Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis

Background and purpose:  Backside wear of the polyethylene insert in total knee arthroplasty (TKA) has been described to produce clinically significant levels of polyethylene debris, which can lead to aseptic loosening and osteolysis. Monoblock design eliminates backside wear of the polyethylene an...

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Main Authors: Mikkel Rathsach Andersen, Müjgan Yilmaz, Nikolaj Winther, Thomas Lind, Henrik Schrøder, Gunnar FLIVIK Flivik, Michael Mørk Petersen
Format: Article
Language:English
Published: Medical Journals Sweden 2025-06-01
Series:Acta Orthopaedica
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Online Access:https://actaorthop.org/actao/article/view/43904
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author Mikkel Rathsach Andersen
Müjgan Yilmaz
Nikolaj Winther
Thomas Lind
Henrik Schrøder
Gunnar FLIVIK Flivik
Michael Mørk Petersen
author_facet Mikkel Rathsach Andersen
Müjgan Yilmaz
Nikolaj Winther
Thomas Lind
Henrik Schrøder
Gunnar FLIVIK Flivik
Michael Mørk Petersen
author_sort Mikkel Rathsach Andersen
collection DOAJ
description Background and purpose:  Backside wear of the polyethylene insert in total knee arthroplasty (TKA) has been described to produce clinically significant levels of polyethylene debris, which can lead to aseptic loosening and osteolysis. Monoblock design eliminates backside wear of the polyethylene and therefore could improve long-term fixation. This randomized clinical trial (RCT) using radiostereometric analysis (RSA) compares micromotion of monoblock and modular polyethylene inserts with 7 years’ follow-up. Methods: 65 patients (mean age 61 years) were randomized to receive either monoblock (n = 32) or modular (n = 33) uncemented trabecular metal tibial components. 35 patients (monoblock = 18, and modular = 17) completed 7 years’ follow-up. The primary endpoint of the study was maximum total point motion (MTPM). Implant translation and rotation are reported as secondary endpoints. Results: After 84 months, the modular group had a statistically significant higher mean MTPM of 1.17 (95% confidence interval [CI] 0.90–1.41) mm compared with the monoblock group of 0.78 (CI 0.55–0.88) mm (P = 0.02). However, there was no difference in continuous migration (from 12–84 months), which was 0.13 mm in the monoblock group and 0.16 mm in the modular group. Conclusion: There was significantly lower early migration in the monoblock group compared with the modular group but no difference in continuous migration after 12 months, which confirms the finding of previous publications.
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spelling doaj-art-093f7c43f7ea46ccad014bb76c49d0622025-08-20T03:31:52ZengMedical Journals SwedenActa Orthopaedica1745-36741745-36822025-06-019610.2340/17453674.2025.43904Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysisMikkel Rathsach Andersen0https://orcid.org/0000-0003-3405-7147Müjgan Yilmaz1Nikolaj Winther2Thomas Lind3Henrik Schrøder4Gunnar FLIVIK Flivik5https://orcid.org/0000-0002-6872-4174Michael Mørk Petersen6https://orcid.org/0000-0002-2324-6420Department of Orthopedics, Herlev Gentofte Hospital, University of Copenhagen; Department of Orthopedics, Rigshospitalet, University of Copenhagen, DenmarkDepartment of Orthopedics, Rigshospitalet, University of Copenhagen, DenmarkDepartment of Orthopedics, Rigshospitalet, University of Copenhagen, DenmarkDepartment of Orthopedics, Herlev Gentofte Hospital, University of Copenhagen, DenmarkDepartment of Orthopedics, Rigshospitalet, University of Copenhagen, DenmarkDepartment of Orthopedics, Skåne University Hospital, Lund University, SwedenDepartment of Orthopedics, Rigshospitalet, University of Copenhagen, Denmark Background and purpose:  Backside wear of the polyethylene insert in total knee arthroplasty (TKA) has been described to produce clinically significant levels of polyethylene debris, which can lead to aseptic loosening and osteolysis. Monoblock design eliminates backside wear of the polyethylene and therefore could improve long-term fixation. This randomized clinical trial (RCT) using radiostereometric analysis (RSA) compares micromotion of monoblock and modular polyethylene inserts with 7 years’ follow-up. Methods: 65 patients (mean age 61 years) were randomized to receive either monoblock (n = 32) or modular (n = 33) uncemented trabecular metal tibial components. 35 patients (monoblock = 18, and modular = 17) completed 7 years’ follow-up. The primary endpoint of the study was maximum total point motion (MTPM). Implant translation and rotation are reported as secondary endpoints. Results: After 84 months, the modular group had a statistically significant higher mean MTPM of 1.17 (95% confidence interval [CI] 0.90–1.41) mm compared with the monoblock group of 0.78 (CI 0.55–0.88) mm (P = 0.02). However, there was no difference in continuous migration (from 12–84 months), which was 0.13 mm in the monoblock group and 0.16 mm in the modular group. Conclusion: There was significantly lower early migration in the monoblock group compared with the modular group but no difference in continuous migration after 12 months, which confirms the finding of previous publications. https://actaorthop.org/actao/article/view/43904ArthroplastyImplantsKneeOsteoarthrosis
spellingShingle Mikkel Rathsach Andersen
Müjgan Yilmaz
Nikolaj Winther
Thomas Lind
Henrik Schrøder
Gunnar FLIVIK Flivik
Michael Mørk Petersen
Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
Acta Orthopaedica
Arthroplasty
Implants
Knee
Osteoarthrosis
title Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
title_full Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
title_fullStr Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
title_full_unstemmed Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
title_short Long-term migration of monoblock vs modular design in uncemented total knee arthroplasty: a secondary report of a randomized trial using radiostereometric analysis
title_sort long term migration of monoblock vs modular design in uncemented total knee arthroplasty a secondary report of a randomized trial using radiostereometric analysis
topic Arthroplasty
Implants
Knee
Osteoarthrosis
url https://actaorthop.org/actao/article/view/43904
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