Prediction of coracoid thickness using a glenoid width-based model: implications for bone reconstruction procedures in chronic anterior shoulder instability.

Background: Chronic anterior shoulder instability with glenoid bone loss can be a very challenging clinical problem. Significant bone loss is commonly managed with the Latarjet procedure. However, in some cases with severe glenoid bone loss, iliac crest bone grafting is required to obtain a graft of adequate size. Iliac crest bone graft is associated with high rates of donor-site complications. Whereas glenoid dimensions can be determined by use of 3-dimensional computed tomography reconstructions, the thickness of the coracoid cannot be easily measured. This study aims to define a ratio between glenoid width and coracoid thickness that can be used in preoperative planning to determine whether coracoid transfer will yield adequate bone graft to restore glenoid contour or whether iliac crest bone graft must be taken.

Methods: We studied 100 paired cadaveric scapulae (50 male and 50 female scapulae). The bony dimensions of the coracoid and glenoid were measured for each specimen.

Results: Coracoid and glenoid dimensions are provided. The mean thickness of the male coracoid was 35.4% of the width of the glenoid. The mean female coracoid thickness was 34.4% of the glenoid width.

Discussion: A new biomorphologic model is presented to predict coracoid thickness and the ability of the Latarjet procedure to restore stability to a given bone-deficient glenoid. This model may aid the shoulder surgeon in preoperative planning and help promote successful outcomes in glenoid reconstruction surgery by determining whether a Latarjet procedure or iliac crest bone graft is the most appropriate procedure given the predicted amount of coracoid bone graft available.