Radiographic evaluation of the acromion in impingement syndrome: comparison with arthroscopic findings in 147 shoulders.

We analyzed standardized scapulolateral and anteroposterior view radiographs in 147 patients with impingement syndrome to detect a subacromial osteophyte or spur, which should be of value in those patients who require surgical treatment. Standard anteroposterior view radiographs with a fixed tube angulation, 0 and 30 degrees, were compared to anteroposterior view radiographs with individual tube angulation (the radiograph beam was tilted caudally, depending on the slope of the acromion). In all patients, we identified an acromion bony overhang on the anteroposterior view radiographs with individual tube angulation having an average thickness of 5 mm, which correlated well with the intraoperative findings at arthroscopic acromioplasty. In only 35% of the patients did we detect a subacromial osteophyte or spur on radiographs with a fixed tube at 0 degrees angulation and in 92%, we found a false impression of a spur on the 30-degree views because of overexposure. We conclude that, anteroposterior view radiographs with an individual caudally-tilted X-ray beam, depending on the acromion slope, can show the whole spur and/ or size of the osteophyte, on the anterior margin of the acromion.