text: My Family Medicine Practice: Tendinitis and Bursitis
  The patient with tendinitis of the shoulder complains of restricted shoulder movement, especially abduction, and localized pain, which is most severe at night and often interferes with sleep. The pain extends from the acromion (the shoulder's highest point) to the deltoid muscle insertion, predominately in the so-called painful arc—that is, when the patient abducts his arm between 50 and 130 degrees. Fluid accumulation causes swelling.
  In calcific tendinitis, calcium deposits in the tendon cause proximal weakness and, if calcium erodes into adjacent bursae, acute calcific bursitis.
  In bursitis, fluid accumulation in the bursae causes irritation, inflammation, sudden or gradual pain, and limited movement. Other symptoms vary according to the affected site. Subdeltoid bursitis impairs arm abduction; prepatellar bursitis (housemaid's knee) produces pain when the patient climbs stairs; hip bursitis makes crossing the legs painful.
  In tendinitis, X-rays may be normal at first but later show bony fragments, osteophyte sclerosis, or calcium deposits. Arthrography is usually normal, with occasional small irregularities on the undersurface of the tendon.
  Diagnosis of tendinitis must rule out other causes of shoulder pain, such as myocardial infarction, cervical spondylosis, and tendon tear or rupture.
  Significantly, in tendinitis, heat aggravates shoulder pain; in other painful joint disorders, heat usually provides relief.
  Localized pain and inflammation and a history of unusual strain or injury 2 to 3 days before onset of pain are the bases for diagnosing bursitis. During early stages, X-rays are usually normal, except in calcific bursitis, in which X-rays may show calcium deposits.
  Therapy to relieve pain includes resting the joint (by immobilization with a sling, splint, or cast), systemic analgesics, application of cold or heat, ultrasound, or local injection of an anesthetic and a corticosteroid to reduce inflammation.
  A mixture of a corticosteroid and an anesthetic such as lidocaine generally provides immediate pain relief. Extended-release injections of a corticosteroid, such as triamcinolone or prednisolone, offer longer pain relief. Treatment also includes oral anti-inflammatory agents.