Relationship of the menstrual cycle phase to anterior cruciate ligament injuries in teenaged female athletes Relaxin Receptors in the Human Female Anterior Cruciate Ligament The Menstrual Cycle, Sex Hormones, and Anterior Cruciate Ligament Injury. Knee ligament behavior following a controlled loading protocol does not differ by menstrual cycle day. The Effects of Generalized Joint Laxity on Risk of Anterior Cruciate Ligament Injury in Young Female Athletes Intraarticular Injuries Associated with Anterior Cruciate Ligament Tear: Findings at Ligament Reconstruction in High School and Recreational Athletes Intercondylar notch size and anterior cruciate ligament injuries in athletes Risk Factors Associated with Noncontact Injury of the Anterior Cruciate Ligament A Randomized Controlled Trial to Prevent Noncontact Anterior Cruciate Ligament Injury in Female Collegiate Soccer Players
Introduction Anterior cruciate ligament ( ACL ) injuries are more common among female athletes compared to male athletes . Several studies have been reported to explain the gender difference in ACL injury rates and several risk factors underlying gender disparity are believed to exist . Hormonal effects are considered to be one of the etiological factors for female non-contact ACL injuries . The objectives of this study were to determine if ACL injuries occurred r and omly or correlated with a specific phase of the female menstrual cycle in teenaged female athletes and then to determine if pre-menstrual and menstrual dysfunctions influenced these ACL injuries . Material s and methods Eighteen of 37 consecutive female athletes , with ACL injuries , met the study criteria : teenage , with regular menstrual cycle , and non-contact injury . The menstrual history , athletic activity , and injury history were collected . Results Seventy-two percent of the subjects had premenstrual symptoms and 83 % had  menstrual symptoms . The subjective activity level at the follicular phase was significantly lowest between the phases . A significant statistical association was found between the phase of the menstrual cycle and ACL injuries ( P = 0.0002 ) . There were more injuries in the ovulatory phase than expected , and fewer injuries occurred in the other phases . Conclusion The results showed a significant increase in non-contact ACL injuries in teenage female athletes during the ovulatory phase of the menstrual cycle and the subjective activity level and the premenstrual and menstrual symptoms might not affect the likelihood of the injuries . These findings suggest that sex hormones might play a role in the incidence of female non-contact ACL injuries Background Noncontact anterior cruciate ligament injuries occur two to eight times more often in women than in men . Changes in ligament laxity and strength have been associated with female hormones such as relaxin . Hypothesis Relaxin receptors are present within the female anterior cruciate ligament . Study Design Controlled laboratory study . Methods Remnants of anterior cruciate ligament were harvested from five women and five men undergoing routine ligament reconstruction . Relaxin was biotinylated and analyzed for biologic activity with use of the mouse interpubic ligament bioassay . Immunohistochemical localization of relaxin receptors was performed with appropriate negative controls and competitive binding assays to determine receptor specificity and saturability . Results Anterior cruciate ligament sections from women but not from men showed uniform specific binding that was limited to synovial lining cells , stromal fibroblasts , and cells lining blood vessels . Specific binding was confirmed in the presence of a 2000-fold excess of human insulin , the structural homolog of relaxin , and competitive inhibition was demonstrated in the presence of a 2000-fold excess of unlabeled relaxin . Conclusions Relaxin exhibits specific saturable binding in the female anterior cruciate ligament , where specific relaxin receptors were present . Clinical Relevance The high incidence of anterior cruciate ligament rupture in female athletes may be partially explained by the effects of relaxin OBJECTIVE : To determine if anterior cruciate ligament ( ACL ) injuries in female athletes occur r and omly or correlate with a specific phase of the menstrual cycle . DESIGN AND SETTING : Female athletes who sustained ACL injuries reported the days of their menstrual cycles and provided saliva sample s for sex-hormone determination . Salivary sex-hormone profiles were assessed to confirm the self-reported menstrual histories . SUBJECTS : A total of 38 female athletes ( 20 college , 15 high school , 1 middle school , 2 recreational ) with recent ACL injuries participated in the study over a 3-year period . MEASUREMENTS : Athletes with recent ACL injuries completed a question naire defining the injury , the last menstrual cycle , prior knee injury , school , and type of birth control used ( if any ) . Each subject provided a 30-cc saliva sample within 72 hours of injury . Saliva sample s were placed into sealed containers and frozen at -20 degrees C. We obtained 13 additional control sample s from uninjured females to test the correlation between saliva and serum sex-hormone levels . Progesterone and estrogen were assayed by radioimmunoassay . Physical examination , magnetic resonance imaging , or surgery confirmed the injury in all subjects . RESULTS : The correlations between saliva and serum estrogen and progesterone were 0.73 ( alpha = .01 ) and 0.72 ( alpha = .01 ) , respectively . Ten of 27 athletes who reported their cycle day at time of injury sustained an ACL injury immediately before or 1 to 2 days after the onset of menses . We rejected the null hypothesis that such high frequency was due to r and om chance . CONCLUSIONS : A significantly greater number of ACL injuries occurred on days 1 