Poster 166: Distal Clavicle versus Traditional and Congruent Arc Latarjet: Comparison of Surface Area and Glenoid Apposition with 3-Dimensional CT and MRI

Abstract

Objectives: Limited studies have compared graft-glenoid apposition and glenoid augmentation area between the latarjet and distal clavicle grafts in glenohumeral stabilization. Additionally, pre-operative planning is typically performed using computerized tomography (CT), and few studies have used 3- dimensional magnetic resonance imaging (3D-MRI) reformations to assess graft dimensions. The purpose of the study was two-fold: 1) compare bony apposition, glenoid augmentation, and graft width among coracoid and distal clavicle bone augmentation techniques and 2) to determine the viability of 3D-MRI to assess bone graft dimensions. Methods: Twenty-four patients with recurrent glenohumeral instability and bone loss were included in this study. 3D-CT and 3D-MRI reformations were utilized to measure pertinent dimensions for five orientations of coracoid and distal clavicle autografts: (1) standard Latarjet (SLJ), (2) congruent arc Latarjet (CLJ), and (3) distal clavicle attached by its posterior surface, (DCP) and (4) inferior surface (DCI), and (5) resected end (DCR). Glenoid augment area was defined as the graft surface area contributing to the glenoid. Bone-on-bone apposition was defined as the graft-glenoid contact area for bone healing potential, and graft width was pertinent for fixation technique. Paired t-tests were performed to compare graft sizes between patients and compare 3D-CT vs 3D-MRI measurements. Results: CLJ had the largest glenoid augmentation area (mean: 318mm2, sd: 74) while SLJ displayed the most apposition (mean: 318mm2, sd: 74). DCI had the largest graft width (mean: 21mm, sd: 4). Paired t- tests revealed no significant differences between Latarjet methods, whereas distal clavicle grafts varied significantly with orientation. All 3D-CT and 3D-MRI measurements were within 1mm of each other, and only two demonstrated statistically significant difference (coracoid width: 13.03 vs 13.98mm, p=0.010; distal clavicle thickness: 9.69 vs 10.77, p=0.002). 3D-CT and 3D-MRI measurements demonstrated strong positive correlation (r>0.6 and p<0.001 for all dimensions). Conclusions: Glenoid augmentation, bony apposition, and graft width can vary with coracoid or distal clavicle graft type and orientation. Differences between 3D-CT and 3D-MRI were small and likely not clinically significant.