Tendinitis (also tendonitis), meaning inflammation of a tendon, is just that: An inflammation or irritation of a tendon, which is the thick, fibrous cord that attaches muscles to bones. It is a type of tendinopathy often confused with the more common tendinosis, which has similar symptoms but requires different treatment. The term tendinitis should be reserved for tendon injuries that involve larger-scale acute injuries accompanied by inflammation. Generally tendinitis is referred to by the body part involved, such as Achilles tendinitis (affecting the Achilles tendon), or patellar tendinitis (jumper’s knee, affecting the patellar tendon). Other common names include tennis elbow, golfer’s elbow, pitcher’s shoulder and swimmer’s shoulder. Stem cells have shown efficacy in the repair and regeneration of tendons.