External rotational alignment of tibial component correlates with two years clinical outcomes in guided motion total knee arthroplasty: a retrospective cross-sectional study

External rotational alignment of tibial component correlates with two years clinical outcomes in guided motion total knee arthroplasty: a retrospective cross-sectional study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article External rotational alignment of tibial component correlates with two years clinical outcomes in guided motion total knee arthroplasty: a retrospective cross-sectional study Tatsunori Kataoka, Miari Wakamiya, Yasushi Oshima, Norishige Iizawa, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7174828/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Proper rotational alignment of the femoral and tibial component is critical for a successful total knee arthroplasty (TKA). However, there are no study that focused on the influence of external rotation of the tibial component have on patient reports outcomes in a guided motion TKA. This study aimed to assess the association between tibial rotational alignment and patient reported outcomes in patients with neutral alignment in all the other planes. Methods The current study was a retrospective cross-sectional study performed at a regional institutional hospital. Patients who underwent primary TKA for knee osteoarthritis with no postoperative coronal malalignment and malrotation of the femoral component were included in the study. Rotational alignment of the tibial component was evaluated using a computed tomography and its relationship between postoperative 2011 Knee Society Score was evaluated by Pearson or Spearman correlation analysis. Results The study included 24 patients, 7 of whom underwent bilateral TKA with a guided motion cruciate substituting implant. Tibial component was 6.2 ± 5.9 degrees externally rotated postoperatively. Externally rotated tibial component resulted with higher scores in walking and standing (one year, two years), and with smaller flexion angle (six months, two years) and lower satisfaction score (two years). Conclusions Tibial rotational alignment influences two years clinical outcomes in total knee arthroplasty. Excessive external rotation should be avoided in a guided motion prosthesis and in future study, threshold of rotational alignment of the tibial component should be clarified. total knee arthroplasty rotational alignment patient reported outcomes Figures Figure 1 Figure 2 Figure 3 Figure 4 1. BACKGROUND Total knee arthroplasty (TKA) is the gold standard treatment for advanced knee osteoarthritis and has excellent long-term survivorship [ 1 ]. However, not all patients are satisfied with the operation, and patient satisfaction after TKA is inferior to that after total hip arthroplasty [ 2 ]. Many factors contribute to patient dissatisfaction following TKA, including unmet expectations, postoperative pain, and malalignment [ 3 , 4 ]. In terms of rotational alignment, femoral component orientation is referenced to the posterior condylar axis, midtrochlear line (Whiteside’s line), and transepicondylar axis [ 5 , 6 ]. For the tibial rotational alignment, Akagi’s line, tibial tuberosity, second metatarsal have been reported as a landmark [ 7 , 8 ]. Inadequate rotational alignment causes polyethylene wear, patellofemoral disorders, and anterior knee pain, all of which lead to dissatisfaction [ 9 – 11 ], and especially internal rotation in both the femoral and tibial component should be avoided. On the other hand, external rotation of the tibial component has been reported not to have an influence on patient reported outcomes [ 12 ]. However, caution is required because studies assessing the association between malrotation and patient reported outcomes have not controlled the mutual relationship of each component, and furthermore, no study have evaluated the influence of rotational alignment of the tibial component have on patient reported outcomes in a guided motion TKA. In a guided motion TKA, tibia is forced to internally rotate during knee flexion to reproduce the medial pivot motion, however when excessive, iliotibial band is tensed which may lead to knee pain [ 13 ]. Therefore, we hypothesized that excessive external rotational alignment of the tibial component in a guided motion TKA would result in inferior clinical outcomes. The aim of this study is to assess the relationship between rotational alignment of the external tibial component and patient reported outcomes in a group of patients with neutral alignment in all the other plane. 2. METHODS This study was a retrospective cross-sectional study performed at a regional institutional hospital, and was approved by the relevant institutional review board (approval number 878), which all patients provided informed consent by an opt-out method. Patients who underwent primary TKA performed by a single fellowship trained orthopaedic surgeon with over 10 years of experience between April 2020 and March 2022, with an asymmetric tibial component for knee osteoarthritis and had postoperative computed tomography (CT) scans were enrolled. The following exclusion criteria were applied: revision TKA or TKA with augmentation, osteoarthritis of the knee secondary to rheumatoid arthritis, infection, trauma, and a history of surgery in the vicinity of the knee, including around-the-knee osteotomy. In addition, patients with postoperative coronal malalignment and malrotation of the femoral component of more than three degrees, were excluded. Furthermore, we defined neutral rotation as between three degrees of internal or external rotation, thus patients with tibial internal rotation of more than three degrees were also excluded. 