Differences in anterior cruciate ligament elasticity and force for knee flexion in women: oral contraceptive users versus non-oral contraceptive users

Abstract

Eighty-two percent of sexually active women aged 15-44 have used oral contraceptive pills (OCP) in the United States. The OCP, an exogenous source of synthetic forms of steroid hormones, prevents ovulation. Hormone changes during the menstrual cycle (MC) are believed to have an impact on anterior cruciate ligament (ACL) laxity due to estrogen. Because the estrogen receptor β resides on human connective tissue, OCP may have potential impact on tendon and ligament synthesis, structure, and biomechanical properties. Temperature has also been known to have an effect on tissue elasticity. Therefore, the purpose of this study was to investigate the differences in ACL elasticity, force to flex the knee (FFK), and knee flexion-extension hysteresis (KFEH) between OCP users and non-OCP users. To investigate these changes, two different knee temperatures were measured. Nineteen young females were divided into two groups: OCP users and non-OCP users. Blood for estradiol serum concentration (E2) was taken before beginning the tests. ACL elasticity, FFK, and KFEH were assessed both at ambient temperature (22 °C) and after 38 °C warming of the leg to stabilize tissue temperature. Assessments were performed four times during the MC. Throughout the MC, ACL elasticity, FFK, and KFEH fluctuated in non-OCP users, but not in OCP users. At ambient temperature, ACL elasticity was significantly lower and FFK and KFEH were significantly higher in OCP users than non-OCP users (p < 0.05). But, no significant differences in FFK and KFEH between the two groups were found after warming to 38 °C.

Do Oral Contraceptives Alter Knee Ligament Damage with Heavy Exercise?

“…The results of the present study agree with previous investigations (Park et al 2009a;Lee et al 2014). OCP users had significantly more pain than non-OCP users after intense exercise in the lower limbs but the pattern was a little different.…”

“…There has been a common theory that the presence of 17-beta estradiol receptors in the ACL is related to ACL laxity at ovulation (Liu et al 1997;Yu et al 1999;Hansen et al 2009;Lee et al 2014). Therefore, the present study attempted to see the difference in pain scale and ACL laxity recovery following a bout of squat.…”

“…The combined OCP contains estrogen and progesterone as synthetic steroids that prevent ovulation by inhibiting the release of follicle-stimulating hormone and luteinizing hormone from the pituitary gland in the brain (Kenny et al 2008;Krishnan and Kiley 2010). The 17-β estradiol receptors on the ACL are well established and therefore, it is of no surprise that OCP users have less ACL laxity than non-OCP users due to consistently lower levels of estradiol (Martineau et al 2004;Lee et al 2014).…”

“…Women have a greater risk for non-contact injuries of anterior cruciate ligament (ACL) compared to men (Zazulak et al 2006). Many studies have investigated if steroid hormones make women more susceptible to knee injuries (Arendt et al 1999;Griffin et al 2000;Zazulak et al 2006;Park et al 2009a, b;Lee et al 2014). One hormone in particular, estradiol, seems to play an important role in protecting women from muscle and ligament damage (Thompson et al 1997;Savage and Clarkson 2002).…”

Correlation between Mechanical Properties of the Ankle Muscles and Postural Sway during the Menstrual Cycle

“…Many researches have studied the relation between sex hormones and structure and mechanical properties found in human connective tissue (Heitz et al 1999;Slauterbeck and Hardy 2001;Shultz et al 2005;Lee et al 2013aLee et al , 2014). An obvious sex-related difference was observed in the role of estrogen in regulating muscle mass and ligament laxity (Lee et al 2013b), and, specifically, its relation to ligament laxity has been investigated (Hansen et al 2009a;Lee et al 2013a).…”