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Background and Aim: Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition. Women with patellofemoral pain syndrome would present significant weakness in many of hip muscle groups when compared with the healthy group. The objective of the present study was to compare the strength of hip abductor, extensor and external rotator muscle groups in sedentary women with bilateral patellofemoral pain syndrome to a matched control group of sedentary women without patellofemoral pain syndrome. 

Materials and Methods: Twelve women with bilateral patellofemoral pain syndrome as experimental group and other twelve matched women as control group participated in this study. Maximum isometric strength for three hip muscles including abductor, extensor and external rotator muscle groups was measured bilaterally in all subjects using a dynamometer fixed on a platform and finally averaged between two limbs and compared with the control group.

Results: The hip abductor, extensor and external rotator muscle groups of experimental group were statistically weaker than that of the control group (p< 0.001).

Conclusion:  It seems that lower limb muscles including hip muscles of women with patellofemoral pain syndrome become weaker due to disuse conditions. 

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Background and Aim: The structure and function of the hamstring and quadriceps can contribute to the development and process of patellofemoral pain syndrome. As open and closed kinetic chain exercises have different effects on the knee joint, the aim of the current study was to investigate motor control of knee joint in both kinetic chains according to voluntary response index aspect.

 

Materials and Methods: 12 healthy knees and 12 injured knees (6 females in each group) were examined. Surface electromyography were performed in knee muscles including vastus medialis oblique, rectus femoris, vastus lateralis and biceps femoris while the subjects were doing flexion-extension of knee joint by isokinetic dynamometer system and one leg semi-squat movement. Then voluntary response index was calculated.

 

Results: There were no significant difference between the patients and healthy groups (p>0.05). In the patient group, correlation between similarity index and magnitude was seen.

 

Conclusion: Probably in the low intensity patellofemoral syndromes, voluntary response index could not differentiate between healthy and the patient groups. In the patients with patellofemoral syndrome group, correlation between similarity index and magnitude may represent co-contraction in their muscles.

 

Keywords: Patellofemoral pain syndrome, Motor control, Voluntary response index, Surface electromyography