Mapping of glenoid bone loss in recurrent anterior shoulder instability: is there a particular deficit pattern?

Background: Glenoid bone loss in recurrent anterior shoulder instability is a challenging problem for shoulder surgeons, and knowledge about the anatomy of glenoid deficits is scarce. In this study, we tried to evaluate the pattern of this pathology.

Methods: Our analysis included 44 shoulders from 44 patients with recurrent anterior shoulder instability accompanied by a clinically relevant glenoid bone loss. The defect size, the localization of the inferior defect edge, and the defect angle were measured, and osseous landmarks were identified. An en face view on 2-dimensional computed tomography scans of each patient was fitted onto a template to create a deficit map for small (<23%) and large (>23%) defects.

Results: The study cohort consisted of 9 women and 35 men with a mean age of 33 ± 11 years at the date of the scan. The defect size and localization of the inferior defect edge showed significant differences between both groups, indicating a more posterior position of larger defects. The defect angle, however, showed no significant difference between small and large defects. Both groups showed a vertical defect pattern.

Conclusion: The osseous glenoid deficit in recurrent anterior shoulder instability shows a vertical pattern with no remarkable differences between small and large defects. This finding can influence biomechanical models as well as surgical reconstruction.