CT evaluation of glenoid joint line restoration with glenoid bone grafting and reverse shoulder arthroplasty in patients with significant glenoid bone loss.

Abstract Background Restoration of native glenohumeral joint line is important for a successful outcome after reverse shoulder arthroplasty (RSA). The aims of this study are to quantify the restoration of glenoid joint line after structural bone grafting and RSA, and to evaluate graft incorporation, correction of glenoid version, and rate of notching. Methods This is a retrospective review of 21 patients who underwent RSA (20 primary, 1 revision) with glenoid bone grafting (15 autografts, 6 allografts). Grammont design implants and baseplate with long peg were used in all patients. Preoperative and postoperative 3D models were created using MIMICS 21.0 (Materialise, Belgium). Preoperative defects were classified and postoperative joint line restoration were assessed based on the lateral aspect of the base of the coracoid. Post-operative CT scans were evaluated for graft incorporation, version correction, and presence of notching. Results Preoperative glenoid defects were classified as massive (5%), large (29%), moderate (52%), and small (14%). The average preoperative version was 8° of retroversion. The average postoperative version was 5° of retroversion. The average preoperative medialization was noted to be 8.5mm medial to native joint line or 0.5mm (range -16.8 – 13.2) lateral to the coracoid base. The postoperative CT scans demonstrated a mean joint line at 12.1mm (range 1.3 – 22.4) lateral to the coracoid base. At 3-month follow-up, all patients demonstrated graft incorporation on CT scans. Graft osteolysis was observed on CT scan in 4.8% of patients at mean follow-up of 19.5 months. Discussion Structural bone grafting of glenoid defect effectively recreates the glenoid anatomy, restores glenoid bone stock, recreates the true glenohumeral joint line, and corrects glenoid deformity. The use of bone grafting also allows lateralization of the baseplate and glenosphere reducing risk of severe scapular notching. Conclusion Restoration of glenoid joint line was achieved in all patients. Glenoid bone grafting is a viable option for restoring glenoid joint line in cases of significant glenoid defects encountered during RSA. Level of Evidence Level IV; Case Series; Treatment Study