Complications and revisions in metal-backed anatomic total shoulder arthroplasty: a comparative study of revision rates between stemless and stemmed humeral components.

ABSTRACT

BACKGROUND: The primary objective of this study was to evaluate and compare the incidence of complications and revision surgeries between in 2 of convertible metal-back glenoid systems in total shoulder arthroplasty (aTSA) groups over a follow-up period of up to 5 years. METHODS: A retrospective analysis included 69 shoulders from 65 patients with primary aTSA. Patients were divided into group 1 (n = 31), receiving convertible cementless stemmed aTSA (Lima SMR) and group 2 (n = 38), receiving humeral head replacement aTSA (Arthrex, Eclipse) both with metal-back glenoid components. Clinical and radiological assessments were conducted at 2, 5, and 10 years postoperatively. Assessments included the following Constant Score, Disabilities of the Arm, Shoulder, and Hand, Shoulder Pain and Disability Index, Subjective Shoulder Value, Glenohumeral Distance, Critical Shoulder Angle, and Lateral Acromion Index. In addition, we compared complications, revision rates, and survival rates between groups using Kaplan-Maier curves and Log-Rank-test. RESULTS: Baseline demographics and preoperative outcome scores showed no significant differences between groups (P ≥ .05). The overall revision rate did not significantly differ between groups (group 132% vs. group 224%, P = .60), nor did the mean time to revision (P = .27). The mean follow-up was 71 ± 41 months (group 1 94 ± 48 months, group 2 53 ± 23 months, P < .001). Kaplan-Meier analysis showed similar midterm survival probabilities (P = .94). Revision reasons included rotator cuff insufficiency (n = 4 in group 1, n = 2 in group 2) and glenoid wear/loosening (n = 5 in group 1, n = 7 in group 2). Interestingly, group 1 demonstrated no occurrence of glenoid metal baseplate or humeral loosening, while complex revisions were more common in the group 2. At 2 and 5 years, nonrevised patients in both groups had similar outcome scores. CONCLUSION: Metal-backed glenoid implants in combination with both stemless and stemmed humeral components in aTSA exhibit comparable revision rates and survival probabilities. Rotator cuff insufficiency and polyethylene wear are the 2 most common complications leading to revision. To facilitate ongoing monitoring and optimize patient safety, we implemented a modification in the follow-up protocol, transitioning to annual appointments or earlier when necessary. This study underscores the unsolved disadvantages in metal-back components and the importance of a midterm to long-term longitudinal assessment of those patients.