Effects of anterior cruciate ligament resection and total knee arthroplasty on lower limb alignment and tibiofemoral rotation

Journal of Orthopaedics and Traumatology https://doi.org/10.1186/s10195-026-00942-6 Article in Press Effects of anterior cruciate ligament resection and total knee arthroplasty on lower limb alignment and tibiofemoral rotation Yongyong Fan, Shujun Chen, Lingjun Jiang, Zhongyi Chen, Mingjiao Wu & Chenglong Wang Received: 26 Jan 2026 Accepted: 29 May 2026 Cite this article as: Fan, Y., Chen, S., Jiang, L. et al. Effects of anterior cruciate ligament resection and total knee arthroplasty on lower limb alignment and tibiofemoral rotation. J Orthop Traumatol (2026). https://doi.org/10.1186/s1019 5-026-00942-6 A E R P S S We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply. IN If this paper is publishing under a Transparent Peer Review model then Peer Review reports will publish with the final article. I T R E L C ©The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ ACCEPTED ARTICLEMANUSCRIPT IN PRESS Effects of Anterior Cruciate Ligament Resection and Total Knee Arthroplasty on Lower Limb Alignment and Tibiofemoral Rotation Yongyong Fan1,2†, Shujun Chen1,2†, Lingjun Jiang1,2†, Zhongyi Chen1,2*, Mingjiao Wu1,2*, Chenglong Wang1,2* 1 Department of Orthopaedics, Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University, Taizhou, Zhejiang, 318000, P.R. China. 2 Department of Orthopaedics, Enze Hospital, Taizhou Enze Medical Center (Group), Taizhou, Zhejiang, 318000, P.R. China. *Corresponding Author E-mail: ; ; †These authors contributed equally to this work. Consent for publication: not applicable. S S E R P Ethical approval: This study has been approved by the Ethics Committee (Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University) (December 25, 2025, Approval number K20251230). All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. E L C IN Consent to participate: Written informed consent was obtained from individual or guardian participants. I T AR Competing interests: The authors declare that they have no competing interests. Funding: This study was supported by Taizhou Science and Technology Plan (Project No. 25ywb62), Zhejiang Science and Technology Plan for Disease Prevention and Control (Project No. 2026JKY312) and Zhejiang Science and Technology Plan for Health Commission (Project No. 2025HY1427). Acknowledgements: We would like to give our sincere appreciation to the reviewers for their helpful comments on this article. Clinical trial number: not applicable. Informed consent: Written informed consent was obtained from all patients. Authors' contributions: Yongyong Fan: design of investigation and data collection. Shujun Chen: data analysis and writing paper. Lingjun Jiang: data analysis. Zhongyi Chen: data collection and data analysis. Mingjiao Wu: data collection, data analysis and writing paper. Chenglong Wang: design of investigation, data collection, data analysis and writing paper. All authors read and approved the final manuscript. Availability of data and materials: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Effects of Anterior Cruciate Ligament Resection and Total Knee Arthroplasty on Lower Limb ACCEPTED ARTICLEMANUSCRIPT IN PRESS Alignment and Tibiofemoral Rotation Abstract Background: The anterior cruciate ligament (ACL) is a key structure that restricts excessive anterior translation of the tibia and maintains rotational stability. This study aims to dynamically and quantitatively assess the direct effects of ACL resection and total knee arthroplasty (TKA) on lower limb alignment and tibiofemoral joint rotation under passive, unloaded conditions and in the pathological state of osteoarthritis. Methods: This retrospective study included 110 patients with varus knee osteoarthritis who underwent Mako for robotic-assisted TKA. Dynamic intraoperative measurements of the lower limb mechanical axis (flexion angle at maximum extension; varus angle) and tibiofemoral rotation at multiple flexion angles (min to max flexion) were recorded at three intervals: pre-ACL resection, post-ACL resection, and post-TKA. The variation in rotation amplitude was calculated for successive flexion intervals. Results: Post-ACL resection, a significant decrease in the flexion angle at the maximum extension and S S E R P varus angle (both p < 0.001) was observed, which was accompanied by increased tibial internal rotation at flexion angles of 60° and above (p < 0.05). Varus alignment was successfully corrected following TKA (p < 0.001). However, tibiofemoral rotational kinematics were significantly modified: the amplitude of internal rotation decreased in the initial flexion arc (min to 30°) but increased in flexion intervals beyond 30° (all p < 0.01). E L C IN Conclusion: Under passive, unloaded osteoarthritic conditions, ACL resection immediately alters I T AR lower limb alignment and increases tibial internal rotation. Although TKA restores coronal alignment, it does not fully restore passive rotational kinematics; whether this affects active weight‑bearing function remains unknown. Accordingly, we hypothesize that rotational stability is as critical as limb alignment in TKA, pending validation with patient-reported outcome measures, functional scores, and postoperative follow-up. Keywords: Tibiofemoral rotation; Total knee arthroplasty; Anterior cruciate ligament; Robotic-assisted surgery; Lower limb alignment Background Total knee arthroplasty (TKA) is the definitive treatment for end-stage knee osteoarthritis (OA), a condition associated with a substanti (...truncated)