3D-Planned Posterior Open-Wedge Glenoid Osteotomy Using a Patient-Specific Cutting Guide in Posterior Shoulder Instability: A Technical Note

Posterior shoulder instability remains a rare but disabling condition often underdiagnosed due to subtle symptoms and delayed presentation. Excessive glenoid retroversion is a key anatomical determinant of posterior humeral head subluxation. When isolated soft tissue repair fails, posterior opening glenoid osteotomy can restore physiological glenoid version. Traditional freehand or fluoroscopic techniques, however, are technically demanding and prone to variability. This technical note describes a 3D-planned posterior open-wedge glenoid osteotomy using a patient-specific cutting guide (PSI) to correct excessive retroversion in posterior instability. Preoperative 3D computed tomography (CT) planning (ONE®, Newclip Technics, Haute-Goulaine, France) allows the virtual correction of retroversion and design of a custom guide conforming to the posterior glenoid surface. The PSI ensures accurate orientation, safe osteotomy execution, and faithful translation of the preoperative plan. Fixation is achieved with a low-profile locking plate, enabling early mobilization.