Duke University researchers who found that osteoarthritic knees, but not hips, are in a constant state of repair say that knee and hip osteoarthritis may need different treatment approaches.
"This suggests the knee has capacity for repair we didn't know about and the main treatment strategy probably would need to focus on turning off the breakdown of knee tissue," says Virginia Kraus, MD, PhD, professor of Rheumatology and Immunology at Duke.
The findings, published in Journal of Biological Chemistry, suggest that for hips, however, halting the degenerative process might not be enough. The hips would need a treatment to both stop degeneration and stimulate factors that could help to begin repair.
The knee is very accessible for injections, so it would make sense to inject the knee with agents that could turn off the degradative processes, and these could be delivered periodically with close monitoring, Kraus said. A cocktail of drugs might be needed for the hip, however, both to halt the degradation and to stimulate the right type of reparative elements.
Kraus and her team discovered a biomarker that is a measure of an altered (deaminated) protein, called D-COMP. In the circulation it signals hip degeneration and in cartilage it provides insight into the repair response of joint tissues. Kraus said this is the first biomarker specific to a particular joint site, and may be developed into a monitoring tool for hip-joint breakdown.
The next step is to understand the reasons for the difference between knees and hips and also to use new tools to analyze the ankle for its level of repair response.