Tibiofemoral and patellofemoral kinematics after kinematic versus mechanical alignment in varus TKA—a dynamic knee rig study
- 1Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich, University Hospital Munich, Ludwig-Maximilians-University Munich, Munich, Germany
- 2Division of Anatomy, Center of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
- 3Experimental Orthopaedics, University Hospital Jena, Campus Eisenberg, Waldkliniken Eisenberg, Friedrich Schiller University Jena, Jena, Germany
Abstract
Introduction: Kinematic alignment (KA) in total knee arthroplasty (TKA) of the varus knee shows promising clinical outcomes by preserving individual joint anatomy. However, it remains unknown whether this results in knee joint kinematics that more closely resemble the native baseline condition than mechanical alignment (MA). Therefore, this study evaluated the direct influence of KA versus MA on tibiofemoral and patellofemoral kinematics and contact biomechanics in the varus knee during a standardized dynamic muscle-loaded squat.
Materials and methods: Seven fresh-frozen human cadaveric knee specimens with constitutional varus (-1.4° to -8.3°) were tested in a dynamic knee rig (30° to 130° flexion) under muscle-controlled loading. Kinematics, retropatellar contact area, peak pressure, and quadriceps force were continuously recorded across three successive states within the same specimen: native, KA TKA, and MA TKA using a medial-pivot implant design. Statistical analysis was performed using one-dimensional statistical parametric mapping, including non-parametric SnPM1D ANOVA and pairwise SnPM{F} tests for kinematics, and paired-samples SPM{t} tests for contact mechanics and quadriceps force.
Results: Between alignment techniques (KA vs. MA), no statistically significant differences emerged regarding kinematics and patellofemoral biomechanics following Holm-Bonferroni correction (all padj > 0.05). Descriptively, KA displayed a trend toward unphysiological anterior femoral translation in deep flexion (100°–120°, p = 0.028; padj = 0.084) and persistent patellar medialization (delta of up to 5 mm) compared to MA, though these did not retain statistical significance post-adjustment. Both TKA techniques significantly reduced patellar contact area (padj < 0.01), illustrating a general TKA effect rather than an alignment-specific difference.
Conclusions: KA was not shown to restore native knee kinematics or patellofemoral mechanics more closely than MA. Descriptive kinematic variations suggest that KA does not automatically optimize functional joint mechanics when using standard implant geometries.
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BibTeX
@article{simon2026tibiofemoral,
title = {{Tibiofemoral and patellofemoral kinematics after kinematic versus mechanical alignment in varus TKA—a dynamic knee rig study}},
author = {Johanna-Maria Simon and Tara Mauritia Siedow and Christoph Thorwächter and Tara Elise Petri and Leandra Bauer and Boris Michael Holzapfel and Peter Ernst Müller and Thomas Richard Niethammer},
journal = {Archives of Orthopaedic and Trauma Surgery},
year = {2026},
month = nov,
doi = {10.1007/s00402-026-06559-y},
url = {https://doi.org/10.1007/s00402-026-06559-y},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Tibiofemoral and patellofemoral kinematics after kinematic versus mechanical alignment in varus TKA—a dynamic knee rig study
AU - Johanna-Maria Simon
AU - Tara Mauritia Siedow
AU - Christoph Thorwächter
AU - Tara Elise Petri
AU - Leandra Bauer
AU - Boris Michael Holzapfel
AU - Peter Ernst Müller
AU - Thomas Richard Niethammer
PY - 2026
DA - 2026/11/03
JO - Archives of Orthopaedic and Trauma Surgery
DO - 10.1007/s00402-026-06559-y
UR - https://doi.org/10.1007/s00402-026-06559-y
AB - Introduction: Kinematic alignment (KA) in total knee arthroplasty (TKA) of the varus knee shows promising clinical outcomes by preserving individual joint anatomy. However, it remains unknown whether this results in knee joint kinematics that more closely resemble the native baseline condition than mechanical alignment (MA). Therefore, this study evaluated the direct influence of KA versus MA on tibiofemoral and patellofemoral kinematics and contact biomechanics in the varus knee during a standardized dynamic muscle-loaded squat. Materials and methods: Seven fresh-frozen human cadaveric knee specimens with constitutional varus (-1.4° to -8.3°) were tested in a dynamic knee rig (30° to 130° flexion) under muscle-controlled loading. Kinematics, retropatellar contact area, peak pressure, and quadriceps force were continuously recorded across three successive states within the same specimen: native, KA TKA, and MA TKA using a medial-pivot implant design. Statistical analysis was performed using one-dimensional statistical parametric mapping, including non-parametric SnPM1D ANOVA and pairwise SnPM{F} tests for kinematics, and paired-samples SPM{t} tests for contact mechanics and quadriceps force. Results: Between alignment techniques (KA vs. MA), no statistically significant differences emerged regarding kinematics and patellofemoral biomechanics following Holm-Bonferroni correction (all padj > 0.05). Descriptively, KA displayed a trend toward unphysiological anterior femoral translation in deep flexion (100°–120°, p = 0.028; padj = 0.084) and persistent patellar medialization (delta of up to 5 mm) compared to MA, though these did not retain statistical significance post-adjustment. Both TKA techniques significantly reduced patellar contact area (padj < 0.01), illustrating a general TKA effect rather than an alignment-specific difference. Conclusions: KA was not shown to restore native knee kinematics or patellofemoral mechanics more closely than MA. Descriptive kinematic variations suggest that KA does not automatically optimize functional joint mechanics when using standard implant geometries.
SN - 0936-8051
SN - 1434-3916
ER -