CLINICAL EVALUATION
Focused history and physical examinations are fundamental elements in the assessment of low back pain. They are especially helpful in the preliminary classification of acute LBP into one of three groups: (1) nonspecific low back pain, (2) LBP potentially associated with radiculopathy or spinal stenosis, or (3) LBP potentially associated with systemic disease. The third category is most important to recognize early; it includes the small proportion of LBP patients with serious or progressive neurologic deficits or underlying medical conditions requiring prompt evaluation (such as tumor, infection, or the cauda equine syndrome), as well as patients with other conditions that may respond to specific treatments (such as ankylosing spondylitis or vertebral compression fracture). The vast majority of these patients experience nociceptive pain referred from somatic structures. The clinical picture associated with this syndrome is one of axial pain predominance, whereas radicular impingement or irritation typically involves leg symptoms in a unilateral or, less commonly, bilateral distribution.
The physical examination of a low back pain patient involves assessment of motor, sensory, and reflex function, as well as strength, range of motion, and neurologic impairments. It must begin with the assessment of vital signs and a systemic survey aimed at identifying evidence of nonmechanical and visceral causes of low back pain, including primarily bony malignancies—such as multiple myeloma—or metastatic malignancies, particularly of the lung, breast, and prostate; disk space infection; nephrolithiasis; pyelonephritis; pancreatitis; aortic aneurysm; or metabolic bone disease. A thorough inspection and palpation of the affected area follow, with careful attention to the presence of deformities or radiation of pain. All patients require evaluation for the certain important “red flags” that may indicate serious disorders.
Neurologic findings, such as saddle anesthesia, bilateral radiculopathy, bilateral leg weakness, urinary retention, and fecal incontinence, are consistent with the diagnosis of cauda equina syndrome and require immediate emergent attention. Malignancy should be suspected in patients with severe low back pain after minor trauma, unrelenting night or rest pain, unexplained weight loss, and progressive neurologic deficit.
Chronic steroid use, immunosuppression, intravenous drug abuse, recent urinary infection, or skin infection near the spine should direct the differential diagnosis toward infectious etiology, particularly epidural abscesses. Fracture is a possible diagnosis in the setting of trauma, osteoporosis, or chronic steroid use.
When there is no neurologic deficit present and LBP is localized to the lumbar spine and buttocks, lumbar strain related to soft tissues, or inflammatory processes at the level of disk, facet joints, or bony end plates are likely considerations.
RANGE OF MOTION
Range of motion in the lumbar spine is dependent on the resistance to movement of the intervertebral disks and the size of the articular surfaces. The most significant degree of motion is in the thickest disks and largest joint surfaces, mostly between L5-S1. Tests for range of motion include flexion, extension, lateral bending, and rotation. The clinician should bear in mind, however, that limitation of spinal range of motion is a nonspecific finding that is not strongly associated with any particular diagnosis.
Flexion. While standing, have the patient fold forward with the knees straight and touch his toes. Measure the distance from the fingertips to the floor. Lumbar pain may prevent full range of motion.
Extension. With the patient standing, place your palm on the patient’s posterosuperior iliac spine and have the patient bend backward as far as possible. Assess the degree of extension. This motion aggravates the pain experienced by patients with spondylolisthesis, whereas flexion results in pain relief.
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