Tendinopathy usually results from repeated small tears or degenerative changes (sometimes with calcium deposits) that occur over years in the tendon.
Tendinitis and tenosynovitis most commonly affect tendons associated with the shoulder (rotator cuff), the tendon of the long head of the biceps muscle (bicipital tendon), flexor carpi radialis or ulnaris, flexor digitorum, popliteus tendon, Achilles tendon (see Achilles Tendinitis), and the abductor pollicis longus and extensor pollicis brevis, which share a common fibrous sheath (the resulting disorder is De Quervain syndrome).
The cause of tendinitis is often unknown. It usually occurs in people who are middle-aged or older as the vascularity of tendons decreases; repetitive microtrauma may contribute. Repeated or extreme trauma (short of rupture), strain, and excessive or unaccustomed exercise probably also contribute. Some fluoroquinolone antibiotics may increase the risk of tendinopathy and tendon rupture.
Risk of tendinitis may be increased by certain systemic disorders—most commonly rheumatoid arthritis, systemic sclerosis, gout, reactive arthritis, and diabetes or, very rarely, amyloidosis or markedly elevated blood cholesterol levels. In younger adults, particularly women, disseminated gonococcal infection may cause acute migratory tenosynovitis.
Affected tendons are usually painful when actively moved or when natural motion is resisted. Occasionally, tendon sheaths become swollen and fluid accumulates, usually when patients have infection, rheumatoid arthritis, or gout. Swelling may be visible or only palpable. Along the tendon, palpation elicits localized tenderness of varying severity.
In systemic sclerosis, the tendon sheath may remain dry, but movement of the tendon in its sheath causes friction, which can be felt or heard with a stethoscope.
Usually, the diagnosis can be based on symptoms and physical examination, including palpation or specific maneuvers to assess pain. MRI or ultrasonography may be done to confirm the diagnosis or rule out other disorders. MRI can detect tendon tears and inflammation (as can ultrasonography).
Rotator cuff tendinitis is the most common cause of shoulder pain. The rotator cuff is composed of four tendons, the supraspinatus, infraspinatus, subscapularis, and teres minor. The supraspinatus tendon is most frequently involved and the subscapularis is second. Active abduction in an arc of 40 to 120° and internal rotation cause pain (see Rotator Cuff Injury/Subacromial Bursitis). Passive abduction causes less pain, but abduction against resistance can increase pain. Calcium deposits in the tendon just below the acromion are sometimes visible on x-ray. Ultrasonography or MRI may help with further evaluation and with treatment decisions.
Volar flexor tenosynovitis (digital flexor tendinitis) is a common musculoskeletal disorder that is often overlooked. Pain occurs in the palm on the volar aspect of the thumb or other digits and may radiate distally. Palpation of the tendon and sheath elicits tenderness; swelling and sometimes a nodule are present. In later stages, the digit may lock when it is flexed, and forceful extension may cause a sudden release with a snap (trigger finger).
Patients with trochanteric bursitis almost always have gluteus medius tendinitis. In patients with trochanteric bursitis, palpation over the lateral prominence of the greater trochanter elicits tenderness. Patients often have a history of chronic pressure on the joint, trauma, a change in gait (eg, due to osteoarthritis, stroke, or leg-length discrepancy), or inflammation at this site (eg, in rheumatoid arthritis).
Symptoms are relieved by rest or immobilization (splint or sling) of the tendon, application of heat (usually for chronic inflammation) or cold (usually for acute inflammation), and high-dose NSAIDs (see Table: Nonsteroidal Anti-inflammatory Drug (NSAID) Treatment of Rheumatoid Arthritis) for 7 to 10 days. Indomethacin or colchicine may be helpful if gout is the cause. After inflammation is controlled, exercises that gradually increase range of motion should be done several times a day, especially for the shoulder, which can develop contractures rapidly.
Injecting a sustained-release corticosteroid (eg, betamethasone 6 mg/mL, triamcinolone 40 mg/mL, methylprednisolone 20 to 40 mg/mL) in the tendon sheath may help; injection is usually indicated if pain is severe or if the problem has been chronic. Injection volume may range from 0.3 mL to 1 mL, depending on the site. An injection through the same needle of an equal or double volume of local anesthetic (eg, 1 to 2% lidocaine) confirms the diagnosis if pain is relieved immediately. Clinicians should be careful not to inject the tendon (which can be recognized by marked resistance to injection); doing so may weaken it, increasing risk of rupture. Patients are advised to rest the adjacent joint to reduce the slight risk of tendon rupture. Infrequently, symptoms can worsen for up to 24 hours after the injection.
Repeat injections and symptomatic treatment may be required. Rarely, for persistent cases, particularly rotator cuff tendinitis, surgical exploration with removal of calcium deposits or tendon repair, followed by graded physical therapy, is needed. Occasionally, patients require surgery to release scars that limit function, remove part of a bone causing repetitive friction, or do tenosynovectomy to relieve chronic inflammation.
Tendinitis and tenosynovitis, unlike tendinopathy (tendon degeneration), involve inflammation.
Pain, tenderness, and swelling tend to be maximal along the tendon's course.
Diagnose most cases by examination, including tendon-specific maneuvers, sometimes confirming the diagnosis with MRI or ultrasonography.
Treat with rest, heat or cold, high-dose NSAIDs, and sometimes corticosteroid injection.