{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T14:13:03Z","timestamp":1789999983556,"version":"4.0.1"},"reference-count":46,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,19]],"date-time":"2026-09-19T00:00:00Z","timestamp":1789776000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Prior NordBord studies have documented eccentric knee-flexor asymmetry during the first postoperative year and at later follow-up after hamstring-autograft ACLR. This study directly compared relative and Newton-based eccentric hamstring deficits between independent male-athlete cohorts tested with the same single-center protocol approximately 12 and 24 months after ACLR. Methods: In this single-center cross-sectional comparative study, 60 male athletes were assessed once in an independent 12-month cohort (n = 30) or 24-month cohort (n = 30) after unilateral primary ACLR. Bilateral eccentric peak force (PF) and mean force (MF) during the Nordic hamstring exercise were recorded with a NordBord device at 50 Hz. For PF, the highest value across three maximal trials was retained independently for each limb, so the retained involved- and uninvolved-limb values could originate from different trials. The primary outcome was PF limb symmetry index (LSI; involved\/uninvolved \u00d7 100); secondary outcomes included MF LSI, bilateral PF values, and PF LSI &lt; 90%. Results: PF LSI was 84.6 \u00b1 9.3% in the 12-month cohort and 93.5 \u00b1 6.8% in the 24-month cohort (mean difference 8.9 percentage points, 95% CI 4.7\u201313.1; p &lt; 0.001; d = 1.09). Involved-limb PF was 32.5 N higher in the 24-month cohort (95% CI 6.8\u201358.2; p = 0.014; d = 0.65), whereas uninvolved-limb PF was similar between cohorts (mean difference 2.5 N, 95% CI \u221221.9 to 26.9; p = 0.838; d = 0.05). PF LSI was &lt;90% in 21\/30 athletes (70.0%; 95% CI 52.1\u201383.3%) in the 12-month cohort and 7\/30 (23.3%; 95% CI 11.8\u201340.9%) in the 24-month cohort (\u03c72 = 13.13; p &lt; 0.001). Conclusions: The smaller eccentric hamstring asymmetry observed in the independent 24-month cohort was driven predominantly by higher involved-limb force rather than by a difference in uninvolved-limb force, yet nearly one quarter of that cohort remained below the 90% LSI benchmark. Postoperative time alone should therefore not substitute for late-stage objective eccentric knee-flexor assessment.<\/jats:p>","DOI":"10.3390\/diagnostics16183042","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T12:50:03Z","timestamp":1789995003000},"page":"3042","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Eccentric Hamstring Force Asymmetry After Anterior Cruciate Ligament Reconstruction: A Cross-Sectional Comparison of Independent 12- and 24-Month Postoperative Cohorts"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9138-6994","authenticated-orcid":false,"given":"Georgios","family":"Kakavas","sequence":"first","affiliation":[{"name":"Fysiotek Spine & Sports Lab, 17562 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5220-8992","authenticated-orcid":false,"given":"Nikolaos","family":"Malliaropoulos","sequence":"additional","affiliation":[{"name":"Sports & Exercise Medicine Clinic, Barts Health NHS Trust, London E1 1BB, UK"},{"name":"Center for Sports & Exercise Medicine, Queen Mary University of London, London E1 4NS, UK"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4916-1206","authenticated-orcid":false,"given":"Robert","family":"Prill","sequence":"additional","affiliation":[{"name":"Center of Orthopaedics and Traumatology, University Hospital Brandenburg\/Havel, Brandenburg Medical School Theodor Fontane, 14770 Brandenburg an der Havel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8650-2746","authenticated-orcid":false,"given":"Florian","family":"Forelli","sequence":"additional","affiliation":[{"name":"Haute-Ecole Arc Sant\u00e9, HES-SO University of Applied Sciences and Arts Western Switzerland, 2800 Del\u00e9mont, Switzerland"},{"name":"Orthopaedic Surgery Department, Clinic of Domont, Ramsay Healthcare, @OrthoLab, 95330 Domont, France"},{"name":"Soci\u00e9t\u00e9 Fran\u00e7aise des Masseurs-Kin\u00e9sith\u00e9rapeutes du Sport Lab, 93380 Pierrefitte-sur-Seine, France"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1032","DOI":"10.26603\/001c.88250","article-title":"Ligament healing after anterior cruciate ligament rupture: An important new patient pathway?","volume":"18","author":"Forelli","year":"2023","journal-title":"Int. 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