Association between the menstrual cycle and anterior cruciate ligament injuries in female athletes

Relative Energy Deficiency in Sport (RED-S) and Knee Injuries: Current Concepts for Female Athletes

In athletes, a mismatch between caloric intake and energy expended in exercise can result in Low Energy Availability (LEA). LEA can lead to Relative Energy Deficiency in Sport (RED-S), where the athlete suffers from physiological derangements and decreased sport performance. The prevalence of RED-S is higher in females than males. RED-S more comprehensively describes the syndrome originally known as "Female Athlete Triad" (FAT). FAT encompasses the triad of LEA (with or without disordered eating), menstrual dysfunction and low bone mineral density. RED-S includes other physiological derangements such as poor cardiovascular health, abnormalities of metabolic rate, immunity, and protein synthesis. Females are already at a higher risk of knee injuries, which has been attributed to a multitude of factors such as hormonal influences, differences in musculoskeletal anatomy and neuromuscular control compared to males. The literature demonstrates an even higher risk of knee injuries in female athletes with symptoms of RED-S. We propose the various factors that influence this risk. A reduction in anabolic hormones can affect muscle development and tendon repair. A relationship between poor neuromuscular control and knee injury has been established, and this can be further worsened in patients with menstrual dysfunction. Chronic deficiency in nutrients such as collagen and vitamin D can result in poorer recovery from microtrauma in tendon and ligaments. All these factors may contribute to increasing the risk of knee injuries, which may include anterior cruciate ligament tears, patella tendinopathy and patellofemoral pain syndrome. This review aims to educate sports clinicians to have a high index of suspicion when treating knee injuries in females; to screen and then manage for RED-S if present, for holistic patient care.

Knee Laxities Changes with Sex-steroids throughout the Menstrual Cycle Phases in Athlete and Non-athlete Females

Objective:  Our study investigated changes of knee laxities in athletes and non-athletes females and relationship between knee laxity and sex-steroid at menstrual cycle phases. Methods:  Forty six healthy females, twenty four athletes and twenty two non-athletes not on hormone contraceptive pills, had no previous knee injuries and with regular menstrual cycles for 3 consecutive months, participated in the study. Medial and lateral knee laxities were determined by varus-valgus tests at follicular, ovulatory and luteal phases. Serum level of relaxin, estrogen, progesterone and testosterone were determined by ELISA and radioimmunoassay. Results:  Knee laxities in athletes and non-athletes at 0° and 20° flexion were the highest in luteal phase with non-athletes possess greater laxity than athletes. Positive correlation between progesterone and relaxin levels with knee laxities were observed. Meanwhile, the levels of both hormones were highest in the luteal phase. Conclusion:  Increased medial and lateral knee laxities in athletes and non-athletes associated with high serum progesterone and relaxin levels in luteal phase may contribute toward increased risk of non-contact knee injury. However, lower knee laxity in athletes than non-athletes suggest that exercise could be a protective factor.

Neo-Natal Castration Leads to Subtle Differences in Porcine Anterior Cruciate Ligament Morphology and Function in Adolescence

Female adolescent athletes are at a higher risk of tearing their anterior cruciate ligament (ACL) than male counterparts. While most work related to hormones has focused on the effects of estrogen to understand the increased risk of ACL injury, there are other understudied factors, including testosterone. The purpose of this study was to determine how surgical castration in the male porcine model influences ACL size and function across skeletal growth. Thirty-six male Yorkshire crossbreed pigs were raised to 3 (juvenile), 4.5 (early adolescent), and 6 months (adolescent) of age. Animals were either castrated (barrows) within 2 weeks after birth or were left intact (boars). Posteuthanasia, joint and ACL size were assessed via MRI, and biomechanics were assessed via a robotic testing system. Joint size increased throughout age, yet barrows had smaller joints than boars. ACL cross-sectional area (CSA), length, volume, and in situ stiffness increased with age, as did the percent contribution of the ACL anteromedial (AM) bundle to resisting loads. Boar ACL, AM bundle, and PL bundle volumes were 19%, 25%, and 15% larger than barrows across ages. However, ACL CSA, in situ stiffness, and bundle contribution were similar between boars and barrows. The barrows had smaller temporal increases in AM bundle function than boars, but these data were highly variable. Early and sustained loss in testosterone leads to subtle differences in ACL morphology but may not influence measures associated with increased injury risk, such as CSA or bundle forces in response to applied loads.

Age of Adolescent Female Soccer Players at First Ankle Sprain and Menarche

Objectives

: To provide targeted interventions for the prevention of first ankle sprains, this study determined the prevalence of ankle sprains in female adolescent soccer players and analyzed the correlation between the age at the first occurrence of ankle sprain and the age at menarche.

Methods

: The study included 131 female participants from three club teams. The mean age was 13.37 ± 0.96 years. A survey was conducted using a questionnaire that requested information regarding the age at which the first ankle sprain occurred, age at menarche, status of ankle problems, extent to which the ankle joint problem affected playing ability, use of medical facilities or other healthcare facilities for the first or recurrent ankle sprains, and methods used to care for their ankle.

Results

Ankle sprains most commonly occurred for the first time at 12 years, followed by the ages of 13, 10, and 11 years. About 25% of participants experienced their first ankle sprain at the age of menarche, 20% at 1 year after menarche, and 16% a year before menarche. The incidence of the first ankle sprain was high in the second and fifth years after starting to play soccer. Medical treatment was rarely received for the second or subsequent injury, although 36% had some sequelae.

