Strengths of lower extremity and lower trunk muscles in females with patellofemoral pain syndrome

  Introduction: Patellofemoral pain syndrome (PFPS) is one of the most common orthopaedic problems of the knee joint. Muscular weakness considered as a risk factor of this syndrome. Muscular weakness can alter lower extremity kinematics and lead to this syndrome. Also according to the kinetic chain, weakness in one motor segment can influence other motor segments. So the aim of this study was to determine the association between muscular strengths of both lower extremity and trunks muscles and PFPS.   Materials and Methods: 40 women participated in this study (20 subjects with PFPS and 20 as controls). In both groups isometric strengths of the lower extremity and lower trunk muscles were evaluated with Nicholas hand-held dynamometer and then compared with each other.   Results: There was a significant decrease in strength of the hip abductors, adductors, external rotators, flexors and extensors, quadriceps, ankle plantarflexors, dorsiflexors, flexor and lateral flexors of the trunk in patients with PFPS. Conclusion: Our results indicate that decrease in strength of the hip and trunk muscles is associated with the knee injury. It seems strengthening of muscles of these areas to be effective in preventing the injury, reducing the risk of more injury and treatment of patients with this syndrome.