occupations involving high knee flexion tasks for at least 30 minutes per day resulted in increases in knee OA occurrence from 122% to 240 %, compared to average workers. The prevalence of OA will continue to increase with the aging workforce and the increasing life expectancy.

Knee savers or knee supporters are devices that are attached to the users’ legs to make users feel more comfortable during high knee flexion tasks. Knee savers have been used to reduce knee joint loading in some sports and occupational activities, such as roofing; however, the mechanism of how or if knee savers can reduce joint loading during deep squatting has not been analyzed on a biomechanical basis and their designs may be improved. Currently, commercially available knee savers of one size/type are intended to be used for individuals with different ranges of motion (ROM) in the lower extremities and different body sizes.

NIOSH researchers are working on a NORA-funded project (Biomechanical Evaluation of Knee Savers for Reducing Joint Load during Squatting) to improve the knee saver design to reduce the knee joint loading, thereby reducing workers’ knee OA risk. NIOSH researchers will develop a biomechanical model to analyze the musculoskeletal loading in the knee joint and in the spine region during high knee flexion tasks such as deep squatting, validating the model using human subject testing data, and applying the biomechanical model to improve the knee saver design. The...