Often I am consulted in the clinic for assessment and treatment of joint pain that has come on without any major trauma. The commonest cause for wear and tear type joint pain is osteoarthrosis (also called osteoarthritis) or degenerative joint disease. Osteoarthritis is the most common form of arthritis and results in the slow destruction of joint cartilage, the springy joint tissue which caps the bone ends and acts as both a shock absorber and bumper. As the cartilage thins,wears and breaks away the joint surfaces roughen, resulting in a loss of the normal smooth motion and frequently pain. But is this pain just a simple symptom or does it indicate a more serious problem?
Recent U.S. research, published 2009 in the journal Arthritis and Rheumatism, is showing that, in mice at least, the pain of osteoarthritis causes biochemical changes within the joints which actually contributes to further joint destruction. It suggests that the chemicals produced when pain is registered within a joint actually contribute to damaging the tough elastic cartilage. The mechanism is unclear in humans but it seems that discomfort from a joint such as a knee or hip registers as pain signals in a specific portion of the spinal cord, the dorsal horn. A specific chemical in this registering process, named interleukin 1 beta, additionally ramps up the immune system’s inflammatory process in response to bodily infection. By manipulating this chemical and therefore the inflammation, the researchers were able to affect both joint pain and the state of the associated arthritis. The speculation being that with the inflammatory process controlled the joint cartilage was able to heal itself. Controlling this “cross talking ” chemical then, which simultaneously affects different body processes of both pain registry and joint inflammation, possibly points a way forwards for new treatments that might break the link. Of course there is always a catch. Such new treatments will be many years away but it is an exciting area for future research.
In the meantime, pain management through inflammatory control, joint manual mobilization, and cartilage friendly strengthening exercise will continue to be mainstays of ongoing therapy.