41 knees from 34 patients were enrolled and thereafter, 2 knees from 2 patients were excluded to health problems not related to the operation, 2 knees from 2 patients were excluded due to coronal malalignment, 5 knees from 5 patients were excluded due to tibial internal rotation, and 1 knee from 1 patient were excluded due to relocation. After exclusion, data were available for 24 patients, 7 of whom underwent bilateral TKA. The knees in the bilateral cases were evaluated separately, giving a total of 31 knees. The mean patient age was 71.1 ± 5.7 (61–84) years; 3 knees were from 2 men, and 28 knees were from 22 women. The implant used was Evolution cruciate-substituting (CS) TKA (MicroPort Orthopedics, Arlington, TN, USA). Operation was performed with a midline skin incision and a medial parapatellar arthrotomy. Cruciate ligaments, meniscus, and bony spurs were subsequently removed, and distal femoral and proximal tibial cuts were performed perpendicular to the mechanical axis. The posterior tibial slope was targeted to be three degrees according to the manufacturer’s recommendation, and the posterior femur was cut parallel to the surgical epicondylar axis (SEA). After completing the bone cuts, step-wise medial soft tissue releases were performed when required, and then the extension and flexion gaps were measured using a spring-loaded ligament balancer (Umihira Co. Ltd., Kyoto, Japan) [ 14 ]. The tibial and femoral component was fixed, according to the Akagi’s line and bone cut surface respectively, and the polyethylene surface were then inserted according to the gap measured by the ligament balancer and spacer block. Postoperative tibial rotational angle was measured by three steps by using the CT images obtained using a helical two-dimensional scanner (Scenaria, Hitachi, Ltd., Tokyo, Japan) operating at 120 kV with a slice thickness of 2.5 mm. Images were loaded and measured using OsiriX software version 11.0 (Pixmeo SARL, Bernez, Switzerland). First, the geometric center of the proximal tibia was identified in the slice just distal to the component by drawing a best-fit oval (Fig. 1 a). Next, the tip of the tibial tubercle was identified on another slice wherein the tubercle is most protruded (Fig. 1 b). The two points were connected, and the resulting line represented the anatomical axis of the tibia. Finally, the posterior surface of the tibial component was identified by connecting the medial and lateral posterior margins of the component, and a perpendicular line of the posterior surface was drawn (Fig. 1 c). This process is identical to the Berger method [ 10 ], and has been used in recent studies evaluating tibial rotational alignment [ 15 , 16 ]. However, this method is appliable only for symmetric tibial components, which the AP axis and the posterior surface of the component is perpendicular. Because the tibial component implanted in this study has an asymmetric shape, to evaluate the angle between the anatomical axis of the tibia and the antero-posterior (AP) axis of the component, 8 degrees, which is the angle between the AP axis and the perpendicular line of the posterior surface of the implanted component, was subtracted from the angle between the anatomical axis of the tibia and the perpendicular line of the posterior surface (Fig. 2 ). Subsequently, 18° was subtracted according to the method described by Berger et al [ 10 ], and a negative value was obtained when the tibial component was externally rotated. Inter- and intra-observer reliability were evaluated by three observers, which was 0.92 and 0.78 respectively. Thereafter, correlation between the tibial rotational alignment and 2011 Knee Society Score (KSS) which was obtained six month, 1 and 2 years postoperatively were evaluated. 2.1 Statistical analysis All statistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). For power analysis, power level was set as 80% with a 0.05 significance level, and the effect size was set at 0.5. The analysis indicated that 30 knees were needed to provide a statistical power of 80%. The Kolomogrov-Smirnov test was used to test the normality, and the correlation between tibial rotational alignment and the outcomes were analyzed by Pearson or Spearman correlation analysis. Values of p < 0.05 were considered statistically significant. 3. RESULTS Postoperatively, tibial component was 6.2 ± 5.9 degrees externally rotated, and extension angle, Knee society knee score, function score, satisfaction significantly improved. On the other hand, expectation significantly worsened (Table 1 ). Significant positive correlation was observed between tibial rotational alignment and flexion angle (six months, two years), satisfaction (two years) (Table 2 , Fig. 3 , 4 ). On the other hand, negative correlation was observed between tibial rotational alignment and walking and standing (one year, two years) (Table 2 ). Table 1 Means of the postoperative rotational alignment and preoperative and postoperative extension angle, flexion angle, and 2011 Knee Society Score. Rotational alignment Femoral component Tibial component -0.2 ± 1.2 -4.9 ± 6.7 Pre-operation Post-operation p-value 6 months 1 year 2 years Extension angle 10 ± 4.9 2.0 ± 3.5 1.1 ± 3.0 0.5 ± 2.0 < 0.05 Flexion angle 119.6 ± 10.5 119.3 ± 8.7 120.1 ± 9.0 120.7 ± 7.0 0.17 2011 Knee Society Score Knee score 41.0 ± 12.9 82.8 ± 17.8 86.5 ± 14.6 90.0 ± 14.4 < 0.05 Function score 46.4 ± 13.1 65.8 ± 14.8 70.5 ± 15.0 70.9 ± 10.2 < 0.05 Satisfaction 13.6 ± 5.3 27.6 ± 5.8 30 ± 6.8 30.9 ± 6.4 < 0.05 Expectation 14 ± 1.5 9.9 ± 2.6 10.4 ± 2.6 11.5 ± 2.6 < 0.05 Table 2 Correlation between tibial rotational alignment and postoperative outcomes. 6 months 1 year 2 years r p r p r p extension angle -0.29 0.12 -0.05 0.81 -0.25 0.2 flexion angle 0.53 0.002 0.22 0.24 0.64 0.00 2011 Knee Society Score knee score objective scores 0.24 0.19 0.62 0.74 0.32 0.1 symptoms 0.17 0.36 0.16 0.38 0.18 0.36 function score walking and standing -0.26 0.16 -0.51 0.04 -0.39 0.04 standard activities 0.14 0.45 0.24 0.19 0.16 0.41 advanced activities -0.14 0.47 0.09 0.63 0.12 0.54 discretionary activities -0.11 0.55 -0.24 0.19 0.23 0.24 satisfaction 0.14 0.44 0.15 0.43 0.42 0.03 expectation 0.36 0.85 0.03 0.89 -0.28 0.16 r: correlation coefficient, p: p-value 4. DISCUSSION The most important findings of the current study were that externally rotated tibial component results with higher walking and standing scores, and with smaller flexion angle and lower satisfaction scores in a group of patients with neutral alignment in all the other planes. This was the first report that clarified the correlation between tibial external rotation and patient reported outcomes in a guided motion TKA. In terms of patient reported outcomes and tibial rotational alignment, Barrack et al [ 11 ] found a significant difference between patients with anterior knee pain and an asymptomatic control group in terms of tibial component rotation, while Bell et al [ 17 ] identified internal rotation as an important factor in pain after TKA by comparing patients with painful TKA with a matched control cohort of pain free patients. Furthermore, Nicoll et al [ 12 ] found that 4.3° of internal rotation was associated with knee pain and observed that the threshold that produced pain was > 9° of internal rotation, whereas Panni et al [ 15 ] reported in a systematic review that excessive internal rotation of the tibial component is a risk factor for inferior functional outcomes. Therefore, we excluded patients with internal rotation over three degrees, thus we could not draw a conclusion about internal tibial rotation and patient reported outcomes in the current study. On the other