Comparison of lower extremity muscles strength, Q angle,knee varus and valgus in women with and without patellofemoral pain syndrome

Patellofemoral pain syndrome is one of the most common causes of anterior knee pain. This syndrome is associated with pain around and behind the knee which is caused by Physical and biomechanical changes resulting from the patella. The purpose of this study was to compare lower extremity strength, Q angle, knee  varus and valgus in women with and without patellofemoral pain syndrome 
Fifteen females with patellofemoral pain syndrome and fifteen pain-free controls participated in this study. Isometric strength, Q angle, knee varus and valgus was measured using multimodal dynamometer. Group differences were assessed using statistical technique of independent student t.
The strength of the hip abductors(P=.01), external rotators(P=.003),quadriceps(P=.01), hamstring(P=.002) and bilateral condylar distance(P=.008) was significantly lower in patients with patellofemoral pain syndrome. In comparison with the control gorup there was no significant difference in isometric strength of the hip adductor (P=.2) in both group. Q angle (P=.003)and Bimalleolar Distance(P=.003) in patient with patellofemoral pain syndrome was significantly greater than control group.
The finding of the present study indicated that there is a correlation between a decrease in strength of lower extremity muscles strength and an increase in Q angle and knee valgus in patellofemoral pain group compared to pain-free control group. It seems that strengthening the lower extremity muscles can be effective in preventing or improving abnormalities such as knee valgus and preventing the risk of patellofemoral pain syndrome.