Over time, the fluid in the cushioning disc between the vertebra decrease, which affects the ability of the disc to function normally. Fissures can develop in the annulus, or outer layer of the disc, making it more susceptible to tears. Vertebral endplate thinning can occur, which affects the blood supply to the disc. These factors can also lead the facet joints on the side of the vertebra to experience an increased workload, which can contribute to degeneration as well.
As degeneration occurs, minor trauma or unusual activity can produce back pain. This can produce muscle pain and spasms, tears in the outer ring of the disc, or annulus, and further degeneration of the nucleus or inner cushioned part of the disc. This can progress to laxity, and instability, as well as entrapment on nerve roots as they exit the vertebra.
Additionally, bone spurs or osteophytes develop in and around the facet joint and discs. The ligaments can thicken and cause narrowing of the spinal canal and compression on the spinal cord. This can cause central spinal stenosis or nerve root entrapment. Movement, or spondylolithesis, may occur, which can cause instability and movement in the spinal column. This may produce pain or weakness, particularly in an arm or leg.
Bones can also lose their density and develop osteopenia or osteoporosis. They can be more likely to fracture or break with trauma. Lifestyle habits such as smoking, being overweight, lack of exercise or exercising too much can also affect bone quality, making your spine more at risk of injury.