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Image-based robotic unicompartmental knee arthroplasty allowed to match the rotation of the tibial implant with the native kinematic knee alignment



Image-based robotic tools improve the accuracy of unicompartmental knee arthroplasty (UKA) positioning, but few studies have examined its effect on axial alignment. The aim of this study was to compare the characteristics of tibial and femoral implant positioning, mainly the tibial rotation, during medial or lateral UKA, performed with an image-based robotic assisted system.


A total of 71 UKA performed between September 2021 and June 2022 (53 medial and 18 lateral) were analyzed. All data regarding implant positioning (rotation, coronal and sagittal alignment) for tibial and femoral components were obtained using MAKO® software (Stryker®, Mahwah, USA) intra-operatively.


The lateral UKA had a mean internal tibial rotation of 15.4 ± 3°, a mean external femoral rotation of 0.96 ± 2.4°, and a mean tibial slope of 4.7 ± 1.3°. The medial UKA had a mean internal tibial rotation of 0.18 ± 2.7°, a mean internal femoral rotation of 0.35 ± 2.2°, and a mean tibial slope of 5.4 ± 1.3°. The tibial rotations, femoral valgus, tibial varus and tibial size significantly differed between medial and lateral UKA (p < 0.05). There was no significant difference in femoral rotation, flexion, femoral size, slope, and polyethylene thickness between medial and lateral UKA.


Medial and lateral UKA had significantly different implantation characteristics related to the biomechanics of the knee compartments. Image-based robotic UKA allowed precise femorotibial positioning per-operatively to match native kinematic alignment.

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Authors and Affiliations



CF: study design, data collection, statistical analysis, literature review, and manuscript writing.

CB: study design, literature review, and manuscript editing.

RC: study design, literature review, and manuscript editing.

JS: literature review and manuscript editing.

FZ: literature review and manuscript editing.

FC: literature review and manuscript editing.

ES: literature review and manuscript editing.

SL: study design, supervision, literature review and manuscript editing.

All the authors read and approved the final manuscript.

Corresponding author

Correspondence to Cécile Batailler.

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Ethical approval

All procedures were performed in accordance with the ethical standards of the institutional and/or national research committee, the 1964 Helsinki declaration and its later amendments, or comparable ethical standards. As per institutional standards, formal patient consent is not required for this type of study.

Conflict of interest

CF, CB, RC, JS, FZ: declare that they have no conflict of interest.

FC: Consultant, royalties, and review activities for Stryker. Consutant for Adler.

ES: institutional research support from Corin.

SL: Consultant for Stryker, Smith and Nephew, Heraeus, Depuy Synthes. Institutional research support to Lepine and Amplitude. Editorial Board for Journal of Bone and Joint Surgery (Am).

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Level of evidence: IV, retrospective, cohort study

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Favroul, C., Batailler, C., Canetti, R. et al. Image-based robotic unicompartmental knee arthroplasty allowed to match the rotation of the tibial implant with the native kinematic knee alignment. International Orthopaedics (SICOT) 47, 519–526 (2023).

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