{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T13:18:24Z","timestamp":1791811104058,"version":"4.3.4"},"reference-count":20,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T00:00:00Z","timestamp":1784505600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T00:00:00Z","timestamp":1784505600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/100015772","name":"Pontif\u00edcia Universidade Cat\u00f3lica De Minas Gerais","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100015772","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["J Robotic Surg"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Robotic total knee arthroplasty (TKA) enables repeated intraoperative quantification of preoperative alignment, flexion deformity, and medial and lateral compartment gaps in extension and at 90\u00b0 flexion before component positioning, but the preoperative patterns guiding functional-alignment planning remain incompletely characterized. This study aimed to derive a pragmatic driver-based classification from preoperative robotic data and evaluate its internal coherence across the surgical workflow. We analyzed 68 consecutive primary functionally aligned robotic TKAs performed by a single surgeon using a CT-based robotic-arm platform. Preoperative variables included hip-knee-ankle angle (HKA), flexion deformity, and independent medial and lateral gaps in extension and at 90\u00b0 flexion. A 10-case formative series informed concept generation; the finalized hierarchy was then applied to all cases using preoperative variables only. Four phenotypes were derived: bone-driven, ligament-driven, flexion-dominant, and mixed\/complex (defined as the co-occurrence of two or more severe deformity drivers). Internal coherence was assessed through release escalation, corrected-state behavior, plan-to-final HKA fidelity, and mechanical and functional-alignment balance. Inter-observer reliability was tested by having five independent surgeons classify all cases blinded, with agreement quantified by Fleiss\u2019 and Cohen\u2019s kappa. All knees were classified: bone-driven, 40\/68 (58.8%); ligament-driven, 6\/68 (8.8%); flexion-dominant, 10\/68 (14.7%); and mixed\/complex, 12\/68 (17.6%). Release escalation occurred in 1\/68 (1.5%), with no posterior capsulotomy. Overall, 58\/63 (92.1%) finished within \u00b1\u20092\u00b0 of planned HKA; strict mechanical balance was achieved in 58\/62 (93.5%) and functional-alignment balance in 61\/62 (98.4%). Flexion-dominant knees showed lower coronal fidelity but complete final balance, suggesting a coronal-sagittal trade-off during functional planning. Inter-observer agreement among the five surgeons was almost perfect (Fleiss\u2019 kappa 0.88, 95% CI 0.81\u20130.93; 92.4% overall agreement). Preoperative HKA, sagittal deformity, and medial-lateral gap asymmetry revealed recurring patterns organized into a four-phenotype driver framework. This classification is best interpreted as an internally coherent derivation framework that showed almost perfect inter-observer reliability (Fleiss\u2019 kappa 0.88) but still requires external, multicenter validation and threshold-sensitivity analysis before its clinical utility can be established.<\/jats:p>","DOI":"10.1007\/s11701-026-03655-4","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T09:33:10Z","timestamp":1784539990000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Preoperative gap phenotypes in functionally aligned robotic total knee arthroplasty: derivation and internal coherence of a driver-based classification"],"prefix":"10.1007","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0612-7275","authenticated-orcid":false,"given":"Eduardo Frois","family":"Temponi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-5919-0193","authenticated-orcid":false,"given":"Jared Philip","family":"Sachs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-3705-958X","authenticated-orcid":false,"given":"Matheus Braga Jacques","family":"Gon\u00e7alves","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3434-2999","authenticated-orcid":false,"given":"Luiz Fernando Machado","family":"Soares","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2683-6386","authenticated-orcid":false,"given":"L\u00facio Hon\u00f3rio","family":"de Carvalho J\u00fanior","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,7,20]]},"reference":[{"issue":"1S","key":"3655_CR1","doi-asserted-by":"publisher","first-page":"102780","DOI":"10.1016\/j.otsr.2020.102780","volume":"107","author":"R Pailh\u00e9","year":"2021","unstructured":"Pailh\u00e9 R (2021) Total knee arthroplasty: latest robotics implantation techniques. 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Bone Joint J 100\u2013B(7):930\u2013937","journal-title":"Bone Joint J"},{"issue":"2","key":"3655_CR3","doi-asserted-by":"publisher","first-page":"867","DOI":"10.1097\/MS9.0000000000002919","volume":"87","author":"O Mostafa","year":"2025","unstructured":"Mostafa O, Malik M, Qayum K, Ishaq U, Khan AM, Wasim AS et al (2025) Robotic-assisted versus conventional total knee arthroplasty: a systematic review and meta-analysis of alignment accuracy and clinical outcomes. Ann Med Surg (Lond) 87(2):867\u2013879","journal-title":"Ann Med Surg (Lond)"},{"key":"3655_CR4","doi-asserted-by":"publisher","first-page":"19","DOI":"10.1051\/sicotj\/2021021","volume":"7","author":"E Sappey-Marinier","year":"2021","unstructured":"Sappey-Marinier E, Pauvert A, Batailler C, Swan J, Cheze L, Servien E et al (2021) Personalized alignment in total knee arthroplasty: current concepts. 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J Robot Surg 19(1):455","journal-title":"J Robot Surg"}],"container-title":["Journal of Robotic Surgery"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s11701-026-03655-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1007\/s11701-026-03655-4","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s11701-026-03655-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T09:33:12Z","timestamp":1784539992000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1007\/s11701-026-03655-4"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,20]]},"references-count":20,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["3655"],"URL":"https:\/\/doi.org\/10.1007\/s11701-026-03655-4","relation":{},"ISSN":["1863-2491"],"issn-type":[{"value":"1863-2491","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,20]]},"assertion":[{"value":"3 June 2026","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"24 June 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"20 July 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"The authors declare no competing interests.","order":1,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"This study was approved by the Research Ethics Committee (CEP) of Hospital Madre Teresa (CAAE 78506523.4.0000.5127; approval no. 6.734.057). The study was conducted in accordance with the Declaration of Helsinki, and written informed consent was obtained from all participants.","order":2,"name":"Ethics","label":"Ethics approval","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors used a large language model solely for AI-assisted copy editing (language, grammar, and formatting). No generative AI tool was used for study design, data analysis, interpretation, or the generation of scientific content. The authors reviewed and take full responsibility for the final manuscript.","order":3,"name":"Ethics","label":"Use of AI","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"703"}}