Tenderness over the interspinous ligaments or over the region of the articular facets between the fifth lumbar and first sacral vertebrae is consistent with lumbosacral disc disease (see Fig. 10-2, sites 2 and 3). Tenderness in this region and in the sacroiliac joints is also a frequent manifestation of ankylosing spondylitis. Arthritic changes at a facet may cause the same tenderness. Tenderness over the costovertebral angle often indicates genitourinary disease, adrenal disease, or an injury to the transverse process of the first or second lumbar vertebra (see Fig. 10-2, site 1). Tenderness on palpation of the paraspinal muscles may signify a strain of muscle attachments or injury to the underlying transverse processes of the lumbar vertebrae. Focal pain in the same parasagittal line along the thoracic spine points to inflammation of the costotransverse articulation between spine and rib (costotransversitis). Other sites of tenderness and the structures implicated by disease are shown in the figure.
In palpating the spinous processes, one notes any deviation in the lateral plane (this may be indicative of fracture or arthritis) or in the anteroposterior plane. A “step-off” forward displacement of the spinous process and exaggerated lordosis are important clues to the presence of spondylolisthesis (see further on).
Abdominal, rectal, and pelvic examinations may lead to the discovery of neoplastic or inflammatory diseases in these body parts that are referred to the lower part of the spine.
On completion of the examination of the back and legs, one turns to a search for motor, reflex, and sensory changes in the lower extremities (see “Herniation of Lumbar Intervertebral Discs,” further on in this chapter).
Depending on the circumstances, these may include a blood count, the acute phase reactants, erythrocyte sedimentation rate and C-reactive protein (especially helpful in screening for spinal osteomyelitis, epidural abscess, or myeloma). Other useful blood tests are calcium, alkaline phosphatase, and prostate-specific antigen (if one suspects metastatic carcinoma of the prostate); serum protein immunoelectrophoresis (myeloma proteins); in special cases, a tuberculin test or serologic test for Brucella; a test for rheumatoid factor; and human leukocyte antigen (HLA) typing (for ankylosing spondylitis), all in the appropriate settings.
Conventional radiographs of the lumbar spine in the anteroposterior, lateral, and oblique planes (preferably with the patient standing) are not very useful in the routine evaluation of low back pain and sciatica but they can disclose some information. Readily demonstrable in plain films are narrowing of the intervertebral disc spaces, bony facetal or vertebral overgrowth, displacement of vertebral bodies (spondylolisthesis), compression and other fractures of the spine, and most importantly, unsuspected infiltration of bone by cancer or myeloma. However, in cases of suspected disc herniation or tumor infiltration of the spinal canal, one generally proceeds directly to MRI if subsequent action is to be taken.