Calling time osteoarthritis

摘要

Osteoarthritis (OA) is a painful and disabling joint disease, caused by the degeneration of the cartilage normally cushioning the ends of bones. It is the most common joint disorder, affecting around 6 million people in the UK, but the mechanism is poorly understood and treatment options are limited to painkillers and eventual joint replacement. OA occurs when cartilage tissue degenerates, as a result of multiple interacting factors including genetics, obesity, mechanical injury and aging. Healthy cartilage tissue comprises an abundant extracellular matrix and one specialised cell-type, the chondrocyte. The majority of the tissue is made up of matrix which provides a strong, lubricated surface at the ends of bones, dissipating shear and compressive forces and allowing joints to articulate smoothly. Because adult chondrocytes very rarely divide, the existing pool of cells is solely responsible for upkeep of the tissue and a fine balance must be achieved between activities which build up and break down matrix components. In OA, this balance is disturbed and chondrocytes excessively degrade their surrounding matrix, leading to tissue destruction and ultimate loss of joint function. The symptoms of OA, which include pain and joint stiffness, are often worse at certain times of day. This suggests that body clocks may play a role in the disease, which is the focus of new research from the University of Manchester.