Tendon injuries include ruptures (complete or partial), tendinitis, tendinosis, tendinopathy, paratenonitis, and tenosynovitis (definitions given below). Tendon injuries, including ruptures, can be classified as acute when they happen suddenly or as chronic when they happen slowly over time. Tendinosis and tendinopathy are chronic in nature by definition. This website focuses mostly on chronic tendon injuries, not acute injuries, but the information here can be useful to those who have acute injuries if chronic problems persist after treatment.
The goal of this site is to help you understand your injury and to highlight research into treatments for chronic tendon injuries. Unlike other sites that offer general information about these injuries, this site also presents information about current research into etiology and treatments for these difficult-to-heal chronic injuries.
Do you have pain in a tendon that started slowly, associated with some specific activity, and then it became so much worse that the pain now accompanies all kinds of activities? Maybe it burns, stings, or aches? Sometimes the pain can start without knowing what activity caused it, but usually you know it started from an activity such as typing, tennis, playing the drums, running, or another repetitive motion activity. Usually you can tell that the pain is located specifically in a tendon and you can point to the spot.
These chronic tendon injuries are called tendinosis or tendinopathy. These words refer to an accumulation over time of small-scale tendon injuries that don't heal properly, resulting in a chronic injury of failed healing. Although you can't see the tendinosis/tendinopathy injury on the outside of your body, researchers can see the injury on the cellular scale by viewing slides of tendons under the microscope. Tendinopathy can occur in many different areas, such as the wrist, forearm, elbow, shoulder, knee, and heel.
Tendons are rope-like structures that attach muscles to bones. Ligaments are similar structures that attach bones to other bones. When muscles and bones move, they exert stresses on the tendons and ligaments that are attached to them.
When your muscles move in new ways or do more work than they can handle, your muscles and tendons can sustain some damage on a cellular scale. If the increase in demand is made gradually, muscle and tendon tissues will usually heal, build in strength, and adapt to new loads. Athletes use these principles to build muscle and tendon strength with good training programs.
You can, however, do some activity that injures a tendon on a microscopic scale and then do more injury before the tendon heals. If you continue the injurious activity, you will gradually accumulate these micro-injuries. When enough injury accumulates, you'll feel pain. This kind of injury that comes on slowly with time and persists is a chronic injury. (Acute tendon injuries, on the other hand, are sudden tears that cause immediate pain and swelling.) Tendon injuries often require patience and careful rehabilitation with physical therapy because tendons heal more slowly than muscles.
Tendinitis: The suffix "itis" means inflammation; the term tendinitis should be reserved for acute tendon injuries accompanied by inflammation.
Tendinosis: The suffix "osis" implies a pathology of chronic degeneration without inflammation. Tendinosis is an accumulation over time of microscopic tendon injuries that don't heal properly. Although inflammation can be involved in the initial stages of the injury, it is the inability of the tendon to heal that perpetuates the pain and disability.
Tendinopathy: Tendinopathy is a term that has no implication about the pathology of the injury, so it is more general and is being used more frequently today. As mentioned on the The Injury page, there is currently some debate about the role of inflammation on the cellular level in tendinopathy (some inflammatory processes do seem to be involved).
Paratenonitis: Paratenonitis is inflammation of a thin sheath of tissue called the paratenon that surrounds some tendons, such as the Achilles.
Tenosynovitis: Tenosynovitis is inflammation of the synovial sheath that surrounds some tendons, such as the flexor tendons in the hands.
Note: This site was originally named Tendinosis.org when it was created in 2002. At that time, researchers were just moving from the term tendinitis to tendinosis after realizing that tendinosis was not an injury of chronic inflammation. But a decade later, the term tendinopathy started to become the preferred term because research has shown that some low level inflammation is involved in tendinopathy. The term tendinopathy acknowledges that we don’t know the exact etiology yet. For the purposes of this site, tendinosis and tendinopathy can be used interchangeably, but tendinopathy is becoming the more frequently used term.
Repetitive Motion: Tendinopathy can result from long hours of activities such as playing sports, using computers, playing musical instruments, or doing manual labor. It can result from activities performed as part of your profession or recreation. Some occupations that have increased risk for chronic tendon injuries include assembly line workers, computer programmers, writers, court recorders, data entry processors, sign language interpreters, cashiers, professional athletes, and musicians.