hand, external rotation of the tibial component has not been reported to have an influence on patient reported outcomes, although we found a positive effect on patient reported outcomes. However, caution is required because there might have been a ceiling effect in the expectation and walking and standing section. Ceiling effect is a statistical construct that describes clustering of patients score towards the upper limit of a scale, and if present, variance in outcome is insufficiently measured above a certain level. Terwee et al reported to consider a ceiling effect being present if 15% or more of respondents achieved the highest score possible [ 18 – 20 ], and because half of the patients scored the maximum score in the walking and standing section, this effect may have influenced the result. In addition, flexion angle was smaller and the satisfaction score was lower when the tibial component was externally rotated. This may be due to the stretching of the iliotibial band. Iliotibial band is a lateral thickening of the fascia lata in the thigh, which passes over the lateral femoral epicondyle and attaches to the Gerdy’s tubercle on the anterolateral aspect of the tibia. Tibial internal rotation is primary resisted by the iliotibial band [ 21 ], and increased tension of the iliotibial band results in external tibial rotation in flexion [ 22 ]. The implant used in the current study was a guided motion TKA, which leads the tibia to internally rotate in knee flexion. Therefore, when the tibial component is externally implanted, the iliotibial band is further stretched in flexion, resulting in lateral knee pain [ 13 ]. This kinematics may result in decreased knee flexion and lower symptoms score. Therefore, excessive external rotation should be avoided in a guided motion implant. This study has some limitations. First, clinical outcomes were only assessed in one type of prosthesis. Therefore, the results of this study are not necessarily applicable to other implants. Second, the threshold for external rotation was not investigated. In future study, we need to clarify the threshold of rotational alignment of the tibial component. Third, most patients in this study were women. However, most patients undergoing TKA in East Asia are women; therefore, the present study reflects the actual clinical situation. Despite these limitations, we believe that our study has revealed clinically important information regarding tibial rotational alignment in TKA. 5. CONCLUSIONS Tibial rotational alignment influences two years clinical outcomes in total knee arthroplasty. Excessive external rotation should be avoided in a guided motion prosthesis and in future study, threshold of rotational alignment of the tibial component should be clarified. Abbreviations TKA Total knee arthroplasty CT computed tomography CS cruciate-substituting SEA surgical epicondylar axis AP antero-posterior KSS Knee Society Score Declarations Ethics approval and consent to participate: This study was approved by the relevant institutional review board of Nippon Medical School Chibahokusoh hospital (approval number 878). Consent for publication: All patients provided informed consent by an opt-out method. Availability of data and materials: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests: The authors declare that they have no competing interests. Funding : Not applicable Authors’ contributions: TK: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing-Original Draft, Visualization; MW: Validation; YO: Writing-Review & Editing; NI: Writing-Review & Editing: TM: Writing-Review & Editing, Supervision. Acknowledgements: None References Ranawat CS, Flynn Jr WF, Saddler S, Hansraj KK, Mayneard MJ. Long-term results of the total condylar knee arthroplasty. A 15-year survivorship study. Clin Orthop Relat Res 1993;286:94–102. Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Comparing patient outcomes after THA and TKA: is there a difference? Clin Orthop Relat Res 2010;468:542–6. Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Patient satisfaction after total knee arthroplasty: Who is satisfied and who is not? Clin Orthop Relat Res 2010;468:57–63. Matsuda S, Kawahara S, Okazaki K, Tashiro Y, Iwamoto Y. Postoperative alignment and ROM affect patient satisfaction after TKA. Clin Orthop Relat Res 2013;471:127–33. Hungerford DS, Krackow KA. Total joint arthroplasty of the knee. Clin Orthop Relat Res 1985 Jan-Feb;(192):23–33. Berger RA, Rubash HE, Seel MJ, Thompson WH, Crossett LS. Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis. Clin Orthop Relat Res 1993 Jan;(286):40–7. Akagi M, Mori S, Nishimura S, Nishimura A, Asano T, Hamanishi C. Variablity of extraarticular tibial rotation references for total knee arthroplasty. Clin Orthop Relat Res 2005 Jul;(436):172–6. Sahin N, Atici T, Ozturk A, Ozkaya G, Ozkan Y, Avcu B. Accuracy of anatomical references used for rotational alignment of tibial component in total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2012 Mar;20(3):565–70. Wasielewski RC, Galante JO, Leighty RM, Natarajan RN, Rosenberg AG. Wear patterns on retrieved polyethylene tibial inserts and their relationship to technical considerations during total knee arthroplasty. Clin Orthop Relat Res 1994 299:31–43. Berger RA, Crossett LS, Jacobs JJ, Rubash HE. Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res 1998 Nov:(356):144–53. Barrack RL, Schrader T, Bertot AJ, Wolfe MW, Myers L. Component rotation and anterior knee pain after total knee arthroplasty. Clin Orthop Relat Res 2001 Nov:(392):46–55. Nicoll D, Rowley DI. Internal rotational error of the tibial component is a major cause of pain after total knee replacement. J Bone Joint Surg Br 2010;92:1238–44. Luyckx L, Luyckx T, Bellemans J, Vicotor J. Iliotibial band traction syndrome in guided motion TKA. A new clinical entity after TKA. Acta Orthop Belg 2010;76(4):507-12. Oshima Y, Iizawa N, Takai S, Majima T. Optimal distraction force for evaluating tibiofemoral joint gaps in posterior stabilized total knee arthroplasty. J Nippon Med Sch 2021;88:361–6. Panni AS, Ascione F, Rossini M, Braile A, Corona K, Vasso M, Hirschmann MT. Tibial internal rotation negatively affects clinical outcomes in total knee arthroplasty: a systematic review. Knee Surg Sports Traumatol Arthrosc 2018;26(6):1636-1644. Babazadeh S, Dowsey MM, Vasimalla MG, Stoney JD, Choong PFM. Knee arthroplasty component malrotation does not affect function or quality of life in the short to medium term. J Arthroplasty 2019;34(7):1382-6. Bell SW, Young P, Drury C, Smith J, Anthony I, Jones B, Blyth M, Mclean A. Component rotational alignment in unexplained painful primary total knee arthroplasty. Knee 2014;21(1):272-7. Terwee CB, Bot SDM, De Boer MR, van derWindt DAWM, Knol DL, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol 2007;60:34-42. McHorney CA, Tarlov AR. Individual-patient monitoring in clinical practice: are available health status surveys adequate? Qual Life Res 1995;4:293-307. Eckhard L, Munir S, Wood D, Talbot S, Brighton R, Walter B, et al. The ceiling effects of patient reported outcome measures for total knee arthroplasty. Orthop Traumatol Surg Res 2021;107(3):102758. Amis A. Anterolateral knee biomechanics. Knee Surg Sports Traumatol Arthrosc 2017;25(4):1015-1023. Merican AM, Amis A. Iiotibial band tension affects patellofemoral and tibiofemoal kinematics. J biomech 2009;42(10):1539-1546. