Lateral Distal Femoral Condyle as a Precise Reference for Distal Femoral Resection in Total Knee Arthroplasty for Severe Varus Knee Osteoarthritis

Lateral Distal Femoral Condyle as a Precise Reference for Distal Femoral Resection in Total Knee Arthroplasty for Severe Varus Knee Osteoarthritis | 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 Lateral Distal Femoral Condyle as a Precise Reference for Distal Femoral Resection in Total Knee Arthroplasty for Severe Varus Knee Osteoarthritis Maozheng Wei, Kuo Hao, Huijun Kang, Lingce Kong, Fei Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2352484/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 Purpose Bone resection was highly valued in total knee arthroplasty (TKA), but how to determine the amount of distal femur resection is still controversial. The purpose of this study was to explore how to use lateral condyle as a reference for distal femoral osteotomy in TKA. Method Imaging data from 118 nonarthritic subjects and 123 osteoarthritis (OA) subjects were used to assess the cartilage wear pattern of the distal femur in varus knees. Measurements were performed on three-dimensional reconstruction after virtual bone cutting. The difference between the resection amount of distal (0°) and posterior (90°) was calculated when the medial condyle was used as a reference in OA patients. The osteotomy amount on lateral was calculated in nonarthritic subjects when the medial condylar osteotomy was consistent with the thickness of the implants. Results In 43% of OA patients, there was༞1mm difference between the 0° and 90° in medial condyle cartilage, and no difference was observed in lateral. When using medial condyle as a reference for osteotomy, there was a difference of 1.3 ± 0.56 mm between the resection amount of 0° and 90°, and the difference was 0.24 ± 0.27 mm when using lateral condyle. Statistical analysis showed that there was a linear correlation between the resection amount of lateral condyle and mechanical lateral distal femoral angle (mLDFA) in nonarthritic subjects (R = 0.72, p <0.001). Conclusions Using the lateral condyle as the reference for distal femoral osteotomy is more suitable for the cartilage wear pattern of the varus knee. The position of cutting guide can be adjusted by preoperative measurements of mLDFA. Total knee arthroplasty Distal femoral resection Cartilage wear Osteoarthritis Varus Figures Figure 1 Figure 2 Figure 3 Introduction Total knee arthroplasty (TKA) is one of the most common and cost-effective operations for end-stage knee osteoarthritis (OA). However, the satisfaction rate of patients with TKA has only been 75 to 80%, mainly due to persistent pain and poor function[ 1 ]. The balance of soft tissue in TKA is affected by many factors, consisting of the looseness of surrounding soft tissue, the variation of bone geometry and the amount of bone cut. In mechanical alignment (MA) the thickness of bone cut should be the same as the implant to attain balanced soft tissue[ 2 , 3 ]. Cartilage wear patterns were strongly influenced by limb alignment, the varus knees showing more loss in early flexion with thinner cartilage in medial compartments. 92% of knees with varus deformity had > 1mm cartilage wear at 0°on the medial femoral condyle and lateral femoral condyle had minor degeneration. The subchondral bone of the medial and lateral femoral condyles has the same single radius of curvature. In arthritic knees with varus alignment, the lateral femoral condyle had more native morphotype.[ 4 – 7 ]. The lateral condyle of the distal femur has less cartilage and bone wear due to the pattern of cartilage wear in patients with varus knees. However, no study has investigated the possible effect of using the lateral condyle as a reference for distal femoral osteotomy. This was a retrospective study conducted to provide anthropometric data by measuring the parameters of virtually resected distal femurs undergoing TKA using a 3D reconstruction process. The hypothesis of this study was that using the lateral condyle as the reference for distal femoral osteotomy is more suitable for the cartilage wear pattern of the varus knee. Method A total of 123 knees from 112 OA patients undergoing TKA and 118 knees from 108 nonarthritic participants were included in the study between April 2020 and June 2021. All included subjects had varus knees with the mechanical alignment of the lower limbs. Lower limb alignment was assessed by the mechanical axes of the femur and tibia on full-length lower limb slices in the standing position. The inclusion criteria of arthritic group were: primary, degenerative and non-inflammatory knee OA with moderate to severe pain and failure of conservative treatment. The exclusion criteria are 1) previous knee surgery; 2) knee joint infection; 3) stiffness or ankylosis of hip joint; 4) bone loss or nerve function defect; 5) the need of highly restrictive prostheses; 6) severe knee joint deformity: knee joint flexion 20°, varus or valgus deformity > 10°. Patients in nonarthritic group consulted the orthopedic surgeon for a complaint unrelated to the cartilage wear, such as a slight soft-tissue injury or avulsion fracture. The nonarthritic subjects with cartilage wear were excluded by magnetic resonance imaging (MRI). The present study was approved by our Institutional Review Board, and informed consent was acquired from all subjects. MRI and Radiographic parameters All subjects of the study underwent full weight-bearing long-leg standing radiographs and lateral knee radiographs according to a standardized protocol to avoid bias. The MRI used for this study were obtained with a 1.5T MRI (Sonata Magnetom, Siemens Medical Solutions, Erlagen, Germany) with the knee in or near full extension. Cartilage wear was measured by applying the best-fit circle on the peripheral boundary of the subchondral bone. The thickness of the cartilage of each condyle was measured at 0° and 90°[ 5 ]. Computed tomography (CT) scans of the knees were obtained by a Philips CT (Philips Medical Systems, The Netherlands) and the acquired imagines were stored by the Picture Archiving and Communication System (PACS). RadiAnt-DICOM software (Medixant Ltd., Poznań, Poland), which has a mouse cursor that can automatically manifest distance and angle, was used to complete the measurements on the CT scans. To reduce the measurement error, two independent experienced orthopedic surgeons checked all of the images and measured relevant parameters in the case of double-blind. The following variables were measured[ 8 , 9 ] and these were illustrated in Fig. 1 I) HKA: Hip-knee-ankle angle. The angle between the line from the center of hip joint to the center of knee joint and the line from the center of knee joint to the center of ankle joint; II) MPTA: Medial proximal tibial angle. The medial angle between the tibial mechanical axis and the proximal tibial joint line connecting the most distal points on the concavity of the subchondral bone of the medial and lateral tibial plateaus; III) mLDFA: Mechanical lateral distal femoral angle. The lateral distal femoral angle between the femoral mechanical axis and the line tangential to the femoral condyles; IV) VCA: Valgus correction angle. The angle between the mechanical and anatomical axes of the femur. 