{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T04:02:21Z","timestamp":1772251341327,"version":"3.50.1"},"reference-count":23,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T00:00:00Z","timestamp":1772236800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T00:00:00Z","timestamp":1772236800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Arthroplasty"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>An augmented reality (AR)-aided navigation system that utilizes a standard smartphone enables accurate alignment of femoral and tibial components in total knee arthroplasty (TKA) and provides real-time intraoperative quantification of joint gaps. This study aimed to integrate the AR-aided navigation system into the surgical technique of restricted kinematic alignment and to evaluate its clinical effectiveness.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We compared 45 restricted kinematic alignment TKAs performed using posterior cruciate ligament (PCL) retaining medial-congruent prosthesis with an AR-aided navigation system and 40 mechanically aligned TKAs performed using PCL resecting posterior-stabilized prosthesis in patients with preoperative varus or neutral lower limb alignment. In the restricted kinematic alignment group, femoral and tibial alignments were determined using calipered and soft tissue\u2013guided techniques, respectively, with the AR-aided navigation system providing real-time confirmation that angular values remained within safe boundaries. The target intraoperative extension gap was a rectangular configuration with equal medial and lateral widths.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Intraoperative measured value of the soft-tissue imbalance with the knee in extension was significantly smaller in the restricted kinematic alignment group than in the mechanical alignment group (1.1\u2009\u00b1\u20091.1\u00b0 vs 2.5\u2009\u00b1\u20092.2\u00b0; 95% CI, 0.7 to 2.2\u00b0;\n                      <jats:italic>P<\/jats:italic>\n                      \u2009&lt;\u20090.001; Cohen\u2019s d\u2009=\u20090.85). After propensity score matching, no significant differences were observed between the groups in either the timed up-and-go test or the 10-m walk test at 1\u00a0week postoperatively (12.6\u2009\u00b1\u20093.5\u00a0s vs 13.2\u2009\u00b1\u20095.3\u00a0s; 95% CI,\u2009\u2212\u20093.0 to 1.7;\n                      <jats:italic>P<\/jats:italic>\n                      \u2009=\u20090.60; and 11.7\u2009\u00b1\u20092.5\u00a0s vs 11.9\u2009\u00b1\u20093.2\u00a0s; 95% CI,\u2009\u2212\u20091.7 to 1.3;\n                      <jats:italic>P<\/jats:italic>\n                      \u2009=\u20090.82, respectively).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Restricted kinematic alignment TKA using PCL retaining medial-congruent prosthesis achieved more balanced intraoperative soft-tissue tension than the mechanical alignment TKA using posterior-stabilized prosthesis. However, early postoperative walking speed did not differ between the two groups.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s42836-026-00371-0","type":"journal-article","created":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T03:07:36Z","timestamp":1772248056000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Restricted kinematic alignment total knee arthroplasty using augmented reality technology to maintain limb alignment within targeted boundaries"],"prefix":"10.1186","volume":"8","author":[{"given":"Sachiyuki","family":"Tsukada","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroyuki","family":"Ogawa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tsutomu","family":"Nakayama","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shiho","family":"Minami","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masayoshi","family":"Saito","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naoyuki","family":"Hirasawa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2026,2,28]]},"reference":[{"issue":"1","key":"371_CR1","doi-asserted-by":"publisher","first-page":"108","DOI":"10.1016\/j.jjoisr.2023.02.003","volume":"1","author":"Y Minoda","year":"2023","unstructured":"Minoda Y. Alignment techniques in total knee