Causes of Spondylosis
Aging is the predominant cause of spondylosis, also known as spinal arthritis. We put our bodies through a lot of stress and strain every day, and over the years, this can change the various structures of the spine. (See Anatomy of Spondylosis to understand what spinal components spondylosis affects). Even before you experience the symptoms of spondylosis—pain and stiffness, for example—your joints and other spine structures are degenerating (that means wearing out).
Cause and Effect Scenario
You should think of the causes of spondylosis as a "cause and effect" scenario. The main cause is aging, but the way aging affects your spine can lead to other changes and problems. Spondylosis is a cascade: One anatomical change occurs, which leads to more degeneration and changes in your spine's structures. These changes combine to cause spondylosis and its symptoms.
Degenerative Disc Disease
Generally, the first part of your spine to wear out are your intervertebral discs. For this reason, patients with spondylosis often also have degenerative disc disease (DDD). The effects of these 2 spinal conditions are very related.
The changes begin in your discs, but eventually the process of aging will affect the other motion segments of your vertebrae. (The discs and the facet joints are considered the motion segments, which means that they help you move.) Over time, the collagen (protein) structure of the annulus fibrosus (that's the outer portion of the intervertebral disc) changes. Additionally, water-attracting molecules—and hence water—in the disc decreases. Both of these changes reduce the disc's ability to handle back movement.
Through degeneration, the disc will become less spongy and much thinner. A thinner disc means that the space between the vertebra above and below the disc gets smaller, which causes a new problem, this time with the facet joints. They help stabilize the spine, and if the disc loses height, the way the facet joints move changes. Then the cartilage that protects the facets begins to wear away, perhaps causing irritation and inflammation of spinal nerve roots. Without the cartilage, the facet joints start to move too much: They "override" and become overly mobile.
Abnormal Spinal Movement
This hypermobility causes another change in your spine. It tries to stop the movement with the growth of small bony elements called bone spurs (osteophytes). Unfortunately, the bone spurs sometimes pinch nerve structures and cause pain. The bone spurs can narrow the space for the spinal cord and nerves—that disorder is called spinal stenosis. Degenerative disc disease won't cause spinal stenosis in everyone, but it's something you should be aware of if you have spondylosis.
Role of Genetics
Your genes can also cause spondylosis. You may be pre-disposed to excessive joint and disc wear and tear, so if someone in your family has or had spondylosis, you may also develop back or neck pain related to spondylosis.
Finally, the way you're living could lead to spondylosis. Smoking, for example, adversely affects your discs and can cause them to degenerate faster. Smoking actually decreases the amount of water in your discs, and water is part of what helps your discs absorb movement. With less water content, your intervertebral discs can wear out sooner.