Comparison of Static Force Sense of Knee Extension between Women with Patellofemoral Pain Syndrome and Healthy Women

Patellofemoaral pain syndrome (PFPS) is a common musculoskeletal disorder. Proprioception is important factor in neuromuscular control. Others studies showed that, because of pain and abnormal stresses on soft tissue around joint and Proprioception may be change in these patients. The aim of this study was investigation of sense of quadriceps muscle force accuracy in patients with PFPS. In this cross-sectional and case –control study, thirty four young women with and without PFPS were participated. Biodex isokinetic dynamometer was used to measure isometric torque and sense of quadriceps static force. Force matching with ipsilateral limb was used by determining of reference force levels (20 and 60%) of maximal voluntary isometric force (MVIF) in 20 and 60 degree of knee flexion and attempting to perception and reproduction of target forces. Absolute error (AE), constant error (CE) and variability error (VE) were calculated for evaluation sense of force accuracy. Data were analyzed by independent T test and Logistics Regression. There was statistically difference in force reproduction error in 60 degree and 60% MVIF between two groups (P<0.005). Sense of force errors were high in patient group. The results confirmed the past studies and showed that proprioception may be altered in PFPS patients because of changes proprioception afferents, specially for quadriceps muscle receptors.