My doctor took an X-ray of my hands and showed me the bone spurs I have growing. The bone spurs confirm that I have osteoarthritis. But what causes these bumps to form in the first place?
The development of osteoarthritis is complex and multifactorial (i.e., there are many risk factors involved). It is safe to say that for as much as we do know about this disease, there is much more we do not understand about it. Scientists are actively exploring who gets osteoarthritis, why and how it develops, and what can be done to prevent (or treat) it.
All aspects of the joint and surrounding soft tissue are affected. These structures support and stabilize the joint and include the cartilage, first layer of bone (called the subchondral bone), ligaments, and tendons. Any injury, damage, shift, or change in these structures can also change the biomechanics, force, and load on a joint. And any of these events can become the first step in the cascade that eventually leads to arthritis.
What exactly are those changes and the chain of events? It might be helpful to look at this first by describing what is seen on X-rays and in the clinic. Early arthritic changes show up on X-rays as a slight narrowing of the joint space. This phase is referred to as the stationary non-erosive stage. The joint remains intact and stable.
The next phase is the destructive erosive phase. Here there is swelling and break down of the cartilage and subchondral layer. The tendons that attach to the bone start to thicken and degenerate. Inflammation of the joint fluid (synovitis) develops and creates an inflammatory phase (not unlike what happens with rheumatoid arthritis).
After the destruction, the joint tries to recover and remodel the damaged area. But all that happens is the formation of osteophytes (bone spurs), cysts, scar tissue, a thickened cartilage, and other bumps on the finger bones called Heberden's nodes.
As you have discovered, osteophytes (bone spurs) are one of the earliest things to show up on X-rays to suggest osteoarthritis is developing. These bumps form where the bone and cartilage meet. Often, the location of the bone spurs is right where the ligament attaches to the bone.
This finding has prompted experts who understand anatomy to suggest perhaps a ligament problem comes first. And as stated already: any injury, damage, shift, or change in the ligaments can also change the biomechanics, force, and load on a joint and the first step in the cascade that eventually leads to arthritis.
Robert A. Kaufmann, MD, et al. Osteoarthritis of the Distal Interphalangeal Joint. In The Journal of Hand Surgery. December 2010. Vol. 35A. No. 12. Pp. 2117-2125.
*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.