arthroplasty. J Joint Surg Res. 2023;1(1):108\u201316.","journal-title":"J Joint Surg Res"},{"key":"371_CR2","doi-asserted-by":"publisher","first-page":"206","DOI":"10.1016\/j.knee.2015.02.019","volume":"22","author":"M Ishikawa","year":"2015","unstructured":"Ishikawa M, Kuriyama S, Ito H, Furu M, Nakamura S, Matsuda S. Kinematic alignment produces near-normal knee motion but increases contact stress after total knee arthroplasty: a case study on a single implant design. Knee. 2015;22:206\u201312.","journal-title":"Knee"},{"key":"371_CR3","doi-asserted-by":"publisher","first-page":"1629","DOI":"10.1007\/s00167-017-4788-z","volume":"26","author":"Y Niki","year":"2018","unstructured":"Niki Y, Nagura T, Nagai K, Kobayashi S, Harato K. Kinematically aligned total knee arthroplasty reduces knee adduction moment more than mechanically aligned total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2018;26:1629\u201335.","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"key":"371_CR4","doi-asserted-by":"publisher","first-page":"948","DOI":"10.1007\/s00167-021-06473-3","volume":"30","author":"SM Howell","year":"2022","unstructured":"Howell SM, Gill M, Shelton TJ, Nedopil AJ. Reoperations are few and confined to the most valgus phenotypes 4 years after unrestricted calipered kinematically aligned TKA. Knee Surg Sports Traumatol Arthrosc. 2022;30:948\u201357.","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"key":"371_CR5","doi-asserted-by":"publisher","first-page":"1588","DOI":"10.2106\/JBJS.J.00772","volume":"93","author":"MA Ritter","year":"2011","unstructured":"Ritter MA, Davis KE, Meding JB, Pierson JL, Berend ME, Malinzak RA. The effect of alignment and BMI on failure of total knee replacement. 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Front Surg. 2021;8:697020.","journal-title":"Front Surg"},{"key":"371_CR8","doi-asserted-by":"publisher","DOI":"10.1186\/s12891-023-06448-0","volume":"24","author":"T Miura","year":"2023","unstructured":"Miura T, Takahashi T, Watanabe J, Kataoka Y, Ae R, Saito H, et al. Postoperative clinical outcomes for kinematically, restricted kinematically, or mechanically aligned total knee arthroplasty: a systematic review and network meta-analysis of randomized controlled trials. BMC Musculoskelet Disord. 2023;24:322.","journal-title":"BMC Musculoskelet Disord"},{"key":"371_CR9","doi-asserted-by":"publisher","DOI":"10.1186\/s40634-019-0212-6","volume":"6","author":"S Tsukada","year":"2019","unstructured":"Tsukada S, Ogawa H, Nishino M, Kurosaka K, Hirasawa N. Augmented reality-based navigation system applied to tibial bone resection in total knee arthroplasty. J Exp Orthop. 2019;6:44.","journal-title":"J Exp Orthop"},{"key":"371_CR10","doi-asserted-by":"publisher","DOI":"10.2106\/JBJS.OA.21.00001","volume":"6","author":"S Tsukada","year":"2021","unstructured":"Tsukada S, Ogawa H, Nishino M, Kurosaka K, Hirasawa N. Augmented reality-assisted femoral bone resection in total knee arthroplasty. JBJS Open Access. 2021;6:e21.00001.","journal-title":"JBJS Open Access"},{"key":"371_CR11","doi-asserted-by":"publisher","first-page":"126","DOI":"10.3928\/01477447-20190424-02","volume":"42","author":"SM Howell","year":"2019","unstructured":"Howell SM. Calipered kinematically aligned total knee arthroplasty: an accurate technique that improves patient outcomes and implant survival. Orthopedics. 2019;42:126\u201335.","journal-title":"Orthopedics"},{"key":"371_CR12","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-025-13195-w","volume":"15","author":"M Ishikawa","year":"2025","unstructured":"Ishikawa M, Ishikawa M, Nagashima H, Hiranaka T. Manual restricted kinematic alignment technique restores postoperative limb alignment in severe knee deformities. Sci Rep. 2025;15:27757.","journal-title":"Sci Rep"},{"key":"371_CR13","doi-asserted-by":"publisher","DOI":"10.1186\/s12891-025-08955-8","volume":"26","author":"S Tsukada","year":"2025","unstructured":"Tsukada S, Ogawa H, Saito M, Minagawa S, Kurita M, Hirasawa N. The augmented reality-aided navigation system may improve rotational alignment of the tibial baseplate in total knee arthroplasty. BMC Musculoskelet Disord. 