Changes

[[File:Radiograph X-ray of knee prosthesis with knee anglesoverhang, annotated.jpg|thumb|[[Projectional radiograph150px|Overhang (arrow) does not seem to have any detrimental effect.<ref>{{cite journal|title=The Impact Of Tibial Component Overhang On Outcome Scores And Pain In Total Knee Replacement|date=2018-02-21|author=S.G.F. Abram, A.G Marsh, F. Nicol, A.S. Brydone, A. Mohammed, S.J. Spencer|journal=Orthopaedic Proceedings}}</ref> It is therefore not necessary to measure or report.]]Knee replacement is evaluated by the following measures:<gallery mode=packed heights=380>File:X-rayof HKA angle with knee prosthesis.jpg|'''HKA''': Hip-knee-ankle angle, which is ideally between 3° [[genu varum|varum]] with angles used to evaluate knee replacement:3° [[Genu valgum|valgum]] from a [[right angle]].<ref name=Inui2013>{{cite journal|last1=Inui|first1=Hiroshi|last2=Taketomi|first2=Shuji|last3=Nakamura|first3=Kensuke|last4=Takei|first4=Seira|last5=Takeda|first5=Hideki|last6=Tanaka|first6=Sakae|last7=Nakagawa|first7=Takumi|title=Influence of navigation system updates on total knee arthroplasty|journal=Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology|volume=5|issue=1|pages=10|year=2013|issn=1758-2555|doi=10.1186/2052-1847-5-10|pmid=23638774|pmc=3653716}} [https://creativecommons.org/licenses/by/2.0 (CC-BY-2.0)]</ref><br>HKAFile: Hip-knee-ankle angle<br>FFC: frontal femoral component angle<br>FTC: frontal tibial component angle<br>LFC: lateral femoral component angle<br>LTC: lateral tibial component angle]]Knee replacement is routinely evaluated by [[projectional radiography]] ("Postoperative X-ray")of normal knee prosthesis, including the following measures:*'''HKA''': Hip-knee-ankle angleanteroposterior view, which is ideally between 3° [[genu varumannotated.jpg|varum]] to 3° [[Genu valgum|valgum]] from a [[right angle]].<ref name=Inui2013/>*- '''FFC''': frontal femoral component angle. It is typically regarded as optimal when being 2–7° in valgus.<ref name="GromovKorchi2014">{{cite journal|last1=Gromov|first1=Kirill|last2=Korchi|first2=Mounim|last3=Thomsen|first3=Morten G|last4=Husted|first4=Henrik|last5=Troelsen|first5=Anders|title=What is the optimal alignment of the tibial and femoral components in knee arthroplasty?|journal=Acta Orthopaedica|volume=85|issue=5|year=2014|pages=480–487|issn=1745-3674|doi=10.3109/17453674.2014.940573|pmid=25036719|pmc=4164865}}</ref>*<br>- '''FTC''': frontal tibial component angle, which is regarded as optimal when being at a [[right angle]]. A varus position of more than 3° has generally been found to increase the failure rate of the prosthesis.<ref name="GromovKorchi2014"/>*File:Postoperative X-ray of normal knee prosthesis, lateral view, annotated.jpg|- '''Anterior femoral notching''' (the femoral component causing reduced thickness of the distal femur anteriorly), seems to cause an increased risk of fractures when exceeding about 3 mm.<ref name="LeeWang2015">{{cite journal|last1=Lee|first1=Ju Hong|last2=Wang|first2=Seong-Il|title=Risk of Anterior Femoral Notching in Navigated Total Knee Arthroplasty|journal=Clinics in Orthopedic Surgery|volume=7|issue=2|year=2015|pages=217|issn=2005-291X|doi=10.4055/cios.2015.7.2.217}}</ref><br>- '''LTC''': lateral (or sagittal) tibial component angle, which is ideally positioned so that the tibia is 0–7° flexed compared to at a right angle with the tibial plate.<ref name="GromovKorchi2014"/> '''LFC''' is the lateral (or sagittal) femoral component angle,<ref name=Inui2013/gallery> but its use is not necessary as long as there are no established clinically relevant reference ranges for it.

Also, unless you know the referring physician is familiar with the same angle terminology, preferably report any deviating angles as varus/valgus deviation or volarventral/dorsal angulation of either, such as:*The An abnormally increased valgus angulation of __° of the femur component in relation to femoral diaphysis.*The A abnormal ventral angulation of __° of the tibial diaphysis in relation to the tibial component.

[[File:Knee prosthesis zones by Knee Society 2015, lateral view.jpg|thumb|150px|KS (Knee Society) zones, for localizing radiolucent zones or other focal changes.<ref name="MeneghiniMont2015">{{cite journal|last1=Meneghini|first1=R. Michael|last2=Mont|first2=Michael A.|last3=Backstein|first3=David B.|last4=Bourne|first4=Robert B.|last5=Dennis|first5=Doug A.|last6=Scuderi|first6=Giles R.|title=Development of a Modern Knee Society Radiographic Evaluation System and Methodology for Total Knee Arthroplasty|journal=The Journal of Arthroplasty|volume=30|issue=12|year=2015|pages=2311–2314|issn=08835403|doi=10.1016/j.arth.2015.05.049}}</ref>]][[File:Knee prosthesis zones by Knee Society 2015, AP view.jpg|thumb|180px|KS zones, AP view.<ref name="MeneghiniMont2015"/>]]Radiolucent lines may indicate loosening of the implant. A radiolucent line thinner than than 2 mm can be tolerated at the cement-bone interface (for cemented implants) or implant-bone interface (for cementless implants) if it remains stable and appears within the first 6 months (cemented implants) or the first 2 years (cementless implants) after surgery.<ref name="Cyteval2016">{{cite journal|last1=Cyteval|first1=C.|title=Imaging of knee implants and related complications|journal=Diagnostic and Interventional Imaging|volume=97|issue=7-8|year=2016|pages=809–821|issn=22115684|doi=10.1016/j.diii.2016.02.015}}</ref> There are various classification systems for specifying the location of radiolucent spaces,<ref name="NapierO’Neill2018">{{cite journal|last1=Napier|first1=Richard J.|last2=O’Neill|first2=Christopher|last3=O’Brien|first3=Seamus|last4=Doran|first4=Emer|last5=Mockford|first5=Brian|last6=Boldt|first6=Jens|last7=Beverland|first7=David E.|title=A prospective evaluation of a largely cementless total knee arthroplasty cohort without patellar resurfacing: 10-year outcomes and survivorship|journal=BMC Musculoskeletal Disorders|volume=19|issue=1|year=2018|issn=1471-2474|doi=10.1186/s12891-018-2128-1}}</ref><ref name="KumarYadav2014">{{cite journal|last1=Kumar|first1=Nishikant|last2=Yadav|first2=Chandrashekhar|last3=Raj|first3=Rishi|last4=Anand|first4=Sumit|title=How to Interpret Postoperative X-rays after Total Knee Arthroplasty|journal=Orthopaedic Surgery|volume=6|issue=3|year=2014|pages=179–186|issn=17577853|doi=10.1111/os.12123}}</ref> including by KS (Knee Society) zones published in 2015.<ref name="MeneghiniMont2015"/>