Reverse Shoulder Arthroplasty
Arthritis of the shoulder joint results from loss of articular (tread) cartilage from the cup or glenoid and the ball or humeral head. The degeneration and bone on bone rubbing of the joint surfaces oftentimes produce significant pain and dysfunction. Arthritic spurs as well as bone erosion can occur. When shoulder arthritis develops, deep, aching pain along with restriction of motion of the shoulder can occur. Use of the shoulder may exacerbate the pain. Occasionally, shoulder arthritis can be caused from inflammatory conditions such as rheumatoid arthritis. As the disease progresses, pain may be present even at rest, or at night. On physical examination, significant restriction of motion as well as grating or grinding sensations may be present with motion of the shoulder. Significant weakness of the shoulder is often present if there is an associated rotator cuff tear. Possible loss of bone identified on x-rays may require further imaging and MRI or CAT scan. Conservative measures include ice, nonsteroidal anti-inflammatories, gentle range of motion and strengthening exercises. Physical therapy and cortisone injections may be of benefit as well. When conservative treatment is no longer effective, replacing the worn and arthritic surfaces may provide the best option for pain relief and improvement of function. When a rotator cuff tear is also present and unrepariable, a reverse shoulder replacement is the preferred option. A large metal sphere is fixed to the cup portion of the shoulder, and a metal stem with a plastic cup is affixed to the upper arm bone. Bone grafting may be necessary if there is bony deficiency of the cup or glenoid. By reversing the ball and socket components from their normal position, the deltoid muscle becomes the predominant mover of the shoulder and an intact rotator cuff is not required. Pain relief is generally good to excellent, and approximately 75-80% of normal motion often results. Physical therapy helps to restore range of motion and strength.