Intra and Inter Reliability of 30 Seconds Chair Stand Test as Self-test for Patients With Knee Osteoarthritis.

Patients will perform the 30 seconds chair stand test as a self-test twice at home with approximately two days apart. The last self-test should be performed approximately one week before the testing with a physical therapist.

Same patients performing the self-test will be tested by a physical therapist approximately one week after the last self-test. The physical therapist will be blind to the self-test results.