|Classification and external resources|
Tendinitis (informally also tendonitis), meaning inflammation of a tendon, is a type of tendinopathy often confused with the more common tendinosis, which has similar symptoms but requires different treatment. (The suffix -itis denotes diseases characterized by inflammation.) 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).
Tendinitis injuries are common in the upper and lower limbs (including the rotator cuff attachments), and are less common in the hips and torso. Individual variation in frequency and severity of tendinitis will vary depending on the type, frequency and severity of exercise or use; for example, rock climbers tend to develop tendinitis in their fingers or elbows, swimmers in their shoulders. Achilles tendinitis is a common injury, particularly in sports that involve lunging and jumping, while Patellar tendinitis is a common among basketball and volleyball players owing to the amount of jumping and landing. A veterinary equivalent to Achilles tendinitis is bowed tendon, tendinitis of the superficial digital tendon of the horse.
Symptoms can vary from aches or pains and local joint stiffness, to a burning that surrounds the whole joint around the inflamed tendon. In some cases, swelling occurs along with heat and redness, and there may be visible knots surrounding joint. With this condition, the pain is usually worse during and after activity, and the tendon and joint area can become stiff the following day as muscles tighten from the movement of the tendon. Many patients report stressful situations in their life in correlation with the beginnings of pain which may contribute to the symptoms. If the symptoms of tendinitis last for several months or longer it is probably tendinosis.
Treatment of tendon injuries is largely conservative. Use of non-steroidal anti-inflammatory drugs (NSAIDs), rest, and gradual return to exercise is a common therapy. Resting assists in the prevention of further damage to the tendon. Ice, compression and elevation are also frequently recommended. Physical therapy, orthotics or braces may also be useful. Initial recovery is typically within 2 to 3 days and full recovery is within 4 to 6 weeks. As tendonosis is more common than tendinitis, and has similar symptoms. It occurs as the acute phase of healing has ended (6-8 weeks) but has left the area insufficiently healed; Treatment of tendinits helps reduce some of the risks of developing tendonosis, which takes longer to heal.
Steroid injections have not been shown to have long term benefits but have been shown to be more effective than NSAIDs in the short term.
In chronic tendinitis or tendonosis laser therapy has been found to be better than conservative treatment at reducing pain; however, no other outcomes were assessed. Both prolotherapy and PRP injections are being used more frequently with good clinical short and long term outcomes in tendonosis - research has been only slightly positive for these treatment modalities due to the poor design of many of the completed studies.
Autologous blood injection is a technique where the area of tendinitis[dubious ] is injected with the patient's own blood in order to stimulate tendon healing. This is the same principal as the long used Tenotomy where the area is re-injured through poking with needles. The procedure does result in a pain flare for several days, as the blood irritates the tendon; however, platelet-derived growth factor, which is contained in platelets, is thought to commence the healing process. The treatment has been tested in two small trials for tennis elbow.
In horses 
In horses tendinitis is called bowed tendon from the appearance of the affected tendon after it heals without treatment. Mesenchymal stem cells, derived from a horse's bone marrow or fat, are currently being used for tendon repair in horses. 
See also 
- Repetitive strain injury
- Achilles Tendinitis
- Calcific tendinitis
- Orthopedic surgery
- Stenosing tenosynovitis
- Tennis elbow
- Tension myositis syndrome
- Khan, KM; Cook JL, Kannus P, Maffulli N, Bonar SF (2002-03-16). "Time to abandon the "tendinitis" myth : Painful, overuse tendon conditions have a non-inflammatory pathology". BMJ 324 (7338): 626–7. doi:10.1136/bmj.324.7338.626. PMC 1122566. PMID 11895810.
- Mayo Clinic (2007). "Patellar tendinitis". Retrieved 2007-06-04.
- Wilson, JJ; Best TM (Sep 2005). "Common overuse tendon problems: A review and recommendations for treatment" (PDF). American Family Physician 72 (5): 811–8. PMID 16156339.
- Gaujoux-Viala C, Dougados M, Gossec L (December 2009). "Efficacy and safety of steroid injections for shoulder and elbow tendonitis: a meta-analysis of randomised controlled trials". Ann. Rheum. Dis. 68 (12): 1843–9. doi:10.1136/ard.2008.099572. PMC 2770107. PMID 19054817.
- "BestBets: Laser therapy in the treatment of tendonitis".
- Edwards SG, Calandruccio JH. (2003). "Autologous blood injections for refractory lateral epicondylitis". J Hand Surg [Am]. 28 (2): 272–8. doi:10.1053/jhsu.2003.50041. PMID 12671860.
- Connell DA, Ali KE, Ahmad M, Lambert S, Corbett S, Curtis M (June 2006). "Ultrasound-guided autologous blood injection for tennis elbow". Skeletal Radiol. 35 (6): 371–7. doi:10.1007/s00256-006-0081-9. PMID 16552606.
- Koch TG, Berg LC, Betts DH (2009). "Current and future regenerative medicine - principles, concepts, and therapeutic use of stem cell therapy and tissue engineering in equine medicine.". Can Vet J 50 (2): 155–65. PMC 2629419. PMID 19412395.