the concentric isokinetic exercise group will perform quadriceps and hamstring concentric isokinetic exercises in addition to the conventional physiotherapy and exercise program 3 times a week during 6 weeks.

the eccentric isokinetic exercise group will perform quadriceps and hamstring eccentric isokinetic exercises in addition to the conventional physiotherapy and exercise program 3 times a week during 6 weeks.

the control group will perform the standard exercise program predetermined by us consisting of stretching exercises and isometric strengthening (these exercises will be done at home, too) and the conventional physiotherapy program will be applied 3 times a week during 6 weeks.

concentric isokinetic exercises

Joint position sense will be evaluated with isokinetic dynamometer at predetermined angles.

Ultrasonographic evaluation is an outcome measure to evaluate muscle structure. In our study ultrasonographic evaluation will be performed to determine the muscle structure (muscle thickness(mm), fascicle length(mm), pennation angle(degree)) of quadriceps and hamstring muscles. Muscle thickness will be defined as the distance between the deeper and upper aponeurosis. The pennation angle will be calculated as the angle of insertion of muscle fascicles into the deep aponeurosis. Fascicle length will be defined as the length of the fascicular path between the superficial and deep aponeurosis.

WOMAC Osteoarthritis Index (score range 0-100) include 3 subscales and will be used to evaluate knee pain(score range 0-20), stiffness (score range 0-8), and functional limitation (score range -68). Womac is comprised of 24 items ( pain-5 items, stiffness-2 items, physical function-17 items). All items are scored on a scale of 0-4. Lower scores indicate lower disability.