and 2 of the menstrual cycle . Salivary sex-hormone levels correlated with the reported cycle day BACKGROUND Females experience a disproportionate number of anterior cruciate ligament injuries compared to males . Increased estradiol concentration has been suggested to alter ligament properties and strength . Determining whether the knee responds differently to an external load at various hormonal levels may be helpful in further explaining the gender disparity . METHODS  Estradiol , progesterone and testosterone  were quantified at menses , near ovulation and at the mid-luteal phase . With one knee serving as the control limb and the other as the experimental limb , displacement at 134N and stiffness between 90 and 134N were recorded with a knee ligament arthrometer on both knees before and after a loading protocol . The protocol consisted of three , 3-min , posterior to anterior normalized loads directed to the posterior calf with a ligament testing device . FINDINGS The loading protocol produced a measurable increase in displacement but not stiffness . Neither displacement nor stiffness measures however were affected by day of the menstrual cycle . No consistent relationships between hormonal concentrations and displacement or stiffness were evident . INTERPRETATION Following a controlled , static external load , displacement and stiffness were not affected differently by day of the menstrual cycle Background Women who participate in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than men . Purpose To prospect ively determine if female athletes with decreased passive knee joint restraint ( greater joint laxity ) and greater side-to-side differences in knee laxity would be at increased risk of anterior cruciate ligament injury . Study Design Case control study ; Level of evidence , 3 . Methods From 1558 female soccer and basketball players who were prospect ively screened , 19 went on to tear their anterior cruciate ligaments . Four height- and mass-matched control subjects were selected from the uninjured screened athletes for comparison with each of the 19 injured subjects , making a total of 95 subjects ( 19 injured ; 76 uninjured ) . Generalized joint-laxity tests and anterior-posterior tibiofemoral translation were quantified using the CompuKT knee arthrometer . A multivariable logistic regression model was constructed to determine predictors of anterior cruciate ligament injury status from recorded laxity measures . Results A multivariable logistic regression model ( chi-square = 18.6 ; P = .002 ) used the independent variables laxity measures of knee hyperextension ( P = .02 ) , wrist and thumb to forearm opposition ( P = .80 ) , fifth-finger hyperextension > 90 ° ( P = .71 ) , side-to-side differences in anterior-posterior tibiofemoral translation ( P = .002 ) , and prior knee injury ( P = .22 ) to predict anterior cruciate ligament-injury status . The vali date d C statistic , or vali date d area under the receiver operating characteristic curve , was 0.72 . For every 1.3-mm increase in side-to-side differences in anterior-posterior knee displacement , the odds of anterior cruciate ligament – injured status increased 4-fold ( 95 % confidence interval , 1.68–9.69 ) . A positive measure of knee hyperextension increased the odds of anterior cruciate ligament-injured status 5-fold ( 95 % confidence interval , 1.24–18.44 ) . Conclusion The current results indicate that increased knee-laxity measures may contribute to increased risk of anterior cruciate ligament injury . The methods to quantify knee joint laxity in this report may be used in conjunction with measures of neuromuscular control of the knee joint to identify high-risk female athletes with high accuracy . Once high-risk female athletes are identified , they may be targeted to the appropriate interventions to reduce injury risk Background Despite research on the increased risk of anterior cruciate ligament tears in female athletes , few studies have addressed sex differences in the incidence of associated intraarticular injuries . Hypothesis When patients are stratified by sport and competition level , no sex differences exist in either the mechanism of injury or pattern of intraarticular injuries observed at  anterior cruciate ligament reconstruction .  Study Design Prospect i ve cohort study . Methods Two hundred twenty-one athletes undergoing anterior cruciate ligament reconstruction met our inclusion criteria of anterior cruciate ligament tear as a singular event without reinjury or history of prior injury or surgery in either knee . Data were collected on competition level ( high school , amateur ) , sport ( basketball , soccer , skiing ) , mechanism of injury , articular cartilage injuries , and meniscal tears . Data were statistically analyzed by sex with the chi-square test and Student 's t-test . Results High school athletes had no significant sex differences in mechanism of injury .  Female soccer athletes had fewer medial meniscal tears than did male athletes , and female basketball players had fewer medial femoral condyle injuries . At the amateur level , female basketball players had more contact injuries , an earlier onset of swelling , and fewer lateral meniscal tears than did male players . Conclusion At the high school level , male and female athletes shared a common mechanism of injury , and yet the female athletes had fewer intraarticular injuries in basketball and soccer . If such intraarticular injuries prove to be a significant risk factor for poor long-term outcome , women may enjoy a better prognosis after reconstruction Published reports agree that there is a strong associa tion between intercondylar notch stenosis and anterior cruciate ligament injuries . In a previously published retrospective study on bilateral anterior cruciate liga ment injuries and associated intercondylar notch ste nosis , we formulated the notch width index to measure and compare intercondylar notch width . The purpose of this prospect i ve study was to establish a normal range for the notch width index and to correlate inter condylar notch size and anterior cruciate ligament in juries . We gathered data on 902 high school athletes , including range of motion , thigh girth , ligament stability and intercondylar notch width using the notch width index .  