New Insights into Inflammation in Osteoarthritis

The most common degenerative joint disease, osteoarthritis (OA) is marked by the breakdown of articular cartilage, which is the type of cartilage that lines the ends of most limb bones. It can afflict any joint—fingers, toes, wrists, ankles, elbows, shoulders, and the spine, as well as the weight-bearing knees and hips. As OA progresses, sufferers often experience inflammation around the affected joint. This inflammation has been attributed to bits of cartilage breaking off and aggravating the synovium, the thin, smooth membrane lining a joint. Yet, MRI detection of prominent synovitis in early OA—when joint cartilage appears normal—suggests that other joint structures may be involved in triggering this inflammation. Recent studies of inflammation in spinal arthritis implicate the enthesis, which is the attachment site of ligament or tendon to bone as being a potential driving factor in joint inflammation.