OBJECTIVE: To investigate the effect of glenohumeral bone structure on anterior shoulder instability by three-dimensional CT reconstruction. METHODS: The clinical data of 48 patients with unilateral anterior shoulder dislocation (instability group) and 46 patients without shoulder joint disease (control group) admitted between February 2012 and January 2024 were retrospectively analyzed. There was no significant difference in gender and side between the two groups ( P>0.05). The patients were significantly younger in the instability group than in the control group ( P<0.05). The glenoid joint morphological parameters such as glenoid height, glenoid width, ratio of glenoid height to width, glenoid inclination, the humeral containing angle, and glenoid version were measured on three-dimensional CT reconstruction of the glenoid. The differences of the above indexes between the two groups were compared, and the differences of the above indexes between the two groups were compared respectively in the male and the female. Random forest model was used to analyze the influencing factors of anterior shoulder instability. RESULTS: The comparison between the two groups and the comparison between the two groups in the male and the female showed that the ratio of of the instability group glenoid height to width was larger than that of the control group, the glenoid width and humeral containing angle were smaller than those of the control group, and the differences were significant ( P<0.05); there was no significant difference in glenoid height, glenoid inclination, and glenoid version between the two groups ( P>0.05). The accuracy of the random forest model was 0.84. The results showed that the top four influencing factors of anterior shoulder instability were ratio of glenoid height to width, the humeral containing angle, age, and glenoid width. CONCLUSION Ratio of glenoid height to width and the humeral containing angle are important influencing factors of anterior shoulder instability.
Humans ; Joint Instability/diagnostic imaging* ; Male ; Female ; Shoulder Joint/diagnostic imaging* ; Shoulder Dislocation/diagnostic imaging* ; Retrospective Studies ; Tomography, X-Ray Computed ; Adult ; Imaging, Three-Dimensional ; Young Adult ; Middle Aged ; Adolescent ; Glenoid Cavity/pathology*

Shoulder surgeons need to be aware of the critical size of the glenoid or humeral osseous defects seen in patients with anterior shoulder instability, since the considerable size of osseous defect is reported to cause postoperative instability. Biomechanical studies have identified the size of the osseous defect which affects stability. Since engagement always occurs between a Hill-Sachs lesion and the glenoid rim, when considering the critical size of the Hill-Sachs lesion, we have to simultaneously consider the size of the glenoid osseous defect. With the newly developed concept of the glenoid track, we are able to evaluate whether a large Hill-Sachs lesion is an "on-track" or "off-track" lesion, and to consider both osseous defects together. In case of an off-track Hill-Sachs lesion, if the glenoid defect is less than 25%, no treatment is required. In this case, the Latarjet procedure or arthroscopic remplissage procedure can be a treatment option. However, if the glenoid defect is more than 25%, treatment such as bone grafting is required. This will convert an off-track lesion to an on-track lesion. After the bone graft or Latarjet procedure, if the Hill-Sachs lesion persists as off-track, then further treatment is necessitated. In case with an on-track Hill-Sachs lesion and a less than 25% glenoid defect, arthroscopic Bankart repair alone is enough.
Biomechanical Phenomena ; *Glenoid Cavity/injuries/pathology/physiopathology ; Humans ; *Humeral Head/injuries/pathology/physiopathology ; Shoulder Dislocation/physiopathology ; *Shoulder Joint/injuries/pathology/physiopathology