What is a lumbar sprain or low back strain?

The difference between a sprain and strain in the back depends to the type of structures involved in the injury. Though the intervertebral discs and bones of the back get a lot of attention in back pain medicine, often the ligaments and muscles are involved, and are the most common cause of acute back pain. A back strain occurs when the muscle fibers are torn or abnormally strained. A low back strain occurs when the ligaments in the lumbar spine become strained or torn. Ligaments are rope-shaped bands of tough, fibrous connective tissue that connect bone to bone. Patients may experience some pain and inflammation from minor tears of these ligaments, or severe pain and loss of function from moderate to major tears. During major tears, the ligaments may become separated from their points of attachment to the bones.

Both lumbar sprains and low back strains are difficult to diagnose, based on a physical examination and basic diagnostics such as X-Ray. Also, lumbar sprains and low back strains involve similar types of symptoms, further making it difficult to distinguish the two conditions. Because of the similarities of symptoms, many physicians group the two conditions into a category called "musculoligamentous injuries". Most musculoligamentous injuries occur in the lumbar spine because this area of the back absorbs most of the weights and pressures from our upper body as we sit, stand, and lift heavy objects. The reason why these two musculoskeletal injuries are often grouped together is because the treatments and prognosis involved for both of them are the same, except in the event of total tears or ruptures that may require surgery (total tears and ruptures in the lumbar spine are very rare).

Nearly everyone will experience lower back pain, at some point in their life. Estimates are that 4 in 5 people have back pain at some point in their life. Though the discs are often involved in cases of chronic back pain, ligaments sprains and muscle strains are usually the cause of the majority of cases of acute back pain - by far the most common type.

Here are some examples of back pain symptoms that would indicate causes other than muscle strains and ligament sprains:
  • Severe, constant pain that can't be alleviated by lying down or changing positions.
  • Progressive lower extremity weakness.
  • Loss of bodily function (bowels and bladder).
However, these symptoms are rare, and the ligaments and muscles are usually involved with most cases of low back pain. The spine is supported by large muscle groups called the paraspinal muscles. These muscles hold the spinal column in place and support the majority of the weight of the upper body. The lumbar vertebrae are supported largely by tough ligaments to maintain the correct curvature of the spine and to stabilize it. The muscles and ligaments are always in use when we hold ourselves erect, and are especially prone to becoming stretched or strained when we engage in activities where we use back posture or put excessive pressures on the muscles and soft tissues of our lower back. The human spine is not well equipped for long, continuous periods of sitting in one position, nor is it especially equipped for the lifting of objects while people are bent at the waist. Because of the American lifestyle and work requirements, both of these types of bad back techniques are often used, and people who use them are more prone to having lower back problems.