Conclusions

Adolescent female soccer players were not injured early in their soccer careers. Most players experienced their first ankle sprain at the age of 12 years, which was at or close to the age of menarche.

Menstrual Cycle Associated Alteration of Vastus Lateralis Motor Unit Function

BACKGROUND

Estrogen and progesterone are the primary female sex hormones and have net excitatory and inhibitory effects, respectively, on neuronal function. Fluctuating concentrations across the menstrual cycle has led to several lines of research in relation to neuromuscular function and performance; however evidence from animal and cell culture models has yet to be demonstrated in human motor units coupled with quantification of circulating hormones. Intramuscular electromyography was used to record motor unit potentials and corresponding motor unit potential trains from the vastus lateralis of nine eumenorrheic females during the early follicular, ovulation and mid luteal phases of the menstrual cycle, alongside assessments of neuromuscular performance. Multi-level regression models were applied to explore effects of time and of contraction level. Statistical significance was accepted as p < 0.05.

RESULTS

Knee extensor maximum voluntary contraction, jump power, force steadiness, and balance did not differ across the menstrual phases (all p > 0.4). Firing rate of low threshold motor units (10% maximum voluntary contraction) was lower during the ovulation and mid luteal phases (β = - 0.82 Hz, p < 0.001), with no difference in motor unit potentials analysed from 25% maximum voluntary contraction contractions. Motor unit potentials were more complex during ovulation and mid luteal phase (p < 0.03), with no change in neuromuscular junction transmission instability (p > 0.3).

CONCLUSIONS

Assessments of neuromuscular performance did not differ across the menstrual cycle. The suppression of low threshold motor unit firing rate during periods of increased progesterone may suggest a potential inhibitory effect and an alteration of recruitment strategy; however this had no discernible effect on performance. These findings highlight contraction level-dependent modulation of vastus lateralis motor unit function over the eumenorrheic cycle, occurring independently of measures of performance.

Higher Rates of Residual Postoperative Instability after Anterior Cruciate Ligament Reconstruction in Female Patients: A Systematic Review of Level II Studies

PURPOSE

To compare revision rates and residual postoperative instability after anterior cruciate ligament (ACL) reconstruction based on biological sex.

METHODS

A systematic review was conducted according to the 2020 PRISMA guidelines. PubMed, Embase, MEDLINE, and Cochrane library databases were queried from database inception through October 2022. Level I and II prospectively-enrolling human clinical studies that compared revision rates and physical examination of postoperative stability after ACL reconstruction between male and female patients were included. Outcomes were stratified by patient sex and quantitatively compared using a χ2 test. Study quality was assessed using the MINORS criteria.

RESULTS

Four studies consisting of 406 patients (50% males) with a mean age of 25 years (range, 13.9-62 years) were identified. Mean follow-up time was 34.4 months (range, 22-60 months). Hamstring tendon autografts were used in 62% of ACL reconstructions in males and in 65% of ACL reconstructions in females, whereas bone-patellar tendon-bone autografts were used in 38% and 35% of procedures in males and females, respectively. A residual positive Lachman test result was more frequently reported among females compared to males (5.8% vs 0.6%; P = 0.03). No significant difference in revision rates or residual pivot-shift on examination was observed between males and females (P = 0.38 and P = 0.08, respectively).

CONCLUSION

Female patients undergoing ACL reconstruction have higher reported rates of residual anterior instability with Lachman than male patients. However, no sex-based differences were identified with residual pivot-shift on examination or rate of revision ACL surgery.

LEVEL OF EVIDENCE

II; Systematic Review of level II studies.

The Accuracy of Early Reproductive History and Physical Activity Participation Recall Across Multiple Age Ranges

Background: The ability to accurately recall specific reproductive health events is an integral aspect of medical decision making and evaluating a female's overall health and wellness across their lifespan. The Health and Reproductive Survey (HeRS) was developed to recall reproductive events and environmental influences on reproductive characteristics throughout the lifespan of a female. This study aimed to determine how reliably women recall certain events during menarche and early reproductive years. It was hypothesized that age at menarche, hormonal contraceptive use, and physical activity would be recalled reliably among all age ranges, while the recall reliability for cycle regularity and length would be more inconsistent with advancing age. Materials and Methods: A total of 144 participants (age: 32.73 ± 11.92), completed the HeRS on two occasions spaced 4 months apart to investigate recall reliability. Cohen's kappa coefficient was used to assess the consistency of categorical responses and 95% limits of agreement were used for continuous data. Results: Although physical activity changes had greater variability than anticipated (0.79), the recall reliability among the youngest (1) and oldest (0.89) age groups was high, and females were able to consistently recall the age of menarche (0.83), physical activity level (0.9), cessation of period during early reproductive years (0.91), and birth control use following menarche (0.85) and during the early reproductive years (0.9). Conclusions: The HeRS is a useful tool for reliably recalling reproductive history and physical activity participation across multiple age ranges and can be utilized to gather crucial information throughout the reproductive lifespan.

Relationship between the knee valgus moment and the hip abductor and adductor activity during single-leg landing

OBJECTIVES

To reveal the relationship between the knee valgus moment (KVM) and the hip abductor and adductor activity during single-leg landing.

DESIGN

A cross-sectional study.

SETTING

Laboratory-based, between April 2020 and May 2021.

PARTICIPANTS

Thirty female collegiate athletes.

