How Tendinosis Differs From Tendinitis

Tendinosis is a condition that is characterized by swelling and pain of a tendon. Tendinosis is often confused with tendinitis, a condition that shares many of the same symptoms but differs greatly in its cause and appearance.

Man holding his elbow
tongwongboot / Getty Images

Difference Between Tendinosis and Tendinitis

The main difference between tendinosis and tendinitis is time. Tendinosis is a chronic (persistent or recurring) condition caused by repetitive trauma or an injury that hasn't healed. By contrast, tendinitis is an acute (sudden, short-term) condition in which inflammation is caused by a direct injury to a tendon. (The differences are reflected in their suffixes, with "-osis" meaning abnormal or diseased and "-itis" meaning inflammation.) The symptoms and patterns of the disease also vary:

  • Tendinosis does not involve inflammation. As such, while it can be painful, there is usually no redness or warmth of the surrounding soft tissues. When examined under a microscope, tiny tears (microtears) of the tendon may be seen, but there would be no evidence of inflammatory cells.
  • Tendinitis, by contrast, does result in inflammation and is characterized by swelling, redness, and warmth in addition to pain. When seen under the microscope, inflammatory cells would be present.

These differences inform how we treat the two conditions and predict the outcomes of those affected.


Tendinosis can occur in many tendons throughout the body, particularly those around major joints. We often refer to them by their location or the specific tendon they affect:

  • Tennis elbow (also known as lateral epicondylitis) is a form of tendinosis caused by overuse. It specifically affects the tendons that connect the forearms muscles to the outside of the elbow. The condition is further aggravated as the muscle repetitively rubs against bony bumps of the elbow, causing wear and tear. In addition to elbow pain, weakness of the grip is also commonly seen.
  • Jumper's knee (also known as patellar tendinosis) involves the tendon that starts on the patella (kneecap) and extends down the front of the knee to the tibial tubercle (the shin bone). As opposed to an acute injury, patellar tendinosis affects athletes and others whose knees are repetitively impacted by jumping or repetitive lifting. It should not be confused with runner's knee (patellofemoral pain syndrome) in which pain is caused by abnormal contact and movement patterns of the patella on the femur (thigh bone).
  • Achilles tendinosis affects the tendon (called the calcaneal tendon) that connects the calf muscles to the calcaneus (heel bone). Achilles and calf tightness can contribute to the condition, particularly in older people, as muscle and connective tissue experience microtears through everyday activities that cause the tendon to flex and retract (like walking or climbing stairs). Bone spurs on the heel can also rub against the tendon, effectively abrading it over time.


One of the most beneficial treatments for tendinosis is physical therapy. Specifically, eccentric contractions of the damaged muscle-tendon have been shown to be effective at reducing pain and healing damaged tissues. In more severe cases where there is a partial (or likely) rupture of a tendon, surgery may be indicated.

Because tendinosis is not associated with inflammation, oral anti-inflammatory drugs, cortisone injections, and cryotherapy (ice application) are less likely to be beneficial when treating the condition.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Charnoff J, Naqvi U. Tendinosis (tendinitis) In: StatPearls.

  2. Buchanan BK, Varacallo M. Tennis elbow (lateral epicondylitis) In: StatPearls.

  3. Santana JA, Sherman Al. Jumpers knee. In: StatPearls.

  4. Shamrock AG, Varacallo M. Achilles tendon ruptures. In: StatPearls.

Additional Reading

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.