{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T02:01:44Z","timestamp":1789696904665,"version":"4.0.1"},"reference-count":31,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2023YFB4606700"],"award-info":[{"award-number":["2023YFB4606700"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013365","name":"West China Hospital, Sichuan University","doi-asserted-by":"publisher","award":["ZYYC21004"],"award-info":[{"award-number":["ZYYC21004"]}],"id":[{"id":"10.13039\/501100013365","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013365","name":"West China Hospital, Sichuan University","doi-asserted-by":"publisher","award":["ZYAI24038"],"award-info":[{"award-number":["ZYAI24038"]}],"id":[{"id":"10.13039\/501100013365","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013365","name":"West China Hospital, Sichuan University","doi-asserted-by":"publisher","award":["2023HXFH024"],"award-info":[{"award-number":["2023HXFH024"]}],"id":[{"id":"10.13039\/501100013365","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Orthopaedic Surgery"],"abstract":"ABSTRACT<\/jats:title>\n \n Background<\/jats:title>\n While kinematic analysis is crucial to characterize multi\u2010planar functional deficits in end\u2010stage knee osteoarthritis (OA), traditional laboratories impose severe physical burdens on patients. In\u2010field markerless systems like OpenCap offer an accessible alternative, yet their repeatability in this population remains underexplored. The objective of this study was to assess the inter\u2010session repeatability of OpenCap for quantifying segment lengths and lower\u2010limb kinematics during gait and sit\u2010to\u2010stand tasks in end\u2010stage knee osteoarthritis (OA) patients.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n Twenty\u2010three patients with end\u2010stage knee OA scheduled for total knee arthroplasty performed gait and sit\u2010to\u2010stand tasks while wearing street clothes across two visits. Segment lengths obtained from static calibration were compared between sessions, while waveform repeatability of lower\u2010limb joint angles was assessed using root mean square deviation (RMSD) and intraclass correlation coefficient (ICC). Additionally, the standard error of measurement (SEM) and minimal detectable change (MDC) were calculated for discrete kinematic parameters.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The segment lengths exhibited moderate to excellent repeatability between sessions (mean\n ICC<\/jats:styled-content>\n : 0.79). Measurement bias was generally minimal (<\u20090.5 cm, except for the upper arm), with the overall 95% limits of agreement ranging from \u22124.51 to 3.98 cm. For gait, the average\n RMSD<\/jats:styled-content>\n and\n ICC<\/jats:styled-content>\n values were 4.0\u00b0 (\n SD<\/jats:styled-content>\n : 0.9) and 0.82 (\n SD<\/jats:styled-content>\n : 0.07), respectively, whereas for the sit\u2010to\u2010stand task, these values were 5.2\u00b0 (\n SD<\/jats:styled-content>\n : 1.1) and 0.69 (\n SD<\/jats:styled-content>\n : 0.08), respectively. The average\n SEM<\/jats:styled-content>\n and\n MDC<\/jats:styled-content>\n values for gait were 2.9\u00b0 and 8.0\u00b0, and for sit\u2010to\u2010stand, 3.0\u00b0 and 8.4\u00b0, respectively.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n OpenCap demonstrates moderate to good inter\u2010session repeatability for static anatomical measurements and gait kinematics in patients with end\u2010stage knee OA, showing promise as a low\u2010burden clinical assessment tool. However, the higher variability observed during the sit\u2010to\u2010stand task necessitates cautious, task\u2010specific interpretation, underscoring the need for further improvements before expanding its use across broader functional assessments.<\/jats:p>\n <\/jats:sec>","DOI":"10.1111\/os.70431","type":"journal-article","created":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T01:05:08Z","timestamp":1789693508000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Inter\u2010Session Repeatability of a Smartphone\u2010Based Markerless System to Measure Segment Length and Lower\u2010Limb Kinematics in Patients With End\u2010Stage Knee Osteoarthritis"],"prefix":"10.1111","author":[{"given":"Chunping","family":"Ye","sequence":"first","affiliation":[{"name":"Department of Orthopedic Surgery and Orthopedic Research Institute West China Hospital, Sichuan University Chengdu Sichuan Province China"},{"name":"School of Physical Education Tianfu College of Southwestern University of Finance and Economics Mianyang Sichuan Province China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2911-8152","authenticated-orcid":false,"given":"Renxin","family":"Ding","sequence":"additional","affiliation":[{"name":"Information Technology Center West China Hospital, Sichuan University Chengdu Sichuan Province China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junqing","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery and Orthopedic Research Institute West China Hospital, Sichuan University Chengdu Sichuan Province China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6132-379X","authenticated-orcid":false,"given":"Yong","family":"Nie","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery and Orthopedic Research Institute West China Hospital, Sichuan University Chengdu Sichuan Province China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8136-9816","authenticated-orcid":false,"given":"Kang","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery and West China Biomedical Big Data Center West China Hospital, Sichuan University Chengdu Sichuan Province 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