3D reconstruction and simulated osteotomy Mimics 21.0 (Materialise, Leuven, Belgium) software was used for 3D reconstruction based on CT scans. Regional growth was performed to segment the femur, and each model was examined and corrected by a senior surgeon prior to measurement. The 3D model files were imported into 3-matic 13.0 (Materialise) for analysis. A sphere was fitted to the surface of the femoral head, and the geometric center point of the sphere was defined as the center of the hip joint. The knee joint was centered at the midpoint of the femoral intercondylar fossa. The femoral mechanical axis was defined as a line connecting the center of the hip and the center of the knee[ 10 ]. The distal femoral and proximal tibial cuts were perpendicular to the mechanical axis. The thickness of distal femur resection was set to be consistent with the implant size of 8mm, including the thickness of cartilage and bone (Fig. 2 )[ 11 ]. Cartilage thickness was set to be consistent with the MRI date. When the lateral condyle was used as the reference, setting the resection depth at 8 mm from the distal lateral condyle. When the medial condyle was used as the reference, setting the resection depth at 8 mm from the distal medial condyle[ 12 ]. Statistical analysis SPSS Statistics Package 21.0 (IBM, Armonk, New York, USA) was used to analyze data and p < 0.05 was defined as statistically significant. Scatterplots for each population were created to demonstrate alignment distributions for healthy and arthritic groups. The data were statistically analyzed by two researchers and all the measured variables and data are described as mean ± standard deviation. The paired-samples t-test was used to analyze the differences between measurement data and Levene's test was used to examine the homogeneity of the data. A linear regression test was performed to evaluate the correlation. The intra-class correlation values (ICC) were calculated to determine the reliability of inter-observer and intra-observer measurements. Results The demographic data of all patients, including gender, age, body mass index (BMI) and side, were collected before the operation and shown in Table 1 . Table 1 Demographic characteristics of the arthritic and nonarthritic groups demographics Arthritic Nonarthritic Participants (n) 112 107 Knees (n) 123 118 Age (years) 67.4 ± 7 31.3 ± 3.7 Sex Male 24% (27) 37% (40) Female 76% (85) 63% (67) BMI (kg/m 2 ) 27.4 ± 3.6 21.8 ± 3.3 Side Left 52% (64) 41% (48) Right 48% (59) 59% (70) Continuous variables are expressed as mean ± standard deviation and categorical variables are expressed as % (n). BMI, body mass index. For varus arthritic knees, there was a difference in cartilage thickness between the distal and posterior condyles on the medial femoral condyle ( p < 0.05). In the medial condyle, the cartilage thickness was 0.17 ± 0.31mm at 0° and 1.08 ± 0.5 mm at 90°. No difference of cartilage thickness was observed in the lateral condyle between 0° and 90°. In the lateral condyle, the cartilage thickness was 1.23 ± 0.43mm at 0° and 1.48 ± 0.47mm at 90°. There was no specificity in the distribution of femoral cartilage in the medial and lateral femoral condyles in nonarthritic knees (Table 2 ). Table 2 Cartilage thickness of the medial and lateral condyle at 0° and 90° 0° 90° P valve Arthritic group Medial condyle (mm) 0.172 ± 0.311 1.093 ± 0.501 P < 0.001 Lateral condyle (mm) 1.232 ± 0.433 0.468 ± 0.468 P < 0.001 Nonarthritic group Medial condyle (mm) Lateral condyle (mm) 1.838 ± 0.193 1.893 ± 0.169 1.904 ± 0.216 1.899 ± 0.18 0.004 0.950 The data was shown as mean ± standard deviation. Three-dimensional reconstruction was used to simulate the osteotomy of osteoarthritis subjects perpendicular to the mechanical axis of the femur. When the medial condyle was used as the reference for distal femoral osteotomy, there was a difference of 1.3 ± 0.56mm between the distal femoral end and posterior femoral condyle, and 43% of patients had a difference of more than 1mm. When the lateral condyle was used as the reference for distal femoral osteotomy, the difference between distal femoral and posterior femoral condyle resection was 0.24 ± 0.27mm. The simulated osteotomy of nonarthritic subjects showed that when the resection amount of the medial distal femoral condyle was set to 8mm, the resection amount of the lateral distal femoral condyle was 4.81 ± 1.76mm. There was a linear correlation between the osteotomy thickness of the lateral condyle and LDFA ( R = 0.72, p <0.001, Table 3 ). A 0.845mm increment in lateral condylar osteotomy was observed with every 1° increment in mLDFA (Fig. 3 ). Table 3 Pearson correlation and r - value of the parameters Parameter Osteotomy thickness of the lateral condyle, mm HKA, ° -0.028 MPTA, ° 0.046 mLDFA, ° 0.845* VCA, ° 0.107 *Statistically significant. HKA, Hip-knee-ankle angle; MPTA, Medial proximal tibial angle; mLDFA, Mechanical lateral distal femoral angle; VCA, Valgus correction angle. Discussion This study proposed a pragmatic comprehensive osteotomy in TKA for patients with varus alignment, which used lateral condyle as a reference when performing distal femoral osteotomy. The position of the distal femoral osteotomy cutting guide could be adjusted by the preoperative measurement of the mLDFA. Precise TKA surgical planning should take into account the pattern of cartilage wear in arthritic patients with varus knees. Residual cartilage in patients with osteoarthritis may affect the accuracy of the osteotomy. Nam et al. proposed surgical planning for TKA based on CT does not consider articular cartilage and could lead to external malrotation of the femoral implant[ 13 ]. The femoral cartilage wear is strongly associated with lower extremity mechanical alignment. MRI measurements of the knee in arthritic patients with varus knees showed that there were 43% of patients with cartilage thickness differences > 1mm between 0° and 90° of medial femoral condyles, consistent with previous reports. The progression of arthritis is accompanied by the wear of femoral cartilage. Johnson et al. found the wear of femoral cartilage is affected by the lower limb alignment through femorotibial cartilage maps and joint kinematics. Cartilage wear of varus knee is mainly concentrated in the medial compartment of early flexion, while valgus knee has more cartilage wear in the posterolateral femoral condyle during deep flexion[ 4 ]. Denis et al. found that 92% of OA patients with varus knee had cartilage wear of more than 1mm at 0° flexion, while the lateral femoral condyle had minor cartilage degeneration. Morphological studies found the subchondral bone of the medial and lateral femoral condyles has the same single radius of curvature and a single transverse axis[ 5 , 7 , 14 ]. There was greater cartilage wear on the medial condyle of the distal femur and more asymmetry wear between 0° and 90° than the lateral. Therefore, we recommend using the lateral femoral condyle as a reference for distal femoral osteotomy. Cartilage thickness in the medial condyle of 0° was found to be significantly less than that on 90° in OA patients with varus knees (Table 2 ), using the medial condyle as a reference resulted in an increase in the radius of curvature in extension. 