The AC joint--acromioclavicular joint--at the end of the clavicle, can be a painful part of rotator cuff disease. Arthritic spurs on its undersurface may impinge on the irritated or torn rotator cuff below, or joint deterioration alone may cause pain.
This may be treated with a corticosteroid injection, which may be successful at decreasing pain. In cases where this does not help, and discomfort is interfering with use, arthroscopic resection---the so-called "Mumford procedure"-- can be easily performed during the arthroscopic procedure for Impingement syndrome alone, when a rotator cuff tear is repaired, or for isolated AC joint arthritis.
When such distal clavicle resection is required, it does not prolong recovery. And, having it performed using the arthroscope avoids the potential downsides of open surgery like a painful scar, or instability at the end of the clavicle.
