Glenoid morphology is associated with the development of instability arthropathy

Background Instability arthropathy (IA) is a major long-term concern in patients with anterior shoulder instability. This study investigated the association of glenoid morphology with the development of IA. Methods The study included 118 patients with unilateral anterior shoulder instability and available bilateral computed tomography scans. Instability-specific information was obtained from all patients. The glenoid morphology of the affected shoulder was compared with the nonaffected contralateral side resembling the constitutional preinjury glenoid shape. Both shoulders were evaluated independently by 3 observers to assess the grade of IA according to a Comprehensive Arthropathy Rating (CAR) system. Associations between IA and the glenoid morphology parameters were investigated. Results The average glenoid retroversion ( P P P P P P  = .001) and more sclerosis and cysts ( P P P  = .001), size of the glenoid defect ( P  = .005), and the contralateral glenoid depth ( P  = .011), glenoid diameter ( P  = .016), and bony shoulder stability ( P  = .029), and negatively with glenoid retroversion of the affected side ( P  = .027). Conclusion Development of IA arthropathy is associated not only with the age of the patients but also with morphologic parameters of the glenoid, including glenoid defect size and the constitutional glenoid concavity shape.