11–26% revision TKAs were performed for instability while part of them had mid-flexion instability[ 15 ]. Clary et al. identify the sudden reduction in the radii-of-curvature of femoral condyle as a potential cause of clinically observed paradoxical anterior femoral translation in mid-flexion[ 16 ]. Different femoral sagittal design in TKA were based on different theories. Multi-radius (MR) design was based on the theory of knee rotation center which was first proposed by Frankel et al in 1971. It reported that knee flexion occurs around a varying transverse axis, the flexion axis varies in a helical fashion during the flexion process, and the instantaneous rotation center of the femoral posterior condyle forms a “J curve’’[ 17 , 18 ]. Single-radius (SR) design had a uniform radius of curvature. It designed based on the principle that superficial medial collateral ligament is isometric throughout its range of movement. SR regards the femoral condyle as a spherical sphere with a single radius[ 19 ]. SR had theoretical advantages, and it provided a more posterior flexion axis and a longer extensor moment arm and maintained stabilization during movement, especially in mid-flexion[ 20 ]. SR design required the radius of curvature in the sagittal plane. No difference in cartilage wear was observed between the distal and posterior condyles of the lateral femoral condyle. Using the lateral femoral condyle as the reference for distal femoral osteotomy has the advantage of keeping the radius of curvature consistent when applying the SR design implants. When the lateral condyle was used as a reference, the resection amount of the distal femur was affected by the geometric shape of the femur, and the position of the osteotomy line of the distal femur should be adjusted by morphological measurement of the femur. In this study, multiple linear regression analysis was performed on the resection amount measured by simulated osteotomy in nonarthritic subjects. mLDFA was linearly correlated with the resection amount differences between the medial and lateral condyles at 0° (R = 0.72, p<0.001), and a 0.85mm increment of osteotomy thickness on lateral condyle was observed with every 1° mLDFA increment when the osteotomy of the medial condyle was set at 8mm (Fig. 3 ). Using Fig. 3 , the surgeon can predict the resection thickness of lateral condyle by measuring mLDFA preoperatively and use this information intra-operatively. The amount of osteotomy may not affect limb alignment but has important implications for ligament tension, tissue balance and clinical outcome[ 16 ]. Many scholars attributed the unsatisfactory results after TKA to the inability of knee prosthesis to simulate physiological and natural knee motion and suggested to amend the surgical strategy[ 20 , 21 ]. Severe deformities lead to elevated joint lines. The least worn part of the joint was often used as a reference for bone cuts, and the wear of bone and cartilage in the medial condyle might result in over-resection[ 22 ]. Mullaji et al. proposed that the thickness of distal femoral resection should be determined according to the degree of bone defect in the medial femoral condyle[ 23 ]. Denis et al. suggested referencing guide should be adjusted to compensate for the mean 1.9mm cartilage wear at the distal medial condyle[ 5 ]. Yue et al. proposed the intercondylar notch ceiling could be used as an accurate landmark to determine the proper distal femoral resection level during TKA[ 10 ]. There were some limitations in this study. First, the nonarthritic group for the image analysis was selected for patients with slight soft-tissue injury or avulsion fracture rather than patients without knee joint disease. The nonarthritic subjects with cartilage wear were excluded by MRI, but there may be potential effects. Second, a relatively small sample size for each subject group, this was due mainly to the relatively lengthy segmentation process. Third, it was a retrospective study with non-randomized design, which had inherent drawbacks. Conclusion With the wear patterns of cartilage in varus osteoarthritic knees treated with TKA, it showed significantly more wear at 0° in the medial compartment than at 90°. Distal femoral resection using medial condyle as reference resulted in > 1 mm difference of resection between 0° and 90°of flexion. It is recommended to take the lateral condyle as the reference for the distal femur osteotomy to obtain a more physiological single radius rotation axis. The mLDFA can be used to adjust the reference position of the cutting guide before TKA. Abbreviations TKA: total knee arthroplasty; OA: osteoarthritis; mLDFA: mechanical lateral distal femoral angle; MA: mechanical alignment; MRI: magnetic resonance imaging; CT: computed tomography; ICC: intra-class correlation values; BMI: body mass index; MR: multi-radius; SR: Single-radius Declarations Ethics approval and consent to participate The present study was approved by the Academic Ethics Committee of the Third Hospital of Hebei Medical University, and all patients provided their informed consent for participation and publication. All of the data and materials are available. Consent for publication Not applicable. Availability of data and material The datasets used or analyzed during the current study are available from the corresponding author on reasonable request. Funding Funded by The National Natural Science Foundation of China (Grant No.81873983). Authors' contributions Fei Wang supervised, coordinated and provided further advice on revisions; Maozheng Wei conceived of the manuscript, and participated in its design, drafted and wrote the manuscript; Kuo Hao conceived of the manuscript, and participated in its design; Huijun Kang conceived of data collection and data analysis; Lingce Kong conceived of literature search and analysis The first draft of the manuscript was written by Maozheng Wei and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgments Thanks for the technical support from the Department of Imaging of the Third Hospital of Hebei Medical University. Authors' information Maozheng Wei. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email: [email protected] . Kuo Hao. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China. Email: [email protected] . Huijun Kang. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email: [email protected] . Lingce Kong. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email: [email protected] . *Corresponding author: Fei Wang Corresponding author at: Department of Orthopaedic Surgery, Third Hospital of Hebei Medical University, Ziqiang Road 139, 050051 Shijiazhuang, China E-mail addresses: [email protected] Tel: +86 -311-88602613 Fax: +86 -311-88602613. References Carr AJ, Robertsson O, Graves S, Price AJ, Arden NK, Judge A, Beard DJ: Knee replacement . Lancet (London, England) 2012, 379 (9823):1331–1340. 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The journal of knee surgery 2022, 35 (2):204–214. Jenny JY, Miehlke R, Saragaglia D, Geyer R, Mercier N, Schoenahl JY, Thiel B: Single - radius , multidirectional total knee replacement . Knee surgery, sports traumatology, arthroscopy: official journal of the ESSKA 2013, 21 (12):2764–2769. Babazadeh S, Dowsey MM, Swan JD, Stoney JD, Choong PF: Joint line position correlates with function after primary total knee replacement: a randomised controlled trial comparing conventional and computer-assisted surgery . The Journal of bone and joint surgery British volume 2011, 93 (9):1223–1231. Mullaji AB, Padmanabhan V, Jindal G: Total knee arthroplasty for profound varus deformity: technique and radiological results in 173 knees with varus of more than 20 degrees . The Journal of arthroplasty 2005, 20 (5):550–561. 