Straight leg raise test The straight leg raise test is a painful pull on the sciatic nerve or one of the nerve roots. It is performed when the patient is supine and the lower extremity is gradually and slowly raised and straightened. The pain elicited should be similar to that normally felt by the patient, e.g., in the same area of the affected nerve root. When the knee is straightened and the lower extremity is raised, the nerve root slides freely through the foramen, and in the case of the L5 nerve root, the foramen is pulled out approximately 12 mm. When the lower extremity is resting on the support surface in the supine position, there is no tension on the sciatic nerve and nerve root. However, when the lower extremity is elevated in knee flexion, the sciatic nerve and its roots remain free of tension. If the knee is straight or the lower extremity is gradually raised with the knee extended, the sciatic nerve travels an increased distance and tension gradually increases. In the normal state, some patients have pain in the posterior thigh due to tension in the s extensor muscle being pulled, called a false positive Lassegue’s sign. When doing the straight leg raise test, 2 points need to be noted: move gently and stop as soon as the patient feels pain. The straight leg raise test should not be done under general anesthesia because of the loss of pain protection mechanism. It is easy to damage the sciatic nerve.