Abstract
BACKGROUND: Coracoid transfer procedures, such as the Bristow and Latarjet procedures, have been shown to be beneficial for patients with traumatic anterior shoulder instability, particularly those with significant bone loss (on the glenoid and/or humeral head) or those engaged in collision sports. The stabilization effect of coracoid transfer is enhanced when the coracoid graft obtains bone union. METHODS: This retrospective study analyzed 38 shoulders from 36 patients who underwent the ASBB procedure between January 2018 and December 2024. Postoperative CT scans were performed immediately after surgery to assess coracoid graft length, depth, horizontal and vertical positioning of the transferred graft, and screw angulations (both axial and sagittal angles). Bone healing was evaluated with CT at 3 and 6 months postoperatively. The Mann-Whitney U test was used to identify factors associated with bone union, and ROC curve analysis determined cutoff values. RESULTS: Fixation screws in shoulders with bone union at 3 and 6 months postoperatively had significantly smaller sagittal angulations compared with those without bone union (p < 0.001 and p = 0.012, respectively). ROC analysis identified that sagittal screw angulation of less than 16° at 3 months (sensitivity: 91 %, specificity: 88 %) and less than 18° at 6 months (sensitivity: 100 %, specificity: 90 %) predicted bone union. CONCLUSIONS: Sagittal screw angulation plays a crucial role in early bone union of the transferred coracoid graft following the ASBB procedure. Maintaining sagittal angulation below the identified thresholds may improve graft stability and patient outcomes.