Tendinitis, tendinosis, tendinopathy, tenosynovitis… Which is it?

Tendons are specialized tissues that connect muscle to bone.  They transmit the forces generated by muscle to bone as they cross a joint, resulting in joint movement.  Basically, skeletal muscle in the body can not cause movement without tendons, so it is important that they are healthy and strong enough to carry the load.  There can be various problems.  Most people starting at age 9 to end of life have pain in a tendon from time to time.   Tendinopathies are one of the most prevalent sports/musculoskeletal pr For patients and parents, a basic understanding can help you know when to get help from a Sports Medicine professional.  For medical practitioners, it is important to be able to distinguish between different types of tendon problems. Future articles will address specific structures such as Achilles and rotator cuff; this article addresses tendon injuries in a broad, introductory fashion.

Not all Sports Medicine professionals use exactly the same terminology for exactly the same problem.  My terminology is modern and generally accepted. Furthermore, tendon injuries and problems morph from one state to another over time, often, and getting a specific diagnosis requires an expert in tendons.


I use this term as a blanket term to describe each of the tendon pathologies, just like “tendonitis” was used (incorrectly in my opinion) for all tendon problems a decade or two ago.  There are some useful specific facts about tendinopathy:

  • Tendinopathy generally relates to micro-tearing in the collagen fibrils that traverse the length of a tendon like the parallel fibers along the length of a boat rope.
  • Tendinopathy is a result of insufficient healing of a tendon from day to day.  It is often related to overuse or under-recovery.
  • Tendinopathy may not hurt, which makes it dangerous, because a person can go from a pain free but diseased tendon to a tendon rupture without warning.
  • When there is robust active healing in a tendon, there is usually discomfort.
  • Biologic factors affect the rate of healing of tendinopathy, which is why PRP (platelet rich plasma) and other growth factor sources work.  Things like nicotine, certain pharmaceuticals such as statins and fluoroquinolones, poor nutrition and a poor metabolism are detrimental to tendon healing and can lead to tendinopathy.
  • Biomechanical factors can cause tendinopathy.  Anything that can increase the “dose” of load to the tendon enthesis – including increased activity, weight, advancing age, and genetic factors can cause tendinopathy.  For athletes, the usual culprit is large repetitive loading and lack of adequate rest in between challenges to the tendon.

Fundamentals of the treatment of tendinopathy include relative rest, time, physiotherapy, avoiding NSAIDs in most cases, and encouraging good blood supply and nutrition.  It is usually a good idea to avoid corticosteroid injections, which can weaken the tendon and predispose it to rupture, particularly in repeated injections. In refractory cases of tendinopathy, I’ll do a debridement of non-viable tendon tissue with a Tenex procedure, leaving healthy tenocytes (tendon cells) intact.  This can be followed up with a regenerative medicine procedures. In all cases, chronic or long-lasting tendon injuries need a heavy dose of patience. Tendons generally hurt while they are actively healing.


Tendinosis is a bad actor.  It is a disorder of impaired inflammation.  In tendinosis, the collagen fibrils do not heal in an organized fashion but become disorganized clumps of abnormal tissue, often forming a lump.  The way I think of this clinically is that a focal part of a tendon has forgotten how to heal, stays chronically unhealthy, and eventually seems to “give up.”  This is a major risk factor for complete rupture of the tendon and for chronicity of the problem. Fortunately, we now have techniques in regenerative medicine that can debride the unhealthy part of the tendon if necessary and / or to “jump start” the natural healing process.  Along with many types of tendinopathy, tendinosis is a particularly good indication for PRP. If there is too much unhealthy inert tissue, I may also need to do a Tenex debridement to clean the area up before PRP.


Inflammation of a tendon can help heal tendon injury.  There are different kinds of inflammation and they are not all bad.  However, sometimes there is too much inflammation or the wrong kind.  Acute pain and tenderness can be this excessive or pathologic inflammation, and this is the kind of tendinopathy that can be called tendinitis.  This should be initially treated with relative rest and often is self-limited. Occasionally immobilization, injection, physiotherapy or a combination of treatments is needed for a tendinitis that is severe or just won’t go away.


Many tendons are encased in a sheath that completely encircles the tendon and allows the tendon to glide within the sheath.  (A notable exception to that is the Achilles tendon, which has a direct covering of the tendon called a peritenon). When the tendon or tendon sheath develops certain types of inflammation, fluid can be secreted in the space between the tendon and the tendon sheath.  This swelling can cause pain and make it difficult for a tendon to move through anatomic pulleys. This may be self limited with rest, but also sometimes requires immobilization, and injection is sometimes required.


Tendon injuries come in various forms.  In general they need rest, nutrition, time, Physical Therapy, massage, and sometimes help from a regenerative sports medicine physician like me.  Steroid injections should generally be avoided except in “rescue” situations.