BIO-RSA vs. metal-augmented baseplate in shoulder osteoarthritis with multiplanar glenoid deformity: a comparative study of radiographic findings and patient outcomes

• Published in: Journal of shoulder and elbow surgery 2023-11, Vol.32 (11), p.2264-2275
• Main Authors: Merolla, Giovanni, Giorgini, Andrea, Bonfatti, Rocco, Micheloni, Gian Mario, Negri, Alberto, Catani, Fabio, Tarallo, Luigi, Paladini, Paolo, Porcellini, Giuseppe
• Format: Article
• Language: English
• Subjects: bone graft; glenoid deformity; metal-augmented baseplate; reverse arthroplasty; Shoulder osteoarthritis
• ISSN: 1058-2746; 1532-6500
• DOI: 10.1016/j.jse.2023.04.028

Reverse shoulder arthroplasty (RSA) requiring extensive reaming to address severe glenoid bone loss increases the risk of glenoid medialization and baseplate failure. We hypothesized that (1) metal-augmented baseplate prevents the medialization of the joint line and preserves glenoid bone stock similarly to bony increased-offset (BIO)-RSA and (2) bone graft viability and healing in BIO-RSA patients become compromised over time. Eighty-one patients (83 shoulders) underwent glenoid lateralization with bone (BIO-RSA group, 44) or metal-augmented baseplate (metallic increased-offset [MIO]-RSA group, 39) and a minimum follow-up of 24 months were included. The orientation and direction of glenoid erosion was identified and recorded using computerized 3D planning. Active range of motion, and the Western Ontario Osteoarthritis of the Shoulder (WOOS) index were assessed before arthroplasty and at the last follow-up visits. Radiographic changes around the glenoid and humeral components were assessed. Healing and thickness of bone graft were evaluated by predefined criteria. Postoperative global glenoid inclination (β angle) and retroversion were also measured. Delta scores of active anterior elevation were higher in the MIO-RSA group (P = .027). The differences in the other planes of shoulder motion and in WOOS index scores between the groups were not significant. Preoperative glenoid retroversion was higher in BIO-RSA patients, and glenoid inclination was similar in both groups. Type B2 and B3 glenoids had a posterior-central (91%) and posterior-superior (90%) erosion with a mean posterior humeral head subluxation of 76% and 78%, respectively. The direction of erosion in type E2 and E3 glenoids was posterior-superior, with a mean posterior humeral head subluxation of 74%. The rate of high position of the glenosphere was higher in the BIO-RSA group (P = .022), whereas the values of β angle and postoperative retroversion were similar in the 2 groups. BIO-RSA group showed radiolucent lines