Medications: Another risk factor for tendon problems is the use of certain drugs. Four classes of drugs have been associated with tendinopathy: quinolones, long-term glucocorticoids, statins, and aromatase inhibitors. Antibiotics in the fluoroquinolone family (such as Cipro, Levaquin, and Avelox) have been associated with serious tendon injuries in some people. Many patients are not informed of this risk and are not given the chance to decide whether to take an alternative antibiotic. In May of 2016 the FDA issued a warning about quinolones, saying that their risks outweigh their benefits for sinusitis, bronchitis, and UTI whenever other treatment options can be used instead (more on this story here). For help or more information you can visit this website: SaferPills.org, The Quinolone Vigilance Foundation, and there is a case study with quite a bit of information here. I receive so many emails from people about fluoroquinolones that I thought I should mention the issue even though it is a different topic than the overuse kind of tendinopathy injuries addressed by this website. Some studies have raised questions about the effects of statins on tendons, such as one study that found differences in collagen construction during healing of tendon injuries with and without statins, and one study that found changes in tendons after chronic exposure to statins, and one study that found statins have negative effects on mesenchymal stem cells; however, a systematic review of literature did not find a cause and effect relationship between statins and tendinopathy, so the jury is still out on statins.
Diabetes and Body Weight: If you are overweight and/or have diabetes, you have increased risk for tendinopathy. Losing weight, improving your diet, and getting your blood sugar under control can improve your tendons.
Genetics: Genetics play a factor in tendinopathy, but much more research is needed in this area. Here is a sampling of some research into genetic variants that seem to be associated with increased risk for tendinopathy:
You can minimize your risk for tendinopathy by using equipment that has good ergonomic design and that is sized correctly for your body, by using good technique for your activity (whether it is sports, music, typing etc.), by taking plenty of breaks, by minimizing long overtime hours (easier said than done!), by maintaining good body weight and blood sugar, and by avoiding fluoroquinolone drugs (see the information in the Who Is At Risk section above for more about fluoroquinolones). You can also listen to your body's pain signals. Warning signs of tendinopathy include burning, stinging, aching, tenderness to the touch, and stiffness.
Tendinopathy usually sneaks up on you. At first the pain only comes after a long or hard session of the activity that aggravates it. Later, the pain comes at lower levels of the activity and lasts longer. Finally, the pain becomes a part of your daily life and even normal activities can make it worse. Try to catch the injury as early as you can.
You should see a specialist for diagnosis and treatment. Sports medicine doctors and physiatrists are often excellent choices for tendinopathy care, and they will likely refer you to a physical therapist. You can also use this site to learn more about your injury and treatments for it.
We had changed the name of the site from tendinosis.org to tendonpain.org in 2015 because the information here covers both tendinosis and tendinopathy. We have now changed the name again in December 2019 to tendoninjury.org because of an unfortunate domain problem; please know that the current tendonpain.org site has no affiliation with this site and if any of our content continues to appppear there it is without our permission.
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Science Daily reports on the recent discovery of the existence of tendon stem cells
Lead study author Chen-Ming Fan of Carnegie Institution for Science is quoted in the Science Daily article, "Tendon stem cells exist, but they must outcompete the scar tissue precursors in order to prevent the formation of difficult, fibrous scars. Finding a therapeutic way to block the scar-forming cells and enhance the tendon stem cells could be a game-changer when it comes to treating tendon injuries."
University of Glasgow: Scientific breakthrough unlocks potential novel tendon therapy
”Tendinopathy is essentially the result of an imbalance between collagen type-1 and type-3 and we have discovered the molecular cause. This breakthrough has allowed us to find a way to alter the levels of collagen type-3 in tendons, with the ultimate aim to get patients with tendon injuries better quicker."
Biologic augmentation of rotator cuff repair with mesenchymal stem cells during arthroscopy improves healing and prevents further tears: a case-controlled study
“This study showed that significant improvement in healing outcomes could be achieved by the use of BMC (bone marrow concentrate) containing MSC (mesenchymal stem cells) as an adjunct therapy in standard of care rotator cuff repair. Furthermore, our study showed a substantial improvement in the level of tendon integrity present at the ten-year milestone between the MSC-treated group and the control patients.”
Treatment of Lateral Epicondylosis Using Allogeneic Adipose-Derived Mesenchymal Stem Cells: A Pilot Study
“This pilot study on the safety and efficacy of allo-MSC injection for treating chronic LE demonstrated that the intervention was safe and efficacious in improving pain, performance, and anatomical defects for more than a 52-week follow-up period. This is the first clinical study using allogeneic MSCs to treat chronic tendinopathy.”
Cell Therapy Ltd announces positive Phase II clinical trial results of Tendoncel ™, a first-in-class topical regenerative medicine for severe tendon injury
“Patients using the non-invasive Tendoncel ™ topical gel for 21 days experienced a clinically relevant and statistically significant improvement in their tendon injury. Reporting an average improvement of 70% on the DASH disability scale and 74% improvement on the PRTEE scale, Tendoncel’s results exceed those expected of injectable treatments and have the advantage of painless topical application.”
Mechanotherapy: how physical therapists’ prescription of exercise promotes tissue repair
“Mechanotransduction is the physiological process where cells sense and respond to mechanical loads. This paper reclaims the term “mechanotherapy” and presents the current scientific knowledge underpinning how load may be used therapeutically to stimulate tissue repair and remodelling in tendon, muscle, cartilage and bone.”