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7174828","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":513779005,"identity":"6b6f981e-19dc-41de-9e1c-6ed431b764ec","order_by":0,"name":"Tatsunori Kataoka","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYBACNmbGxgcMByTk+NmbD8AEE/Bq4WNnPmxw4ICFsWTPMbhK/Frk+NnSJA4cqEjccMPHgFiH8ZhJfzgjkThzBs+3Rzf+MMjzNzA8e0BAi7HFgRsSxv3SvduNc9sYDGccYEjHax9Qi+GNAx8kZGfOObtNOreBgXEDA0OaBAEtBhJALYwbbuQ8k875w2BPhBa2JAmgwxSBWtikc9gYEonQAgzkM2ckQIFsJp3bJpE84zABv8j3H2x8UHGsDhSVIIfZ2Pa396Q9wKcFHQCdxMyTRooOMGA/RrKWUTAKRsEoGNYAACM4SpDpaUm6AAAAAElFTkSuQmCC","orcid":"","institution":"Nippon Medical School Chiba Hokusoh Hospital","correspondingAuthor":true,"prefix":"","firstName":"Tatsunori","middleName":"","lastName":"Kataoka","suffix":""},{"id":513779006,"identity":"b95968ff-2e96-4299-9e81-57be0e3043ad","order_by":1,"name":"Miari Wakamiya","email":"","orcid":"","institution":"Nippon Medical School Chiba Hokusoh Hospital","correspondingAuthor":false,"prefix":"","firstName":"Miari","middleName":"","lastName":"Wakamiya","suffix":""},{"id":513779007,"identity":"13a7051a-7cf6-4ddc-8d23-8230f2ba1c69","order_by":2,"name":"Yasushi Oshima","email":"","orcid":"","institution":"Nippon Medical School Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yasushi","middleName":"","lastName":"Oshima","suffix":""},{"id":513779008,"identity":"a2aee633-f97b-409d-99f8-036abaaba0a7","order_by":3,"name":"Norishige Iizawa","email":"","orcid":"","institution":"Heisei Tateishi Hospital","correspondingAuthor":false,"prefix":"","firstName":"Norishige","middleName":"","lastName":"Iizawa","suffix":""},{"id":513779010,"identity":"dd5f1f81-75b9-4618-8288-60889a865666","order_by":4,"name":"Tokifumi Majima","email":"","orcid":"","institution":"Nippon Medical School Hospital","correspondingAuthor":false,"prefix":"","firstName":"Tokifumi","middleName":"","lastName":"Majima","suffix":""}],"badges":[],"createdAt":"2025-07-21 08:08:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7174828/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7174828/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91218646,"identity":"f759a8cd-ac1d-44ab-99e0-0b2ac49e60ef","added_by":"auto","created_at":"2025-09-12 20:31:50","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":50810,"visible":true,"origin":"","legend":"\u003cp\u003eBerger method applied to the asymmetric tibial component. (a) The geometric center of the proximal tibia (circle dot) was identified in the slice just distal to the component by drawing the best fit oval (white oval). (b) The tip of the tibial tubercle (black triangle) was identified on the slice wherein the tubercle is most protruded. Two points were connected, and the resulting line represented the anatomical axis of the tibia (gray solid line). (c) The posterior surface of the component (black solid line) was identified by connecting the medial and lateral posterior margins of the component, and a line perpendicular to the posterior surface (black dotted line) was drawn.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7174828/v1/52a996569c2db10adf7cb89f.jpg"},{"id":91218648,"identity":"8869d369-c041-46c0-89ce-d34ffeb5983e","added_by":"auto","created_at":"2025-09-12 20:31:50","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":44349,"visible":true,"origin":"","legend":"\u003cp\u003eFinal calculation to determine rotational alignment in asymmetric tibial component. The angle between the anatomical axis of the tibia (gray solid line) and the AP axis of the component (black dashed line) was determined by subtracting the angle between the AP axis and the line perpendicular to the posterior surface (black dotted line), which was 8 degrees, from the angle between the anatomical axis of the tibia and the line perpendicular to the posterior surface.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7174828/v1/54d2b5162c3ac991710b8bc3.jpg"},{"id":91218647,"identity":"97eeb772-5a2e-4261-a002-9802c9b7d605","added_by":"auto","created_at":"2025-09-12 20:31:50","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":52692,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot of the knee flexion angle and rotational alignment of the tibial component. Negative values for rot. angle indicate that the tibial component is externally rotated.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7174828/v1/64aa7097a98af19a4259907c.jpg"},{"id":91219326,"identity":"f29143ec-e6a8-4a64-a71b-a74a857dc27f","added_by":"auto","created_at":"2025-09-12 20:39:50","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":55420,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot of the 2011 KSS satisfaction score and rotational alignment of the tibial component. Negative values for rot. angle indicate that the tibial component is externally rotated.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7174828/v1/2252a2e8d2351fd0c3a9f9b6.jpg"},{"id":91344916,"identity":"583f2137-2f0c-491f-9564-7902c8ad1591","added_by":"auto","created_at":"2025-09-15 13:46:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":776226,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7174828/v1/b61c98b9-0e34-4613-bf7b-158b4c5cfbda.