Scapular Spine Dimensions and Suitability as a Glenoid Bone Graft Donor Site

Abstract

Background: Current structural bone graft options used for glenoid augmentation in glenohumeral instability have known drawbacks. The scapular spine may be a possible alternative graft choice, but its dimensions and anatomy are not fully reported. Hypothesis: The scapular spine’s harvestable graft dimensions will be similar to harvestable dimensions of the coracoid and iliac crest. Study Design: Descriptive laboratory study. Methods: The scapular spine, coracoid, and iliac crest dimensions were recorded and compared bilaterally in 50 patients with 3-dimensional computed tomography imaging. The portion of the scapular spine with the largest harvestable dimensions was quantified and its location defined. Measurements were independently taken by 2 investigators and averaged for the final result. Results: The scapular spine has 81.5 mm of harvestable length and a “flare” located approximately 49.6 mm lateral to the medial scapular border, where the widest harvestable cross section is located (mean harvestable dimensions: 10.9-mm height, 11.5-mm width). Mean coracoid dimensions were 24-mm length, 14.2-mm height, and 10.6-mm width. Mean iliac crest width was 14.7 mm. In sum, 96% of scapular spines, 85% of coracoids, and 100% of iliac crests exceeded minimum dimensions of 8 mm × 8 mm × 20 mm. The coronal radius of curvature of the glenoid was significantly different from the corresponding plane of all measured structures. Conclusion/Clinical Relevance: The scapular spine has dimensions similar to the coracoid and iliac crest in the majority of patients and is therefore appropriate for further investigation as a potential graft choice in glenohumeral instability. A harvest location 49.6 mm lateral to the medial scapular border will provide the largest cross-sectional graft while avoiding the acromial base.