Back pain and related symptoms rank among the second most frequent medical complaints. Disability from low back pain is second only to the common cold as a cause of lost work time and is the most common cause of disability in people under 45 years of age.
In the United States, the lifetime prevalence of back pain is approximately 80%, with a one-year prevalence rate of 15% to 20%„the highest prevalence is in the 45 to 64 age group.
In reality, the natural history of acute low back pain is very favorable and the same is true for sciatica (an inflammation of the sciatic nerve, characterized by pain and tenderness through the thigh and leg):
- 60% recover in 1 to 3 weeks;
- 90% recover in 6 to 8 weeks; and
- 95% recover in 12 weeks.
- Serious causes of low back pain (e.g. cancer) are uncommon (less than 1%).
The onset of acute low back pain most often is the result of mechanical damage due to excessive and prolonged poor posture and mechanics, a sedentary lifestyle and inadequate conditioning. Seemingly trivial stress such as bending over, sneezing or coughing can produce a herniated disc when superimposed on chronic wear and tear. People in a sedentary occupation have a high risk of herniating a disc.
During the flexion that occurs with sitting, intradiscal pressure is greatest and the disc exerts pressure on the thinnest, least supported area of the supporting ligament known as the annulus fibrosus. As a result, the disc can herniate.
Mechanical low back pain may be defined as pain secondary to overuse of a normal anatomic structure (muscle strain) or pain secondary to injury or deformity of an anatomic structure (herniated nucleus pulporus). Mechanical low back pain is usually aggravated by static loading of the spine (prolonged sitting or standing), long levered activities (e.g. vacuuming) or levered postures (bending forward). It is eased when the spine is balanced by multidirectional forces (e.g., walking) or when the spine is unloaded (e.g., reclining).
The history and physical examination is the first step in the evaluation and management of low back pain. Based on this information and specific guidelines, x-rays may be ordered; however, not every patient with low back pain requires x-rays.
Since the natural history of low back pain is favorable, most patients can start initial and usually successful therapy without the benefit of x-rays, a CT scan or MRI scan. Though radiographic evaluation may identify anatomic alterations in the lumbar spine, studies have shown that these may correlate poorly with the presence or severity of low back pain. The physician must take all the clinical data together and formulate a diagnosis and treatment plan based upon all the collected information. The physician does not want to intervene with inappropriate surgery nor overlook the possibility of a serious complication associated with a mechanical disorder (cauda equina syndrome) or a secondary cause of back pain (malignancy); the latter can be identified in the history and physical by certain "red flags."
The majority of patients will improve with controlled physical activity, physical therapy, nonaddictive non-steroidal anti-inflammatory drugs, and, in appropriate patients, muscle relaxants. Surgical invention is reserved for the patient who has not shown improvement on conservative therapy and has undeniable symptoms and signs (sciatica) associated with a mechanical disorder (herniated disc) that can be corrected by surgical intervention.
Chronic low back pain is a complex disorder that must be managed with a multi-disciplinary approach that addresses the physical, psychologic and socioeconomic aspects of the illness. Fortunately, chronic low back pain affects only a small percentage of patients.
Obesity and smoking correlate unfavorably with low back pain and may adversely affect the progression of the disorder. Overall physical fitness will correlate favorably with recovery from low back pain and return to work. Training, education and ergonomic intervention may reduce the incidence of back disorders.
The competitive athlete and most individuals who exercise regularly maintaining a level of fitness, are less prone to lumbar spine injury and problems due to the strength and flexibility of supporting structures. These structures include strong abdominal and lumbar paraspinal muscles for support, and flexible gluteal and hamstring muscles.
Problems involving the lumbar spine are rare in athletes and account for less than 10% of sports-related injuries. Sports such as gymnastics, football and racquet sports have a higher incidence of associated lumbar spine problems related to repetitive twisting and bending motions. Most injuries are minor, self-limited and respond quickly to conservative treatment. The incidence of lumbar spine problems with the casual or weekend athlete may be higher and related to the individual's level of fitness. Prevention through proper conditioning and technique is important.