The population was then followed prospect ively and anterior cruciate ligament injuries were recorded and correlated with notch width index in a blind manner . Two-year results showed that the overall anterior cru ciate ligament injury rate was 3 % . The normal intercon dylar notch ratio was 0.231 ± 0.044 . Intercondylar notch width index for men was larger than that for women . Athletes sustaining noncontact anterior cru ciate ligament tears have statistically significant inter condylar notch stenosis ( notch width index , 0.189 ) . Ten of 14 athletes with noncontact anterior cruciate liga ment injuries had a notch width index that was at least 1 SD below the mean . Athletes with contact anterior cruciate ligament injuries had a mean of 0.233 . We conclude that athletes with a stenotic intercondylar notch are at significantly greater risk for sustaining noncontact anterior cruciate ligament injury Background : The causes of noncontact anterior cruciate ligament injury remain an enigma . Purpose : To prospect ively evaluate risk factors for noncontact anterior cruciate ligament injuries in a large population of young athletic people . Study Design : Prospect i ve cohort study . Methods : In 1995 , 1198 new United States Military Academy cadets underwent detailed testing and many parameters were documented . During their 4-year tenure , all anterior cruciate ligament injuries that occurred were identified . Statistical analyses were used to identify the factors that may have predisposed the cadets to noncontact anterior cruciate ligament injuries . Results : Among the 895 cadets who completed the entire 4-year study , there were 24 noncontact anterior cruciate ligament tears ( 16 in men , 8 in women ) . Significant risk factors included small femoral notch width , generalized joint laxity , and , in women , higher than normal body mass index and KT-2000 arthrometer values that were 1 st and ard deviation or more above the mean . The presence of more than one of these risk factors greatly increased the relative risk of injury . All female cadets who had some combination of risk factors sustained noncontact anterior cruciate ligament injuries , indicating that some combinations of factors are especially perilous to the female knee . Conclusion : Several risk factors may predispose young athletes to noncontact anterior cruciate ligament injury Background Neuromuscular and proprioceptive training programs can decrease noncontact anterior cruciate ligament injuries ; however , they may be difficult to implement within an entire team or the community at large . Hypothesis A simple on-field alternative warm-up program can reduce noncontact ACL injuries . Study Design R and omized controlled trial ( clustered ) ; Level of evidence , 1 . Methods Participating National Collegiate Athletic Association Division I women 's soccer teams were assigned r and omly to intervention or control groups . Intervention teams were asked to perform the program 3 times per week during the fall 2002 season . All teams reported athletes ’ participation in games and practice s and any knee injuries . Injury rates were calculated based on athlete exposures , expressed as rate per 1000 athlete exposures . A z statistic was used for rate ratio comparisons . Results Sixty-one teams with 1435 athletes completed the study ( 852 control athletes ; 583 intervention ) . The overall anterior cruciate ligament injury rate among intervention athletes was 1.7 times less than in control athletes ( 0.199 vs 0.340 ; P = .198 ; 41 % decrease ) . Noncontact anterior cruciate ligament injury rate among intervention athletes was 3.3 times less than in control athletes ( 0.057 vs 0.189 ; P = .066 ; 70 % decrease ) . No anterior cruciate ligament injuries occurred among intervention athletes during practice versus 6 among control athletes ( P = .014 ) . Game-related noncontact anterior cruciate ligament injury rates in intervention athletes were reduced by more than half ( 0.233 vs 0.564 ; P = .218 ) . Intervention athletes with a history of anterior cruciate ligament injury were significantly less likely to suffer another anterior cruciate ligament injury compared with control athletes with a similar history ( P = .046 for noncontact injuries ) . Conclusion This program , which focuses on neuromuscular control , appears to reduce the risk of anterior cruciate ligament injuries in collegiate female soccer players , especially those with a history of anterior cruciate ligament injury
The clinical relevance of this finding is that female athletes may be more predisposed to anterior cruciate ligament injuries during the preovulatory phase of the menstrual cycle .
These findings may lead to potential interventions targeted toward this phase of the menstrual cycle to reduce the incidence of anterior cruciate ligament injury
Several theories have been proposed to explain the 3- to 6-fold gender difference in the incidence of anterior cruciate ligament injuries .
One potential theory for the increased incidence is based on gender-related hormonal differences between men and women , especially after puberty and the onset of menses in the female athlete .
The purpose of this systematic review was to compile and systematic ally analyze the published literature to determine if the menstrual cycle is associated with anterior cruciate ligament injury risk and to provide an objective comparison of the published results .