Tendons are cords of tissue that anchor muscles to bones. They slide back and forth as our muscles contract and our joints flex. To prevent chafing and to keep them in position, the tendons are enclosed in special coverings called sheaths, that are lubricated. When something goes wrong that prevents the tendon from moving smoothly, pain and stiffness result. When tendons are damaged and inflamed, the condition is commonly known as tendinitis. If the problem is in the lining of the tendon’s sheath, it’s called tenosynovitis.

Causes

The most common causes of tendinitis are strain, overexertion, injury, repetitive movements, and sudden or unaccustomed movements. Tendinitis is most common in seniors and middle-aged people, since the tendons of older individuals lack the elasticity of younger people and have sustained hundreds of microscopic tears due to wear and tear over the years.

There are certain diseases that can cause tendinitis, such as rheumatoid arthritis, gout, Reiter’s syndrome, lupus, and diabetes. Sometimes, people with gout have uric acid crystals that appear in the tendon sheath that cause friction and tearing. Very high blood cholesterol levels may also be linked with this condition. Quinolone antibiotics, which are synthetically produced, (e.g., ciprofloxacin, levofloxacin, moxifloxacin) may increase the risk of tendon rupture.

Some common types of tendinitis include the following:

Rotator cuff tendinitis affects tennis players, swimmers, and anyone who frequently lifts their arms above the head and in a forward motion. This causes several shoulder tendons to rub together. Inflammation can set in and, if severe and untreated, may start to erode the tendons. Rotator cuff tendons hold the upper arm bone in the shoulder socket.

Achilles tendinitis involves the strongest tendon in the body, the one that connects the heel to the leg muscles. It’s usually caused by running uphill or downhill, jumping, or engaging in sports that require sudden stopping and starting. Wearing shoes with either very soft-padded heels or very stiff soles, especially for someone whose ankles roll in, may also contribute to Achilles tendinitis. Achilles tendinitis requires special care, as the Achilles tendon must handle great force from the upper body. Special caution is especially warranted if the inflammation is due to the quinolone medications mentioned above.

Flexor digital tenosynovitis (trigger finger) may be seen in people with rheumatoid arthritis and diabetes. A protrusion or thickening of the tendon catches in the tendon sheath, causing the finger to bend and stick.

De Quervain’s tenosynovitis (De Quervain’s syndrome) affects the tendon sheaths extending from above the wrist to the thumb. The most common cause is excessive wringing of the wrist or other repetitive movements. In some cases, rheumatoid arthritis may be involved.

Tennis elbow is medically known as epicondylitis, since inflammation occurs at the part of the elbow where the tendon inserts. Of course, it has many other triggers besides tennis.

Symptoms and Complications

The primary symptom of most types of tendinitis is pain. Some positions or movements can cause a greater degree of pain than others. You may also feel the lack of smoothness in the movement of the affected muscle. Sometimes, the tendon sheath fills with liquid and becomes inflamed. In other cases, it’s dry and causes obvious friction when you move. In severe cases, tendons can rupture, causing increased pain and swelling and possibly permanent change in function of the related muscle and joint.

Serious complications of tendinitis and tenosynovitis include contractures, or tightening, of the tendon, scarring, called adhesions, muscle wasting, and disability. The shoulder is the most vulnerable joint since it can freeze up, a condition called “frozen shoulder.” What may start out as tendinitis becomes frozen shoulder when adhesions limit the motion and cause pain when stretching. People do not notice the difference. Keeping inflamed joints flexible through their whole range of motion helps prevent contractures and adhesions. In serious cases, the rotator cuff tendons can tear, which may lead to prolonged weakness and pain the shoulder.   

Making the Diagnosis

Doctors have a wide range of tests to check for damage to different tendons. De Quervain’s syndrome, for example, is detected by the test known as Finkelstein’s sign. With the affected hand, you make a fist with the thumb closed onto the palm by the fingers, then flex your wrist in all directions. If there’s pain at the top of the wrist just behind the thumb, then it’s a clear indication of De Quervain’s syndrome. Similar tests exist for all types of tendinitis.

Your doctor will also want to know if the problem is strain- or injury-related, or if some other disease is the cause. Most other diseases can be ruled out using simple blood tests. Your doctor may also recommend imaging tests such as an ultrasound or a magnetic resonance imaging (MRI) scan. 

Treatment and Prevention

Most cases of tendinitis and tenosynovitis clear up with adequate rest, application of warm or cold compresses, and if absolutely necessary, use of nonsteroidal anti-inflammatory medications (NSAIDs; e.g., ibuprofen, naproxen). For some people, corticosteroid (e.g., triamcinolone, methylprednisolone) injections with or without an anesthetic are used to help with inflammation and pain. A splint or cast may be needed to hold the joint in place and rest the irritated tendon, but not for long because it can cause contractures, muscle wasting, and adhesions.

Physiotherapy techniques such as ultrasound or interferential current can be useful to reduce pain and swelling. There is some evidence that certain chiropractor treatments, such as manual and manipulative therapy, can be used to help with shoulder disorders, such as rotator cuff injuries.

Surgery is rarely used for tendinitis, but it’s sometimes necessary in cases of separated shoulder or ruptured tendons. Seriously torn shoulder cuffs often have to be sutured back in place in a procedure called rotator cuff repair.

Tenosynovectomy relieves inflammation over the long-term by drawing synovium out of the tendon sheaths. Synovium is a membrane that lines the sheaths that secretes synovial fluid. Normally, this fluid lubricates the joint, but too much of it can cause the sheath to swell.