They say that you don’t appreciate what you’ve got until it’s gone, and this is certainly true when it comes to the human body. Aging causes atrophy and loss of elasticity of many systemic tissues ranging from those that make up the lenses of our eyes, to arteries of our hearts, to the frontal cortex of our brains. The muscles, tendons and ligaments that hold our frames together are no exception.
However, there is one important tissue of the musculoskeletal system that many people rarely think about: cartilage. There are three types of cartilage:
- Elastic cartilage — a springy type of cartilage that gives shape to our ears and the tips of our noses
- Hyaline cartilage — a springy, tough, and elastic cartilage found around the windpipe and between the ribs and joints
- Fibrocartilage — the toughest type of cartilage, found between the bones of the hip and pelvis as well as between the discs and vertebrae of the spine
It is this third type of cartilage, or rather the lack of it, that is so often the cause of chronic back pain, especially in older adults. Age-related changes to cartilage and related tissues can result in the following:
- Degenerative disc disease — Just as the pillows in our beds get more compressed with usage over time, the discs of our spine can become brittle and flattened. Discs may bulge out or vertebrae may no longer sit properly on top of each other, both of which can also cause compression on the spinal cord.
- Ligament thickening — Our spinal ligaments can ossify (turn from ligament to bone). This can lead to a narrowing of the space between the vertebrae and spinal cord.
- Spinal osteoarthritis — The fibrocartilage that covers the facet joints (which connect the backs of the adjacent vertebrae) can become inflamed and degenerate. When this happens, sometimes the impinged vertebrae can form bone spurs in the body’s attempt to repair itself. Bone spurs, or osteophytes, are tiny, pointed outgrowths of bones. Although they are not painful in and of themselves, they can irritate or grow into the space around the spinal cord. Sometimes a compression of the spinal nerves results.
All of these conditions can result in spinal stenosis, a narrowing of the space in the spinal canal. According to the National Center for Biotechnology Information database, acquired lumbar spinal stenosis is a “significant cause of disability in the elderly” with a prevalence of 19.4% for populations aged between 60-69 years of age. It is also the most common cause of spinal surgery in patients over 65 years old.
Classic symptoms of lumbar spinal stenosis include pain exacerbated by prolonged walking or standing, numbness, tingling, and muscle weakness. Although most cases of spinal stenosis tend to have a gradual onset, severe cases, typically injury-induced, can result in loss of motor function in the legs. The most extreme instance of lumbar spinal stenosis, the rarely occurring cauda equina syndrome, can result in loss of control of bladder and bowels and require immediate surgery.
Because any prolonged pressure on spinal nerves can result in crippling pain and possible permanent damage, it is vital for clinicians to accurately diagnose and treat spinal stenosis. Non-contrast MRI is most commonly used to determine the extent of the narrowing of space in the spinal canal.
There are lots of things that disappear as we age. In the case of lumbar spinal stenosis, that missing thing is empty space.