Effect of Quadriceps Exercise Training on Muscle Fiber Angle in Patients With Patellofemoral Pain Syndrome

Background: Imbalance between the vastus medialis oblique (VMO) muscle and the vastus lateralis oblique (VTO) Vastus lateralis has been thought to be a primary cause of abnormal patellar tracking, possibly leading to patellofemoral pain syndrome (PFPS). Objectives: The purpose of this study was to investigate the effect of quadriceps muscle strengthening exercises on the ratio of VMO to VL oblique and longus muscle fiber angles. Patients and Methods: Thirty-five subjects (23 females and 12 males, mean age 26.6 years ± 1.1 SD) with PFPS were randomized into an exercise group or a control group. The exercise group performed knee extension exercises for four weeks based on the Kaya exercise program (three times per week), while the control group received no treatment. Measurements included knee extensor concentric and eccentric muscle torque using a Biodex isokinetic machine and the fiber angle of the VMO, VL oblique and longus muscles using ultrasonography, all of which were evaluated at the time of the initial examination and at the end of the four-week period. Results: There were no significant differences in the muscle strength and fiber angle of the VMO, VL oblique and longus muscles after training between the control and experimental groups (P > 0.05). Conclusions: The study findings indicate that short-term exercises had no significant effect on the ratio of VMO to VL muscle fiber angles in patients with PFPS.