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Objectives and questions: The glenoid component and its fixation in bone are critical factors for implant longevity in anatomic total shoulder arthroplasty (aTSA). This study compares long-term survival rates of keeled and pegged glenoid components.

Material and methods: A retrospective analysis was conducted on 90 patients who underwent aTSA between 2011 and 2016. Patients were divided into three groups: Keeled-CoCr (n=38): Keeled glenoid components with cobalt-chromium humeral components, Pegged-CoCr (n=14): Pegged glenoid components with cobalt-chromium humeral components, and Pegged-Titanium (n=38): Pegged glenoid components with titanium-coated humeral components.

Propensity-score matching was performed between the Keeled-CoCr and Pegged-Titanium groups to control for confounders such as age, sex, and glenoid morphology. The primary outcome was implant survival, analyzed using Kaplan-Meier survival curves and log-rank tests. Secondary outcomes included clinical scores (Constant Score), glenohumeral distance (GHD) at baseline and after 5 years, and changes in GHD over time. Data were compared using Kruskal-Wallis and Wilcoxon tests with a significance level of 0.05.

Results: The groups showed no significant differences in age (Keeled-CoCr: 69.0 [60.2; 73.8], Pegged-CoCr: 68.0 [63.8; 69.8], Pegged-Titanium: 68.0 [57.0; 73.0], p=0.889), sex distribution (male: 47.4%, 28.6%, 50%, p=0.375), or glenoid morphology (p=0.919).

Implant survival was significantly longer for Keeled-CoCr components (102 [79.8; 128] months) compared to Pegged-CoCr (66.0 [60.5; 74.5] months) and Pegged-Titanium (73.0 [36.0; 95.2] months, p<0.0001). Survival in the Keeled-CoCr group was significantly longer than Pegged-CoCr (p=0.004) and Pegged-Titanium (p=0.001), with no significant difference between the two pegged groups (p=0.521).

Constant Scores were significantly higher in the Keeled-CoCr group (80.0 [73.0; 83.0]) compared to Pegged-CoCr (37.5 [26.8; 55.0]) and Pegged-Titanium (32.5 [24.2; 46.5], p<0.001). Scores for Keeled-CoCr were significantly better than both pegged groups (p<0.001), with no significant difference between Pegged-CoCr and Pegged-Titanium (p=0.499).

Revision rates were lower for Keeled-CoCr (13%) compared to Pegged-CoCr (53%) and Pegged-Titanium (53%, p<0.001). The GHD showed no significant differences at baseline (p=0.126) or after 5 years, nor did the reduction in GHD over time: Keeled-CoCr: 1.30 [0.80; 2.30], Pegged-CoCr: 2.60 [1.02; 3.58], Pegged-Titanium: 2.40 [1.20; 3.00], p=0.231.

Discussion and conclusions: Our results suggest that keeled glenoid components may have better long-term survival and functional outcomes than pegged components in anatomic total shoulder arthroplasty. However, this study focuses on a singleimplant from one manufacturer. Further research is needed to confirm whether these findings apply to other designs and brands.