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Updated February 09, 2015.

A tendon is a tough yet flexible band of fibrous tissue. The tendon is the structure in your body that connects your muscles to the bones. The skeletal muscles in your body are responsible for moving your bones, thus enabling you to walk, jump, lift, and move in many ways. When a muscle contracts it pulls on a bone to cause movements. The structure that transmits the force of the muscle contraction to the bone is called a tendon.


Tendons come in many shapes and sizes. Some are very small, like the ones that cause movements of your fingers, and some are much larger, such as your Achilles tendon in your heel. When functioning normally, these tendons glide easily and smoothly as the muscle contracts.

Sometimes the tendons become inflamed for a variety of reasons, and the action of pulling the muscle becomes irritating. If the normal smooth gliding motion of your tendon is impaired, the tendon will become inflamed and movement will become painful. This is called tendonitis, and literally means inflammation of the tendon.

Causes of Tendonitis

There are hundreds of tendons scattered throughout our body, but it tends to be a small handful of specific tendons that cause problems. These tendons usually have an area of poor blood supply that leads to tissue damage and poor healing response. This area of a tendon that is prone to injury is called a "watershed zone," an area when the blood supply to the tendon is weakest. In these watershed zones, they body has a hard time delivering oxygen and nutrients necessary for tendon healing--that's why we see common tendon problems in the same parts of the body.

Tendonitis is most often an overuse injury. Often people begin a new activity or exercise that causes the tendon to become irritated. Tendon problems are most common in the 40-60 year old age range. Tendons are not as elastic and forgiving as in younger individuals, yet bodies are still exerting with the same force.

Occasionally, there is an anatomical cause for tendonitis. If the tendon does not have a smooth path to glide along, it will be more likely to become irritated and inflamed. In these unusual situations, surgical treatment may be necessary to realign the tendon.

Symptoms of Tendonitis

Tendonitis is almost always diagnosed on physical examination. Findings consistent with tendonitis include:

• Tenderness directly over the tendon
• Pain with movement of muscles and tendons
• Swelling of the tendon

X-rays & MRIs: Are They Necessary?
Studies such as x-rays and MRIs are not usually needed to make the diagnosis of tendonitis. While they are not needed for diagnosis of tendonitis, x-rays may be performed to ensure there is no other problem, such as a fracture, that could be causing the symptoms of pain and swelling. X-rays may show evidence of swelling around the tendon.

MRIs are also good tests identify swelling, and will show evidence of tendonitis. However, these tests are not usually needed to confirm the diagnosis; MRIs are usually only performed if there is a suspicion of another problem that could be causing the symptoms.

Once the diagnosis of tendonitis is confirmed, the next step is to proceed with appropriate treatment. Treatment depends on the specific type of tendonitis. Once the specific diagnosis is confirmed, the appropriate treatment of tendonitis can be initiated.

<sub>Sources:

Almekinders, LC. "Tendinitis and other chronic tendinopathies" J. Am. Acad. Ortho. Surg., May 1998; 6: 157 - 164.</sub>