{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T03:12:54Z","timestamp":1779333174697,"version":"3.51.4"},"reference-count":41,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100000069","name":"National Institute of Arthritis and Musculoskeletal and Skin Diseases","doi-asserted-by":"publisher","award":["P50AR080581"],"award-info":[{"award-number":["P50AR080581"]}],"id":[{"id":"10.13039\/100000069","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["DGE\u20102236662"],"award-info":[{"award-number":["DGE\u20102236662"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal Orthopaedic Research"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Achilles tendon ruptures cause muscle\u2013tendon structural and functional deficits that persist years after the initial injury. A healthy Achilles tendon contains three semi\u2010independent subtendons that slide relative to each other during muscle contractions in healthy adults. However, such sliding decreases postinjury as load sharing\u2014likely caused by intratendinous adhesions\u2014increases between adjacent subtendons. This study quantifies changes in subtendon load sharing 6\u201312 months following Achilles tendon rupture when patients are cleared by their surgeon to fully return to physical activities. We combined transverse plane ultrasound imaging with neuromuscular electrical stimulation of individual triceps surae muscles and applied a Kanade\u2013Lucas\u2013Tomasi point tracking algorithm to characterize subtendon behavior. We developed a surrogate measure of subtendon load sharing by quantifying differences in point displacement trajectory angles between select regions within the tendon cross section. In patients recovering from rupture injuries (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u200919), subtendon load sharing significantly increased in the injured tendon compared to the contralateral uninjured side during lateral gastrocnemius (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009=\u20090.0094), medial gastrocnemius (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009=\u20090.021), and soleus stimulations (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009=\u20090.048). These differences were not present between right and left legs in the uninjured cohort (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u200917). Linear regression analysis also revealed that the presence of tendon injury was significantly associated with subtendon load sharing, with injured tendons showing up to a 44% decrease in subtendon independence compared to the contralateral uninjured tendon during gastrocnemius stimulations.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Statement of Clinical Significance:<\/jats:bold>\n                    These results propose a novel biomarker of tendon health and suggest muscle\u2010dependent changes in subtendon function following Achilles tendon rupture.\n                  <\/jats:p>","DOI":"10.1002\/jor.70182","type":"journal-article","created":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T05:10:03Z","timestamp":1774588203000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Novel Measurement of Altered Achilles Subtendon Load Sharing 6\u201312 Months Following Rupture"],"prefix":"10.1002","volume":"44","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-0946-5927","authenticated-orcid":false,"given":"Kathryn S.","family":"Strand","sequence":"first","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3625-1082","authenticated-orcid":false,"given":"Todd J.","family":"Hullfish","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maggie M.","family":"Wagner","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Devyn","family":"Russo","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Max","family":"Zawel","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9792-4474","authenticated-orcid":false,"given":"Douglas E.","family":"Schaubel","sequence":"additional","affiliation":[{"name":"Department of Biostatistics, Epidemiology and Informatics University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Casey Jo","family":"Humbyrd","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0269-2170","authenticated-orcid":false,"given":"Josh R.","family":"Baxter","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery University of Pennsylvania Philadelphia Pennsylvania 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