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-2352484","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":158626320,"identity":"22307fed-1cb3-494b-b7b9-c5a94ad3d9ea","order_by":0,"name":"Maozheng Wei","email":"","orcid":"","institution":"Third Hospital of Hebei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Maozheng","middleName":"","lastName":"Wei","suffix":""},{"id":158626321,"identity":"453f43a4-38fa-4baf-8460-70399c2a4559","order_by":1,"name":"Kuo Hao","email":"","orcid":"","institution":"Third Hospital of Hebei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kuo","middleName":"","lastName":"Hao","suffix":""},{"id":158626322,"identity":"fb102235-b4eb-4bfb-b059-fc90d3ac3202","order_by":2,"name":"Huijun Kang","email":"","orcid":"","institution":"Third Hospital of Hebei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Huijun","middleName":"","lastName":"Kang","suffix":""},{"id":158626323,"identity":"a492d539-e59d-4cf3-be08-c7f077b566b9","order_by":3,"name":"Lingce Kong","email":"","orcid":"","institution":"Third Hospital of Hebei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lingce","middleName":"","lastName":"Kong","suffix":""},{"id":158626324,"identity":"09591a67-1791-4d52-bbd5-bb788bfa30f4","order_by":4,"name":"Fei Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYDCCAxCKn4GZ+cCBDz+I08LYAKQkG5jZEg/O7CFJCwOP8WEONiJ08B1vfv7g457DEvzsPB8OM/AwyPOLHcCvRfLMMcPGGc8OS0g28244XGDBYDhzdgJ+LQY3chibeQ7crjM4DNQyg4chweA2kVok7A/zPDjMw0aKFgNmHgbitID8MnPGgf8SEofZDICBLEHYL8AQe/Dhw4E0Cf7+w48/fPhhI88vTUALOpAgTfkoGAWjYBSMAuwAAKqMSh5/dlEnAAAAAElFTkSuQmCC","orcid":"","institution":"Third Hospital of Hebei Medical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Fei","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2022-12-07 06:29:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2352484/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2352484/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":30223494,"identity":"bfebc14b-71a0-40e5-9221-190a2195a64c","added_by":"auto","created_at":"2022-12-12 18:56:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":649567,"visible":true,"origin":"","legend":"\u003cp\u003eRadiographic measurements of coronal parameters. \u003cstrong\u003eA\u003c/strong\u003e Hip-knee-ankle angle (HKA) is angle between the line from the center of hip joint to the center of knee joint and the line from the center of knee joint to the center of ankle joint; Valgus correction angle (VCA) is the angle between the mechanical and anatomical axes of the femur. \u003cstrong\u003eB\u003c/strong\u003e Mechanical lateral distal femoral angle (mLDFA) is the lateral distal femoral angle between the femoral mechanical axis and the line tangential to the femoral condyles. \u003cstrong\u003eC\u003c/strong\u003eMedial proximal tibial angle (MPTA) is the medial angle between the tibial mechanical axis and the proximal tibial joint line connecting the distalmost points on the concavity of the subchondral bone of the medial and lateral tibial plateaus;\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-2352484/v1/50c161b7f18dff14733613f1.png"},{"id":30223495,"identity":"95b1c392-28f2-4c26-ba8a-c511e31de738","added_by":"auto","created_at":"2022-12-12 18:56:42","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":624700,"visible":true,"origin":"","legend":"\u003cp\u003eSimulated femoral resection. The cutting plane (β) was perpendicular to the mechanical axis (α). The thickness of distal femur resection was set to 8mm, including the thickness of cartilage and bone. Cartilage thickness was consistent with the measurement by MRI.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-2352484/v1/7ca1a3ed591ba97ab54ea445.png"},{"id":30224071,"identity":"717d3197-b40f-4627-92b2-e9a52a625a2b","added_by":"auto","created_at":"2022-12-12 19:04:42","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":486198,"visible":true,"origin":"","legend":"\u003cp\u003eScatterplot of the osteotomy thickness versus the mechanical lateral distal femoral angle (mLDFA). The black line indicates the linear correlation between the two variables\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-2352484/v1/c2e6a89f5eb93422f3c461f0.png"},{"id":30615955,"identity":"91fd84b4-93c4-4f0b-8162-635eb42ce533","added_by":"auto","created_at":"2022-12-21 10:14:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2331048,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2352484/v1/0dd3cf26-a109-430f-9036-827cc87a26e6.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Lateral Distal Femoral Condyle as a Precise Reference for Distal Femoral Resection in Total Knee Arthroplasty for Severe Varus Knee Osteoarthritis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTotal knee arthroplasty (TKA) is one of the most common and cost-effective operations for end-stage knee osteoarthritis (OA). However, the satisfaction rate of patients with TKA has only been 75 to 80%, mainly due to persistent pain and poor function[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The balance of soft tissue in TKA is affected by many factors, consisting of the looseness of surrounding soft tissue, the variation of bone geometry and the amount of bone cut. In mechanical alignment (MA) the thickness of bone cut should be the same as the implant to attain balanced soft tissue[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCartilage wear patterns were strongly influenced by limb alignment, the varus knees showing more loss in early flexion with thinner cartilage in medial compartments. 92% of knees with varus deformity had\u0026thinsp;\u0026gt;\u0026thinsp;1mm cartilage wear at 0\u0026deg;on the medial femoral condyle and lateral femoral condyle had minor degeneration. The subchondral bone of the medial and lateral femoral condyles has the same single radius of curvature. In arthritic knees with varus alignment, the lateral femoral condyle had more native morphotype.[\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The lateral condyle of the distal femur has less cartilage and bone wear due to the pattern of cartilage wear in patients with varus knees. However, no study has investigated the possible effect of using the lateral condyle as a reference for distal femoral osteotomy.\u003c/p\u003e \u003cp\u003eThis was a retrospective study conducted to provide anthropometric data by measuring the parameters of virtually resected distal femurs undergoing TKA using a 3D reconstruction process. The hypothesis of this study was that using the lateral condyle as the reference for distal femoral osteotomy is more suitable for the cartilage wear pattern of the varus knee.