Anatomic vs. reverse shoulder arthroplasty for the treatment of Walch B2 glenoid morphology: a systematic review and meta-analysis.

Background: Walch B2 glenoid morphology with glenohumeral osteoarthritis is a difficult degenerative pattern to manage for shoulder surgeons. Anatomic total shoulder arthroplasty (TSA) in combination with eccentric reaming or bone grafting are the traditional methods of treatment. Newer approaches such as TSA with posteriorly augmented glenoid components and reverse shoulder arthroplasty (RSA) may offer better stability for the posteriorly subluxated biconcave B2 wear pattern. The aim of this systematic review is to compare mid-term surgical and functional outcomes of Walch B2 glenoids without significant rotator cuff pathology treated with TSA and RSA. Methods: The review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines by searching the MEDLINE (PubMed) and Embase (Elsevier) databases. Inclusion criteria were clinical studies that evaluated the outcomes and complications of TSA or RSA in the setting of B2 glenoid morphology without significant rotator cuff pathology. Data relevant to TSA and RSA surgical outcomes were extracted and compiled, and outcomes were compared. A meta-analysis of proportions of complication and revision rates among TSA and RSA groups was performed. Results: Overall, 16 articles were included with 414 TSAs and 78 RSAs. The average follow-up duration was 54.1 ± 14.8 months for patients undergoing TSA and 44.8 ± 10.1 months for patients undergoing RSA. The TSA group was further subdivided based on the use of eccentric reaming (135 TSAs), an augmented glenoid component (84 TSAs), or bone grafting (11 TSAs) or was unspecified (184 TSAs). Overall, patients undergoing TSA and RSA demonstrated mean improvements of 50.1 ± 8.5° and 64.7 ± 5.2° in active flexion, 58.5 ± 10.3° and 68.9 ± not reported° in active abduction, and 31.3 ± 5.7° and 29.0 ± 10.2° in active external rotation, respectively. In regard to functional outcome scores, patients undergoing TSA and RSA showed mean Constant score improvements of 38.8 ± 5.3 and 46.6 ± 3.1 points and American Shoulder and Elbow Surgeons score improvements of 48.2 ± 1.0 and 49.2 ± 25.3 points, respectively. Results of the meta-analysis with mid-term follow-up data demonstrated pooled complication rates of 9% (95% confidence interval [CI], 1%-22%) for TSA and 6% (95% CI, 0%-28%) for RSA and pooled revision rates of 2% (95% CI, 0%-8%) for TSA and 1% (95% CI, 0%-15%) for RSA. Conclusion: In the setting of Walch B2 glenoid morphology, TSA with eccentric reaming or an augmented component yields comparable outcomes to RSA. Based on the patient's age, activity level, and expectations, both TSA and RSA can be considered a reasonable option to treat Walch B2 glenoid morphology.