Postoperative Diagnosis: 1. Impingement syndrome left shoulder. 2. AC synovitis left shoulder Procedure: Arthroscopy with subacromial decompression and AC resection left shoulder. The patient was placed supine on the operating table and prepped and draped in usual sterile fashion. The scope was introduced from a posterior portal and the joint was inspected. The rotator cuff looked in good condition. The articular surfaces looked good. The bicep also was in good condition. We went subacromially and there was a fair amount of bursal inflammation encountered. We did a thorough bursectomy. A ligament chisel was used to take down the coracoacromial ligament. A high-speed bur was used to do a subacromial decompression going from lateral to medial. We took off about 2 cm of bone anteriorly. Part of the acromion is surgically corrected. Next we opened the AC joint through an anterosuperior portal. High-speed bur was used to grind off about 10 mm of distal clavicle because there was a large subchondral cyst and we wanted to get this totally ground out, which we did. Then the wounds were irrigated out, Nylon suture was placed in our portals. The patient was placed in a bulky dressing and an arm sling and sent to the recovery room in stable condition. Code the procedure.v