MAIN OUTCOME MEASURES

KVM, hip adduction angle, hip internal rotation angle, knee valgus angle (KVA), gluteus medius muscle activity, adductor longus muscle activity, adductor longus to gluteus medius activity ratio (ADD/GMED), and vertical component of the ground reaction force (vGRF).

RESULTS

Stepwise multiple regression analysis was performed. KVM was significantly positively associated with KVA (β = 0.613, p < 0.001), vGRF (β = 0.367, p = 0.010), and ADD/GMED (β = 0.289, p = 0.038).

CONCLUSIONS

Increased KVA, vGRF, and ADD/GMED were the independent factors that contributed to increased KVM during single-leg landing, and only ADD/GMED was found among the muscle activity values. The relative muscle activity of the gluteus medius and adductor longus, rather than those of the gluteus medius or adductor longus alone, may be useful in preventing anterior cruciate ligament injury during single-leg landing.

Neo-natal castration leads to subtle differences in porcine anterior cruciate ligament morphology and function in adolescence

Female adolescent athletes are at a higher risk of tearing their anterior cruciate ligament (ACL) than male counterparts. While most work related to hormones has focused on the effects of estrogen to understand the increased risk of ACL injury, there are other understudied factors, including testosterone. The purpose of this study was to determine how surgical castration in the male porcine model influences ACL size and function across skeletal growth. Thirty-six male Yorkshire crossbreed pigs were raised to 3 (juvenile), 4.5 (early adolescent), and 6 months (adolescent) of age. Animals were either castrated (barrows) within 1-2 weeks after birth or were left intact (boars). Post-euthanasia, joint and ACL size were assessed via MRI, and biomechanics were assessed via a robotic testing system. Joint size increased throughout age, yet barrows had smaller joints than boars (p<0.001 for all measures). ACL cross-sectional area (CSA), length, volume, and stiffness increased with age (p<0.0001), as did ACL anteromedial (AM) bundle percent contribution to resisting loads (p=0.012). Boar ACL, AM bundle, and PL bundle volumes were 19% (p=0.002), 25% (p=0.003), and 15% (p=0.04) larger than barrows across ages. However, CSA, stiffness, and bundle contribution were similar between boars and barrows (p>0.05). The barrows had smaller temporal increases in AM bundle percent function than boars, but these data were highly variable. Thus, early and sustained loss in testosterone leads to subtle differences in ACL morphology, but may not influence measures associated with increased injury risk, such as CSA or bundle forces in response to applied loads.

Menstrual Cycle and Sport Injuries: A Systematic Review

The presence of female athletes has only increased in recent years, as has the incidence of injuries in female sports activities. These injuries are conditioned by multiple factors, including hormonal agents. It is estimated that the menstrual cycle may be related to the predisposition to suffer an injury. However, a causal relationship has not yet been established. The aim of this study was to analyse the relationship between the menstrual cycle and injuries in female sports practice. A systematic search of the scientific literature available in PubMed, Medline, Scopus, Web of Science, and Sport Discus was carried out in January 2022. With 138 articles, only eight studies were found that met the selection criteria for this study. Peak estradiol is associated with increased laxity, strength, and poor use of neuromuscular control. Thus, the ovulatory phase is associated with an increased risk of injury. In conclusion, it seems that hormonal fluctuations throughout the menstrual cycle alter values such as laxity, strength, body temperature, and neuromuscular control, among others. This fact causes women to constantly adapt to hormonal variations, which exposes them to a higher risk of injury.

Evaluation of sex differences in rodent anterior cruciate ligament injury

The relative contributions of sex differences in anatomy, biomechanics, and hormones to the increased risk of anterior cruciate ligament (ACL) injury in female athletes remains unknown. The purpose of this study is to investigate sex differences in anatomy and biomechanics of the native and reconstructed ACL using our established murine model. A total of 140 12-week-old wild-type C57Bl/6 (70 male vs. 70 female) mice were used for this study. ACL reconstruction was performed on 120 mice who were split into four groups: Group 1 (30 males sacrificed at 14 days), Group 2 (30 females sacrificed at 14 days), Group 3 (30 males sacrificed at 28 days), and Group 4 (30 females sacrificed at 28 days). Tendon graft-to-bone healing was assessed by biomechanical, histological, and micro-CT analysis. Twenty mice were used for baseline testing. Females showed significantly higher anterior (p < 0.05) and total displacement (p < 0.05). Males demonstrated a significantly higher load-to-failure force of native ACLs compared to females (p < 0.05). There was no significant difference in load-to-failure force in the ACL autograft. There were no significant sex differences in histological analysis of graft integration or tibial slope. The increased knee laxity and reduced load-to-failure of the native ACL observed in the female mice are consistent with some of the proposed risk factors driving the increased risk of ACL injury in females. Understanding the relative contributions of factors driving sex differences in material properties of the ACL will provide insight into the sex differences in ACL injury and future prevention strategies.

Stiffness of Muscles and Tendons of the Lower Limb of Professional and Semiprofessional Athletes Using Shear Wave Elastography

OBJECTIVE

Shear wave elastography (SWE) allows assessment of muscle and tendon stiffness and can be used to diagnose soft tissue pathologies such as tendinopathies. In sports medicine, SWE may have the potential to uncover structural changes early on before they lead to functional impairment. To systematically analyze possible differences in tendon and muscle stiffness of the lower limb between professional (PG) and semiprofessional female athletes (SG) using SWE and to compile reference values for developing preventive medicine approaches for professional athletes.

