Low back pain is the cause of much time lost from work in the USA, with about 400,000 workers disabled by back pain each year. It has been estimated that 80% of the population suffers low back pain at some time. All physicians are called on at least occasional to advise patients with this complanint, and a systematic approach is necessary to differentiate the numerous possible causes. Diagnosis and management can be frustrating, because the exact cause of most low back pain is uncertain and no cure is known. The first task is to identify the relatively few cases with specific causes that can be treated. The less rewarding and more demanding task is to provide long-term guidance and management for patients for whom specific remedies are unavailable.
a. Symptoms and Signs: The most common cause of low back pain is mechanical strain. Patients complain of pain related to overexertion. Pain may immediately follow lifting or other forms of exertion or may have a more insidious onset after prolonged physical activity. Many patients in this group demonstrate generally poor conditioning, with poor abdominal muscle tone and poor posture.
Pain from lumbar strain is exacerbated by bending or lifting and relieved by rest. Pain is often described as a deep-seated aching that is dull and somewhat diffuse. Pain is most severe in the lumbosacral area and may radiate into the buttocks. Palpation reveals tenderness in the paraspinous area, with “trigger points” or “knots” in the erector spinae. Spasm of the paraspinous muscles is a common finding, and the patient may have a slight list toward the nonpainful side. Motion is limited by pain.
Physical examination is remarkable for the lack of neurologic involvement. Deep tendon reflexes are present and symmetric. Motor power and sensation in the lower extremities are normal. Rectal tone is normal. The straight leg-raising test is normal. This test is performed with the patient lying supine on the examining table. The examiner lifts the patient’s leg, which is extended at the hip and knee. This maneuver passively stretches the sciatic nerve and results in transmission of tension to the lumbosacral roots that contribute to the nerve. The lack of radicular leg pain associated with straight leg raising diminishes the likelihood of spinal nerve compression as the source or symptoms.
b. X-Ray Findings: X-ray examination may reveal changes such as lumbar disk space narrowing and osteophytosis or may be entirely normal. Because x-ray signs are nonspecific, many clinicians avoid x-ray studies during the initial evaluation. X-rays should be obtained for persons over age 50, in whom metastatic tumors are more likely, and those under age 20, in whom symptomatic congenital or developmental anomalies may be present. For other patients, x-rays may be obtained during subsequent ivsits if symptoms do not resolve within weeks.
Course & Progsis
The usual course of lumbar strain is spontaneous remission with time. Relapses of pain are commonly precipitated by stressful activity, though months may pass without symptoms. Some patients complain of constant pain without real remission. Probing inquiry frequently reveals profound depression in these individuals, for whom illness and disability have become dominant elements in their lives. When strain is attributed to working conditions, the clinical course may be complicated by considerations of secondary gain.
Patients who fail to respond to rest and supportive measures must be carefully reexamined to rule out development of neurologic compromise. Those who remain neurologically normal must be encouraged to return to normal activities as rapidly as possible. Prolonged reliance upon analgesics must be discourage.
Management of lumbar strain includes analgesics and rest during the acute phase. A firm board beneath the patient’s mattress provides support for tender spinal muscles. Abdominal conditioning and spinal muscle strengthening exercises are prescribed only when pain subsides. Typical exercises include bent-knee sit-ups and hamstring and spinal muscle stretching. Lumbosacral corsets with steel stays provide mechanical support for the spine by compresing and reinforcing the flaccid abdominal wall proper body mechanics should be discussed with the patient, especially the proper manner of lifting objects while bending the legs rather than the spine. Postural exercises may be useful and most effectively taught by trained physical therapists.