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"External rotational alignment of tibial component correlates with two years clinical outcomes in guided motion total knee arthroplasty: a retrospective cross-sectional study","fulltext":[{"header":"1. BACKGROUND","content":"\u003cp\u003eTotal knee arthroplasty (TKA) is the gold standard treatment for advanced knee osteoarthritis and has excellent long-term survivorship [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, not all patients are satisfied with the operation, and patient satisfaction after TKA is inferior to that after total hip arthroplasty [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Many factors contribute to patient dissatisfaction following TKA, including unmet expectations, postoperative pain, and malalignment [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn terms of rotational alignment, femoral component orientation is referenced to the posterior condylar axis, midtrochlear line (Whiteside\u0026rsquo;s line), and transepicondylar axis [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. For the tibial rotational alignment, Akagi\u0026rsquo;s line, tibial tuberosity, second metatarsal have been reported as a landmark [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Inadequate rotational alignment causes polyethylene wear, patellofemoral disorders, and anterior knee pain, all of which lead to dissatisfaction [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], and especially internal rotation in both the femoral and tibial component should be avoided. On the other hand, external rotation of the tibial component has been reported not to have an influence on patient reported outcomes [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eHowever, caution is required because studies assessing the association between malrotation and patient reported outcomes have not controlled the mutual relationship of each component, and furthermore, no study have evaluated the influence of rotational alignment of the tibial component have on patient reported outcomes in a guided motion TKA. In a guided motion TKA, tibia is forced to internally rotate during knee flexion to reproduce the medial pivot motion, however when excessive, iliotibial band is tensed which may lead to knee pain [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTherefore, we hypothesized that excessive external rotational alignment of the tibial component in a guided motion TKA would result in inferior clinical outcomes. The aim of this study is to assess the relationship between rotational alignment of the external tibial component and patient reported outcomes in a group of patients with neutral alignment in all the other plane.\u003c/p\u003e"},{"header":"2. METHODS","content":"\u003cp\u003eThis study was a retrospective cross-sectional study performed at a regional institutional hospital, and was approved by the relevant institutional review board (approval number 878), which all patients provided informed consent by an opt-out method. Patients who underwent primary TKA performed by a single fellowship trained orthopaedic surgeon with over 10 years of experience between April 2020 and March 2022, with an asymmetric tibial component for knee osteoarthritis and had postoperative computed tomography (CT) scans were enrolled. The following exclusion criteria were applied: revision TKA or TKA with augmentation, osteoarthritis of the knee secondary to rheumatoid arthritis, infection, trauma, and a history of surgery in the vicinity of the knee, including around-the-knee osteotomy. In addition, patients with postoperative coronal malalignment and malrotation of the femoral component of more than three degrees, were excluded. Furthermore, we defined neutral rotation as between three degrees of internal or external rotation, thus patients with tibial internal rotation of more than three degrees were also excluded.\u003c/p\u003e\u003cp\u003e41 knees from 34 patients were enrolled and thereafter, 2 knees from 2 patients were excluded to health problems not related to the operation, 2 knees from 2 patients were excluded due to coronal malalignment, 5 knees from 5 patients were excluded due to tibial internal rotation, and 1 knee from 1 patient were excluded due to relocation. After exclusion, data were available for 24 patients, 7 of whom underwent bilateral TKA. The knees in the bilateral cases were evaluated separately, giving a total of 31 knees. The mean patient age was 71.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7 (61\u0026ndash;84) years; 3 knees were from 2 men, and 28 knees were from 22 women. The implant used was Evolution cruciate-substituting (CS) TKA (MicroPort Orthopedics, Arlington, TN, USA).\u003c/p\u003e\u003cp\u003eOperation was performed with a midline skin incision and a medial parapatellar arthrotomy. Cruciate ligaments, meniscus, and bony spurs were subsequently removed, and distal femoral and proximal tibial cuts were performed perpendicular to the mechanical axis. The posterior tibial slope was targeted to be three degrees according to the manufacturer\u0026rsquo;s recommendation, and the posterior femur was cut parallel to the surgical epicondylar axis (SEA). After completing the bone cuts, step-wise medial soft tissue releases were performed when required, and then the extension and flexion gaps were measured using a spring-loaded ligament balancer (Umihira Co. Ltd., Kyoto, Japan) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The tibial and femoral component was fixed, according to the Akagi\u0026rsquo;s line and bone cut surface respectively, and the polyethylene surface were then inserted according to the gap measured by the ligament balancer and spacer block.\u003c/p\u003e\u003cp\u003ePostoperative tibial rotational angle was measured by three steps by using the CT images obtained using a helical two-dimensional scanner (Scenaria, Hitachi, Ltd., Tokyo, Japan) operating at 120 kV with a slice thickness of 2.5 mm. Images were loaded and measured using OsiriX software version 11.0 (Pixmeo SARL, Bernez, Switzerland). First, the geometric center of the proximal tibia was identified in the slice just distal to the component by drawing a best-fit oval (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Next, the tip of the tibial tubercle was identified on another slice wherein the tubercle is most protruded (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The two points were connected, and the resulting line represented the anatomical axis of the tibia. Finally, the posterior surface of the tibial component was identified by connecting the medial and lateral posterior margins of the component, and a perpendicular line of the posterior surface was drawn (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). This process is identical to the Berger method [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], and has been used in recent studies evaluating tibial rotational alignment [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, this method is appliable only for symmetric tibial components, which the AP axis and the posterior surface of the component is perpendicular.