Abstract
Purpose
Coracoid transfer is an effective reconstructive procedure for complex glenohumeral joint instability. Recently, the congruent-arc Latarjet procedure has been described which orients the coracoid graft undersurface flush to the glenoid articular margin. The purported advantage of this modification is that the radii of curvature of the coracoid undersurface and the anterior glenoid rim are believed to be similar, and therefore, congruent. The purpose of this study was to determine the dimensions of the coracoid and to compare the radius of curvature (ROC) of the coracoid undersurface to the ROC of the intact glenoid and various glenoid bone-loss scenarios.
Method
Thirty-four CT-based 3D models of the shoulder were examined using commercially available software. The mean dimensions of the coracoid were determined and the ROC was calculated for the coracoid undersurface, the intact glenoid as well as 20%, 35% and 50% anterior glenoid bone-loss scenarios. Intra and inter-rater statistics were calculated.
Results
The mean length, width and thickness of the coracoid were: 16.8 mm, 15.0 mm, and 10.5 mm, respectively. The mean ROC values were: coracoid: 13.6 mm, intact glenoid: 13.8 mm, 20% anterior glenoid bone-loss: 27.6 mm, 35% bone-loss: 30.5 mm, and 50% bone-loss: 33.3 mm. The coracoid ROC was not significantly different from the intact glenoid (p=0.75), however, was significantly less (p<0.01) than all glenoid bone-loss scenarios. Intra- and inter-rater reliability was good/excellent.
Conclusion
The congruent-arc Latarjet is truly congruent if the coracoid is fixated to an intact anterior glenoid rim. In glenoids with 20% or greater anterior bone-loss, the congruent-arc Latarjet is no longer congruent.
