Effects of Osteoarthritis

By Edward S. Pratt, M.D., M.B.A.

Unfortunately, even with the optimal lifestyle, our spines do age. The arthritic wear and tear on our spines can create several common medical problems.  They include degenerative disc disease, spinal stenosis, degenerative spondylolisthesis and degenerative scoliosis.

Degenerative Disc Disease is a condition in which the aging intervertebral disc becomes a “pain generator”. As a disc wears out it loses its ability to move, support weight, and cushion the vertebrae above and below. Stresses in the disc caused by movement cause microscopic injury, inflammation and pain usually by stimulating small nerves within the outer ring or annulus of the disc. Any increase in activity induces further microscopic injury to the annulus and adjacent bone, inciting further inflammation and pain. Treatment consists of anti inflammatory medications such as Ibuprofen, Aspirin and others, which help inhibit the inflammation caused by microscopic tissue injury, and exercises which improve core strength in the muscles around the spine allowing them to stabilize the trunk and support some of the weight. In an aging spine it can be very challenging to verify the exact structure which is causing pain. Many times there are many structures at each disc level that are arthritic and many levels involved. Provocative discography has been the standard in verifying which levels and which structures are generating pain, yet even discography has been very controversial. Discography consists of injecting saline or radiographic dye into the discs to determine if the pressure thus created reproduces the patient’s typical pain pattern. A study properly done can help differentiate this very complicated mix of multilevel structures that are causing pain from those that are not.

In patients with intractable pain from an identifiable disc, that have failed all other treatments, minimal access spinal fusion or disc replacement is usually offered. Minimal access fusion consists of gaining access to the disc through a small tube, removing the annulus and placing a spacer into the disc space which restores disc height. Bone is filled in around the spacer to promote the vertebra growing solidly together. This solid union, removes the stresses placed upon the annulus, prevents microscopic injury, turns off the inflammatory response that follows and decreases pain. Artificial disc replacements act to replace the biologic disc with a man made joint made of plastic and titanium. This new joint supports the weight without causing tissue injury and therefore again shuts off inflammation and pain. In early studies, disc replacement in those patients that met the criteria, was at least as successful limiting pain as fusion.

Spinal Stenosis occurs when the spinal canal that transmits the nerves between spinal cord and limb becomes narrowed. This narrowing is usually caused by arthritic deformation of the joints around the canal, ligament enlargement or in folding, and occasionally by abnormal sliding of the vertebrae which can pinch the nerves (spinal instability). The normal canal must be narrowed at least 50% for the nerves within to become squeezed or their accompanying blood supply to be limited. This usually causes pain, tingling, numbness and weakness in the legs, which comes on with activity and is relieved after a few minutes of rest, a symptom known as neurogenic claudication. The canal is slightly enlarged by bending forward, which is why patients with the advanced form of this condition will lean forward when they walk, or bend over a walker or shopping cart to get relief. Treatment includes core strengthening, epidural steroids injections and surgery. Strengthening only helps the patient maintain optimum trunk position which can occasionally help. Steroid injections minimize inflammation of nerves within the area of narrowing, perhaps allowing their minor swelling to subside and give them a bit more room. Epidurals are effective 65%-70% of the time short term; however this quickly decreases to about 35% improvement at 6 months. Surgery consists of removing arthritic tissues to open the canal back to its original size. It is usually about 85% effective in improving symptoms, requires an approximately two day hospital stay and will have patients back to pre surgical activity levels within four to six weeks.

Degenerative spondylolisthesis often accompanies spinal stenosis. Here the joints between two vertebrae become loose, and the upper vertebrae (and all the vertebrae above it) slip forward on the vertebrae below. The vertebrae become unhinged, which places greater stresses upon the discs and facets at that level. Advanced arthritis and disc collapse are often seen at levels of spondylolisthesis, and because the spinal canal develops a kink in it at that location, stenosis is never too far away. Treatment is conservative at first consisting of the same physical therapy, core trunk strengthening and stabilization exercises. Epidural steroids targeting compressed and inflamed nerves can also help. When surgery for nerve compression is necessary it is usually desirable to perform fusion as well. The reason for this is that the surgical procedure to decompress the spinal canal results in a destabilizing of the slip which in nearly half the patients will progress. As the slip gets worse the nerve compression usually recurs and the pain comes back. Thus decompression without fusion in this condition fails nearly 50% of the time, an unacceptably high failure rate for any surgery.

Degenerative scoliosis is a common consequence of advanced spinal arthritis. As arthritis becomes severe often the disc spaces will not collapse the same amount on the left and right. If several adjacent discs collapse on one side and not on the other a curve will develop. Where advanced curves in adolescents are corrected and fused relatively easily, the aging spine is considerably more stiff, and the bone less strong. Moreover, aging individuals are more prone to surgical complications. Bracing is often considered in order to help control pain during activities. Again exercise and core strengthening are central themes. Any surgery of scoliosis consists of a long incision, multiple levels of bone grafting and metal instrumentation, in order to promote a solid fusion of the vertebral levels from the top of the incision to the bottom. In older individuals this can subsequently lead to secondary degeneration above the fusion, and aggravation of the weight bearing joints below it. These would include the sacroiliac joints, hip joints and knee joints. For these reasons and others, surgical treatment of degenerative scoliosis is done only as a last resort.