{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T16:51:26Z","timestamp":1792083086528,"version":"4.4.0"},"reference-count":19,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T00:00:00Z","timestamp":1783900800000},"content-version":"vor","delay-in-days":12,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["esskajournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J. exp. orthop."],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>To establish decade\u2010specific magnetic resonance imaging (MRI)\u2010based reference values for the medial meniscal extrusion index (MEI) in adults without significant structural knee pathology and to assess associations with age and sex. The hypothesis was that decade\u2010specific MEI values would increase with age, without meaningful sex\u2010related differences, while remaining low in knees without significant structural abnormalities on MRI.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>In June 2025, knee MRI examinations from a single tertiary orthopaedic centre were retrospectively screened until 500 eligible knees were identified (100 per decade, ages 20\u201369; balanced by sex). Inclusion criteria were age 20\u201369 years, 1.5\u2010T MRI, and no definite\/moderate osteoarthritis on MRI. Exclusion criteria included root, radial or complex meniscal tears; significant focal chondral lesions; ligament injury; discoid meniscus; prior knee surgery; inflammatory disease; evident anatomical abnormalities; and marked bone marrow edema. MEI was measured on coronal images as the ratio of extruded medial meniscus to total medial meniscal width. Linear regression tested the association between age and MEI, including an age\u2009\u00d7\u2009sex interaction term. Reference values were reported per decade as mean, standard deviation (SD) and mean\u2009+\u20091 SD and +\u20092 SD. Interobserver reliability was assessed using the intraclass correlation coefficient (ICC).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      MEI was positively associated with age (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u2009=\u20090.0019 per year,\n                      <jats:italic>R<\/jats:italic>\n                      <jats:sup>2<\/jats:sup>\n                      \u2009=\u20090.072,\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). No significant age\u2009\u00d7\u2009sex interaction was detected. Mean MEI increased from 0.041 in the 20\u201329 decade to 0.122 in the 60\u201369 decade. The mean\u2009+\u20091 SD threshold approached a 20% MEI cut\u2010off in the 50\u201359 decade and exceeded it in the 60\u201369 decade. Interobserver reliability was excellent (ICC\u2009\u2248\u20090.82).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>MEI increased progressively with age in knees without significant structural pathology on MRI, with no meaningful sex\u2010related differences. Decade\u2010specific MEI reference intervals may support age\u2010adjusted interpretation of isolated medial meniscal extrusion, particularly in older adults, while reinforcing its role as an adjunctive imaging finding.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Level of Evidence<\/jats:title>\n                    <jats:p>Level III, retrospective cohort study.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/jeo2.70839","type":"journal-article","created":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T14:30:13Z","timestamp":1783953013000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Meniscal extrusion increases with age: Decade\u2010specific magnetic resonance imaging reference values"],"prefix":"10.1002","volume":"13","author":[{"given":"Riccardo","family":"Compagnoni","sequence":"first","affiliation":[{"name":"Department of Biomedical, Surgical and Dental Sciences Universit\u00e0 degli Studi di Milano Milan Italy"},{"name":"2 \u00b0 Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9006-124X","authenticated-orcid":false,"given":"Rossella","family":"Ravaglia","sequence":"additional","affiliation":[{"name":"University of Milan, School of Specialization in Orthopedics and Traumatology Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matteo","family":"Parmigiani","sequence":"additional","affiliation":[{"name":"2 \u00b0 Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"},{"name":"University of Milan, School of Specialization in Orthopedics and Traumatology Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alessio","family":"Maione","sequence":"additional","affiliation":[{"name":"1\u00b0 Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Filippo Pierfrancesco","family":"Calanna","sequence":"additional","affiliation":[{"name":"1\u00b0 Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paolo","family":"Ferrua","sequence":"additional","affiliation":[{"name":"Week Surgery, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pietro Simone","family":"Randelli","sequence":"additional","affiliation":[{"name":"1\u00b0 Clinica Ortopedica, ASST Centro Specialistico Ortopedico Traumatologico Gaetano Pini\u2010CTO Milan Italy"},{"name":"Department of Biomedical Sciences for Health Laboratory of Applied Biomechanics Universit\u00e0 degli Studi di Milano Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,7,13]]},"reference":[{"key":"e_1_2_13_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-018-4885-7"},{"key":"e_1_2_13_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.knee.2023.09.010"},{"key":"e_1_2_13_4_1","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2474-12-248"},{"key":"e_1_2_13_5_1","doi-asserted-by":"publisher","DOI":"10.1186\/s43019-024-00236-3"},{"key":"e_1_2_13_6_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-023-07525-6"},{"key":"e_1_2_13_7_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-022-07089-x"},{"key":"e_1_2_13_8_1","doi-asserted-by":"publisher","DOI":"10.2214\/ajr.183.1.1830017"},{"key":"e_1_2_13_9_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-020-06363-0"},{"key":"e_1_2_13_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/ksa.12183"},{"key":"e_1_2_13_11_1","doi-asserted-by":"publisher","DOI":"10.1177\/03635465221131005"},{"key":"e_1_2_13_12_1","doi-asserted-by":"publisher","DOI":"10.1097\/JSA.0000000000000327"},{"key":"e_1_2_13_13_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00402-023-04934-7"},{"key":"e_1_2_13_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.joca.2011.05.004"},{"key":"e_1_2_13_15_1","doi-asserted-by":"publisher","DOI":"10.1002\/jeo2.70544"},{"key":"e_1_2_13_16_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-023-49868-7"},{"key":"e_1_2_13_17_1","doi-asserted-by":"publisher","DOI":"10.52965\/001c.74881"},{"key":"e_1_2_13_18_1","doi-asserted-by":"publisher","DOI":"10.1002\/jeo2.70126"},{"key":"e_1_2_13_19_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12891-023-06807-x"},{"key":"e_1_2_13_20_1","doi-asserted-by":"publisher","DOI":"10.1002\/jeo2.70031"}],"container-title":["Journal 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