PATELLOFEMORAL PAIN SYNDROME: SENSITIVITY ANALYSIS OF MUSCLE PARAMETERS FOR EXPEDITED RECOVERY UTILIZING AN OPENSIM MODEL FOR LOWER EXTREMITIES

摘要

Patellofemoral pain syndrome (PFPS) is a musculoskeletal condition characterized by anterior knee pain. The symptoms associated with PFPS can be further aggravated through activities that increase patellofemoral compressive forces. Despite the number of mechanisms that are considered to contribute to this disorder, there is no consensus about its etiology, causing difficulty in prescribing the appropriate treatment or physical therapy. To properly evaluate PFPS, the influences of various muscles and their geometries on knee joint reaction forces for a human subject during a normal gait cycle were observed by conducting parametric analysis using OpenSim. The muscles that were seen to be most critical and have a potential effect in reducing the pain experienced at the knee joint are the soleus, iliopsoas, and gastrocnemius muscles. It was observed that individually increasing the length of the soleus and iliopsoas muscles from 75% to 125% of their default lengths resulted in decrease in knee joint reaction forces of up to 400 N (57%) in the x-direction and 600 N (40%) in the y-direction for the soleus and 550 N (38%) in the x-direction and 1000 N (29%) in the y-direction for the iliopsoas. It was also seen that by indirectly reducing the cross-sectional area of the gastrocnemius muscles from 125% to 75% of their default value resulted in decreases in knee joint reaction forces of up to 250 N (50%) in the x-direction and 500 N (42%) in the y-direction. Therefore, exercises should be advised to specifically stretch or strengthen the soleus and iliopsoas, and the gastrocnemius muscles should be rested. Pain and recovery time may be substantially reduced with the utilization of a targeted physiotherapy treatment plan. It can be coupled with longterm physiotherapy program for improving muscle fitness.