{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T01:04:29Z","timestamp":1792803869887,"version":"4.5.0"},"reference-count":38,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2024,8,7]],"date-time":"2024-08-07T00:00:00Z","timestamp":1722988800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"F\u00e9d\u00e9ration Internationale de Football Association (FIFA\u00ae)","id":[{"id":"https:\/\/ror.org\/0381nq624","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Children"],"abstract":"<jats:p>Background: Football, as the most popular sport worldwide, has long been under suspicion of causing varus knee alignment as early as adolescence. However, no causal relationship has yet been found. The first step to do so would be to determine the prevalence of lower leg malalignment among male junior football players depending on age, performance level and the number of active seasons played. Methods: Leg axis alignment in frontal plane was determined in male junior football players of different age levels between 7 and 18 years by measuring the intercondylar\/intermalleolar distance (ICD\/IMD) in an upright position. In addition to anthropometric data, multiple sport-specific data such as the start of their football career or training time per week were collected by means of questionnaires (clinical trial registration number: DRKS00020446). Results: 207 male junior football players were included in this survey. The mean age was 12.8 years. Within the group of 15 to 18 year olds, the prevalence of varus knee malalignment was highest at just under a third (32.1%). In the subpopulation that played actively for more than ten seasons, 28.9% showed varus leg axis. Regarding performance level, the highest IMD\/ICD values and highest prevalence of varus alignment were found among football players who play on a semi-professional level (16.7%), compared to amateur (11.4%) and high-performance levels (2.8%). Conclusions: Further research is necessary to investigate if this high prevalence of varus knee in children of a higher age and higher playing levels is due to the selection bias of football players with varus knee or a real development of varus knee in individuals.<\/jats:p>","DOI":"10.3390\/children11080953","type":"journal-article","created":{"date-parts":[[2024,8,7]],"date-time":"2024-08-07T11:33:52Z","timestamp":1723030432000},"page":"953","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["High Prevalence of Varus Knee Malalignment in Adolescent Football Players\u2014Clinical Lower Leg Axis Measurements of Male Junior Football Players Aged 7 to 18 Years"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4109-1901","authenticated-orcid":false,"given":"Clemens","family":"Memmel","sequence":"first","affiliation":[{"name":"Department of Pediatric Surgery and Orthopedics, Clinic St. Hedwig, Barmherzige Brueder Regensburg, KUNO Pediatric University Medical Center, 93049 Regensburg, Germany"},{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dominik","family":"Sporrer","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1739-8524","authenticated-orcid":false,"given":"Dominik","family":"Szymski","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4838-9644","authenticated-orcid":false,"given":"Johannes","family":"Weber","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexander","family":"Hanke","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery and Orthopedics, Clinic St. Hedwig, Barmherzige Brueder Regensburg, KUNO Pediatric University Medical Center, 93049 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1580-0273","authenticated-orcid":false,"given":"Markus","family":"Denzinger","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery and Orthopedics, Clinic St. Hedwig, Barmherzige Brueder Regensburg, KUNO Pediatric University Medical Center, 93049 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4996-8808","authenticated-orcid":false,"given":"Maximilian","family":"Kerschbaum","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0208-4650","authenticated-orcid":false,"given":"Volker","family":"Alt","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Werner","family":"Krutsch","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthias","family":"Koch","sequence":"additional","affiliation":[{"name":"Department of Trauma Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany"},{"name":"FIFA Medical Center of Excellence, University Medical Center Regensburg, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,7]]},"reference":[{"key":"ref_1","unstructured":"FIFA Communications Division, Information Services (2024, July 15). 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