{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T18:09:43Z","timestamp":1789754983398,"version":"4.0.1"},"reference-count":23,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>\n                    This study aimed to evaluate both the relative and absolute reliability of ultrasound-based measurements of changes in medial knee joint space width under valgus stress in healthy individuals. Seventeen healthy adult males (34 knees) underwent ultrasound assessments under unloaded and valgus-loaded (10 Nm) conditions. The medial knee joint space width was measured using a standardized ultrasound protocol, and changes were calculated as the difference between loaded and unloaded conditions. Intra- and inter-rater reliability between two physical therapists with different experience levels were evaluated using intraclass correlation coefficients, and absolute reliability was assessed via Bland-Altman analysis, standard error of measurement, and minimal detectable change at the 95% confidence level. A significant increase in medial knee joint space width (ranging from 1.33 to 1.41 mm) was observed under valgus stress compared to the unloaded condition (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.001). The intraclass correlation coefficient for intra-rater reliability across two separate measurement days was 0.88 (95% confidence interval: 0.77\u20130.94), whereas that for inter-rater reliability was 0.84 (95% confidence interval: 0.70\u20130.92). Bland-Altman analysis revealed only random measurement error, with minimal detectable change at the 95% confidence level values below 1.0 mm (0.51 mm intra-rater; 0.65 mm inter-rater). Ultrasound imaging could provide sufficient reliability to quantify changes in medial knee joint space width during valgus stress testing in healthy individuals. These values suggest that changes exceeding these thresholds may reflect changes beyond measurement error. However, further studies with larger sample sizes and involving patients with ligamentous injuries are needed to confirm the clinical applicability of this method.\n                  <\/jats:p>","DOI":"10.1371\/journal.pone.0358761","type":"journal-article","created":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T17:42:32Z","timestamp":1789753352000},"page":"e0358761","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Relative and absolute reliability of medial knee joint space width measurement using ultrasound imaging during valgus stress testing"],"prefix":"10.1371","volume":"21","author":[{"given":"Ryoga","family":"Hayashi","sequence":"first","affiliation":[{"name":"Nantaru Orthopedic Clinic","place":["Otaru, Hokkaido, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hayato","family":"Kawaji","sequence":"additional","affiliation":[{"name":"Soseigawadori Orthopedic Clinic","place":["Sapporo, Hokkaido, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-7677-3817","authenticated-orcid":true,"given":"Satoru","family":"Kojima","sequence":"additional","affiliation":[{"name":"School of Rehabilitation Sciences, Health Sciences University of Hokkaido","place":["Kanazawa, Tobetsu-cho, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,9,18]]},"reference":[{"issue":"8","key":"pone.0358761.ref001","doi-asserted-by":"crossref","first-page":"1257","DOI":"10.2106\/00004623-198163080-00007","article-title":"Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees","volume":"63","author":"ES Grood","year":"1981","journal-title":"J Bone Joint Surg Am"},{"issue":"9","key":"pone.0358761.ref002","doi-asserted-by":"crossref","first-page":"1328","DOI":"10.2106\/00004623-199409000-00008","article-title":"The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments in knees with and without an associated rupture of the anterior cruciate ligament. 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IKDC 2000 form. https:\/\/www.sportsmed.org\/uploads\/main\/files\/general\/IKDC\/AOSSM_IKDC_English_US.pdf. Accessed 2026 February 5."},{"issue":"1","key":"pone.0358761.ref023","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1002\/(SICI)1097-0258(19980115)17:1<101::AID-SIM727>3.0.CO;2-E","article-title":"Sample size and optimal designs for reliability studies","volume":"17","author":"SD Walter","year":"1998","journal-title":"Stat Med"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0358761","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T17:42:38Z","timestamp":1789753358000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0358761"}},"subtitle":[],"editor":[{"given":"Emad A.","family":"Aboelnasr","sequence":"first","affiliation":[{"name":"Cairo University Faculty of Physical Therapy","place":["EGYPT"]}],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,9,18]]},"references-count":23,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9,18]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0358761","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,18]]}}}