Morphometric analysis of the coracoid process in the Chinese population: clinical strategies for fracture fixation.

Purpose: The coracoid process presents surgical challenges due to its irregular anatomical morphology, further compounded by a paucity of population-specific morphometric data in the Chinese population. This study aimed to systematically analyze the morphometric characteristics of the coracoid process in the Chinese population and simulate mid-axial screw placement through the vertical portion of the coracoid, thereby providing anatomical guidance for surgical fixation of coracoid base fractures.

Methods: Seven scapular specimens and 12 three-dimensional CT reconstructions were analyzed. Measurements were set the length, width, and thickness of the horizontal portion, the height, width, and thickness of the vertical portion, as well as the length and width of the glenoid cavity. Simulated mid-axial screw trajectories were assessed for angulation relative to the glenoid plane and scapular body plane, and the extreme range of each entry angle was defined. Specimen measurements were compared to the CT data. Entry point distances from anatomical landmarks and screw trajectory lengths were measured.

Results: In the scapular specimens, the length of the horizontal portion was 37.94 ± 4.02 mm, with a width of 13.74 ± 1.35 mm and a thickness of 9.40 ± 0.90 mm. The height of the vertical portion was 19.14 ± 1.64 mm, with a width of 24.99 ± 1.30 mm and a thickness of 9.97 ± 1.43 mm. The length of the glenoid cavity was 41.21 ± 4.50 mm, and the width was 29.39 ± 4.12 mm. In the glenoid plane, the screw trajectory angle was 51.33° ± 16.04°, and the extreme range of entry angle was 53.53° ± 6.05°. For the scapular body plane, it was 8.67° ± 6.36° and 63.86° ± 6.36°, respectively. The CT data measurements aligned with those of the specimens except for the extreme range of entry angles (P < 0.05). The optimal entry point was 10 mm lateral to the medial border of the horizontal portion, slightly below the midpoint of its superior-inferior axis, with a trajectory length of about 40 mm.

Conclusion: This study delineates the anatomical dimensions of the coracoid process in the Chinese population and defines safe parameters for mid-axial screw placement through the vertical portion, including entry point localization, trajectory orientation, and angulation limits. These findings enhance the precision and safety of coracoid-related surgical interventions.