{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T20:09:09Z","timestamp":1790885349948,"version":"4.1.0"},"reference-count":25,"publisher":"SAGE Publications","issue":"1","license":[{"start":{"date-parts":[[2023,1,1]],"date-time":"2023-01-01T00:00:00Z","timestamp":1672531200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Medtronic Sofamor Danek Inc."},{"name":"Japan Medical Dynamic Marketing Inc."},{"name":"Meitoku Medical Institution Jyuzen Memorial Hospital"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["J Orthop Surg (Hong Kong)"],"published-print":{"date-parts":[[2023,1]]},"abstract":"<jats:p>Background: The interaction between knee osteoarthritis and spinal deformity and knee flexion (KF) remains unclear. We aimed to clarify the relationship between KF in the standing position and the severity of spinal deformity and knee osteoarthritis. Methods: We analyzed older volunteers aged over 60 years who participated in the musculoskeletal screening program. The participant\u2019s characteristics and standing radiographic parameters were assessed. After a preliminary analysis, a propensity score-matched model was established with adjustments for age, sex, and body mass index (BMI). Cases were divided into KF (knee angle [KA] \u226510\u00b0) and non-KF (KA &lt;10\u00b0) groups. Results: In a preliminary analysis of 252 cases (42\u00a0KF and 210 non-KF), there were significant differences in age and BMI between the KF and non-KF groups (all p &lt; 0.05). Using a one-to-one propensity score-matched analysis, 38 pairs of cases were selected. There were significantly higher values of C7 sagittal vertical axis, T1 pelvic angle, pelvic tilt, pelvic incidence minus lumbar lordosis, KA, ankle angle, and pelvic shift in the KF group than in the non-KF group (all p &lt; 0.05). In the KF group, 71.1% of the cases had severe spinal deformity (defined as marked deformity by the SRS-Schwab classification), and 31.6% had severe knee osteoarthritis (defined as a Kellgren Lawrence grade \u22653). Of the 31.6%, 7.9% were attributable to knee osteoarthritis alone, and 23.7% to both knee osteoarthritis and spinal deformity. Conclusions: This study clarified that compensatory changes due to spinopelvic malalignment, not due to knee osteoarthritis alone, mainly affected KF in the standing position.<\/jats:p>","DOI":"10.1177\/10225536231169575","type":"journal-article","created":{"date-parts":[[2023,4,11]],"date-time":"2023-04-11T06:52:56Z","timestamp":1681195976000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":8,"title":["Why does knee flexion in the standing position occur? Spinal deformity or knee osteoarthritis"],"prefix":"10.1177","volume":"31","author":[{"given":"Jili","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7722-2205","authenticated-orcid":false,"given":"Hiroki","family":"Ushirozako","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Yamato","sequence":"additional","affiliation":[{"name":"Division of Geriatric Musculoskeletal Health, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomohiko","family":"Hasegawa","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Go","family":"Yoshida","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomohiro","family":"Banno","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hideyuki","family":"Arima","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu City, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shin","family":"Oe","sequence":"additional","affiliation":[{"name":"Division of Geriatric Musculoskeletal Health, Hamamatsu University School of Medicine, 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