O2047 RELATIONSHIP BETWEEN OS ACROMIALE AND AC JOINT ANATOMICAL POSITION

Abstract

Aims: Most of the orthopaedic literature on os acromiale (OA) is focused on corresponding clinical implication, such as impingement syndrome and rotator cuff tear; whilst, although it is present in 8% of subjects, scarce information is reported on the causes that may predispose to it. Our aim is to investigate whether the origin of OA is related to position of AC joint. Methods: The acromions of 211 volunteers (control group) and 33 subjects, respectively, without or with OA have been radiographically (axillary view) classiþed in accordance to the Edelson and Taitzñ method. The latter distinguishes the acromion in three types on the basis of the distance between the anterior aspect of the acromion and AC joint. Out of 33 subjects with os acromiale, 11 were shoulder painless. We have compared among them the frequencies of the types of acromion observed in the two investigated cohorts. Results: Half (52.1%) of the acromions of the control group had the articular facet for the AC joint on the acromion tip whilst in 45.4% facet was tip distally located. On the other hand, out of 33 subjects with OA, 18.1% and 81.1% had, respectively, AC joint lying on or distally to the acromion tip. Conclusions: Our data suggest that the longer is the distance of AC joint from the anterior edge of the acromion, the higher is the possibility that an OA origin.