Introduction and purpose: Several factors (vascular, morphological, biomechanical, etc.) have been associated with the etiopathogeny of the rotator cuff. The purpose of this study is to assess the influence of the acromial coverage index (ACI) on the development of rotator cuff tears.

Materials and methods: A comparative analysis was made of three groups of patients with a total of 62 females and 47 males with a mean age of 49.84 years. Group I included patients operated on for a rotator cuff tear (n=45), group II contained patients with a rotator cuff tear which evolved satisfactorily with rehabilitation treatment (n=36) and group III was made up of a group of control individuals with no pathology (n=38). All patients in groups I and II had a rotator cuff tear detected via either MRI or Arthro-CT. ACI is defined as the perpendicular to the tangent of the glenoid cavity until the outermost part of the acromion and the perpendicular to the tangent of the glenoid cavity which coincides with the diameter of the humeral head.

Results: Group I had a mean ACI of .68, group II of .72 and group III of .59, i.e. there are statistically significant differences between groups I and III (p< 0.0001) and between group II and III (p< 0.0001). No statistically significant differences exist between group I and II (p< 0.219). No statistically significant differences exist between right and left arm involvement (p< 0.471). There are statistically significant differences between males and females (p< 0.0001).

Conclusions: (1) ACI is significantly higher in patients with rotator cuff tears than in the control group. (2) ACI is significantly higher in females than in males. (3) There are no statistically significant differences with respect to the involvement’s laterality. (4) ACI would seem to have an influence on the etiopathogeny of rotator cuff tears.