The most helpful signs in detecting nerve root compression are passive straight-leg raising (possible up to almost 90° in normal individuals) with the patient supine and variations of this test. Raising the straight leg places the sciatic nerve and its roots under tension, thereby producing radicular, radiating pain from the buttock through the posterior thigh if there is compression of these neural structures. This maneuver is the usual way in which compression of the L5 or S1 nerve root is detected (Lasègue sign), however, it may also cause an anterior rotation of the pelvis around a transverse axis, increasing stress on the lumbosacral joint and causing milder radiating pain if this joint is arthritic or otherwise diseased. Straight raising of the opposite leg (“crossed straight-leg raising,” Fajersztajn sign) may also cause pain on the affected side and is a more specific sign of prolapsed disc than is the Lasègue sign but far less sensitive. The many derivatives of the straight-leg raising sign are discussed in the section on lumbar disc disease further on and summarized in the review by Ropper and Zafonte. Asking the seated patient to extend the leg so that the sole of the foot can be inspected is a way of checking for a feigned Lasègue sign.
A patient with lumbosacral strain or disc disease (except in the acute phase or if the disc fragment has migrated laterally) can usually extend or hyperextend the spine with little or no aggravation of pain. If there is an active inflammatory process or fracture of the vertebral body or posterior elements, hyperextension may be markedly limited. In disease of the upper lumbar roots, hyper-extension of the leg with the patient prone is the motion that is most limited and reproduces pain; however, in some cases of lower lumbar disc disease with thickening of the ligamentum flavum, this movement is also painful.
Maneuvers in the lateral decubitus position yield less information but are useful in eliciting joint disease. In cases of sacroiliac joint disease, abduction of the upside leg against resistance reproduces pain in the sacroiliac region, sometimes with radiation of the pain to the buttock, posterior thigh, and symphysis pubis. Hyperextension of the upside leg with the downside leg flexed is another test for sacroiliac disease. Rotation and abduction of the leg evoke pain in a diseased hip joint and with trochanteric bursitis. A helpful indicator of hip disease is the Patrick test: With the patient supine, the heel of the offending leg is placed on the opposite knee and pain is evoked by depressing the flexed leg and externally rotating the hip.
Gentle palpation and percussion of the spine are the last steps in the examination. It is preferable to first palpate the regions that are the least likely to evoke pain. At all times the examiner should know what structures are being palpated (Fig. 10-2). Localized tenderness is seldom pronounced in disease of the spine because the involved structures are so deep. Nevertheless, tenderness over a spinous process or jarring by gentle percussion may indicate the presence of local spinal inflammation (as in disc space infection), pathologic or traumatic compression fracture, metastasis, epidural abscess, or a disc lesion.