Tendonitis is caused by overusing a tendon or injury. It may be the result of:
- a sports injury – for example, sports that involve throwing or using a racquet may increase your risk of tendonitis in your elbow
- a repetitive strain injury (repeated overuse of muscles) – for example, using a computer mouse may be linked to tendonitis in your wrist
A tear in the tendon because of an injury may also cause inflammation (swelling).
Medical conditions
For reasons that are not known, tendonitis tends to occur more commonly in people with diabetes than in the general population.
Also, tenosynovitis (inflammation of the sheath surrounding the tendon) is sometimes associated with rheumatoid arthritis.
