A common cause of low back and leg pain is lumbar spinal stenosis. As we age, our spines change. These normal wear-and-tear effects of aging can lead to narrowing of the spinal canal. This condition is called spinal stenosis. Spinal stenosis occurs when the space around the spinal cord narrows. This puts pressure on the spinal cord and the spinal nerve roots, and may cause pain, numbness, or weakness in the legs.
What causes spinal stenosis?
In the spine, arthritis can result as the disk degenerates and loses water content. In children and young adults, disks have high water content. As we get older, our disks begin to dry out and weaken. This problem causes settling, or collapse, of the disk spaces and loss of disk space height. As the spine settles, two things occur.
First, weight is transferred to the facet joints.
As the facet joints experience increased pressure, they also begin to degenerate and develop arthritis, similar to that occurring in the hip or knee joint. The cartilage that covers and protects the joints wears away. If the cartilage wears away completely, it can result in bone rubbing on bone.To make up for the lost cartilage, your body may respond by growing new bone in your facet joints to help support the vertebrae. Over time, this bone overgrowth-called spurs-may narrow the space for the nerves to pass through.
Second, the tunnels that the nerves exit through become smaller.
Another response to arthritis in the lower back is that ligaments around the joints increase in size. This also lessens space for the nerves. Once the space has become small enough to irritate spinal nerves, painful symptoms result.