It has been believed that osteoarthritis is caused by a breakdown of the articular cartilage that lines the ends of most bones. Pieces of this cartilage break off and aggravate the synovial lining the joint.

But now two researchers in the UK, Dennis McGonagle of the University of Leeds and Michael Benjamin of Cardiff University have discovered that there may be another factor in the development of osteoarthritis.

Professors McGonagle and Benjamin suspected that the enthesis, also called Sharpey’s fibers, which is the attachment site of ligament or tendon to bone, was potentially a factor in causing inflammation in the joint. Their theory was developed by studying the structure they called the “synovial-entheseal complex” (SEC). This includes the fibrocartilage at the ends of the tendons and ligaments.

To validate their theory, they studied ligament and tendon samples from different sites on 60 cadavers. These included arms, legs and spinal column. They were looking for soft tissue damage and inflammatory cells and at the structure of the SECs. They found that a high percentage of the entheses showed degenerative changes, such as cell clustering and/or fissuring. Likewise, they found a high factor of attachments with inflammatory cells within the enthesis itself.

This led them to suggest that this degeneration of the attachments could result in the symptoms emanating from the SEC. And since these are high stress areas they also believe that biomechanical factors could play an important part in inflammatory and degenerative arthritis.

Hopefully this research will lead to the development and new and better treatments for the pain of osteoarthritis.