METHODS

Standardized SWE of both lower limb tendons and muscles (Achilles tendon [AT], soleus muscle insertion [SM], patellar tendon [PT], quadriceps tendon [QT], vastus medialis muscle [VM]) in the longitudinal plane was performed with the tendons in relaxed position in 24 healthy professional female athletes (PG) in comparison with 24 healthy semiprofessional female athletes (SG).

RESULTS

Median tendon and muscle stiffness was significantly higher in professional athletes (AT:PG, 11.12 m/s vs SG, 7.33 m/s, P < .001; SM: 1.77 m/s vs 1.14 m/s, P < .001; VM: 1.63 m/s vs 0.87 m/s, P < .001; QT: 3.31 m/s vs 2.61 m/s, P < .05). There was no significant difference in patellar tendon stiffness between PG and SG (PT: 2.57 m/s vs 3.21, P = .25).

CONCLUSION

Professional female athletes have higher stiffness values than semiprofessional female athletes in lower limb muscles and tendons, except for the patellar tendon. Knowledge of such differences is necessary for diagnosing tendinopathy and injuries. Musculoskeletal SWE could offer great benefits in sports medicine as well as in rehabilitation and preventive medicine.

Effects of orally administered hormonal contraceptives on the musculoskeletal system of healthy premenopausal women—A systematic review

Introduction

The musculoskeletal system (MSK) is one of the extragonadal target tissues of sex hormones: osteoblasts and osteocytes express estrogen receptors, while in fibroblasts of the anterior cruciate ligament (ACL) and myocytes of the vastus lateralis muscle (MVL), estrogen and progesterone receptors can be detected by immunoassay. Indeed, upon binding of sex hormones to the extragonadal receptors, the MSK seems to respond to varying levels of sex hormones with structural adaptation. Hormonal contraceptives can affect the musculoskeletal system; however, there is a lack of high‐quality studies, and no recommendation for female athletes exists.

Material and Methods

This is a systematic review of publications on the effects of oral hormonal contraceptives on the biomechanical properties of tendons, muscles and ligaments, muscle strength, and soft tissue regeneration. A systematic database search was performed using MESH keywords and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) methodology in Pubmed and Cochrane to identify studies investigating the influence of oral hormonal contraceptives on muscles, tendons, and ligaments of healthy, adult, premenopausal women. The risk of bias in the studies included was assessed by two independent researchers using the ROBINS‐I Tool.

Results

Nine comparative studies were identified that met the inclusion criteria. Endpoints were muscle strength and biomechanical tissue properties. No significant influence of oral hormonal contraceptives on muscle strength was found, although general muscle growth and Type I fiber growth were found to be significantly increased in a dose‐dependent manner. There was a negative effect on regeneration of muscle strength after exercise. The stiffness of tendons remained unchanged, while their size adaptation to load increased.

Conclusion

The anabolic effect could be beneficial for specific sports, whereas reduced muscle regeneration could be disadvantageous for women exercising with high‐performance demands. The different effects on tendons and ligaments and the functional consequences of altered ligament and muscle stiffness, especially with regard to synthetic hormones, should be further investigated.

The Incidence, Cost, and Burden of Concussion in Women's Rugby League and Rugby Union: A Systematic Review and Pooled Analysis

Background

The extent of concussion injury in the rugby codes for women is unclear.

Objective

Our aim was to review all published studies reporting concussion injuries from match and training participation in rugby codes and report the pooled data estimates for rugby league and union concussion injury epidemiology.

Methods

We conducted a systematic literature analysis of concussion in rugby league and rugby union for published studies from January 1990 to July 2021. Data from 16 studies meeting the inclusion criteria were extracted for women’s concussion injuries and were subsequently pooled. Costs from Accident Compensation Corporation (ACC) data were attributed to the results to provide cost estimates.

Results

The pooled analysis match injury incidence of women’s concussion was higher for rugby league (10.3 per 1000 match hours) than rugby 15 s (2.8 per 1000 match hours) or rugby 7 s (8.9 per 1000 match hours). There was a fourfold difference in the pooled incidence of concussion in women’s rugby league (risk ratio [RR] 4.53, 95% confidence interval [CI] 1.8–11.3]; p = 0.0001) when compared with rugby 15 s. There was also a ninefold higher risk of a concussion during match participation compared with training participation for women’s rugby 15 s (RR 9.3, 95% CI 1.29–66.78; p = 0.0070). The total estimated costs for the concussions reported were NZ$1,235,101. For rugby 7 s, the pooled concussive injury burden was 33.2 days.

Conclusions

Our pooled analysis clarified the extent of concussion injury and the possible associated costs at several levels of the game for women’s rugby codes. The pooled mean days lost because of concussions was 33 days. As this was considerably longer than the 7- to 10-day expected timeframe outlined in the Concussion in Sport Consensus statement, these guidelines need to be updated to include sex-specific differences.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-022-01645-8.

Sexual Dimorphisms in Anterior Cruciate Ligament Injury: A Current Concepts Review

Background:

Although most anterior cruciate ligament (ACL) injuries occur in male athletes, female athletes are consistently observed to be at a higher risk for sports-specific ACL injury.

Purpose:

To provide a thorough review of what is known about the sexual dimorphisms in ACL injury to guide treatment and prevention strategies and future research.

Study Design:

Narrative review.

