Comparable clinical outcomes but different postoperative Dynamic Alignment of the Knee (DyAK) patterns between cruciate-retaining and posterior-stabilized inserts in functionally aligned robotic-assisted total knee arthroplasty.
6 affiliations
- 1School of Health Rehabilitation Sciences University of Patras Patras Greece.
- 22nd Department of Orthopaedic Surgery Hygeia Hospital of Athens Marousi Greece.
- 3Department of Orthopedic Surgery Aspetar Orthopedic and Sports Medicine Hospital Doha Qatar.
- 4Department of Orthopedics and Traumatology Ankara Yıldırım Beyazıt University Ankara Turkey.
- 5Orthopaedics Surgery and Sports Medicine Department FIFA Medical Center of Excellence Croix-Rousse Hospital, Hospices Civils de Lyon, Lyon North University Hospital Lyon France.
- 6Université de Lyon, Université Gustave Eiffel, Université Claude Bernard Lyon 1 Lyon France.
Abstract
The influence of polyethylene insert design during robotic-assisted total knee arthroplasty (TKA) performed according to functional alignment (FA) principles remains poorly understood. This study compared cruciate-retaining (CR) and posterior-stabilized (PS) inserts with respect to implant positioning, clinical outcomes, implant survivorship and postoperative dynamic knee behaviour using the Dynamic Alignment of the Knee (DyAK) classification. A retrospective comparative study was performed on 284 primary functionally aligned robotic-assisted TKAs. The cohort comprised 148 CR and 136 PS fixed-bearing cemented implants with a minimum follow-up of 3 years (median 44.5 months). Clinical outcomes included Knee Society Score (KSS) and Forgotten Joint Score (FJS). Intraoperative robotic implant positioning, bone resections, polyethylene thickness, DyAK classification, complications and Kaplan-Meier implant survivorship were compared between groups. The CR group demonstrated greater preoperative varus alignment (median robotic hip-knee-ankle angle [rHKA] 5° vs. 3°, p = 0.01). Compared with PS implants, CR inserts were implanted with greater tibial varus (2° vs. 1°, p < 0.0001), greater posterior tibial slope (3° vs. 1°, p < 0.0001) and slightly greater femoral external rotation (p = 0.009). Polyethylene inserts >9 mm were required more frequently in the PS group (39.0% vs. 15.5%, p < 0.0001). At final follow-up, KSS knee (p = 0.56), KSS function (p = 0.62) and FJS (p = 0.06) were comparable between groups. No statistically significant difference in survivorship was detected for aseptic loosening (0.68% vs. 0.74%, p = 0.95) and all-cause revision (2.03% vs. 1.47%, p = 0.72). The DyAK classification changed significantly more frequently in the PS group than in the CR group (69.9% vs. 52.7%, p = 0.003), despite similar postoperative clinical outcomes. CR and PS polyethylene inserts showed no significant differences in final clinical scores or implant survivorship at a minimum follow-up of 3 years but demonstrated different patterns of postoperative dynamic alignment, suggesting that the DyAK classification may provide complementary information beyond conventional outcome measures. Level III.
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BibTeX
@article{koutserimpas2026comparable,
title = {{Comparable clinical outcomes but different postoperative Dynamic Alignment of the Knee (DyAK) patterns between cruciate-retaining and posterior-stabilized inserts in functionally aligned robotic-assisted total knee arthroplasty.}},
author = {Christos Koutserimpas and Enejd Veizi and Sébastien Lustig and Konstantinos Dretakis},
journal = {Journal of experimental orthopaedics},
year = {2026},
month = oct,
doi = {10.1002/jeo2.70963},
url = {https://europepmc.org/article/MED/42953403},
note = {CC BY},
}
RIS
TY - JOUR
TI - Comparable clinical outcomes but different postoperative Dynamic Alignment of the Knee (DyAK) patterns between cruciate-retaining and posterior-stabilized inserts in functionally aligned robotic-assisted total knee arthroplasty.
AU - Christos Koutserimpas
AU - Enejd Veizi
AU - Sébastien Lustig
AU - Konstantinos Dretakis
PY - 2026
DA - 2026/10/28
JO - Journal of experimental orthopaedics
DO - 10.1002/jeo2.70963
UR - https://europepmc.org/article/MED/42953403
AB - The influence of polyethylene insert design during robotic-assisted total knee arthroplasty (TKA) performed according to functional alignment (FA) principles remains poorly understood. This study compared cruciate-retaining (CR) and posterior-stabilized (PS) inserts with respect to implant positioning, clinical outcomes, implant survivorship and postoperative dynamic knee behaviour using the Dynamic Alignment of the Knee (DyAK) classification. A retrospective comparative study was performed on 284 primary functionally aligned robotic-assisted TKAs. The cohort comprised 148 CR and 136 PS fixed-bearing cemented implants with a minimum follow-up of 3 years (median 44.5 months). Clinical outcomes included Knee Society Score (KSS) and Forgotten Joint Score (FJS). Intraoperative robotic implant positioning, bone resections, polyethylene thickness, DyAK classification, complications and Kaplan-Meier implant survivorship were compared between groups. The CR group demonstrated greater preoperative varus alignment (median robotic hip-knee-ankle angle [rHKA] 5° vs. 3°, p = 0.01). Compared with PS implants, CR inserts were implanted with greater tibial varus (2° vs. 1°, p < 0.0001), greater posterior tibial slope (3° vs. 1°, p < 0.0001) and slightly greater femoral external rotation (p = 0.009). Polyethylene inserts >9 mm were required more frequently in the PS group (39.0% vs. 15.5%, p < 0.0001). At final follow-up, KSS knee (p = 0.56), KSS function (p = 0.62) and FJS (p = 0.06) were comparable between groups. No statistically significant difference in survivorship was detected for aseptic loosening (0.68% vs. 0.74%, p = 0.95) and all-cause revision (2.03% vs. 1.47%, p = 0.72). The DyAK classification changed significantly more frequently in the PS group than in the CR group (69.9% vs. 52.7%, p = 0.003), despite similar postoperative clinical outcomes. CR and PS polyethylene inserts showed no significant differences in final clinical scores or implant survivorship at a minimum follow-up of 3 years but demonstrated different patterns of postoperative dynamic alignment, suggesting that the DyAK classification may provide complementary information beyond conventional outcome measures. Level III.
SN - 2197-1153
ER -