\u003c/p\u003e"},{"header":"Method","content":"\u003cp\u003eA total of 123 knees from 112 OA patients undergoing TKA and 118 knees from 108 nonarthritic participants were included in the study between April 2020 and June 2021. All included subjects had varus knees with the mechanical alignment of the lower limbs. Lower limb alignment was assessed by the mechanical axes of the femur and tibia on full-length lower limb slices in the standing position. The inclusion criteria of arthritic group were: primary, degenerative and non-inflammatory knee OA with moderate to severe pain and failure of conservative treatment. The exclusion criteria are 1) previous knee surgery; 2) knee joint infection; 3) stiffness or ankylosis of hip joint; 4) bone loss or nerve function defect; 5) the need of highly restrictive prostheses; 6) severe knee joint deformity: knee joint flexion\u0026thinsp;\u0026lt;\u0026thinsp;90\u0026deg;, flexion contracture\u0026thinsp;\u0026gt;\u0026thinsp;20\u0026deg;, varus or valgus deformity\u0026thinsp;\u0026gt;\u0026thinsp;10\u0026deg;. Patients in nonarthritic group consulted the orthopedic surgeon for a complaint unrelated to the cartilage wear, such as a slight soft-tissue injury or avulsion fracture. The nonarthritic subjects with cartilage wear were excluded by magnetic resonance imaging (MRI). The present study was approved by our Institutional Review Board, and informed consent was acquired from all subjects.\u003c/p\u003e\n\u003cdiv class=\"Section2\" id=\"Sec3\"\u003e\n \u003ch2\u003eMRI and Radiographic parameters\u003c/h2\u003e\n \u003cp\u003eAll subjects of the study underwent full weight-bearing long-leg standing radiographs and lateral knee radiographs according to a standardized protocol to avoid bias. The MRI used for this study were obtained with a 1.5T MRI (Sonata Magnetom, Siemens Medical Solutions, Erlagen, Germany) with the knee in or near full extension. Cartilage wear was measured by applying the best-fit circle on the peripheral boundary of the subchondral bone. The thickness of the cartilage of each condyle was measured at 0\u0026deg; and 90\u0026deg;[\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eComputed tomography (CT) scans of the knees were obtained by a Philips CT (Philips Medical Systems, The Netherlands) and the acquired imagines were stored by the Picture Archiving and Communication System (PACS). RadiAnt-DICOM software (Medixant Ltd., Poznań, Poland), which has a mouse cursor that can automatically manifest distance and angle, was used to complete the measurements on the CT scans. To reduce the measurement error, two independent experienced orthopedic surgeons checked all of the images and measured relevant parameters in the case of double-blind.\u003c/p\u003e\n \u003cp\u003eThe following variables were measured[\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e] and these were illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003eI) HKA: Hip-knee-ankle angle. The angle between the line from the center of hip joint to the center of knee joint and the line from the center of knee joint to the center of ankle joint;\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003eII) MPTA: Medial proximal tibial angle. The medial angle between the tibial mechanical axis and the proximal tibial joint line connecting the most distal points on the concavity of the subchondral bone of the medial and lateral tibial plateaus;\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003eIII)\u0026nbsp;\u003c/span\u003e\u003cspan\u003emLDFA: Mechanical lateral distal femoral angle. The lateral distal femoral angle between the femoral mechanical axis and the line tangential to the femoral condyles;\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003eIV)\u0026nbsp;\u003c/span\u003e\u003cspan\u003eVCA: Valgus correction angle. The angle between the mechanical and anatomical axes of the femur.\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cdiv class=\"Section3\" id=\"Sec4\"\u003e\n \u003ch2\u003e3D reconstruction and simulated osteotomy\u003c/h2\u003e\n \u003cp\u003eMimics 21.0 (Materialise, Leuven, Belgium) software was used for 3D reconstruction based on CT scans. Regional growth was performed to segment the femur, and each model was examined and corrected by a senior surgeon prior to measurement. The 3D model files were imported into 3-matic 13.0 (Materialise) for analysis.\u003c/p\u003e\n \u003cp\u003eA sphere was fitted to the surface of the femoral head, and the geometric center point of the sphere was defined as the center of the hip joint. The knee joint was centered at the midpoint of the femoral intercondylar fossa. The femoral mechanical axis was defined as a line connecting the center of the hip and the center of the knee[\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e]. The distal femoral and proximal tibial cuts were perpendicular to the mechanical axis. The thickness of distal femur resection was set to be consistent with the implant size of 8mm, including the thickness of cartilage and bone (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e)[\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e]. Cartilage thickness was set to be consistent with the MRI date. When the lateral condyle was used as the reference, setting the resection depth at 8 mm from the distal lateral condyle. When the medial condyle was used as the reference, setting the resection depth at 8 mm from the distal medial condyle[\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec5\"\u003e\n \u003ch2\u003eStatistical analysis\u003c/h2\u003e\n \u003cp\u003eSPSS Statistics Package 21.0 (IBM, Armonk, New York, USA) was used to analyze data and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was defined as statistically significant. Scatterplots for each population were created to demonstrate alignment distributions for healthy and arthritic groups. The data were statistically analyzed by two researchers and all the measured variables and data are described as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. The paired-samples t-test was used to analyze the differences between measurement data and Levene\u0026apos;s test was used to examine the homogeneity of the data. A linear regression test was performed to evaluate the correlation. The intra-class correlation values (ICC) were calculated to determine the reliability of inter-observer and intra-observer measurements.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe demographic data of all patients, including gender, age, body mass index (BMI) and side, were collected before the operation and shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\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\u003eDemographic characteristics of the arthritic and nonarthritic groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003edemographics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArthritic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNonarthritic\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParticipants (n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e112\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e107\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnees (n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e118\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24% (27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37% (40)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76% (85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63% (67)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSide\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeft\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52% (64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41% (48)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48% (59)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59% (70)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eContinuous variables are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation and categorical variables are expressed as % (n). BMI, body mass index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFor varus arthritic knees, there was a difference in cartilage thickness between the distal and posterior condyles on the medial femoral condyle (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In the medial condyle, the cartilage thickness was 0.