{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T14:07:51Z","timestamp":1768831671593,"version":"3.49.0"},"reference-count":41,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2023,3,3]],"date-time":"2023-03-03T00:00:00Z","timestamp":1677801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The purpose of this study was to propose a novel classification of varus thrust based on gait analysis with inertial motion sensor units (IMUs) in patients with medial knee osteoarthritis (MKOA). We investigated thigh and shank acceleration using a nine-axis IMU in 69 knees with MKOA and 24 (control) knees. We classified varus thrust into four phenotypes according to the relative medial\u2013lateral acceleration vector patterns of the thigh and shank segments: pattern A (thigh medial, shank medial), pattern B (medial, lateral), pattern C (lateral, medial), and pattern D (lateral, lateral). Quantitative varus thrust was calculated using an extended Kalman filter-based algorithm. We compared the differences between our proposed IMU classification and the Kellgren\u2013Lawrence (KL) grades for quantitative varus thrust and visible varus thrust. Most of the varus thrust was not visually perceptible in early-stage OA. In advanced MKOA, increased proportions of patterns C and D with lateral thigh acceleration were observed. Quantitative varus thrust was significantly increased stepwise from patterns A to D. This novel IMU classification has better clinical utility due to its ability to detect subtle kinematic changes that cannot be captured with conventional motion analysis even in the early stage of MKOA.<\/jats:p>","DOI":"10.3390\/s23052797","type":"journal-article","created":{"date-parts":[[2023,3,6]],"date-time":"2023-03-06T02:28:34Z","timestamp":1678069714000},"page":"2797","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["A Novel Classification of Coronal Plane Knee Joint Instability Using Nine-Axis Inertial Measurement Units in Patients with Medial Knee Osteoarthritis"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3427-2675","authenticated-orcid":false,"given":"Hiroaki","family":"Tsukamoto","sequence":"first","affiliation":[{"name":"Department of Orthopedic Surgery, Kita-Akita Municipal Hospital, Shimosugi, Kamishimizusawa 16-29, Kitaakita 018-4221, Japan"},{"name":"Department of Orthopedic Surgery, Graduate School of Medicine, Akita University, Hondo 1-1-1, Akita 010-8543, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9533-1125","authenticated-orcid":false,"given":"Kimio","family":"Saito","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Graduate School of Medicine, Akita University, Hondo 1-1-1, Akita 010-8543, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hidetomo","family":"Saito","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Graduate School of Medicine, Akita University, Hondo 1-1-1, Akita 010-8543, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4939-9545","authenticated-orcid":false,"given":"Hiroaki","family":"Kijima","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Graduate School of Medicine, Akita University, Hondo 1-1-1, Akita 010-8543, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4420-4326","authenticated-orcid":false,"given":"Manabu","family":"Akagawa","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Omagari Kosei Medical Center, Omagari Torimachi 8-65, Senboku 014-0027, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3248-0059","authenticated-orcid":false,"given":"Akira","family":"Komatsu","sequence":"additional","affiliation":[{"name":"National Institute of Technology, Sendai College, Natori 981-1239, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takehiro","family":"Iwami","sequence":"additional","affiliation":[{"name":"Department of System Design Engineering, Faculty of Engineering Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naohisa","family":"Miyakoshi","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Graduate School of Medicine, Akita University, Hondo 1-1-1, Akita 010-8543, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1940","DOI":"10.1136\/ard.2010.129742","article-title":"Varus and valgus alignment and incident and progressive knee osteoarthritis","volume":"69","author":"Sharma","year":"2010","journal-title":"Ann. 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