What is it?
Osteoarthrits (OA) is condition associated with deterioration in the cartilage of joints. The deterioration most commonly occurs as people grow older. Cartilage contains specific components that are maintained by chondrocytes. Over time, chondrocytes lose the ability to produce cartilage components that support the joint. Cartilage deterioration is associated with roughening of cartilage surfaces and local joint inflammation directed against cartilage debris. In response to this cartilage deterioration, the cartilage thins allowing greater forces to be placed on the underlying bone. The bone responds to these abnormal forces with overgrowth. Joints with osteoarthritis have abnormal contours and are painful. Joints in the spine are prone to develop osteoarthritis.
Intervertebral discs start losing water when you are in your 20’s. When discs lose water, they lose their ability to act as shock absorbers between the vertebrae. They become thinner. When the space is narrowed, greater pressure is placed on the facet joints in the back of the vertebrae. These joints are made for guiding motion, not for weight-bearing. Cartilage covers joint surfaces and acts as cushions. When increased pressure is placed upon these facet joints, the cartilage wears out causing the bones to rub together, potentially causing pain and stiffness. This change is known as osteoarthritis or OA.
The main symptom of OA of the spine is back pain. OA of the spine however can occur without causing pain. Why certain facet joints with OA are painful and others are not is not known. Usually, spine pain caused by facet joint OA is worse with standing, bending backward, or lying flat in bed. Pain may radiate across neck into the shoulders, or across the low back into the buttocks or upper thighs. OA pain does not typically radiate into the arms or legs.
The presence of osteoarthritic changes can be observed with standard x-rays or MRI scans. However, these techniques are unable to identify the location or presence of pain.
The non-surgical therapy of OA of the spine may include a number of options.
Medication: Many medications have the potential to decrease pain generated by irritated joints and muscles. These include non-steroidal anti-inflammatories, analgesics, muscle relaxants, and anti-depressants. An increasing concern is the potential toxicities of long-term use of these medicines in older individuals who develop OA of the spine. Side effects of these medications include, gastrointestinal bleeding, elevated blood pressure, and change in mental function.
Facet Joint Block: An alternate to oral medicine is facet joint blocks. Facet joint blocks are injections of a long acting anesthetic around a facet joint. Once the painful joint is identified, the injection can be accomplished with fluoroscopic guidance of the needle to the joint. If the block is successful, a “killing” of the nerve can be accomplished by burning the nerve with radio waves. Alternatively, the nerve can be frozen with a cold probe. In some patients, this procedure can result in decreased pain lasting one to two years at which time the procedure can be repeated.
Surgery: Surgical therapy of osteoarthritis is controversial. Some spine surgeons believe that fusing portions of the spine that are causing only back pain result in individuals with less spine pain. In many circumstances, the individual has traded one spine pain for another. In the neck, the benefits of spinal fusion may be better, but patients remain at risk of progressive osteoarthritis at other levels of the spine.
As a generalization, spine surgery is offered for individuals with leg or arm pain, not those with pain limited to the spine alone. An exception to this rule is spinal instability. Stabilization of the spine can offer symptom relief for those with associated spine pain. The decision to do surgery in this circumstance should only occur after an informed discussion with a spine surgeon
Prevention: Disc degeneration starts in the third decade of life. Minor changes start with the production of abnormal collagen. These collagens appear in the setting of oxidative stress associated with smoking.
References: Borenstein DG, Wiesel SW, Boden SD: Low Back and Neck Pain: Comprehensive Diagnosis and Management. 3rd Edition. Philadelphia: W. B. Saunders, 2004.