Concentric hip muscle function and quadriceps-hamstring ratio in athletes with and without patellofemoral pain syndrome

Background: Patellofemoral pain syndrome (PFPS) is a commonly seen condition in athletes. Several potential contributing factors have been postulated. Although hip muscle strength has been suggested to play a major role, concentric hip muscle function in athletes with PFPS has not been formally investigated. Objectives: We aimed to compare the concentric hip muscle strength in athletes with PFPS with that of controls, and to derive a concentric knee extension-to-flexion (quadriceps: hamstring) ratio Subjects and Methods: University athletes with PFPS (n=25) and asymptomatic controls (n = 25) were studied. Concentric torque of the hip abductors, adductors, flexors and extensors along with concentric knee extensors and flexors torque were assessed. Participants rated their knee pain in the week before the study on a visual analog scale and a self-administered anterior knee pain scale (AKPS). Strength testing was performed at 60°/s. Results: Participants with PFPS exhibited much lower concentric hip abduction, adduction, flexion and extension peak torque compared to controls. The concentric hip abduction to adduction and extension to flexion ratios showed no difference. Quadriceps:hamstring ratio was higher for PFPS participants. Conclusion: We propose that concentric hip muscle strength is significantly affected in PFPS. Clinicians are urged to include concentric strengthening exercises for the hip along with quadriceps and hamstring muscles during the rehabilitation of athletes with PFPS.

Key-words:

Patellofemoral pain syndrome - concentric hip muscle strength - quadriceps:hamstring ratio.