Rotator cuff tears associated with os acromiale.

INTRODUCTION

Os acromiale is a rare anatomical condition; its incidence in cadaver studies has been found to be approximately 8%. In this retrospective study we investigated the incidence and types of os acromiale in patients with rotator cuff tears.

METHODS

We assessed operation notes and axillary radiographs for the presence and the type of os acromiale in 1000 consecutive patients with open rotator cuff repairs.

RESULTS

62 patients (6.2%) showed an os acromiale in the axillary radiographs. In 6 of these the os acromiale was not described in the operation notes. 57 os meso-acromiale and 5 os pre-acromiale were found. The average number of tendons involved in the cuff tear was the same (1.4) in patients with and without os acromiale. The average age of patients with os acromiale was 55 years, and 56 years in patients without os acromiale.

INTERPRETATION: Os acromiale is a co-condition in patients with rotator cuff tear. The prevalence of os acromiale in patients with rotator cuff tear is similar to that in a standard population with unknown integrity status of the rotator cuff. Thus, it seems debatable whether an os acromiale is a pathological condition leading to rotator cuff tears.