\u003c/p\u003e\u003cp\u003eBecause the tibial component implanted in this study has an asymmetric shape, to evaluate the angle between the anatomical axis of the tibia and the antero-posterior (AP) axis of the component, 8 degrees, which is the angle between the AP axis and the perpendicular line of the posterior surface of the implanted component, was subtracted from the angle between the anatomical axis of the tibia and the perpendicular line of the posterior surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Subsequently, 18\u0026deg; was subtracted according to the method described by Berger et al [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], and a negative value was obtained when the tibial component was externally rotated. Inter- and intra-observer reliability were evaluated by three observers, which was 0.92 and 0.78 respectively.\u003c/p\u003e\u003cp\u003e Thereafter, correlation between the tibial rotational alignment and 2011 Knee Society Score (KSS) which was obtained six month, 1 and 2 years postoperatively were evaluated.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Statistical analysis\u003c/h2\u003e\u003cp\u003eAll statistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). For power analysis, power level was set as 80% with a 0.05 significance level, and the effect size was set at 0.5. The analysis indicated that 30 knees were needed to provide a statistical power of 80%. The Kolomogrov-Smirnov test was used to test the normality, and the correlation between tibial rotational alignment and the outcomes were analyzed by Pearson or Spearman correlation analysis. Values of \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. RESULTS","content":"\u003cp\u003ePostoperatively, tibial component was 6.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9 degrees externally rotated, and extension angle, Knee society knee score, function score, satisfaction significantly improved. On the other hand, expectation significantly worsened (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Significant positive correlation was observed between tibial rotational alignment and flexion angle (six months, two years), satisfaction (two years) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). On the other hand, negative correlation was observed between tibial rotational alignment and walking and standing (one year, two years) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMeans of the postoperative rotational alignment and preoperative and postoperative extension angle, flexion angle, and 2011 Knee Society Score.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRotational alignment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eFemoral component\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003eTibial component\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e-0.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e-4.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePre-operation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c6\" namest=\"c3\"\u003e\u003cp\u003ePost-operation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e1 year\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2 years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExtension angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.05\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlexion angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e119.6\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e119.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e120.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e120.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003e2011 Knee Society Score\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eKnee score\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41.0\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e82.8\u0026thinsp;\u0026plusmn;\u0026thinsp;17.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e86.5\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e90.0\u0026thinsp;\u0026plusmn;\u0026thinsp;14.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.05\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFunction score\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e46.4\u0026thinsp;\u0026plusmn;\u0026thinsp;13.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e65.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e70.5\u0026thinsp;\u0026plusmn;\u0026thinsp;15.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e70.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.05\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSatisfaction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e30\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.05\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExpectation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.05\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCorrelation between tibial rotational alignment and postoperative outcomes.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e6 months\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e1 year\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e2 years\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003er\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eextension angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eflexion angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e0.53\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.64\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.00\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003e2011 Knee Society Score\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003eknee score\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eobjective scores\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esymptoms\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003efunction score\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ewalking and standing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e-0.51\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.04\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e-0.39\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.04\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003estandard activities\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eadvanced activities\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ediscretionary activities\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esatisfaction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.42\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eexpectation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003er: correlation coefficient, p: p-value\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"4. DISCUSSION","content":"\u003cp\u003eThe most important findings of the current study were that externally rotated tibial component results with higher walking and standing scores, and with smaller flexion angle and lower satisfaction scores in a group of patients with neutral alignment in all the other planes. This was the first report that clarified the correlation between tibial external rotation and patient reported outcomes in a guided motion TKA.