Test protocol – Prone lying active knee flexion. A. Correct – Prone lying active knee flexion at least 90° without (rot) movement of the low back and pelvis. B Not correct Pelvis rotates with knee flexion. Rating protocol: As patients did not know the tests, only clear movement dysfunction was rated as "not correct". If the movement control improved by instruction and correction, it was considered that it did not infer a relevant movement dysfunction.