Comparative glenoid reconstruction strategies in reverse shoulder arthroplasty: a meta-analysis of standard reconstruction, bony increased offset, and metal-augmented increased offset techniques.

backgroundGlenoid reconstruction strategy is a critical determinant of biomechanics, implant fixation, and clinical outcomes in reverse shoulder arthroplasty (RSA). While standard reconstruction remains widely used, biological increased offset (BIO-RSA) and metal-based modified increased offset (MIO-RSA) techniques have been increasingly adopted to address glenoid bone loss and medialization. However, comparative clinical evidence among these contemporary strategies remains inconsistent. This meta-analysis provides the most comprehensive comparative evaluation to date of standard RSA, BIO-RSA, and MIO-RSA in primary RSA.

methodsA systematic search of four electronic databases identified randomized controlled trials and comparative observational studies evaluating glenoid reconstruction strategies in primary RSA. Eighteen studies encompassing approximately 3000 shoulders were included. Pairwise comparisons were performed between BIO-RSA versus standard RSA, MIO-RSA versus standard RSA, and BIO-RSA versus MIO-RSA. Outcomes included functional scores, patient-reported outcome measures, range of motion, pain, radiographic findings, postoperative complications, and revision surgery. Pooled analyses were conducted using fixed- or random-effects models according to heterogeneity.

resultsFunctional outcomes demonstrated selective differences across reconstruction strategies. BIO-RSA achieved higher Constant–Murley scores compared with standard RSA (MD + 3.94, p = 0.005) and MIO-RSA (MD + 9.47, p = 0.03), as well as greater improvement in Subjective Shoulder Value versus MIO-RSA (MD + 5.88, p = 0.02). MIO-RSA was associated with higher UCLA scores (MD + 1.01, p = 0.04) and lower SPADI scores (MD − 3.48, p = 0.006) compared with standard RSA. Objective range-of-motion outcomes were largely equivalent across techniques, with the exception of greater external rotation following BIO-RSA versus standard RSA (MD + 4.64°, p = 0.03). Pain outcomes did not differ significantly between groups. Radiographically, BIO-RSA demonstrated a lower risk of scapular notching compared with standard RSA (RR 0.60, p = 0.004), while implant loosening rates were similar across techniques. Overall complication rates were comparable; however, revision surgery occurred less frequently with MIO-RSA compared with standard RSA (RR 0.31, p = 0.003).

conclusionStandard, biological, and metal-augmented glenoid reconstruction strategies in RSA demonstrate broadly comparable safety and functional performance, with selective, outcome-specific advantages rather than global superiority. BIO-RSA offers benefits in rotational function, functional improvement, and scapular notching reduction, whereas MIO-RSA provides advantages in selected patient-reported outcomes and revision risk. These findings support an individualized, anatomy-driven approach to glenoid reconstruction selection in contemporary reverse shoulder arthroplasty.