{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T20:54:35Z","timestamp":1789937675681,"version":"4.0.1"},"reference-count":39,"publisher":"Wiley","issue":"11","license":[{"start":{"date-parts":[[2022,4,19]],"date-time":"2022-04-19T00:00:00Z","timestamp":1650326400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2022,4,19]],"date-time":"2022-04-19T00:00:00Z","timestamp":1650326400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2022,4,19]],"date-time":"2022-04-19T00:00:00Z","timestamp":1650326400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/501100006447","name":"University of Zurich","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100006447","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100006447","name":"Universit\u00e4t Z\u00fcrich","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100006447","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Knee surg. sports traumatol. arthrosc."],"published-print":{"date-parts":[[2022,11]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Purpose<\/jats:title><jats:p>Rotation of the tibia relative to the femur was recently identified as a contributing risk factor for patellar instability, and correlated with its severity. The hypothesis was that in patellofemoral dysplastic knees, an increase in femorotibial rotation can be reliably detected on anteroposterior (AP) radiographs by an overlap of the lateral femoral condyle over the lateral tibial eminence.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Sixty patients (77\u00a0knees) received low\u2010dose computed tomography (CT) of the lower extremity for assessment of torsional malalignment due to recurrent patellofemoral instability. Three\u2010dimensional (3D) surface models were created to assess femorotibial rotation and its relationship to other morphologic risk factors of patellofemoral instability. On weight\u2010bearing AP knee radiographs, a femoral condyle\/lateral tibial eminence superimposition was defined as a positive winking sign. Using digitally reconstructed radiographs of the 3D models, susceptibility of the winking sign to vertical\/horizontal AP knee radiograph malrotation was investigated.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>A positive winking sign was present in 30\/77\u00a0knees (39.0%) and indicated a 6.3\u2009\u00b1\u20091.4\u00b0 increase in femorotibial rotation (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.001). Femoral condyle\/tibial eminence superimposition of 1.9\u00a0mm detected an increased femorotibial rotation (&gt;\u200915\u00b0) with 43% sensitivity and 90% specificity (AUC\u2009=\u20090.72; <jats:italic>p<\/jats:italic>\u2009=\u20090.002). A positive winking sign (with 2\u00a0mm overlap) disappeared in case of a 10\u00b0 horizontally or 15\u00b0 vertically malrotated radiograph, whereas a 4\u00a0mm overlap did not disappear at all, regardless of the quality of the radiograph. In absence of a winking sign, on the other hand, no superimposition resulted within 20\u00b0 of vertical\/horizontal image malrotation. Femorotibial rotation was positively correlated to TT\u2013TG (<jats:italic>R<\/jats:italic><jats:sub>2<\/jats:sub>\u2009=\u20090.40, <jats:italic>p<\/jats:italic>\u2009=\u20090.001) and patellar tilt (<jats:italic>R<\/jats:italic><jats:sub>2<\/jats:sub>\u2009=\u20090.30, <jats:italic>p<\/jats:italic>\u2009=\u20090.001).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>The winking sign reliably indicates an increased femorotibial rotation on a weight\u2010bearing AP knee radiograph and could prove useful for day\u2010by\u2010day clinical work. Future research needs to investigate whether femorotibial rotation is not only a prognostic factor but a potential surgical target in patients with patellofemoral disorders.<\/jats:p><\/jats:sec><jats:sec><jats:title>Level of evidence<\/jats:title><jats:p>III.<\/jats:p><\/jats:sec>","DOI":"10.1007\/s00167-022-06971-y","type":"journal-article","created":{"date-parts":[[2022,4,19]],"date-time":"2022-04-19T04:02:46Z","timestamp":1650340966000},"page":"3651-3658","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["The winking sign is an indicator for increased femorotibial rotation in patients with recurrent patellar instability"],"prefix":"10.1002","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0350-8101","authenticated-orcid":false,"given":"Andreas","family":"Flury","sequence":"first","affiliation":[{"name":"<!--<label>1<\/label>--> Department of Orthopedics Balgrist University Hospital, 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F.","family":"Fucentese","sequence":"additional","affiliation":[{"name":"<!--<label>1<\/label>--> Department of Orthopedics Balgrist University Hospital, University of Zurich Forchstrasse 340 8008 Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lazaros","family":"Vlachopoulos","sequence":"additional","affiliation":[{"name":"<!--<label>1<\/label>--> Department of Orthopedics Balgrist University Hospital, University of Zurich Forchstrasse 340 8008 Zurich Switzerland"},{"name":"<!--<label>2<\/label>--> Research in Orthopedic Computer Science (ROCS) Balgrist University Hospital, University of Zurich Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,4,19]]},"reference":[{"key":"e_1_2_11_2_2","unstructured":"AckermannJ HaslerJ GrafDN FucenteseSF VlachopoulosLThe effect of native knee rotation on the tibial\u2010tubercle\u2010trochlear\u2010groove distance in patients with 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December 2021","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"29 March 2022","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"19 April 2022","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors declare that they have no conflict of interest. Prof. Dr. Fucentese is a member of the ESSKA-EKA osteotomy group and receives personal fees for being a consultant for Medacta SA, Storz, Zimmer-Biomet, and Smith&Nephew. These financial activities are outside the submitted work.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Conflict of interest"}},{"value":"Ethical approval for this study was obtained from Zurich Cantonal Ethics Commission: 2021-01428. The study was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki and in accordance with the HIPAA.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethical approval and consent to participate"}}]}}