This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Anterior cruciate ligament (ACL) tears are a major health risk for female athletes. Early degenerative arthritis of the knee is more likely to develop in women with ACL tears as compared to their uninjured counterparts. ACL tears normally produce 6 - 12 months of disability after the injury. The National Collegiate Athletic Association Injury Surveillance Survey data identifies that female college athletes have a 3 - 8 times higher rate of ACL tears compared to males. ACL tears produce immediate and delayed disability in women. Little is known about modifiable risk factors in the prevention of ACL tears. Discovering these factors has been identified as a major goal by the National Institute of Arthritis Musculoskeletal and Skin Diseases (NIAMS) and the Office of Research on Women's Health. There are a number of proposed risk factors for instance a proposed association between ACL tears and the menstrual cycle. Over the menstrual cycle, changes are seen in the ACL measurements. The fluctuation of estrogen levels are proposed to be the cause of the changes in the ACL properties. Muscle-tendons complexes, including the Achilles tendon (AT), provide additional stability to the knee joint. These secondary restraints play an important role in the stability of the knee. Estrogen and progesterone affect the collagen content of tendons and ligaments (like the ACL and AT). Some investigators have recommended oral contraceptives, which prevents the estrogen spike, in order to prevent injury. These recommendations are premature since ACL risk factors have not been thoroughly studied and any current recommendations for the use of oral contraceptives are from retrospective studies with small sample sizes. Further, prospective, adequately powered, studies are needed to define the affects of supplemental hormones such as oral contraceptives (OCP) on the stretch and strain properties of the ACL. Previous studies quantifying the change in ACL laxity measurements across the menstrual cycle while a woman is on OCPs do not exist.
The specific aims of the proposed research project are first, to identify the affects of a monophasic OCPs on ACL measurements across the menstrual cycle. The secondary aim of the proposed research project is to identify the affects of monophasic OCPs on tendon extensibility across the menstrual cycle. Lastly, the proposed project will be used as preliminary data for a cross-over study investigating the change in ACL measurements with and without OCPs in an RO3 or RO1 application to NIAMS, which will carry out a more comprehensive evaluation on the risk factors for ACL tears.
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