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Tendinitis and Tendinosis

Last Updated: Mar 1, 2019


Tendons are cord-like bands of tissue that connect muscles to bone. Tendon tissue is made of a tough, fibrous substance called collagen that can withstand quite a bit of force and tension. However, severe forces or repetitive force over time can cause tiny “microtears” in tendon tissue, leading to injury.

extensor carpi radialis brevis and posterior of elbow joint

Tendinitis is inflammation (redness, swelling, heat, soreness) that occurs when the body’s immune system detects an injury and responds. In the case of tendinitis (also spelled ‘tendonitis’), the body increases the flow of blood and infection-fighting substances to the injured tendon.

Tendinosis is a degenerative injury to the tendon that doesn’t provoke an immune response. It occurs when repetitive, unrelenting stress over time causes the breakdown of collagen, growth of abnormal blood vessels, and thickening of the tendon’s sheath (covering). Research suggests that many injuries diagnosed as tendinitis are actually tendinosis.

Tendon injuries occur in all parts of the body, but are most common in these parts:

Many common sports afflictions, including tennis elbow, swimmer’s shoulder, and jumper’s knee are actually forms of tendinitis/tendinosis.

Tendon injury usually isn’t serious in itself. On the other hand, weakened tendons increase a person’s risk of further injuries, like sprains. In severe cases, the tendon may rupture (tear) and require surgical repair.


Sudden, severe trauma can damage the tendons instantly. However, most tendon injuries are caused by repetitive injury. Even a relatively minor stress can tear and degrade the tendon tissue if it’s repeated over and over. Examples include:

  • Work tasks such as typing, clicking a mouse, clenching a steering wheel or using power tools
  • Hobbies like gardening, shoveling, raking and painting
  • Sports such as golf, tennis, baseball, basketball, bowling, running and swimming.

Poor posture and form during these repeated movements can increase stress on the tendons and make injury more likely.

In unusual cases, tendinitis/tendinosis is caused by infection or a reaction to medication.

The incidence of tendon injury increases with age, and it’s especially common after age 40. Some medical conditions can increase the risk, including arthritis, gout, and thyroid disorders.


Symptoms of a tendon injury usually occur near a joint at the attachment point between the bone and muscle.

The first sign is often dull, aching pain that worsens with movement. The affected area is frequently tender to the touch. Some mild swelling may be present.

People with tendinitis of the shoulder may notice an occasional “snapping” sound during movement and may experience freezing (loss of motion) in the shoulder joint.


Tendon injury is usually mild and doesn’t require a doctor’s care. To care for tendinitis/tendinosis at home:

  • Avoid activities that aggravate the injured area, but do try to go about your daily routine as much as you are able.
  • To reduce swelling, apply cold packs for up to 20 minutes 1-2 times on the day pain starts. (But do not apply ice directly to the skin.)
  • Compress the area with an elastic bandage to further reduce swelling.
  • After swelling has stopped, apply heat from a heating pad or hot bath to relieve pain and promote healing.
  • If possible, elevate the area to promote circulation.
  • To control pain and swelling, take over-the-counter anti-inflammatory medications like ibuprofen.
  • After a few days of rest, try gently moving the affected are to prevent joint stiffness.

See a doctor if:

  • Pain interferes with your activities and persists for more than a few days
  • Pain worsens rapidly
  • You have a fever
  • The painful area is swollen, red and warm to the touch
  • Joint pain occurs in more than one place.

A physician can usually diagnose tendinitis based on a patient’s history and physical exam. Imaging tests such as ultrasound, X-ray, or MRI may be ordered to rule out other types of injury. Blood tests can detect infection, which is a rare cause of tendon injury.


Treatment for severe or persistent tendinitis may include:

  • Physical therapy to strengthen the tendons and muscles and preserve range of motion. Therapy may include exercises and fitting of splints, braces, and orthotics.
  • Injections of corticosteroids (powerful anti-inflammatory medications) into the area around the tendon. This helps relieve swelling and pain, but may increase the risk of tendon rupture.
  • Surgical repair is used in rare cases to repair ruptured tendons or those that don’t respond to more conservative treatment.

With proper management, most tendon injuries improve within a few weeks, though some take several months to heal.


To protect your tendons from injury:

  • Stop and rest if you notice pain during any activity.
  • Make sure your workspace follows ergonomic principles. Your chair height, desktop height and keyboard position should be matched to your arm length. Many workplaces provide free ergonomic consults.
  • Make sure your sports equipment and clothing is in good condition, suited to your sport and conforms to the latest safety standards. This is especially important with athletic shoes.
  • Train properly. When starting a new sport or after a period of inactivity, ramp up your exertion level gradually so your muscles have a chance to strengthen and adjust.
  • Stretch properly before and after exercise to improve range of motion.
  • Use good technique and form when playing sports. Consider professional coaching when beginning a new sport or using a new piece of exercise equipment.
  • Work occasional cross-training into your regimen to give your tendons and joints a rest. (For example, a runner might choose to bike or swim once a week.)


  • Bass, Evelyn. “Tendinopathy: Why the Difference Between Tendinitis and Tendinosis Matters.” International Journal of Therapeutic Massage and Bodywork, 2012. 5(1): 14-17. Accessed June 22, 2014.
  • “Peroneal Tendinosis.” American Orthopedic Foot and Ankle Society, 2014. Accessed June 22, 2014.
  • “Tendinitis.” Cleveland Clinic, 2014. Accessed June 22, 2014.
  • “Tendinitis.” Mayo Foundation for Medical Education and Research, 2011. Accessed June 22, 2014.
  • “Tendinitis and Bursitis.” American College of Rheumatology, 2013. Accessed June 22, 2014.
  • “Tendinitis of the Long Head of the Biceps.” American Academy of Orthopedic Surgeons, 2009. Accessed June 22, 2014.

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.