Acromial Morphology Does Not Correlate with Age at Time of Rotator Cuff Tear: A Cross-Sectional Study

Background: The purpose of this study was to determine if scapular anatomy differs between younger and older patients with atraumatic full-thickness supraspinatus tears. Methods: The critical shoulder angle, acromial index and lateral acromial angle were measured on standardized radiographs of two groups of patients who underwent arthroscopic repair of full-thickness degenerative supraspinatus tears. Group 1 included 61 patients under the age of 50 years while Group 2 included 45 patients over the age of 70 years. The mean critical shoulder angle, acromial index, and lateral acromial angle were then compared. Results: There was no significant difference between groups for the critical shoulder angle (p =.433), acromial index (p =.881) or lateral acromial angle (p =.263). Interobserver reliability for critical shoulder angle, acromial index, and lateral acromial angle was nearly perfect (interclass correlation coefficient 0.996, 0.996, 0.998, respectively). No significant correlation existed between age and critical shoulder angle (p =.309), acromial index (p =.484) or lateral acromial angle (p =.685). Discussion: While the critical shoulder angle and acromial index were found to be high and in the typical range for patients with rotator cuff tears in both groups, there were no significant differences in acromial morphology between Groups 1 and 2.