Gaenslen’s test is used to distinguish between lumbosacral and SI joint pathology. To perform this test, position the patient supine close to the edge of the examination table. Ask the patient to flex both hips and knees, bringing the thighs to her chest so that the lumbar spine is pressed against the examination table. Then, hyperextend one hip with one hand, and with the other, apply force to increase flexion on the opposite side. The test is positive for SI joint pathology if the patient experiences pain with this maneuver.