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31mm at 0\u0026deg; and 1.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 mm at 90\u0026deg;. No difference of cartilage thickness was observed in the lateral condyle between 0\u0026deg; and 90\u0026deg;. In the lateral condyle, the cartilage thickness was 1.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43mm at 0\u0026deg; and 1.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47mm at 90\u0026deg;. There was no specificity in the distribution of femoral cartilage in the medial and lateral femoral condyles in nonarthritic knees (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\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\u003eCartilage thickness of the medial and lateral condyle at 0\u0026deg; and 90\u0026deg;\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u0026deg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90\u0026deg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e valve\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArthritic group\u003c/p\u003e \u003cp\u003eMedial condyle (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.172\u0026thinsp;\u0026plusmn;\u0026thinsp;0.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.093\u0026thinsp;\u0026plusmn;\u0026thinsp;0.501\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral condyle (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.232\u0026thinsp;\u0026plusmn;\u0026thinsp;0.433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.468\u0026thinsp;\u0026plusmn;\u0026thinsp;0.468\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNonarthritic group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedial condyle (mm)\u003c/p\u003e \u003cp\u003eLateral condyle (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.838\u0026thinsp;\u0026plusmn;\u0026thinsp;0.193\u003c/p\u003e \u003cp\u003e1.893\u0026thinsp;\u0026plusmn;\u0026thinsp;0.169\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.904\u0026thinsp;\u0026plusmn;\u0026thinsp;0.216\u003c/p\u003e \u003cp\u003e1.899\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003cp\u003e0.950\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eThe data was shown as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThree-dimensional reconstruction was used to simulate the osteotomy of osteoarthritis subjects perpendicular to the mechanical axis of the femur. When the medial condyle was used as the reference for distal femoral osteotomy, there was a difference of 1.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56mm between the distal femoral end and posterior femoral condyle, and 43% of patients had a difference of more than 1mm. When the lateral condyle was used as the reference for distal femoral osteotomy, the difference between distal femoral and posterior femoral condyle resection was 0.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27mm.\u003c/p\u003e \u003cp\u003eThe simulated osteotomy of nonarthritic subjects showed that when the resection amount of the medial distal femoral condyle was set to 8mm, the resection amount of the lateral distal femoral condyle was 4.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.76mm. There was a linear correlation between the osteotomy thickness of the lateral condyle and LDFA (\u003cem\u003eR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.72, \u003cem\u003ep\u003c/em\u003e\u003c0.001, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). A 0.845mm increment in lateral condylar osteotomy was observed with every 1\u0026deg; increment in mLDFA (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePearson correlation and \u003cem\u003er\u003c/em\u003e - value of the parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOsteotomy thickness of the lateral condyle, mm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHKA, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.028\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMPTA, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emLDFA, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.845*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVCA, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.107\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e*Statistically significant. HKA, Hip-knee-ankle angle; MPTA, Medial proximal tibial angle; mLDFA, Mechanical lateral distal femoral angle; VCA, Valgus correction angle.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study proposed a pragmatic comprehensive osteotomy in TKA for patients with varus alignment, which used lateral condyle as a reference when performing distal femoral osteotomy. The position of the distal femoral osteotomy cutting guide could be adjusted by the preoperative measurement of the mLDFA.\u003c/p\u003e \u003cp\u003ePrecise TKA surgical planning should take into account the pattern of cartilage wear in arthritic patients with varus knees. Residual cartilage in patients with osteoarthritis may affect the accuracy of the osteotomy. Nam et al. proposed surgical planning for TKA based on CT does not consider articular cartilage and could lead to external malrotation of the femoral implant[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe femoral cartilage wear is strongly associated with lower extremity mechanical alignment. MRI measurements of the knee in arthritic patients with varus knees showed that there were 43% of patients with cartilage thickness differences\u0026thinsp;\u0026gt;\u0026thinsp;1mm between 0\u0026deg; and 90\u0026deg; of medial femoral condyles, consistent with previous reports. The progression of arthritis is accompanied by the wear of femoral cartilage. Johnson et al. found the wear of femoral cartilage is affected by the lower limb alignment through femorotibial cartilage maps and joint kinematics. Cartilage wear of varus knee is mainly concentrated in the medial compartment of early flexion, while valgus knee has more cartilage wear in the posterolateral femoral condyle during deep flexion[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Denis et al. found that 92% of OA patients with varus knee had cartilage wear of more than 1mm at 0\u0026deg; flexion, while the lateral femoral condyle had minor cartilage degeneration. Morphological studies found the subchondral bone of the medial and lateral femoral condyles has the same single radius of curvature and a single transverse axis[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. There was greater cartilage wear on the medial condyle of the distal femur and more asymmetry wear between 0\u0026deg; and 90\u0026deg; than the lateral. Therefore, we recommend using the lateral femoral condyle as a reference for distal femoral osteotomy.