Subacromial Impingement (also known as Bursitis, Impingement Syndrome, Rotator Cuff Tendinitis, Supraspinatis tendonitis) occurs with repeated use of your arm overhead and in patients who develop small bony spurs which trap the rotator cuff tendons above the main shoulder joint.
Treatment include Injections and physiotherapy often improve this condition, but repeated steroid injections should be avoided.
Arthroscopic Surgery involves spring-cleaning of the subacromial bursa with removal of the bony spur. This is called Arthroscopic Sub-acromial Decompression.