{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,30]],"date-time":"2026-10-30T06:55:26Z","timestamp":1793343326204,"version":"4.5.0"},"reference-count":32,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"3","content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,2,4]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>Anterior cruciate ligament (ACL) injuries may lead to long-term neuromuscular and structural adaptations in thigh muscles. Although quadriceps dysfunction is well reported, chronic changes in other muscle groups, especially in nonoperatively managed ACL-deficient individuals, remain poorly understood.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>The present cohort study utilized Osteoarthritis Initiative data to assess longitudinal thigh muscle changes in individuals with ACL tears confirmed on magnetic resonance imaging (MRI) and no history of reconstruction. A validated deep-learning model segmented muscle cross-sectional area and quantified intra-muscular adipose tissue and contractile percentage. Quantitative MRI data were obtained at baseline and at 4-year follow-up. Propensity score matching (1:2 to 1:3) controlled for baseline covariates. Strength was assessed with use of standardized Osteoarthritis Initiative protocols. Linear mixed-effects models compared longitudinal changes between ACL-deficient and ACL-intact thighs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>\n                      A total of 1,207 thighs were analyzed, including 92 with ACL tears and 1,115 controls, with a mean patient age of 61 \u00b1 9 years. Over 4 years, ACL-deficient thighs exhibited progressive hamstring atrophy (\u221228.18 mm\n                      <jats:sup>2<\/jats:sup>\n                      \/year; 95% confidence interval, \u221242.43 to \u221213.92; p &lt; 0.001) and sartorius atrophy (\u22123.02 mm\n                      <jats:sup>2<\/jats:sup>\n                      \/year; 95% confidence interval, \u22125.15 to \u22120.89; p = 0.006). No significant differences were observed in quadriceps or adductor cross-sectional area. Hamstring force decreased significantly (\u22123.49 N\/year; 95% confidence interval, \u22126.62 to \u22120.36; p = 0.029), whereas quadriceps force and specific force showed no significant changes. Intra-muscular adipose tissue and contractile percentage did not significantly differ between groups. Findings had been similar in unmatched patients\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions:<\/jats:title>\n                    <jats:p>The present findings highlight selective muscle deterioration in the posterior thigh muscles following ACL injury, with minimal changes in quadriceps morphology, over time. These results underscore the importance of long-term, targeted rehabilitation strategies focusing on hamstring preservation. This study represents the first longitudinal matched-cohort analysis of muscle morphology and fat infiltration in unreconstructed ACL-deficient knees.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Level of Evidence:<\/jats:title>\n                    <jats:p>\n                      Prognostic\n                      <jats:underline>Level II<\/jats:underline>\n                      . See Instructions for Authors for a complete description of levels of evidence.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.2106\/jbjs.25.00641","type":"journal-article","created":{"date-parts":[[2025,12,10]],"date-time":"2025-12-10T19:00:24Z","timestamp":1765393224000},"page":"219-226","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":2,"title":["Thigh Muscle Changes in the ACL-Deficient Knee"],"prefix":"10.2106","volume":"108","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0327-7967","authenticated-orcid":false,"given":"Osama","family":"Alzobi","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery, Surgical Specialty Center, Hamad Medical Corporation, Doha, Qatar"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6398-8448","authenticated-orcid":false,"given":"Bahram","family":"Mohajer","sequence":"additional","affiliation":[{"name":"University of Pennsylvania, Philadelphia, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-8023-4083","authenticated-orcid":false,"given":"Jean","family":"Fleuriscar","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5991-5924","authenticated-orcid":false,"given":"Shadpour","family":"Demehri","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4293-6662","authenticated-orcid":false,"given":"Bashir A.","family":"Zikria","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2025,12,10]]},"reference":[{"issue":"6","key":"bib1-20260204","doi-asserted-by":"crossref","first-page":"1502","DOI":"10.1177\/0363546516629944","article-title":"Incidence of Anterior Cruciate Ligament Tears and Reconstruction: A 21-Year Population-Based Study","volume":"44","author":"Sanders","year":"2016","journal-title":"Am J Sports Med."},{"issue":"2","key":"bib2-20260204","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1249\/MSS.0000000000003574","article-title":"Knee Extensor and Flexor Force Control after ACL Injury and Reconstruction: A Systematic 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