Methods:

We conducted a comprehensive literature search for ACL-related studies published between January 1982 and September 2017 to identify pertinent studies regarding ACL injury epidemiology, prevention strategies, treatment outcomes, and dimorphisms. By performing a broad ACL injury search, we initially identified 11,453 articles. After applying additional qualifiers, we retained articles if they were published in English after 1980 and focused on sex-specific differences in any of 8 different topics: sex-specific reporting, difference in sports, selective training, hormonal effects, genetics, neuromuscular and kinematic control, anatomic differences, and outcomes.

Results:

A total of 122 articles met the inclusion criteria. In sum, the literature review indicated that female athletes are at significantly higher risk for ACL injuries than are their male counterparts, but the exact reasons for this were not clear. Initial studies focused on intrinsic differences between the sexes, whereas recent studies have shifted to focus on extrinsic factors to explain the increased risk. It is likely both intrinsic and extrinsic factors contribute to this increased risk, but further study is needed. In addition to female patients having an increased risk for ACL injuries, they are less likely than are male patients to undergo reconstructive surgery, and they experience worse postsurgical outcomes. Despite this, reconstructive surgery remains the gold standard when knee stability, return to sports, and high functional outcome scores are the goal, but further research is needed to determine why there is disparity in surgical rates and what surgical techniques optimize postsurgical outcomes for female patients.

Conclusion:

Male athletes often predominated the research concerning ACL injury and treatment, and although sex-specific reporting is progressing, it has historically been deficient. ACL injuries, prevention techniques, and ACL reconstruction require further research to maximize the health potential of at-risk female athletes.

The effect of the menstrual cycle on collagen metabolism, growth hormones and strength in young physically active women

This study aimed to investigate the effect of the menstrual cycle on strength, functioning of the GH/IGF-1 axis and collagen metabolism in physically active women. Twenty-four physically active and eumenorrheic women volunteered to participate in the study (body mass 60.3 ± 9.18 kg, age 21.8 ± 0.92 years). Blood samples were obtained between the 5th and 8th days (the follicular phase) and between the 19th and 22th days (the luteal phase) of the menstrual cycle to determine sex steroid concentrations (follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), oestradiol (E2) and progesterone (P)). Also insulin-like growth factor 1 (IGF-1) and collagen metabolism markers (synthesis (PICP) and breakdown (ICTP)) and maximum voluntary contraction (MVC) were measured. MVC was higher in the luteal phase 164.1 ± 34.77 [N m] (F(1.23) = 4.59; p = 0.043). The recorded collagen synthesis marker (PICP = 296.4 ± 35.61 [ng/ml]) was at the upper level of the reference range (30-300), with an insignificant decrease in the luteal phase (Z = 1.612; p = 0.107) and a significant increase in oestradiol concentration (Z = 4.286; p = 0.0001). The marker of collagen breakdown (ICTP = 4.16 ± 0.68 [μg/l]) was reduced by 6.8% in the same phase (Z = 1.764; p = 0.137). The variability of physical abilities (MVC) during the menstrual cycle showed that menstrual status should be taken into account in determination of the training loads. Increasing the load in the luteal phase seems to be favoured by a beneficial change in collagen metabolism (lower synthesis decrease, lower breakdown increase) observed in physically active women.

Cranial Cruciate Ligament Rupture in Dogs: Review on Biomechanics, Etiopathogenetic Factors and Rehabilitation

Cranial cruciate ligament (CrCL) rupture is one of the most common orthopaedic conditions in veterinary medicine. CrCL plays a fundamental role in the stability and biomechanics of the femoral-tibio-patellar joint, and its incorrect functionality severely impacts on the quality of life of patients. In dogs, the structural weakening of this joint due to the progressive degeneration of the ligament is the most accredited etiopathogenetic hypothesis in relation to the dog signalment (breed, sex and age) and the stifle joint conformation. In humans, this injury is often traumatic and generally occurs during sporting activities. CrCL rupture can be managed conservatively or surgically, and decisions regarding treatment are due to numerous factors: the patient’s age and health, the degree of stifle instability, and cost. Physiotherapy protocols play an important role in rehabilitation, with similar goals in humans and dogs: pain management, physiological articular range of motion recovery, periarticular and core muscle strengthening, and proprioceptive deficit correction. Physiotherapy, even if often neglected in veterinary medicine, is mandatory for the recovery of the correct functionality of the injured limb and for the return to normal daily and sporting activities.

Comprehensive Lower Extremities Joints Range of Motion Profile in Futsal Players

The purposes of this study were to describe the lower extremities joints range of motion (ROM) profile using a comprehensive approach in futsal players and to examine potential player position (goalkeepers vs. outfield players), competitive level (first [top] division vs. second division), number of playing years, sex (males vs. females), and bilateral (dominant limb vs. non-dominant limb) differences. A total of 72 male and 67 female elite futsal players from 11 clubs were measured of passive hip (flexion with knee flexed [HF_KF] and extended [HF_KE], extension [HE], abduction [HA], external [HER], and internal [HIR] rotation), knee (flexion [KF]) and ankle (dorsiflexion with knee flexed [ADF_KF] and extended [ADF_KE]) ROMs. Bayesian inferences exploring differences between player position, competitive level, sex and limb were made. A Bayesian correlation analysis was conducted to explore the influence of playing years on joints ROMs. The results showed no significant player position or competitive level related differences in any average ROM score. However, statistically significant sex-related differences were documented whereby female players reported higher hip and knee joints ROM average values than their male counterparts. Especially relevant were the proportions of males (72%) and players from teams engaged in the second division (61%) displaying limited HF_KE ROMs. Likewise, around 35% of all players showed restricted ADF_KF ROMs. In addition, approximately 21, 18, 22, and 25% of the futsal players were identified as having bilateral asymmetries (≥8°) for HA, HIR, HER, and KF ROMs, respectively. Finally, Bayesian correlation analysis did not report any significant association between years of playing futsal and ROM measures (all r values < 0.34). The implications that these restricted HF_KE and ADF_KF ROMs and bilateral asymmetries in hip (abduction, internal and external rotation) and knee (flexion) ROMs caused by the practice of futsal may have on physical performance and injury risk warrant future research.

