Back Pain - Causes of low back pain

Article by Adjunct A/Prof Hee Hwan Tak

Back Pain - Causes of low back pain

Adjunct A/Prof Hee Hwan Tak

Orthopaedic Surgeon
National University of Singapore(NUS) 1990
Royal College of Surgeons of Glasgow 1995
Royal College of Surgeons of Edinburgh 1995
2000 Clinical Fellowship in Spinal Surgery in USA, training at the Tulane University, New Orleans, Louisiana and the University of Kentucky in Louisville and Lexington 
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Is your lower back weak?

Lower back pain is the second most common reason for absence from work, after common flu. There are many causes of low back pain, but fortunately, most acute low back pain resolves after a period of six weeks.

What causes lower back pain?

The most common cause of low back pain is acute back strain, due to several factors: poor posture and poorly executed movement(s). After a short period of rest and anti-inflammatory medications, the pain mostly resolves.

Reason for prolonged pain

For low back pain that does not subside after several weeks, you must rule our structural problem with the spine, notably the intervertebral disc.

The disc allows flexibility as well as supports the body while you go about in your daily routine.

 Due to repetitive stresses and aging, the disc(s) may wear out over time. One of the early changes in the degeneration of the disc is the gradual loss of ability of the disc to retain fluid in the centre of the disc, leading to it becoming more brittle and flatter.

The outer wall of the disc (annulus fibrosis) may tear, thereby causing extrusion of the inner disc material toward the nervous tissue that is contained in the spinal column.

You may complain of not only low back pain, but also shooting pain originating from the back, going down the buttock, thigh, and calf. This condition is called herniated, prolapsed, or “slipped” disc.

Spondylolisthesis

From the middle aged onwards, the space available for the nerves contained in the spinal column gradually becomes less. This condition is called spinal stenosis, and is caused by gradual 360-degree encroachment from thickened ligament in the spinal canal, bone spurs from the facet (spinal) joints, and extrusion of the disc(s). You may complain of increasing back and leg pain whenever you stand or walk, and will need to find a place to sit in order to get some relief form the pain. Some cases of spinal stenosis are associated with instability of the spine, where the vertebra slips forward in relation to the vertebra below. This is called spondylolisthesis. In other cases of spinal stenosis, the spine may also be crooked, a condition known as degenerative scoliosis.

Spine problem

Back pain may also originate from the loss of integrity of the bony structure of the spine. Examples are fractures, tumors, and infections. Osteoporotic spinal fractures are the most common type of fractures encountered in the spine, and the word osteoporosis defines the typical age of these patients. Other causes e.g. spine infections are relatively rare in Singapore. In our neighbouring countries, tuberculosis of the spine leading to destruction and fractures of the spine are still commonly seen. Certain types of cancer, notably thyroid, lung, breast, prostate, and kidney are known for their ability to spread and involve the spine in the disease process.

Certain rheumatic conditions (e.g. rheumatoid arthritis, ankylosing spondylitis) can also have involvement of the spine. Classically, ankylosing spondylitis affects young males, and often begins in the sacro-iliac joints located between the sacrum (bottom portion of the spinal column) and the pelvis.

Back pain may not always derive from the spinal column and its supportive structures. You may complain of back pain, but what actually it means is that you are actually having referred pain to the spine, the originating source being somewhere else.

Other causes of back pain

Often, the problem lies in the organs located close to the spine e.g. pancreas, small intestines (duodenum), kidneys, uterus, and aorta. Besides the feeling back pain, you may have other symptoms to alert your doctor that the source may not come from your spine but elsewhere.

Medical treatment

In assessing the cause of your low back pain, you doctor will take a detailed history documenting the location, duration, frequency, and characteristics of the pain. Your doctor will also specifically ask you for any problems with the functioning of your nerves e.g. weakness, numbness, tingling (pins and needles), bladder and bowel control. Symptoms of general unwell and malaise will also be asked, in order to rule out potentially life and limb threatening spinal conditions. Examination of the spinal column will subsequently be performed to check the location of the tenderness, as well as the presence of impaired mobility of your spinal column. Testing to check the integrity of the nerves will also be done in a slow and careful manner. The testing will involve checking the strength of the various muscle groups moving the joints, reflexes of the extremities, as well as the feeling of the skin.

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