Inflammation of a tendon, the fibrous tissue that connects a muscle to a bone. It can occur at the musculotendinous junction, at the point of insertion on the bone (enthesopathy) or in the middle of the tendon. The causes of tendinitis are varied and often associated. Some cases of tendinitis are caused by repeated microtrauma, particularly occupational or sports-related, while others are degenerative in origin, as ageing of the tissues causes wear and tear, or even rupture, of the collagen fibres that make up the tendon. Tendinitis can also be linked to an inflammatory joint disease, such as ankylosing spondylitis or rheumatoid arthritis.