[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-454867-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-454867-en":131},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","the-length-of-lateral-radiographs-significantly-impacts-the-measurement-of-the-femoral-intramedullary-axis-in-patients-undergoing-total-knee-arthroplasty","The length of lateral radiographs significantly impacts the measurement of the femoral intramedullary axis in patients undergoing total knee arthroplasty","","Accurate sagittal-plane femoral component alignment is essential for total knee arthroplasty (TKA) success, yet the intramedullary axis (IMA) derived from lateral radiographs may vary due to femoral bowing and the use of short-segmented knee radiographs (SSKR). A retrospective study of 153 primary TKA patients compared IMA from SSKR versus conventional lateral radiographs (CLR), using a two-circle measurement approach. Results showed a significantly more posterior IMA on SSKR, frequent clinically relevant outliers, and a positive association between visible femoral shaft length and angular deviation, independent of demographic factors.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/healthcare/","Healthcare",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/the-length-of-lateral-radiographs-significantly-impacts-the-measurement-of-the-femoral-intramedullary-axis-in-patients-undergoing-total-knee-arthroplasty/454867/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/the-length-of-lateral-radiographs-significantly-impacts-the-measurement-of-the-femoral-intramedullary-axis-in-patients-undergoing-total-knee-arthroplasty/454867.png","ImageObject",300,407,{"name":42,"@type":43},"Pentious","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-30","2026-09-30",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",14,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"Why does the study focus on the IMA when planning total knee arthroplasty?","Question",{"text":63,"@type":64},"Sagittal-plane alignment of the femoral component is crucial for TKA outcomes. In manual TKA, surgeons commonly reference the intramedullary axis (IMA) on lateral radiographs to guide femoral component alignment.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How did the study compare short-segmented and conventional lateral radiographs?",{"text":68,"@type":64},"The study determined the femoral IMA on both full conventional lateral radiographs (CLR) and a simulated 12.5 cm distal segment representing SSKR. A two-circle method was used, and the angular deviation between the axes was measured in degrees by two observers.",{"name":70,"@type":61,"acceptedAnswer":71},"What were the main findings about the effect of radiograph length?",{"text":72,"@type":64},"Referencing the IMA on SSKR produced a significantly more posterior axis than CLR, with an average angular deviation of 2.3°. Deviation exceeded 2° in 57 cases (38%), and angular deviation increased with visible femoral shaft length, remaining an independent predictor after adjustment.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},454867,1790794400,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,110,115,120,123,127],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":97,"doc_module":4,"doc_module_name":25,"category_name":98,"show_sort_weight":99,"slug":100},5,"Comic",60,"comic",{"id":102,"doc_module":4,"doc_module_name":25,"category_name":103,"show_sort_weight":104,"slug":105},6,"Technology",50,"technology",{"id":107,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":108,"slug":109},7,40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":112,"show_sort_weight":113,"slug":114},8,"Research & Report",30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":124,"doc_module":4,"doc_module_name":25,"category_name":125,"show_sort_weight":124,"slug":126},10,"Lifestyle","lifestyle",{"id":128,"doc_module":4,"doc_module_name":25,"category_name":129,"show_sort_weight":97,"slug":130},19,"General","general",{"code":4,"msg":82,"data":132},{"doc_id":79,"user_id":133,"nickname":42,"user_avatar":134,"doc_module":4,"category_id":107,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":116,"language":140,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":12,"update_tm":144,"read_time":145,"preview_page_count":4},1374404730887,"https://ap-avatar.wpscdn.com/davatar_6f874abed73319feea01a86fa6f0fab8","El Kayali et al. Arthroplasty (2026) 8:3  \n[https://doi.org/10.1186/s42836-025-00350-x](https://doi.org/10.1186/s42836-025-00350-x)  \nArthroplasty  \n RESEARCH Open Access  \nThe