\u003c/p\u003e \u003cp\u003eCartilage thickness in the medial condyle of 0\u0026deg; was found to be significantly less than that on 90\u0026deg; in OA patients with varus knees (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), using the medial condyle as a reference resulted in an increase in the radius of curvature in extension. 11\u0026ndash;26% revision TKAs were performed for instability while part of them had mid-flexion instability[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Clary et al. identify the sudden reduction in the radii-of-curvature of femoral condyle as a potential cause of clinically observed paradoxical anterior femoral translation in mid-flexion[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDifferent femoral sagittal design in TKA were based on different theories. Multi-radius (MR) design was based on the theory of knee rotation center which was first proposed by Frankel et al in 1971. It reported that knee flexion occurs around a varying transverse axis, the flexion axis varies in a helical fashion during the flexion process, and the instantaneous rotation center of the femoral posterior condyle forms a \u0026ldquo;J curve\u0026rsquo;\u0026rsquo;[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Single-radius (SR) design had a uniform radius of curvature. It designed based on the principle that superficial medial collateral ligament is isometric throughout its range of movement. SR regards the femoral condyle as a spherical sphere with a single radius[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. SR had theoretical advantages, and it provided a more posterior flexion axis and a longer extensor moment arm and maintained stabilization during movement, especially in mid-flexion[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. SR design required the radius of curvature in the sagittal plane. No difference in cartilage wear was observed between the distal and posterior condyles of the lateral femoral condyle. Using the lateral femoral condyle as the reference for distal femoral osteotomy has the advantage of keeping the radius of curvature consistent when applying the SR design implants.\u003c/p\u003e \u003cp\u003eWhen the lateral condyle was used as a reference, the resection amount of the distal femur was affected by the geometric shape of the femur, and the position of the osteotomy line of the distal femur should be adjusted by morphological measurement of the femur. In this study, multiple linear regression analysis was performed on the resection amount measured by simulated osteotomy in nonarthritic subjects. mLDFA was linearly correlated with the resection amount differences between the medial and lateral condyles at 0\u0026deg; (R\u0026thinsp;=\u0026thinsp;0.72, p\u003c0.001), and a 0.85mm increment of osteotomy thickness on lateral condyle was observed with every 1\u0026deg; mLDFA increment when the osteotomy of the medial condyle was set at 8mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Using Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the surgeon can predict the resection thickness of lateral condyle by measuring mLDFA preoperatively and use this information intra-operatively. The amount of osteotomy may not affect limb alignment but has important implications for ligament tension, tissue balance and clinical outcome[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Many scholars attributed the unsatisfactory results after TKA to the inability of knee prosthesis to simulate physiological and natural knee motion and suggested to amend the surgical strategy[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Severe deformities lead to elevated joint lines. The least worn part of the joint was often used as a reference for bone cuts, and the wear of bone and cartilage in the medial condyle might result in over-resection[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Mullaji et al. proposed that the thickness of distal femoral resection should be determined according to the degree of bone defect in the medial femoral condyle[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Denis et al. suggested referencing guide should be adjusted to compensate for the mean 1.9mm cartilage wear at the distal medial condyle[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Yue et al. proposed the intercondylar notch ceiling could be used as an accurate landmark to determine the proper distal femoral resection level during TKA[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere were some limitations in this study. First, the nonarthritic group for the image analysis was selected for patients with slight soft-tissue injury or avulsion fracture rather than patients without knee joint disease. The nonarthritic subjects with cartilage wear were excluded by MRI, but there may be potential effects. Second, a relatively small sample size for each subject group, this was due mainly to the relatively lengthy segmentation process. Third, it was a retrospective study with non-randomized design, which had inherent drawbacks.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWith the wear patterns of cartilage in varus osteoarthritic knees treated with TKA, it showed significantly more wear at 0\u0026deg; in the medial compartment than at 90\u0026deg;. Distal femoral resection using medial condyle as reference resulted in \u0026gt;\u0026thinsp;1 mm difference of resection between 0\u0026deg; and 90\u0026deg;of flexion. It is recommended to take the lateral condyle as the reference for the distal femur osteotomy to obtain a more physiological single radius rotation axis. The mLDFA can be used to adjust the reference position of the cutting guide before TKA.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eTKA: total knee arthroplasty;\u003c/p\u003e\n\u003cp\u003eOA: osteoarthritis;\u003c/p\u003e\n\u003cp\u003emLDFA: mechanical lateral distal femoral angle;\u003c/p\u003e\n\u003cp\u003eMA: mechanical alignment;\u003c/p\u003e\n\u003cp\u003eMRI: magnetic resonance imaging;\u003c/p\u003e\n\u003cp\u003eCT: computed tomography;\u003c/p\u003e\n\u003cp\u003eICC: intra-class correlation values;\u003c/p\u003e\n\u003cp\u003eBMI:\u0026nbsp;body mass index;\u003c/p\u003e\n\u003cp\u003eMR: multi-radius;\u003c/p\u003e\n\u003cp\u003eSR: Single-radius\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study was approved by the Academic Ethics Committee of the Third Hospital of Hebei Medical University, and all patients provided their informed consent for participation and publication. All of the data and materials are available.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe datasets used or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFunded by The National Natural Science Foundation of China (Grant No.81873983).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFei Wang\u0026nbsp;supervised, coordinated and provided further advice on revisions;\u003c/p\u003e\n\u003cp\u003eMaozheng Wei\u0026nbsp;conceived of the manuscript, and participated in its design, drafted and wrote the manuscript;\u003c/p\u003e\n\u003cp\u003eKuo Hao\u0026nbsp;conceived of the manuscript, and participated in its design;\u003c/p\u003e\n\u003cp\u003eHuijun Kang conceived of\u0026nbsp;data collection and data analysis;\u003c/p\u003e\n\u003cp\u003eLingce Kong conceived of literature search and analysis\u003c/p\u003e\n\u003cp\u003eThe first draft of the manuscript was written by\u0026nbsp;Maozheng Wei\u0026nbsp;and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThanks for the technical support from the Department of Imaging of the Third Hospital of Hebei Medical University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMaozheng Wei. