the study will be done to investigate the effect of hip adduction isometric contraction on the pain level by VAS and knee extensors peak torque by using the isokinetic dynamometer in patients with unilateral patellofemoral pain syndrome

the study will be done to investigate the effect of isometric hip adduction that will be measured by the hand held dynamometer (the manual muscle tester) to measure the produced adduction torque and its effect on the peak torque of knee extension by the knee extensors which will be measured by the isokinetic dynamometer in addition to measuring the pain intensity before and through the assessment by using the visual analogue scale

Inclusion Criteria:

• Anterior or retro-patellar knee pain from at least 2 of the following Activities: (1) prolonged sitting; (2) stair climbing; (3) squatting; (4) running; (5) kneeling; and (6) hopping/jumping (Tyler et al., 2006).
• Insidious onset of symptoms unrelated to a traumatic incident and persistent for at least 6 weeks (subacute or chronic pain).
• They will be diagnosed as a PFPS case by a physician
• The patient's age will be ranged from 18-35 years to limit the possibility that PFPS over age 35 may have been complicated by arthritic changes, and also the patients should have closed epiphyseal growth plates (Robinson and Nee, 2007).

Exclusion Criteria:

• A history of any of the following condition: meniscal or other intra articular pathologic conditions; cruciate or collateral ligament involvement.
• A history of traumatic patellar subluxation or dislocation.
• Previous surgery in the knee and hip joints.
• Any lower limb bony/congenital deformity.
• Ankle, Knee and hip joints osteoarthritis.
• A history of any conditions affects muscle strength: diabetes mellitus, rheumatoid arthritis.
• Pregnancy.

patients suffering from unilateral patellofemoral pain syndrome

the outcomes can be used in future researches concerning this field of interest