{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T15:32:40Z","timestamp":1787758360205,"version":"build-2784847793"},"reference-count":42,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Early functional rehabilitation after acute Achilles tendon rupture is increasingly used in nonoperative protocols, but the definition of \u201cearly\u201d remains highly heterogeneous across the literature and no standardized timing threshold has been established. This narrative review clarifies the conceptual and operational definitions of early rehabilitation and examines the unresolved timing-threshold problem. Existing evidence supports early functional rehabilitation without a demonstrated increase in rerupture risk compared with delayed immobilization. Early rehabilitation may improve short-term functional recovery; however, clear long-term superiority over more delayed strategies has not been demonstrated. Substantial heterogeneity persists in the initiation of weightbearing and range of motion and in orthosis duration. Although weightbearing within four weeks is commonly used as an operational definition of early rehabilitation for evidence synthesis, it is not a biologically or clinically validated threshold. The literature also lacks granular evidence defining a timing\u2013response relationship or an optimal initiation window. Current evidence therefore supports early functional rehabilitation as a reasonable strategy, but future research should identify validated timing\u2013response relationships and patient-specific strategies.<\/jats:p>","DOI":"10.3390\/jcm15176597","type":"journal-article","created":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T15:04:32Z","timestamp":1787756672000},"page":"6597","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["How Early Is Early? Defining Functional Rehabilitation After Acute Achilles Tendon Rupture: A Narrative Review"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5381-0048","authenticated-orcid":false,"given":"Masanori","family":"Hashimoto","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9866-503X","authenticated-orcid":false,"given":"Youichi","family":"Yasui","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomoyuki","family":"Nakasa","sequence":"additional","affiliation":[{"name":"Department of Musculoskeletal Reconstruction and Biomaterials, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3156-5904","authenticated-orcid":false,"given":"Hirotaka","family":"Kawano","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9038-8840","authenticated-orcid":false,"given":"Wataru","family":"Miyamoto","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1497","DOI":"10.2106\/JBJS.M.01273","article-title":"Nonoperative Dynamic Treatment of Acute Achilles Tendon Rupture: The Influence of Early Weight-Bearing on Clinical Outcome: A Blinded, Randomized Controlled Trial","volume":"96","author":"Barfod","year":"2014","journal-title":"J. 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