\u003c/p\u003e\u003cp\u003eIn terms of patient reported outcomes and tibial rotational alignment, Barrack et al [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] found a significant difference between patients with anterior knee pain and an asymptomatic control group in terms of tibial component rotation, while Bell et al [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] identified internal rotation as an important factor in pain after TKA by comparing patients with painful TKA with a matched control cohort of pain free patients. Furthermore, Nicoll et al [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] found that 4.3\u0026deg; of internal rotation was associated with knee pain and observed that the threshold that produced pain was \u0026gt;\u0026thinsp;9\u0026deg; of internal rotation, whereas Panni et al [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] reported in a systematic review that excessive internal rotation of the tibial component is a risk factor for inferior functional outcomes. Therefore, we excluded patients with internal rotation over three degrees, thus we could not draw a conclusion about internal tibial rotation and patient reported outcomes in the current study.\u003c/p\u003e\u003cp\u003eOn the other hand, external rotation of the tibial component has not been reported to have an influence on patient reported outcomes, although we found a positive effect on patient reported outcomes. However, caution is required because there might have been a ceiling effect in the expectation and walking and standing section. Ceiling effect is a statistical construct that describes clustering of patients score towards the upper limit of a scale, and if present, variance in outcome is insufficiently measured above a certain level. Terwee et al reported to consider a ceiling effect being present if 15% or more of respondents achieved the highest score possible [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], and because half of the patients scored the maximum score in the walking and standing section, this effect may have influenced the result.\u003c/p\u003e\u003cp\u003eIn addition, flexion angle was smaller and the satisfaction score was lower when the tibial component was externally rotated. This may be due to the stretching of the iliotibial band. Iliotibial band is a lateral thickening of the fascia lata in the thigh, which passes over the lateral femoral epicondyle and attaches to the Gerdy\u0026rsquo;s tubercle on the anterolateral aspect of the tibia. Tibial internal rotation is primary resisted by the iliotibial band [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], and increased tension of the iliotibial band results in external tibial rotation in flexion [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The implant used in the current study was a guided motion TKA, which leads the tibia to internally rotate in knee flexion. Therefore, when the tibial component is externally implanted, the iliotibial band is further stretched in flexion, resulting in lateral knee pain [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This kinematics may result in decreased knee flexion and lower symptoms score. Therefore, excessive external rotation should be avoided in a guided motion implant.\u003c/p\u003e\u003cp\u003eThis study has some limitations. First, clinical outcomes were only assessed in one type of prosthesis. Therefore, the results of this study are not necessarily applicable to other implants. Second, the threshold for external rotation was not investigated. In future study, we need to clarify the threshold of rotational alignment of the tibial component. Third, most patients in this study were women. However, most patients undergoing TKA in East Asia are women; therefore, the present study reflects the actual clinical situation. Despite these limitations, we believe that our study has revealed clinically important information regarding tibial rotational alignment in TKA.\u003c/p\u003e"},{"header":"5. CONCLUSIONS","content":"\u003cp\u003eTibial rotational alignment influences two years clinical outcomes in total knee arthroplasty. Excessive external rotation should be avoided in a guided motion prosthesis and in future study, threshold of rotational alignment of the tibial component should be clarified.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTKA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eTotal knee arthroplasty\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ecomputed tomography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ecruciate-substituting\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSEA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003esurgical epicondylar axis\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eAP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eantero-posterior\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eKSS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eKnee Society Score\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThis study was approved by the relevant institutional review board of Nippon Medical School Chibahokusoh hospital (approval number 878).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eAll patients provided informed consent by an opt-out method.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e: Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contributions:\u003c/strong\u003e TK: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing-Original Draft, Visualization; MW: Validation; YO: Writing-Review \u0026amp; Editing; NI: Writing-Review \u0026amp; Editing: TM: Writing-Review \u0026amp; Editing, Supervision.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e None\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRanawat CS, Flynn Jr WF, Saddler S, Hansraj KK, Mayneard MJ. Long-term results of the total condylar knee arthroplasty. A 15-year survivorship study. Clin Orthop Relat Res 1993;286:94\u0026ndash;102.\u003c/li\u003e\n\u003cli\u003eBourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Comparing patient outcomes after THA and TKA: is there a difference? Clin Orthop Relat Res 2010;468:542\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eBourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Patient satisfaction after total knee arthroplasty: Who is satisfied and who is not? Clin Orthop Relat Res 2010;468:57\u0026ndash;63.