Does sex affect second ACL injury risk? A systematic review with meta-analysis

OBJECTIVE

To determine sex-based differences in risk of a second ACL injury (overall and by laterality) following primary ACL reconstruction in athletes who are attempting to return to sport.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Systematic search of five databases conducted in August 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies reporting sex-based differences in the incidence of second ACL injury in athletes attempting to return-to-sports and who were followed for at least 1 year following primary ACL reconstruction.

RESULTS

Nineteen studies were included in this review, with seven studies excluded from the primary meta-analysis due to high risk of bias. The remaining 12 studies (n=1431 females, n=1513 males) underwent meta-analysis, with all 19 studies included in a sensitivity analysis. Total second ACL injury risk was 21.9% (females: 22.8%, males: 20.3%). Females were found to have 10.7% risk of an ipsilateral ACL injury and 11.8% risk of a contralateral ACL injury. Males were found to have 12.0% risk of an ipsilateral ACL injury and 8.7% risk of a contralateral ACL injury. No statistically significant differences were observed for total second ACL injury risk (risk difference=-0.6%, 95% CI -4.9 to 3.7, p=0.783, I²=41%) or contralateral ACL injury risk (risk difference=1.9%, 95% CI -0.5% to 4.4%, p=0.113, I²=15%) between sexes. Females were found to have a 3.4% absolute risk reduction in subsequent ipsilateral ACL injury risk compared with males (risk difference=-3.4%, 95% CI -6.7% to -0.02%, p=0.037, I²=35%).

CONCLUSION

Both sexes have >20% increased risk of experiencing a second ACL injury. Any difference in the absolute risk of either a subsequent ipsilateral or contralateral ACL injury between sexes appears to be small.

REGISTRATION

PROSPERO (CRD42020148369).

Physiological Monitoring Detected Changes During Women's Soccer Anterior Cruciate Ligament Injury

A growing number of studies utilizing wearable technologies are examining the influence of the autonomic nervous system (ANS) on intense training, recovery, and injury risk. Exercise biometric (EB) data were collected on collegiate, female soccer players during a preseason camp. One player sustained an anterior cruciate ligament (ACL) injury. Baseline anthropometric and EB data were compared to non-injured, position-matched teammates.

All players had similar baseline testing. The injured athlete had a higher body mass index (BMI) and slower vision reaction time (RT). On the day of her injury (DOI), relative percentage heart rate recovery (tHRR) between intense training sets was calculated. Relative percentage tHRR was much lower for the injured athlete, indicating reduced recovery between training sets immediately prior to the injury. Also on DOI, the injured athlete had a lower glomerular filtration rate (GFR).

In addition to BMI and RT differences, the lower relative percentage tHRR and GFR on the DOI observed for the injured athlete may reflect an imbalanced ANS recovery, and potentially to risk factors leading to her ACL injury.

Acute Effects of a High Volume vs. High Intensity Bench Press Protocol on Electromechanical Delay and Muscle Morphology in Recreationally Trained Women

The purpose of the present investigation was to compare the acute responses on muscle architecture, electromechanical delay (EMD) and performance following a high volume (HV: 5 sets of 10 reps at 70% of 1 repetition maximum (1RM)) and a high intensity (HI: 5 sets of 3 reps at 90% of 1RM) bench press protocol in women. Eleven recreationally trained women (age = 23.3 ± 1.8 y; body weight = 59.7 ± 6.0 kg; height = 164.0 ± 6.3 cm) performed each protocol in a counterbalanced randomized order. Muscle thickness of pectoral (PEC MT) and triceps muscles (TR MT) were collected prior to and 15 min post each trial. In addition, EMD of pectoral (PEC EMD) and triceps (TR EMD) muscles were calculated during isometric bench press maximum force tests performed at the same timepoints (IBPF). Significantly greater increases in PEC MT (p < 0.001) and TR MT (p < 0.001) were detected following HV compared to HI. PEC EMD showed a significantly greater increase following HV compared to HI (p = 0.039). Results of the present study indicate that the HV bench press protocol results in greater acute morphological and neuromuscular changes compared to a HI protocol in women. Evaluations of muscle morphology and electromechanical delay appear more sensitive to fatigue than maximum isometric force assessments.

Risk factors associated with atraumatic posterolateral rotatory instability

Background

Traumatic posterolateral rotatory instability after elbow dislocation or fracture dislocation has been well described. However, few reports cover atraumatic posterolateral rotatory instability as a cause of lateral-sided elbow pain. We assessed the risk factors and epidemiology of atraumatic posterolateral rotatory instability in a case-control study.

