JSES - 2026-08-21 - Journal Article
Migration patterns of the humeral component of the stemless Simpliciti Shoulder System in stemless anatomic total shoulder arthroplasty A radiostereometric and clinical study with 60-month follow-up.
de Bruin LJE, Brinke BT, Oomen R, Hoelen M, Hesseling B, Mathijssen N
Topics
Key Takeaway
The stemless Simpliciti humeral component achieves stable fixation by 12 months in 87% of cases, with median translation of <0.2 mm and rotation of <0.4° between 24 and 60 months, though 3 of 23 implants showed continuous migration without clinical consequence.
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Summary
This prospective longitudinal study used model-based RSA to characterize humeral component migration of the stemless Simpliciti system at 5 years in 23 patients undergoing anatomic TSA. Median translation along all three axes was <0.2 mm and median rotation <0.4° between 24 and 60 months, indicating plateau fixation. Three patients demonstrated continuous migration beyond 24 months without clinical deterioration or implant failure, and all PRO scores (Constant-Murley, OSS, DASH, VAS) improved within 12 months and remained stable thereafter.
Key Limitation
With only 23 patients and 3 continuous-migration cases, the study is critically underpowered to determine whether continuous migration beyond 24 months predicts eventual aseptic loosening or revision.
Original Abstract
BACKGROUND
The role of continuous migration in predicting long-term outcomes in total shoulder arthroplasty is yet unknown. We aimed to investigate migration patterns of the stemless humeral component of the Simpliciti Shoulder System using model-based radiostereometric analysis (MB-RSA) at five years postoperatively.
METHODS
In this prospective longitudinal cohort study, MB-RSA was used to assess implant migration of the stemless Simpliciti Shoulder system. Primary outcomes were fixation and migration patterns of the humeral component. Secondary outcomes were the Constant-Murley Score, Oxford Shoulder Score (OSS), Disability of the Arm, Shoulder and Hand (DASH) score, the visual analogue scale (VAS), and complications. Linear mixed models were performed to analyze the primary and secondary outcomes. A Mann Whitney-U test was performed to explore differences between the groups with continuous migration and non-continuous migration of the humeral component at the 5-year follow-up. Alfa inflation was prevented with the Bonferroni correction.
RESULTS
Twenty-three patients were included and had 5 years of follow-up. Median of the total translation between 24 months and 60 months (IQR) along the x-, y-, z-axis was -0.11 mm (IQR -0.47 to 0.02), -0.19 mm (IQR -0.28 to 0.03), and 0.15 mm (IQR -0.24 to 0.32), respectively. Median of the total rotation between 24 and 60 months around these axes was -0.37° (IQR -0.67 to 0.28), -0.10° (IQR -1.52 to 1.84), and -0.22° (IQR -0.85 to 0.43), respectively. Three patients showed continuous implant migration between 24 and 60 months. All clinical outcomes improved and stabilized in the first 12 months postoperatively and remained stable between 24 and 60 months.
CONCLUSION
The current study demonstrated that stemless Simpliciti Shoulder systems remained stable between 24 and 60 months, when already stabilized before within the first 12 months. Furthermore, in three implants continuous migration persisted up to 60 months postoperatively, without impacting clinical outcomes or implant survival. We further demonstrated that implant stabilization is still possible after 24 months of follow-up.
LEVEL OF EVIDENCE
Level IV, Case Series, Treatment Study.