2025;26:704.","journal-title":"BMC Musculoskelet Disord"},{"key":"371_CR14","doi-asserted-by":"publisher","first-page":"106","DOI":"10.1016\/j.jjoisr.2024.06.003","volume":"2","author":"S Tsukada","year":"2024","unstructured":"Tsukada S, Ogawa H, Saito M, Kusakabe T, Nishino M, Hirasawa N. Relationship between intra-operative joint gap and knee flexion angle after posterior-stabilized total knee arthroplasty. J Joint Surg Res. 2024;2:106\u201310.","journal-title":"J Joint Surg Res"},{"key":"371_CR15","doi-asserted-by":"publisher","first-page":"1013","DOI":"10.1007\/s00167-007-0331-y","volume":"15","author":"T Matsumoto","year":"2007","unstructured":"Matsumoto T, Mizuno K, Muratsu H, Tsumura N, Fukase N, Kubo S, et al. Influence of intra-operative joint gap on post-operative flexion angle in osteoarthritis patients undergoing posterior-stabilized total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2007;15:1013\u20138.","journal-title":"Knee Surg Sports Traumatol Arthrosc"},{"key":"371_CR16","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1302\/0301-620X.103B2.BJJ-2020-1050.R1","volume":"103-B","author":"SJ MacDessi","year":"2021","unstructured":"MacDessi SJ, Griffiths-Jones W, Harris IA, Bellemans J, Chen DB. Coronal plane alignment of the knee (CPAK) classification. 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Orthop Traumatol Surg Res. 2024;110:103842.","journal-title":"Orthop Traumatol Surg Res"},{"key":"371_CR21","doi-asserted-by":"publisher","first-page":"140","DOI":"10.1097\/CORR.0000000000003193","volume":"483","author":"JP Gibbons","year":"2025","unstructured":"Gibbons JP, Zeng N, Bayan A, Walker ML, Farrington B, Young SW. No difference in 10-year clinical or radiographic outcomes between kinematic and mechanical alignment in TKA: a randomized trial. Clin Orthop Relat Res. 2025;483:140\u20139.","journal-title":"Clin Orthop Relat Res"},{"key":"371_CR22","doi-asserted-by":"publisher","first-page":"2069","DOI":"10.2106\/JBJS.24.01098","volume":"107","author":"T Tsuda","year":"2025","unstructured":"Tsuda T, Hino K, Kutsuna T, Watamori K, Kinoshita T, Horita Y, et al. Minimized medial soft tissue release with bone-recut adjustment improves short-term outcomes: compared with medial release in posterior-stabilized total knee arthroplasty. J Bone Joint Surg Am. 2025;107:2069\u201376.","journal-title":"J Bone Joint Surg Am"},{"key":"371_CR23","doi-asserted-by":"publisher","first-page":"S852","DOI":"10.1016\/j.arth.2022.02.059","volume":"37","author":"DF Scott","year":"2022","unstructured":"Scott DF, Gray CG. Outcomes are better with a medial-stabilized vs a posterior-stabilized total knee implanted with kinematic alignment. J Arthroplasty. 2022;37:S852\u20138.","journal-title":"J Arthroplasty"}],"container-title":["Arthroplasty"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s42836-026-00371-0.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1186\/s42836-026-00371-0","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s42836-026-00371-0.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T03:07:37Z","timestamp":1772248057000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1186\/s42836-026-00371-0"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,28]]},"references-count":23,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["371"],"URL":"https:\/\/doi.org\/10.1186\/s42836-026-00371-0","relation":{},"ISSN":["2524-7948"],"issn-type":[{"value":"2524-7948","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,28]]},"assertion":[{"value":"23 November 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"21 January 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"28 February 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"This study was approved by the institutional review board of the Hokusuikai Kinen Hospital. All procedures were performed in accordance with the Declaration of Helsinki. Informed consent was obtained in the form of opt-out on the website.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"Not applicable.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"One of the authors (S.T.) received royalties during the study period from Zimmer Biomet Japan. All other authors declare no potential conflicts of interest.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"14"}}