The classic physical examination of a herniated disc is the straight leg raise test; however, it is also a frequently misleading test. The straight leg raise is performed with the patient in the supine position, and the examiner passively and slowly raises the patient’s lower extremity with the knee joint straight. In a normal person, the straight leg elevation test allows the L5 and S1 nerve roots to slip approximately 2 to 6 mm within the spinal canal and intervertebral foramen. Misconceptions about the straight leg elevation test The first misconception: what its positive presentation consists of. First of all, it should be clear that back pain caused by manipulation is not considered a positive result. More importantly, the posterior femoral pain or lower extremity pain produced only when the lower extremity is elevated from the examination table to between 30o and 70o is considered positive. When the leg is elevated more than 70o, the nerve roots do not produce any further deformation in the spinal canal; many patients instead feel discomfort with tension in the hamstrings. When the leg is elevated less than 30o, there is no tension in the nerve roots within the spinal canal. Those so-called positive results that occur at less than 30o of straight leg elevation may be better understood by the examiner to help explain this unreliable finding. The second misconception: that any type of compression of a spinal nerve root can cause a positive presentation on the straight leg raise test. Isolated compression of a nerve root is not sufficient to elicit signs of nerve tension. More likely, the inflammatory process is equally important in producing this symptom. Chronic nerve root compression, as seen in lumbar spinal stenosis, does not usually elicit signs of nerve root tension; therefore, the straight leg raise test is more appropriate for acute disc herniation with nerve root inflammation rather than chronic disc herniation or spinal stenosis. The third misconception is that a positive straight leg raise test can be performed regardless of the location of the herniated disc. The manual examination usually does not cause movement of the L4 nerve root, so the test is only indicated for the diagnosis of L5 and S1 nerve root provocation signs. Since a lumbar disc herniation involving the upper lumbar nerve roots usually causes only femoral nerve provocation, a more appropriate spinal nerve root tension test for the diagnosis of upper lumbar nerve root involvement is the femoral nerve pull test. The femoral nerve tension test is performed with the patient in a prone position with the knee flexed at 90o and the hip passively hyperextended. The pain can occur at any angle of the maneuver, and some patients cannot even lie prone because the position alone is sufficient to induce a pull on the femoral nerve and trigger symptoms. The straight leg raise test has a high correlation with various parameters that indicate the patient’s pain level. Positive straight leg elevation test results almost always correlate linearly with rest pain, nocturnal pain, pain after coughing and pain medication, and the degree of reduction in walking distance. However, despite the sensitivity of the straight leg raise test, the degree of restriction was not related to the size and location of the herniated disc. The size of the herniated disc decreased over time, and the shape of the herniation did not correlate with the corresponding improvement in the straight leg raise test. A more valuable physical examination for lumbar disc herniation is the alternating straight leg raise test. The alternating straight leg elevation test is similar to the conventional straight leg elevation test, except that the healthy limb is also elevated. The positive sign is recurrent radicular pain in the contralateral limb when one lower limb or the symptomatic side is elevated. It has been reported that 97% of lumbar disc herniations can be detected when this sign is positive.