New cause of osteoarthritis identified by research into a rare disease

A new mechanism of joint destruction caused by a natural material that grinds away healthy cartilage and worsens osteoarthritis has been identified in human hip joints for the first time, says a study published in the Journal of Anatomy.
Alkaptonuria (AKU) is a metabolic disease in which homogentisic acid builds up in joint cartilage, causing changes to its physical properties. UK experts studying the hip of a man with AKU recently found the presence of high density mineralised protrusions (HDMP), which have only been seen before in horses. These protrusions are caused as the body acts to fill in cracks in joint cartilage and can snap off, leading to sharp, dense particles in the joint, which grind against healthy tissue.
To confirm their findings, the team studied eight hips donated for research by people with osteoarthritis and found the same results as in the man with AKU.
“There is no cure for osteoarthritis, but it is one of the leading causes of disability, causing immense pain and difficulty of movement to sufferers,” explains Prof Jim Gallagher, who led the work. “The discovery of HDMP in humans means that for the first time we are seeing an important mechanism in the process which causes the disease. In effect these small, sharp particles could act like an abrasive powder scouring the surfaces of the joint.
“Studying a rare illness like AKU is a worthwhile project in itself, but it can also help with new insights into much more common diseases. This is a case in point, and because of our work on AKU, we are now able to add a new piece to the puzzle of an illness that affects millions.”

The Autumn issue of Arthritis Digest contains an in-depth feature about AKU including expert opinion, latest research developments and a true story. Subscribe here to make sure you don’t miss it: www.arthritisdigest.co.uk/subscribe/.

For the AKU Society visit www.akusociety.org.

Image credit: Enzymlogic