Methods

A retrospective review of all patients treated operatively for atraumatic posterolateral rotatory instability during a 6-year period was compared with a group of patients with extensor carpi radialis brevis tendinopathy without instability treated during the same time period. Bivariate and multiple logistic regression statistical analyses were used to investigate the following risk factors: gender, age, hand dominance, diabetes, smoking, body mass index, corticosteroid injection history, and duration of symptoms. Disabilities of the Arm, Shoulder, and Hand and pain scores were obtained preoperatively and postoperatively.

Results

Thirteen patients with atraumatic posterolateral rotatory instability were compared with 12 patients with extensor carpi radialis brevis tendinopathy. Multivariate analysis revealed patients with atraumatic posterolateral rotatory instability were more likely to have multiple corticosteroid injections (P = .05) and present with a longer duration of symptoms (P = .03). Postoperative pain scores improved in both groups.

Conclusions

Atraumatic posterolateral rotatory instability should be considered in the differential diagnosis of lateral elbow when patients present with a protracted clinical course. Statistically, posterolateral rotatory instability patients more often present with a history of multiple corticosteroid injections.

The relationship between the female athlete triad and injury rates in collegiate female athletes

Background

This study aimed to clarify the relationship between the triad risk assessment score and the sports injury rate in 116 female college athletes (average age, 19.8 ± 1.3 years) in seven sports at the national level of competition; 67 were teenagers, and 49 were in their 20s.

Methods

Those with menstrual deficiency for >3 months or <6 menses in 12 months were classified as amenorrheic athletes. Low energy availability was defined as adolescent athletes having a body weight <85% of ideal body weight, and for adult athletes in their 20s, a body mass index ≤17.5 kg/m². Bone mineral density (BMD) was measured on the heel of the right leg using an ultrasonic bone densitometer. Low BMD was defined as a BMD Z-score <−1.0. The total score for each athlete was calculated. The cumulative risk assessment was defined as follows: low risk (a total score of 0–1), moderate risk (2–5), and high risk (6). The injury survey recorded injuries referring to the injury survey items used by the International Olympic Committee.

Results

In swimming, significantly more athletes were in the low-risk category than in the moderate and high-risk categories (p = 0.004). In long-distance athletics, significantly more athletes were in the moderate-risk category than in the low and high-risk categories (p = 0.004). In the moderate and high-risk categories, significantly more athletes were in the injury group, whereas significantly more athletes in the low-risk category were in the non-injury group (p = 0.01). Significantly more athletes at moderate and high-risk categories had bone stress fractures and bursitis than athletes at low risk (p = 0.023).

Discussion

These results suggest that athletes with relative energy deficiency may have an increased injury risk.

Acute Achilles Tendon Ruptures

There is an ever-evolving debate about the best treatment option for Achilles tendon ruptures. There was a relative consensus that operative treatment yielded the best outcomes. Much of this is based on results in athletic populations. Conservative treatment was considered only for the elderly and those with very inactive lifestyles. There has been an evolution, however, with more surgeons utilizing an aggressive functional rehabilitation with conservative management. Surgical intervention still is the treatment of choice for elite-level athletes. The treatment of choice for patient populations other than elite athletes remains an individual choice between patient and physician.

Relationship Between Anterior Knee Laxity and General Joint Laxity During the Menstrual Cycle

Background

Anterior cruciate ligament (ACL) injury has been reported to have a higher incidence in women than in men.

Purpose/Hypothesis

The purpose was to examine the relationship of anterior knee laxity (AKL), stiffness, and generalized joint laxity (GJL) with respect to the menstrual cycle. It was hypothesized that AKL and GJL would increase during the ovulation phase, when estrogen levels are high.

Study Design

Descriptive laboratory study.

Methods

A total of 15 female university students aged >20 years and with normal menstrual cycles were evaluated. AKL was measured as anterior tibial displacement of the femur after application of 44-, 89-, and 133-N loads to the tibia. Stiffness was calculated as Δ force/Δ displacement at loads between 44 and 89 N and between 89 and 133 N. The University of Tokyo joint laxity test was used for evaluation of GJL. The participants' menstrual cycle was divided into the early follicular, late follicular, ovulation, and luteal phases using the basal body temperature method and an ovulation kit; AKL and GJL were measured once during each phase. Participants were also stratified according to the presence or absence of genu recurvatum (GR).

Results

There was no significant difference in AKL, stiffness, or GJL among the menstrual phases. In the GR group, AKL values at 89 N and 133 N were significantly higher in the ovulation phase than in the early follicular phase (P = .025 and P =.018, respectively); there were no significant differences in AKL among the phases in the non-GR group. In addition, the GR group in the ovulation phase had significantly higher AKL values at 44 N, 89 N, and 133 N compared with the non-GR group (P = .013, P = .005, and P = .010, respectively). There were no significant differences in GJL among the phases in the GR or non-GR groups.

Conclusion

Women with GR may have increased AKL in the ovulation phase when compared with the early follicular phase, which may be a risk factor for ACL injury.

Clinical Relevance

The results of this study suggest that the ovulation phase may be related to the greater incidence of ACL injuries in women.

Injury Incidence Across the Menstrual Cycle in International Footballers

Objectives: This study aimed to assess how menstrual cycle phase and extended menstrual cycle length influence the incidence of injuries in international footballers.

