Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform

(1) Introduction: Precise femoral component rotation is critical for achieving symmetric flexion-gap balance and physiologic patellofemoral tracking in mechanically aligned total knee arthroplasty (TKA). Surgeons often infer an appropriate rotational target from the patient’s coronal limb alignment,...

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Main Authors: Utkarsh Anil, Catherine Di Gangi, Lachlan Anderson, Charles C. Lin, Matthew Hepinstall, Morteza Meftah, Armin Arshi
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Bioengineering
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Online Access:https://www.mdpi.com/2306-5354/12/7/727
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author Utkarsh Anil
Catherine Di Gangi
Lachlan Anderson
Charles C. Lin
Matthew Hepinstall
Morteza Meftah
Armin Arshi
author_facet Utkarsh Anil
Catherine Di Gangi
Lachlan Anderson
Charles C. Lin
Matthew Hepinstall
Morteza Meftah
Armin Arshi
author_sort Utkarsh Anil
collection DOAJ
description (1) Introduction: Precise femoral component rotation is critical for achieving symmetric flexion-gap balance and physiologic patellofemoral tracking in mechanically aligned total knee arthroplasty (TKA). Surgeons often infer an appropriate rotational target from the patient’s coronal limb alignment, yet the strength of this relationship remains uncertain. (2) Methods: We identified 695 consecutive patients undergoing primary TKA with a preoperative planning CT scan. The surgical transepicondylar axis (sTEA) and posterior condylar axis (PCAxis) were identified and the angle between them was measured. The angle between the mechanical axis of the femur and tibia was used to measure the coronal alignment of the limb. (3) Results: The mean sTEA was 3.0° externally rotated to the PCAxis (range 3.1° internal to 9.2° external). The mean coronal alignment was 4.3° varus (range −12.5° valgus to 24.5° varus). There were 465 patients with >2° varus and 101 patients with >2° valgus. The mean sTEA was 2.9 ± 1.9° externally rotated relative to the PCAxis in the valgus group and 2.8 ± 2.0° in the varus group, with no statistically significant difference (<i>p</i> = 0.7). (4) Conclusions: There is significant variation in the femoral rotation axes between patients, but no significant relationship between overall limb coronal alignment and the magnitude of femoral rotation axes variation. This reinforces the need for independent assessment of rotational landmarks when performing mechanically aligned TKA.
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spelling doaj-art-adc8020db7bd4e38bc63d249bee2b73f2025-08-20T03:13:36ZengMDPI AGBioengineering2306-53542025-07-0112772710.3390/bioengineering12070727Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty PlatformUtkarsh Anil0Catherine Di Gangi1Lachlan Anderson2Charles C. Lin3Matthew Hepinstall4Morteza Meftah5Armin Arshi6Department of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USADepartment of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USAAnne Burnett Marion School of Medicine at TCU, Fort Worth, TX 76104, USADepartment of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USADepartment of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USADepartment of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USADepartment of Orthopedic Surgery, NYU Langone Orthopedic Hospital, New York, NY 10010, USA(1) Introduction: Precise femoral component rotation is critical for achieving symmetric flexion-gap balance and physiologic patellofemoral tracking in mechanically aligned total knee arthroplasty (TKA). Surgeons often infer an appropriate rotational target from the patient’s coronal limb alignment, yet the strength of this relationship remains uncertain. (2) Methods: We identified 695 consecutive patients undergoing primary TKA with a preoperative planning CT scan. The surgical transepicondylar axis (sTEA) and posterior condylar axis (PCAxis) were identified and the angle between them was measured. The angle between the mechanical axis of the femur and tibia was used to measure the coronal alignment of the limb. (3) Results: The mean sTEA was 3.0° externally rotated to the PCAxis (range 3.1° internal to 9.2° external). The mean coronal alignment was 4.3° varus (range −12.5° valgus to 24.5° varus). There were 465 patients with >2° varus and 101 patients with >2° valgus. The mean sTEA was 2.9 ± 1.9° externally rotated relative to the PCAxis in the valgus group and 2.8 ± 2.0° in the varus group, with no statistically significant difference (<i>p</i> = 0.7). (4) Conclusions: There is significant variation in the femoral rotation axes between patients, but no significant relationship between overall limb coronal alignment and the magnitude of femoral rotation axes variation. This reinforces the need for independent assessment of rotational landmarks when performing mechanically aligned TKA.https://www.mdpi.com/2306-5354/12/7/727posterior condylar angletransepicondylar axisgap balancingrobotic CT planningpatient-specific instrumentationthree-dimensional CT imaging
spellingShingle Utkarsh Anil
Catherine Di Gangi
Lachlan Anderson
Charles C. Lin
Matthew Hepinstall
Morteza Meftah
Armin Arshi
Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
Bioengineering
posterior condylar angle
transepicondylar axis
gap balancing
robotic CT planning
patient-specific instrumentation
three-dimensional CT imaging
title Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
title_full Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
title_fullStr Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
title_full_unstemmed Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
title_short Coronal Alignment Does Not Adequately Predict Femoral Rotation Axes in Total Knee Arthroplasty: Application of a 3D Image-Based Robotic-Assisted Arthroplasty Platform
title_sort coronal alignment does not adequately predict femoral rotation axes in total knee arthroplasty application of a 3d image based robotic assisted arthroplasty platform
topic posterior condylar angle
transepicondylar axis
gap balancing
robotic CT planning
patient-specific instrumentation
three-dimensional CT imaging
url https://www.mdpi.com/2306-5354/12/7/727
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AT matthewhepinstall coronalalignmentdoesnotadequatelypredictfemoralrotationaxesintotalkneearthroplastyapplicationofa3dimagebasedroboticassistedarthroplastyplatform
AT mortezameftah coronalalignmentdoesnotadequatelypredictfemoralrotationaxesintotalkneearthroplastyapplicationofa3dimagebasedroboticassistedarthroplastyplatform
AT arminarshi coronalalignmentdoesnotadequatelypredictfemoralrotationaxesintotalkneearthroplastyapplicationofa3dimagebasedroboticassistedarthroplastyplatform