LAUSR

INTRODUCTION The purpose was to evaluate the relationship between acromial morphology and location of acromial fractures following reverse shoulder arthroplasty (RSA) and determine whether fracture location and displacement impact clinical outcomes. METHODS A multicenter retrospective review was performed on RSAs complicated by acromial fractures. Radiographs were compared to determine the differences in acromial morphology as well as fracture orientation and pattern between patients with Levy I (n= 17) and Levy II (n= 25) fractures. Patients with a minimum of 2-year follow-up were selected to examine the association between clinical outcomes and fracture location and displacement. Twenty-two patients were stratified based on whether they achieved the American Shoulder and Elbow Surgeons (ASES) minimal clinically important difference (MCID= 20 points). The groups were then compared for fracture location and displacement using measurements such as acromion-humeral distance (AHD). RESULTS The Levy I group had a higher acromial slope than the Levy II group (127° vs. 117°; p< 0.001). Levy type I fractures had a transverse pattern occurring in the coronal plane whereas Levy type II fractures had an oblique pattern occurring in the sagittal plane (p < 0.001). At final follow-up, 12/22 patients (55%) achieved the MCID. Those who did not achieve the MCID had more displaced fractures including a lower AHD (8 vs. 20 mm, p = 0.007). There was no difference in distribution of Levy type I and type II fractures based on the MCID cutoff (p= 0.093). CONCLUSION Increased acromial slope is associated with transverse fractures in the Levy I region, whereas a lower acromial slope is associated with oblique fractures in the Levy II region. Overall, 55% of patients achieved the MCID at mid-term follow-up. Those who did not achieve the MCID got worse postoperatively, and this was associated with increased fracture displacement.