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email: [email protected].\u003c/p\u003e\n\u003cp\u003eKuo Hao. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, China. Email: [email protected].\u003c/p\u003e\n\u003cp\u003eHuijun Kang. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email:\u0026nbsp;[email protected].\u003c/p\u003e\n\u003cp\u003eLingce Kong. Department of orthopaedic surgery, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, China 050051. Email: [email protected].\u003c/p\u003e\n\u003cp\u003e*Corresponding author: Fei Wang\u003c/p\u003e\n\u003cp\u003eCorresponding author at: Department of Orthopaedic Surgery, Third Hospital of Hebei Medical University, Ziqiang Road 139, 050051 Shijiazhuang, China E-mail addresses: [email protected] Tel: +86 -311-88602613 Fax: +86 -311-88602613.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCarr AJ, Robertsson O, Graves S, Price AJ, Arden NK, Judge A, Beard DJ: \u003cb\u003eKnee replacement\u003c/b\u003e. 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Orthopaedics \u0026amp; traumatology, surgery \u0026amp; research: OTSR 2017, \u003cb\u003e103\u003c/b\u003e(7):1047\u0026ndash;1056.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMichael Johnson J, Mahfouz MR: \u003cb\u003eCartilage loss patterns within femorotibial contact regions during deep knee bend\u003c/b\u003e. 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The Journal of bone and joint surgery American volume 2010, \u003cb\u003e92\u003c/b\u003e(1):98\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSappey-Marinier E, Batailler C, Swan J, Malatray M, Cheze L, Servien E, Lustig S: \u003cb\u003ePrimary osteoarthritic knees have more varus coronal alignment of the femur compared to young non\u003c/b\u003e-\u003cb\u003earthritic knees in a large cohort study\u003c/b\u003e. \u003cem\u003eKnee surgery, sports traumatology, arthroscopy: official journal of the ESSKA\u003c/em\u003e 2022, \u003cb\u003e30\u003c/b\u003e(2):428\u0026ndash;436.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChoi YS, Kim TW, Song SC, Kim SY, Chang MJ, Kang SB: \u003cb\u003eAsymmetric transepicondylar axis between varus and valgus osteoarthritic knees in windswept deformity can be predicted by hip\u003c/b\u003e-\u003cb\u003eknee\u003c/b\u003e-\u003cb\u003eankle angle difference\u003c/b\u003e. \u003cem\u003eKnee surgery, sports traumatology, arthroscopy: official journal of the ESSKA\u003c/em\u003e 2022, \u003cb\u003e30\u003c/b\u003e(9):3024\u0026ndash;3031.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYue B, Wang J, Wang Y, Yan M, Zhang J, Zeng Y: \u003cb\u003eThe intercondylar notch ceiling\u003c/b\u003e: \u003cb\u003ean accurate reference for distal femoral resection in total knee arthroplasty for severely degenerated varus knees\u003c/b\u003e. \u003cem\u003eKnee surgery, sports traumatology, arthroscopy: official journal of the ESSKA\u003c/em\u003e 2017, \u003cb\u003e25\u003c/b\u003e(9):2818\u0026ndash;2824.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMinoda Y, Mizokawa S, Ohta Y, Ikebuchi M, Itokazu M, Yamamura K, Nakamura S, Nakamura HJKs, sports traumatology, arthroscopy: official journal of the ESSKA: \u003cb\u003ePosterior reference guides do not always maintain the size of posterior femoral condyles in TKA\u003c/b\u003e. 2016, \u003cb\u003e24\u003c/b\u003e(8):2489\u0026ndash;2495.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlakeney W, Beaulieu Y, Puliero B, Kiss MO, Vendittoli PA: \u003cb\u003eBone resection for mechanically aligned total knee arthroplasty creates frequent gap modifications and imbalances\u003c/b\u003e. \u003cem\u003eKnee surgery, sports traumatology, arthroscopy: official journal of the ESSKA\u003c/em\u003e 2020, \u003cb\u003e28\u003c/b\u003e(5):1532\u0026ndash;1541.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNam JH, Koh YG, Kim PS, Park JH, Kang KT: \u003cb\u003eEffect of the presence of the articular cartilage on the femoral component rotation in total knee arthroplasty in female and varus osteoarthritis knees\u003c/b\u003e. 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The Journal of arthroplasty 2005, \u003cb\u003e20\u003c/b\u003e(5):550\u0026ndash;561.\u003c/span\u003e\u003c/li\u003e\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, Distal femoral resection, Cartilage wear, Osteoarthritis, Varus","lastPublishedDoi":"10.21203/rs.3.rs-2352484/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2352484/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\n\u003cp\u003eBone resection was highly valued in total knee arthroplasty (TKA), but how to determine the amount of distal femur resection is still controversial. The purpose of this study was to explore how to use lateral condyle as a reference for distal femoral osteotomy in TKA.\u003c/p\u003e\n\u003ch2\u003eMethod\u003c/h2\u003e\n\u003cp\u003eImaging data from 118 nonarthritic subjects and 123 osteoarthritis (OA) subjects were used to assess the cartilage wear pattern of the distal femur in varus knees. Measurements were performed on three-dimensional reconstruction after virtual bone cutting. The difference between the resection amount of distal (0°) and posterior (90°) was calculated when the medial condyle was used as a reference in OA patients. The osteotomy amount on lateral was calculated in nonarthritic subjects when the medial condylar osteotomy was consistent with the thickness of the implants.\u003c/p\u003e\n\u003ch2\u003eResults\u003c/h2\u003e\n\u003cp\u003eIn 43% of OA patients, there was༞1mm difference between the 0° and 90° in medial condyle cartilage, and no difference was observed in lateral. When using medial condyle as a reference for osteotomy, there was a difference of 1.3 ± 0.56 mm between the resection amount of 0° and 90°, and the difference was 0.24 ± 0.27 mm when using lateral condyle. Statistical analysis showed that there was a linear correlation between the resection amount of lateral condyle and mechanical lateral distal femoral angle (mLDFA) in nonarthritic subjects (R = 0.72, \u003cem\u003ep\u003c/em\u003e\u0026lt;0.001).\u003c/p\u003e\n\u003ch2\u003eConclusions\u003c/h2\u003e\n\u003cp\u003eUsing the lateral condyle as the reference for distal femoral osteotomy is more suitable for the cartilage wear pattern of the varus knee. The position of cutting guide can be adjusted by preoperative measurements of mLDFA.\u003c/p\u003e","manuscriptTitle":"Lateral Distal Femoral Condyle as a Precise Reference for Distal Femoral Resection in Total Knee Arthroplasty for Severe Varus Knee Osteoarthritis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-12-12 18:56:37","doi":"10.21203/rs.3.rs-2352484/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":"24fc6dab-27c0-4dad-b340-0580a6c99203","owner":[],"postedDate":"December 12th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-04-18T16:59:24+00:00","versionOfRecord":[],"versionCreatedAt":"2022-12-12 18:56:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2352484","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2352484","identity":"rs-2352484","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}