{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,3]],"date-time":"2025-11-03T04:47:28Z","timestamp":1762145248522,"version":"3.41.0"},"reference-count":31,"publisher":"National Athletic Trainers' Association","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2013,1,1]]},"abstract":"<jats:sec>\n                  <jats:title>Context<\/jats:title>\n                  <jats:p>Although changes in anterior knee laxity (AKL) across the menstrual cycle have been reported, the effects of cyclic knee laxity changes on the underlying characteristics of the load-displacement (stiffness) curve generated during anterior loading of the tibia relative to the femur are relatively unknown.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Objective<\/jats:title>\n                  <jats:p>To describe the anterior load-displacement curve during anterior loading of the tibia relative to the femur using incremental stiffnesses and to compare underlying stiffness measures between days of the cycle when AKL is at its minimum and maximum.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Design<\/jats:title>\n                  <jats:p>Descriptive laboratory study.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Setting<\/jats:title>\n                  <jats:p>University laboratory.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Patients or Other Participants<\/jats:title>\n                  <jats:p>Fifty-seven recreationally active women.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Main Outcome Measure(s)<\/jats:title>\n                  <jats:p>Anterior knee laxity and 6 incremental stiffness measures (N\/mm) were obtained with an instrumented knee arthrometer on days 1\u20136 of menses and days 0\u20138 postovulation during 2 consecutive menstrual cycles. Participants were then classified in tertiles based on the maximum change (difference between maximum and minimum) in AKL, and incremental stiffness was compared on days of minimum versus maximum laxity between the lowest (&amp;lt;1.24 mm cyclic laxity change = laxity \u201cnonresponders\u201d [n = 19]) and highest (&amp;gt;1.75 mm cyclic laxity change = laxity \u201cresponders\u201d [n = 19]) tertiles.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>All participants displayed decreasing stiffness initially (0\u201320 N &amp;gt; 20\u201340 N and 40\u201360 N), followed by incrementally increasing stiffness (40\u201360 N &amp;lt; 60\u201380 N &amp;lt; 80\u2013100 N &amp;lt; 100\u2013130 N) (P \u2264 .05). Responders demonstrated decreased stiffness between the days of minimum and maximum AKL at the 10\u2013130-N increment versus the 0\u201320-N and 20\u201340-N increments (P \u2264 .05); nonresponders had no change in stiffness.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>Participants who experienced larger magnitudes of cyclic changes in AKL also experienced decreases in terminal (100\u2013130 N) stiffness during anterior knee joint loading. Decreases in incremental stiffness at higher anterior directed loads may adversely affect passive restraint systems, resulting in altered arthrokinematics during functional activity.<\/jats:p>\n               <\/jats:sec>","DOI":"10.4085\/1062-6050-47.6.07","type":"journal-article","created":{"date-parts":[[2017,3,2]],"date-time":"2017-03-02T15:06:05Z","timestamp":1488467165000},"page":"39-46","source":"Crossref","is-referenced-by-count":7,"title":["Anterior Knee Stiffness Changes in Laxity \u201cResponders\u201d Versus \u201cNonresponders\u201d Across the Menstrual Cycle"],"prefix":"10.4085","volume":"48","author":[{"given":"Randy J.","family":"Schmitz","sequence":"first","affiliation":[{"name":"Department of Kinesiology, University of North Carolina at Greensboro"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sandra J.","family":"Shultz","sequence":"first","affiliation":[{"name":"Department of Kinesiology, University of North Carolina at Greensboro"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"2557","reference":[{"issue":"2","key":"2020060408331899400_i1062-6050-48-1-39-b01","doi-asserted-by":"crossref","first-page":"242","DOI":"10.2106\/00004623-198466020-00011","article-title":"Measurement of knee stiffness and laxity in patients with documented absence of the anterior cruciate ligament","volume":"66","author":"Markolf","year":"1984","journal-title":"J Bone Joint Surg Am"},{"issue":"7","key":"2020060408331899400_i1062-6050-48-1-39-b02","doi-asserted-by":"crossref","first-page":"1380","DOI":"10.1177\/0363546508317411","article-title":"Varus\/valgus and internal\/external torsional knee joint stiffness differs between sexes","volume":"36","author":"Schmitz","year":"2008","journal-title":"Am J Sports Med"},{"issue":"4","key":"2020060408331899400_i1062-6050-48-1-39-b03","doi-asserted-by":"crossref","first-page":"557","DOI":"10.2106\/00004623-199072040-00014","article-title":"Direct measurement of resultant forces in the anterior cruciate ligament: an in vitro study performed with a new experimental technique","volume":"72","author":"Markolf","year":"1990","journal-title":"J Bone Joint Surg Am"},{"issue":"3","key":"2020060408331899400_i1062-6050-48-1-39-b04","doi-asserted-by":"crossref","first-page":"588","DOI":"10.1177\/0363546508326713","article-title":"Changing hormone levels during the menstrual cycle affect knee laxity and stiffness in healthy female subjects","volume":"37","author":"Park","year":"2009","journal-title":"Am J Sports Med"},{"issue":"12","key":"2020060408331899400_i1062-6050-48-1-39-b05","doi-asserted-by":"crossref","first-page":"1655","DOI":"10.1016\/S0021-9290(01)00142-7","article-title":"A method for quantifying the anterior load-displacement behavior of the human knee in both the low and high stiffness regions","volume":"34","author":"Eagar","year":"2001","journal-title":"J Biomech"},{"issue":"5","key":"2020060408331899400_i1062-6050-48-1-39-b06","doi-asserted-by":"crossref","first-page":"583","DOI":"10.2106\/00004623-197658050-00001","article-title":"Stiffness and laxity of the knee\u2014the contributions of the supporting structures. 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