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The report defines a “critical point” on the capitellum surface where breach predicts potential engagement and imminent dislocation. Two fracture or fracture-dislocation cases with “Osborne-Cotterill lesion” were treated with fixation and bone grafting, secured using posterior plating to counter instability.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/engagement-of-the-radial-head-in-posterior-capitellum-fracture-defining-the-critical-point/447483/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/engagement-of-the-radial-head-in-posterior-capitellum-fracture-defining-the-critical-point/447483.png","ImageObject",300,407,{"name":92,"@type":93},"hdkawk","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-05","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":19},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What is the “critical point” on the capitellum?","Question",{"text":112,"@type":113},"It is the posterior edge area of the capitellum surface that the radial head must pass to relocate or engage a shallow depression, forewarning potential engagement and imminent dislocation.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How are cases with “Osborne-Cotterill lesion” treated in this report?",{"text":117,"@type":113},"Both cases underwent fracture reduction and fixation, with bone grafting of the lesion and posterior plating to secure the graft and counteract the lesion.",{"name":119,"@type":110,"acceptedAnswer":120},"When does the article recommend bone grafting and posterior plating?",{"text":121,"@type":113},"When the capitellar critical point is breached—roughly a quarter of the capitellar articular surface or less when the radial head is injured—to impede potential dislocation.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},447483,1790810685,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":19,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":34,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144},3985747859855,"https://ap-avatar.wpscdn.com/davatar_276721f389ce27ea32af1340a28f341c","Case Report  Journal of Orthopaedic Case Reports 2025 December:15( 12) :Page 231-237   \nEngagement of the Radial Head in Posterior Capitellum Fracture:  \nDefining the Critical Point  \nMojahed Sakhnini1  \nLearning Point of the Article:  \nIn the context of trauma to the elbow with a posterior defect of more than a quarter of the articular surface of the capitellum, filling the defect with bone graft and locking it with a posterior distal plate is advised to prevent radial engagement in the defect.  \nAbstract  \nIntroduction: Elbow dislocation is usually treated conservatively with a good outcome. When there is associated injury to the capitellum,“Osborne-Cotterill Lesion,” then the clinical course is less predictable and controversial. In this article, we attempt to define the critical point on thecapitellum surfacethat, when breached, forebodes potential engagement of theradial head in the defect and imminent dislocation.  \nCase Report: We present two cases of fracture and fracture dislocation of the elbow with “Osborne-Cotterill lesion ” They were treated with fracture reduction and fixation. In the first case, a posterior plate was utilized for the olecranon, and in the second case, cannulated screws were employed forthecapitellum fracture. In both cases, a posterior humeral plate was applied to counteract the “Osborne-Cotterill lesion”with bone grafting of the defect.  \nConclusion: When the critical point of the capitellum is breached (roughly a quarter of the capitellar articular surface or less when the radial head is injured),we recommend bone grafting the defect and plating the posterior capitellum to impede potential dislocation.  \nKeywords: Elbow, Osborne-Cotterilllesion, dislocation, engagement, bone graft, critical point, instability, lateral ulnar collateral ligament.  \nIntroduction  \nIn the literature, the “Osborne-Cotterill Lesion” is defined as a depression fracture in the capitellum caused by radial head dislocation impinging upon the capitellum, resulting in a crater [1, 2]. The fragment is produced when the radial head dislocates laterally and posteriorly as it hits the capitellum at this specific location in a predicted manner [2, 3]. The lesion could cause engagement of the radial head, and the radial head may become dislocated and remain stuck in that position, necessitating open reduction [4]. Surgical intervention that reanimates the lateral ulnar collateral ligament (LUCL) with reinsertion or  \nreconstruction alone may potentially lead to instability, dislocation, or a limited range of motion [5,6]. We present a different approach to treat this enigmatic problem. We suggest bone grafting the “Osborne-Cotterill Lesion” and adding a posterior plate to secure the graft and further thicken the barrier against dislocation. We will discuss this strategy using two case studies and present a simple algorithm to help determine when to address the “Osborne-Cotterill Lesion surgically”  \nDefining thecritical point  \nThe anatomy of the radiocapitellar joint is intriguing; there is a  \n\n| \u003Cbr>Access this article online\u003Cbr>\u003Cbr>Website: [www.jocr.co.in](www.jocr.co.in)\u003Cbr>\u003Cbr>DOI:\u003Cbr>[https://doi.org/10.13107/jocr.2025.v15.i12.6518](https://doi.org/10.13107/jocr.2025.v15.i12.6518) | Author’s Photo Gallery\u003Cbr>\u003Cbr>\u003Cbr>Dr. Mojahed Sakhnini\u003Cbr>1Department of Orthopaedic Surgery, Tzafon Medical Center, Tiberias, Israel.\u003Cbr>Address of Correspondence:\u003Cbr>Dr. Mojahed Sakhnini,\u003Cbr>Department of Orthopaedic Surgery, Tzafon Medical Center, Tiberias, Israel. [E-mail:](E-mail: mojahed.sakh@gmail.com)[ mojahed.sakh@gmail.com](E-mail: mojahed.sakh@gmail.com) |\n| --- | --- |\n| Submitted: 26/09/2025; Review: 18/10/2025; Accepted: November 2025; Published: December 2025 |  |\n| DOI: [https://doi.org/10.13107/jocr.2025.v15.i12.6518](https://doi.org/10.13107/jocr.2025.v15.i12.6518)\u003Cbr>© The Author(s). 2025 Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ([https://creativ","cbCaidVIuhvPpNg5","https://ap.wps.com/l/cbCaidVIuhvPpNg5","pdf",12140799,"English","# Introduction\n# Case Report\n## Case 1\n## Case 2\n# Conclusion\n# Defining the Critical Point","[{\"question\":\"What is the “critical point” on the capitellum?\",\"answer\":\"It is the posterior edge area of the capitellum surface that the radial head must pass to relocate or engage a shallow depression, forewarning potential engagement and imminent dislocation.\"},{\"question\":\"How are cases with “Osborne-Cotterill lesion” treated in this report?\",\"answer\":\"Both cases underwent fracture reduction and fixation, with bone grafting of the lesion and posterior plating to secure the graft and counteract the lesion.\"},{\"question\":\"When does the article recommend bone grafting and posterior plating?\",\"answer\":\"When the capitellar critical point is breached—roughly a quarter of the capitellar articular surface or less when the radial head is injured—to impede potential dislocation.\"}]","Engagement of the Radial Head in Posterior Capitellum Fracture - Defining the Critical Point | PDF",1790720749,18]