{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T08:08:20Z","timestamp":1789459700073,"version":"build-2803163510"},"reference-count":37,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T00:00:00Z","timestamp":1789084800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T00:00:00Z","timestamp":1789430400000},"content-version":"vor","delay-in-days":4,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"name":"Universit\u00e4tsklinikum Hamburg-Eppendorf (UKE)"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Sports Sci Med Rehabil"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>Professional football players have an increased prevalence of genu varum, which is a risk factor for developing knee osteoarthritis. It remains unclear at what stage of adolescence varus progression is most pronounced and which factors are associated with this progression. Therefore, this study aimed to investigate the factors associated with varus progression over a two-year observation period in a selected cohort of adolescent male professional academy football players.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A total of 31 male youth academy football players aged 12\u201317 years who demonstrated varus progression during the oberservation period were included. The static mean mechanical femorotibial axis angle (MAA) of both legs was measured using a two-dimensional and marker-based method (DIERS leg axis analysis system). Players\u2019 age, height, BMI and dominant kicking leg were also assessed. Measurements were performed in 2021 and after a 24-month observation period. Changes and correlations over the observation period were statistically analyzed using SPSS.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Age-related differences were observed in the extent of MAA: the youngest athletes had the lowest MAA at baseline (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.049), which increased more over the following two years than the older players. Greater increases in height during the observation period (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.008), low initial height (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.035), BMI (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.043) and less varus deformity (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.017) were found to be significant factors associated with an increase in MAA.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Within this selected cohort, the increase in MAA over the two-year observation period was most pronounced in the younger athletes. Greater increases in height and associated weight gain were the variables most strongly associated with increasing varus alignment during the observation period. These findings may help to inform the timing of future preventive strategies, although their effectiveness for influencing leg-axis development remains to be established.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s13102-026-02035-7","type":"journal-article","created":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T10:17:16Z","timestamp":1789121836000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Two-year follow-up of varus progression in young professional football players"],"prefix":"10.1186","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-5686-1317","authenticated-orcid":false,"given":"Hannah","family":"Gablac","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lars","family":"Schwalm","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Behrendt","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Hoffmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthias","family":"Krause","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karl-Heinz","family":"Frosch","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G\u00f6tz","family":"Welsch","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dimitris","family":"Dalos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,9,11]]},"reference":[{"issue":"11","key":"2035_CR1","doi-asserted-by":"publisher","first-page":"3619","DOI":"10.1007\/s00167-016-4348-y","volume":"24","author":"W Colyn","year":"2016","unstructured":"Colyn W, Agricola R, Arnout N, Verhaar JA, Bellemans J. 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All procedures involving human participants were performed in accordance with the ethical standards of the institutional research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Informed consent was obtained from all patients and volunteers involved in this study. Written informed consent to participate was obtained from all participants and, for participants under the age of 16 years, from their parents or legal guardians prior to participation.","order":1,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Not applicable.","order":2,"name":"Ethics","label":"Consent for publication","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors declare no competing interests.","order":3,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"420"}}