Acromial morphology in patients with calcific tendinitis of the shoulder

The purpose of this study was to evaluate whether the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement.

Digital radiographs of 150 shoulders were evaluated with the open source DICOM-Viewer OsiriX. 50 patients had symptomatic calcific tendinitis of the shoulder, 50 had subacromial impingement without calcifications or rotator cuff tears, 50 with bruised shoulder that were previously asymptomatic served as controls. Acromial shape according to Bigliani et al. acromial tilt (AT) according to Kitay et al. and Aoki et al. acromion index (AI) according to Nyffeler et al. and lateral acromial angle (LAA) according to Banas et al. were measured.

Both calcific (0.72; P = 0.001) and impingement groups (0.73; P = 0.008) were significantly different from controls (0.67) using AI measure, while only the calcific group (79.5°) was different from controls (84.1°) using LAA (P < 0.001), and only the impingement group (32.9°) was different from controls (29.2°) using AT (P < 0.001). An LAA <70° only occurred in two patients with calcific tendinitis.

The hypothesis of this study was that the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement was only confirmed for the AI. The AI of shoulders with calcific tendinitis is comparable to that of shoulders with subacromial impingement.