Arthritic knees, but not hips, have robust repair response

February 10, 2012

Researchers at Duke University Medical Center used new tools they developed to analyze knees and hips and discovered that osteoarthritic knee joints are in a constant state of repair, while hip joints are not.

"This suggests the 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," said Virginia Kraus, M.D., Ph.D., professor of and at Duke. "I was hugely surprised to find this."

This suggests that knee and hip osteoarthritis may need different treatment approaches, Kraus said.

Perhaps the natural repair response would be sufficient to lead to a reversal or halting of the disease process in the knee if the joint breakdown could be halted, Kraus said.

"At least with the knee you've got an ongoing repair response that we didn't appreciate until now," Kraus said. "If you could capitalize on that and turn off the degradative (breakdown) processing you might have some good effects."

The findings, published in the on Friday, Feb. 10, suggest that for , however, turning off the degenerative process might not be enough. The hips would need a treatment to both turn off of the degenerative process as well as 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. "That seems like a very viable strategy."

A number of are being tested in to turn off the joint breakdown processes, and Kraus is hopeful that this approach will lead to treatment breakthroughs for osteoarthritis.

A cocktail of drugs might be needed for the hip, however, both to turn off the degradation and to stimulate the right type of reparative elements.

"I am speculating that a single agent would work for the knee," Kraus said.

The findings about the knee were shocking to her, because the literature for years had compared the knee and ankle. Scientists knew the ankle was resistant to osteoarthritis, but the knee was very susceptible.

The thinking was that the ankle joint bones fit together well, like a ball in a socket, so the joint cartilage is less likely to degrade, while the knee joint bones fit less well together and require tissue, like the meniscus, to create a better fit – so knee cartilage is more likely to degrade.

"What we found is startling, because the hip joint also has a ball-in-socket structure yet it degrades and fails to mount a strong repair response," Kraus said. "We think this means that joint congruency alone cannot explain the difference in the repair response of joints, so there is more to learn."

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 the to analyze the ankle for its level of repair response.

"Why is the ankle less susceptible than the knee to ?" Kraus asked. "Can we develop other tools to be specific indicators of joint health for other joints in the body?"

Explore further: Study indicates nanoparticles could help pain-relieving osteoarthritis drugs last longer

Related Stories

Study indicates nanoparticles could help pain-relieving osteoarthritis drugs last longer

October 26, 2011
A novel study demonstrates that using nanoparticles to deliver osteoarthritis drugs to the knee joint could help increase the retention of the drug in the knee cavity, and therefore reduce the frequency of injections patients ...

Study suggests key to avoiding ankle re-injury may be in the hips and knees

October 17, 2011
Nearly all active people suffer ankle sprains at some point in their lives, and a new University of Georgia study suggests that the different ways people move their hip and knee joints may influence the risk of re-injury.

Recommended for you

Fluid in the knee holds clues for why osteoarthritis is more common in females

June 26, 2017
Researchers have more evidence that males and females are different, this time in the fluid that helps protect the cartilage in their knee joints.

Biologics before triple therapy not cost effective for rheumatoid arthritis

May 29, 2017
Stepping up to biologic therapy when methotrexate monotherapy fails offers minimal incremental benefit over using a combination of drugs known as triple therapy, yet incurs large costs for treating rheumatoid arthritis (RA). ...

Drug for refractory psoriatic arthritis shows promise in clinical trial

May 24, 2017
In a pivotal phase-3 clinical trial led by a Stanford University School of Medicine investigator, patients with psoriatic arthritis for whom standard-of-care pharmaceutical treatments have provided no lasting relief experienced ...

Cross-species links identified for osteoarthritis

May 17, 2017
New research from the University of Liverpool, published today in the journal npj Systems Biology and Applications, has identified 'cell messages' that could help identify the early stages of osteoarthritis (OA).

Osteoarthritis could be prevented with good diet and exercise

May 12, 2017
Osteoarthritis can potentially be prevented with a good diet and regular exercise, a new expert review published in the Nature Reviews Rheumatology reports.

Rodents with trouble walking reveal potential treatment approach for most common joint disease

May 11, 2017
Maintaining the supply of a molecule that helps to nourish cartilage prevented osteoarthritis in animal models of the disease, according to a report published in Nature Communications online May 11.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.