Tendonitis is a condition in which a tendon, such as the Achilles or patellar, becomes inflamed or irritated. It is often caused by repetitive strain or injury to the affected area, whether by mild impact or more serious trauma.

Tendonitis is characterized by pain in and around the tendon and often a loss of motion. Poor stretching and conditioning before playing sport is a common cause of tendonitis, as is having an incorrect posture while at work. 

Patients are more likely to develop tendonitis when engaging in sport or exercise they are not used to undertaking regularly. Stress on the joint due to conditions such as rheumatoid arthritis and thyroid disorders may also be a root cause. 

Physicians might recommend physical therapy or, in more severe cases, surgical options may be explored. Anti-inflammatory medication and topical gels may also be used to treat the condition.