87 patients with subacromial impingement were randomized to one of three treatment groups: arthroscopic acromioplasty, open acromioplasty, or to a physiotherapy program. Patients were followed-up for a minimum of 10 years after intervention, with outcomes related to subjective function (Constant score), shoulder range of motion, shoulder strength in abduction, and ultrasonic and radiographic evaluations. At final follow-up, Constant score was significant greater in the open acromioplasty compared to physical therapy alone, and range of motion in elevation was significantly greater in both the arthroscopic and open acromioplasty groups compared to physical therapy alone. However, range of motion in internal rotation, strength, ultrasonographic and radiographic findings did not significantly differ between the three groups at final follow-up.