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Correlation between glenoid bone structure and recurrent anterior dislocation of the shoulder joint.

BACKGROUND
To investigate the anatomical characteristics and symmetry of the bilateral glenoid structures of Chinese people and to explore the relationship between the glenoid bone structure and recurrent anterior dislocation.


MATERIALS AND METHODS
The control group included 131 individuals with no history of shoulder dislocation. The dislocation group consisted of 131 patients with a history of unilateral shoulder dislocation. All subjects underwent CT scans. Glenoid shape (pear-shaped, inverted comma-shaped, oval-shaped), width, height, depth, version angle, area, maximum fitting circle area and volume were measured.


RESULTS
There was no significant difference in normal bilateral glenoid of Chinese people (P > 0.05). There were statistically significant differences in depth, height to width ratio, maximum fitting circle area and shape between the dislocation and control groups (P < 0.05). Regression analyses showed that the glenoid depth (odds ratio 0.48; P < 0.01), the glenoid height to width ratio (odds ratio 28.61; P < 0.01), the glenoid maximum fitting circle area (odds ratio 1.01; P < 0.01) and the glenoid shape (P < 0.05; pear-shaped odds ratio 0.432; inverted comma-shaped odds ratio 0.954) were associated with anterior shoulder instability. Pear-shaped and inverted comma-shaped glenoid had lower risk of recurrent anterior shoulder dislocation compared to oval glenoid. ROC curve analysis showed that individuals with anterior shoulder instability had smaller glenoid depth and larger height to width ratio and the glenoid maximum fitting circle area compared with the control group.


CONCLUSIONS
The normal bilateral glenoids of Chinese people are basically symmetrical. The glenoid shape, depth, height to width ratio and maximum fitting circle area are risk factors for recurrent anterior shoulder dislocation. Evaluation of the glenoid bone structure enables more accurate prediction of the risk of recurrent shoulder dislocation.