length of lateral radiographs    \nsignificantly impacts the measurement of the femoral intramedullary axis in patients undergoing total knee arthroplasty  \nMoses K. D. El Kayali1,2*, Luis V. Bürck 1, Stephen Fahy3 and Lorenz Pichler1,4  \nAbstract  \nBackground Accurate femoral component alignment in the sagittal plane is crucial for total knee arthroplasty (TKA) success. In manual TKA, sagittal alignment is typically guided by the intramedullary axis (IMA) determined on lateral radiographs. However, due to femoral bowing, the IMA varies along the femoral shaft, raising the question of the optimal level for referencing this axis. As short-segmented knee radiographs (SSKR) are increasingly used in clinical practice, it is unclear whether they introduce systemic deviations in IMA determination. This study aimed to compare the IMA derived from SSKR and conventional lateral radiographs (CLR), and to assess whether axis deviation increases with femoral shaft length.  \nMethods This retrospective analysis included 153 patients undergoing primary TKA. The femoral IMA was determined using a two-circle method on both the full CLR and a 12.5 cm distal segment simulating SSKR. For the CLR axis, one circle was positioned at the most proximal point of the femoral shaft visible on the radiograph, and the second circle was placed 5 cm proximal to the distal femoral joint line. For the SSKR-based axis, the distal circle remained identical, while the proximal circle was repositioned 12.5 cm proximal to the joint line. Measurements were performed twice by two observers. The angular deviation between CLR-and SSKR-based axes was reported in degrees. A onesample t-test was used to test for statistical significance. Clinically relevant deviation was defined as ≥ 2°, and the number and percentage of such outlier cases were reported. Correlation between femoral shaft length and angular deviation was analyzed using Pearson correlation. A multivariable regression tested whether femoral length independently predicted angular deviation after adjusting for age, sex, BMI, and side.  \nResults The IMA on SSKR was significantly more posterior than on CLR, with a mean angular deviation of 2 . 3° ± 1. 1°(95% CI: 2 .2–2. 5; P \u003C 0. 001; Cohen’s d = 2 . 1) . In 57 cases (38%), deviation exceeded the clinically relevant threshold of ≥ 2° . A significant positive correlation was found between the visible femoral shaft length and the angular deviation between CLR and SSKR axes (r = 0 . 504, P \u003C 0. 001) . In multivariable regression, femoral length remained an independent predictor of angular deviation after adjustment for age, sex, BMI, and side (P \u003C 0. 001) .  \nConclusion Referencing the IMA on SSKR results in a significantly more posterior axis compared to CLR, which may lead to increased femoral component flexion inTKA. Given the high incidence of outlier cases and their association  \n*Correspondence:  \nMoses K. D. El Kayali  \n[moses.elkayali@charite.de](moses.elkayali@charite.de)  \nFull list of author information is available at the end of the article  \n© The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission","cbCaisyNMhLMx3B3","https://ap.wps.com/l/cbCaisyNMhLMx3B3","pdf",1297411,"English","# Abstract\n# Background\n# Methods\n# Results\n# Conclusion\n# Keywords\n# Introduction","[{\"question\":\"Why does the study focus on the IMA when planning total knee arthroplasty?\",\"answer\":\"Sagittal-plane alignment of the femoral component is crucial for TKA outcomes. In manual TKA, surgeons commonly reference the intramedullary axis (IMA) on lateral radiographs to guide femoral component alignment.\"},{\"question\":\"How did the study compare short-segmented and conventional lateral radiographs?\",\"answer\":\"The study determined the femoral IMA on both full conventional lateral radiographs (CLR) and a simulated 12.5 cm distal segment representing SSKR. A two-circle method was used, and the angular deviation between the axes was measured in degrees by two observers.\"},{\"question\":\"What were the main findings about the effect of radiograph length?\",\"answer\":\"Referencing the IMA on SSKR produced a significantly more posterior axis than CLR, with an average angular deviation of 2.3°. Deviation exceeded 2° in 57 cases (38%), and angular deviation increased with visible femoral shaft length, remaining an independent predictor after adjustment.\"}]","The length of lateral radiographs significantly impacts the measurement of the femoral intramedullary axis in patients undergoing total knee arthroplasty | PDF",1790741553,23]