\u003c/li\u003e\n\u003cli\u003eMatsuda S, Kawahara S, Okazaki K, Tashiro Y, Iwamoto Y. Postoperative alignment and ROM affect patient satisfaction after TKA. Clin Orthop Relat Res 2013;471:127\u0026ndash;33.\u003c/li\u003e\n\u003cli\u003eHungerford DS, Krackow KA. Total joint arthroplasty of the knee. Clin Orthop Relat Res 1985 Jan-Feb;(192):23\u0026ndash;33.\u003c/li\u003e\n\u003cli\u003eBerger RA, Rubash HE, Seel MJ, Thompson WH, Crossett LS. Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis. Clin Orthop Relat Res 1993 Jan;(286):40\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eAkagi M, Mori S, Nishimura S, Nishimura A, Asano T, Hamanishi C. Variablity of extraarticular tibial rotation references for total knee arthroplasty. Clin Orthop Relat Res 2005 Jul;(436):172\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eSahin N, Atici T, Ozturk A, Ozkaya G, Ozkan Y, Avcu B. Accuracy of anatomical references used for rotational alignment of tibial component in total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2012 Mar;20(3):565\u0026ndash;70.\u003c/li\u003e\n\u003cli\u003eWasielewski RC, Galante JO, Leighty RM, Natarajan RN, Rosenberg AG. Wear patterns on retrieved polyethylene tibial inserts and their relationship to technical considerations during total knee arthroplasty. Clin Orthop Relat Res 1994 299:31\u0026ndash;43.\u003c/li\u003e\n\u003cli\u003eBerger RA, Crossett LS, Jacobs JJ, Rubash HE. Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res 1998 Nov:(356):144\u0026ndash;53.\u003c/li\u003e\n\u003cli\u003eBarrack RL, Schrader T, Bertot AJ, Wolfe MW, Myers L. Component rotation and anterior knee pain after total knee arthroplasty. Clin Orthop Relat Res 2001 Nov:(392):46\u0026ndash;55.\u003c/li\u003e\n\u003cli\u003eNicoll D, Rowley DI. Internal rotational error of the tibial component is a major cause of pain after total knee replacement. J Bone Joint Surg Br 2010;92:1238\u0026ndash;44.\u003c/li\u003e\n\u003cli\u003eLuyckx L, Luyckx T, Bellemans J, Vicotor J. Iliotibial band traction syndrome in guided motion TKA. A new clinical entity after TKA. Acta Orthop Belg 2010;76(4):507-12.\u003c/li\u003e\n\u003cli\u003eOshima Y, Iizawa N, Takai S, Majima T. Optimal distraction force for evaluating tibiofemoral joint gaps in posterior stabilized total knee arthroplasty. J Nippon Med Sch 2021;88:361\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003ePanni AS, Ascione F, Rossini M, Braile A, Corona K, Vasso M, Hirschmann MT. Tibial internal rotation negatively affects clinical outcomes in total knee arthroplasty: a systematic review. Knee Surg Sports Traumatol Arthrosc 2018;26(6):1636-1644.\u003c/li\u003e\n\u003cli\u003eBabazadeh S, Dowsey MM, Vasimalla MG, Stoney JD, Choong PFM. Knee arthroplasty component malrotation does not affect function or quality of life in the short to medium term. J Arthroplasty 2019;34(7):1382-6.\u003c/li\u003e\n\u003cli\u003eBell SW, Young P, Drury C, Smith J, Anthony I, Jones B, Blyth M, Mclean A. Component rotational alignment in unexplained painful primary total knee arthroplasty. Knee 2014;21(1):272-7.\u003c/li\u003e\n\u003cli\u003eTerwee CB, Bot SDM, De Boer MR, van derWindt DAWM, Knol DL, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol 2007;60:34-42.\u003c/li\u003e\n\u003cli\u003eMcHorney CA, Tarlov AR. Individual-patient monitoring in clinical practice: are available health status surveys adequate? Qual Life Res 1995;4:293-307.\u003c/li\u003e\n\u003cli\u003eEckhard L, Munir S, Wood D, Talbot S, Brighton R, Walter B, et al. The ceiling effects of patient reported outcome measures for total knee arthroplasty. Orthop Traumatol Surg Res 2021;107(3):102758.\u003c/li\u003e\n\u003cli\u003eAmis A. Anterolateral knee biomechanics. Knee Surg Sports Traumatol Arthrosc 2017;25(4):1015-1023.\u003c/li\u003e\n\u003cli\u003eMerican AM, Amis A. Iiotibial band tension affects patellofemoral and tibiofemoal kinematics. J biomech 2009;42(10):1539-1546. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"total knee arthroplasty, rotational alignment, patient reported outcomes","lastPublishedDoi":"10.21203/rs.3.rs-7174828/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7174828/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eProper rotational alignment of the femoral and tibial component is critical for a successful total knee arthroplasty (TKA). However, there are no study that focused on the influence of external rotation of the tibial component have on patient reports outcomes in a guided motion TKA. This study aimed to assess the association between tibial rotational alignment and patient reported outcomes in patients with neutral alignment in all the other planes.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003e The current study was a retrospective cross-sectional study performed at a regional institutional hospital. Patients who underwent primary TKA for knee osteoarthritis with no postoperative coronal malalignment and malrotation of the femoral component were included in the study. Rotational alignment of the tibial component was evaluated using a computed tomography and its relationship between postoperative 2011 Knee Society Score was evaluated by Pearson or Spearman correlation analysis.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe study included 24 patients, 7 of whom underwent bilateral TKA with a guided motion cruciate substituting implant. Tibial component was 6.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9 degrees externally rotated postoperatively. Externally rotated tibial component resulted with higher scores in walking and standing (one year, two years), and with smaller flexion angle (six months, two years) and lower satisfaction score (two years).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eTibial rotational alignment influences two years clinical outcomes in total knee arthroplasty. Excessive external rotation should be avoided in a guided motion prosthesis and in future study, threshold of rotational alignment of the tibial component should be clarified.\u003c/p\u003e","manuscriptTitle":"External rotational alignment of tibial component correlates with two years clinical outcomes in guided motion total knee arthroplasty: a retrospective cross-sectional study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 20:31:45","doi":"10.21203/rs.3.rs-7174828/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"52eb3492-6976-4698-8975-a59da53dba8a","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-15T13:38:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 20:31:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7174828","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7174828","identity":"rs-7174828","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}