Influence of Coracoglenoid Space on the Stability of Scapular Neck Fractures: Biomechanical Study

Abstract Background: The anatomical variation of the coracoglenoid space has the potential to influence the stability of scapular neck fractures. This paper aimed to investigate the path-mechanical mechanisms of different types of coracoglenoid space on the scapular neck fractures by morphometric analysis and biomechanical experiments.Methods: A total of 68 dry scapulae (left: 36; right: 32) were collected, the types of coracoglenoid space delimited by a boundary based on the ratio of the mean values of CGD to the mean values of CGN. Each specimen of a different type was under static axial compressive load test to failure. The average failure loads, stiffness, and energy for each specimen were calculated.Results: Two types of coracoglenoid space were identified. The incidence of Type Ⅰ (2.4 < ratio ≤ 3.5) (‘‘hook’’ shape) was found to be 53%, that of Type Ⅱ (3.5 < ratio ≤ 5.0) (‘‘square bracket’’ shape) was found to be 47%. There was no statistically significant difference in the two types between different body sides (P > 0.05). The average maximum failure load of these two types was 1270.82 ± 318.85 N and 1529.18 ± 467.29 N, respectively (P = 0.011). The measures of the average failure stiffness and energy of Type Ⅱ were significantly higher than Type Ⅰ (896.75 ± 281.14 N/mm vs. 692.91 ± 217.9 5N/mm, P = 0.001; 2100.38 ± 649.54 N⋅mm vs. 1712.71 ± 626.02 N⋅mm, P = 0.015, respectively).Conclusions: The variation of coracoglenoid space is large in different individuals, hook-like space is associated with fewer forces, stiffness, and energy, which constitute an anatomical predisposition to the scapular neck fractures.