Methods: Over a 4-year period, injuries from England international footballers at training camps or matches were recorded, alongside self-reported information on menstrual cycle characteristics at the point of injury. Injuries in eumenorrheic players were categorized into early follicular, late follicular, or luteal phase. Frequencies were also compared between injuries recorded during the typical cycle and those that occurred after the cycle would be expected to have finished. Injury incidence rates (per 1,000 person days) and injury incidence rate ratios were calculated for each phase for all injuries and injuries stratified by type.

Results: One hundred fifty-six injuries from 113 players were eligible for analysis. Injury incidence rates per 1,000 person-days were 31.9 in the follicular, 46.8 in the late follicular, and 35.4 in the luteal phase, resulting in injury incidence rate ratios of 1.47 (Late follicular:Follicular), 1.11 (Luteal:Follicular), and 0.76 (Luteal:Late follicular). Injury incident rate ratios showed that muscle and tendon injury rates were 88% greater in the late follicular phase compared to the follicular phase, with muscle rupture/tear/strain/cramps and tendon injuries/ruptures occurring over twice as often during the late follicular phase compared to other phases 20% of injuries were reported as occurring when athletes were “overdue” menses.

Conclusion: Muscle and tendon injuries occurred almost twice as often in the late follicular phase compared to the early follicular or luteal phase. Injury risk may be elevated in typically eumenorrheic women in the days after their next menstruation was expected to start.

The Menstrual Cycle May Affect Anterior Knee Laxity and the Rate of Anterior Cruciate Ligament Rupture: A Systematic Review and Meta-Analysis

BACKGROUND

Women have a higher risk of anterior cruciate ligament (ACL) tears than men, the causes of which are multifactorial. The menstrual cycle and its hormonal effect on the knee may contribute to knee laxity and ACL injury. This work reviewed published studies examining the effects of the phases of the menstrual cycle on anterior knee laxity and the rate of ACL tears.

METHODS

A systematic review with meta-analysis and meta-regression was performed. Studies with data comparing the menstrual cycle phase with ACL injury or anterior knee laxity were included for analysis. Data with regard to patient demographic characteristics, anterior knee laxity, ACL injury, and menstrual cycle phases were extracted from the included studies.

RESULTS

In this study, 1,308 search results yielded 396 articles for review, of which 28 met inclusion criteria. Nineteen studies of knee laxity with 573 combined subjects demonstrated a mean increase in laxity (and standard deviation) of 0.40 ± 0.29 mm in the ovulatory phase compared with the follicular phase and a mean increase in laxity of 0.21 ± 0.21 mm in the luteal phase compared with the follicular phase. Nine studies examining ACL tears with 2,519 combined subjects demonstrated a decreased relative risk (RR) of an ACL tear in the luteal phase compared with the follicular and ovulatory phases combined (RR, 0.72 [95% confidence interval, 0.56 to 0.89]). There were no differences in ACL tear risk between any of the other phases.

CONCLUSIONS

An increased risk of an ACL tear does not appear to be associated with periods of increased laxity in this meta-analysis. Although this suggests that hormonal effects on an ACL tear may not be directly related to increases in knee laxity, the methodologic heterogeneity between published studies limits the conclusions that can be drawn and warrants further investigation.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Return to Play and Performance in the Women's National Basketball Association After Anterior Cruciate Ligament Reconstruction

Background:

The incidence of anterior cruciate ligament (ACL) injuries in Women’s National Basketball Association (WNBA) athletes continues to increase. There is a paucity of data regarding return-to-play (RTP) rates and performance after ACL reconstruction in these athletes.

Purpose:

To quantify RTP rates and performance after ACL reconstruction in WNBA athletes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

All ACL tears sustained in the WNBA from 1997 through 2018 were identified. Body mass index (BMI), age, and position at the time of injury were collected for each player. RTP rates were calculated, and performance data were collected for each player before and after injury to determine changes in playing time and statistical performance. Players who successfully returned to play after ACL reconstruction were compared with a group of healthy controls who were matched by age, years of experience, position, height, and BMI. Statistics at 1 and 3 years after injury were compared to assess acute and longitudinal changes in performance relative to preinjury baseline.

Results:

A total of 59 WNBA players sustained ACL tears during the study period, and 41 (69.5%) were able to successfully RTP. Players played a mean of 7.5 ± 12.8 fewer games, played 5.0 ± 9.2 fewer minutes per game, and scored 3.7 ± 5.0 fewer points per game in their first year after RTP compared with the year before injury. Athletes with ACL reconstruction demonstrated significantly decreased performance measures regarding games played, games started, minutes, rebounds, assists, and blocks per game in their first season after RTP compared with control athletes in the same indexed year; however, these differences resolved by year 3 after surgery.

Conclusion:

WNBA athletes have a high RTP rate after ACL reconstruction. Players may experience an initial decrease in playing time and performance when returning to play; however, these variables were found to return to baseline over time.

Ground Reaction Forces Are Predicted with Functional and Clinical Tests in Healthy Collegiate Students

Increased vertical and posterior ground reaction forces (GRFs) are associated with anterior cruciate ligament (ACL) injury. If a practical means to predict these forces existed, ACL injury risk could be attenuated. Forty-two active college-age individuals (21 females, 20.66 ± 1.46 y, 70.70 ± 2.36 cm, 82.20 ± 7.60 kg; 21 males, 21.57 ± 1.28 y, 65.52 ± 1.87 cm, 64.19 ± 9.05 kg) participated in this controlled laboratory study. GRFs were ascertained by having the subjects perform a unilateral landing task onto a force plate. Several clinical measures (Fat Free Mass (FFM), dorsiflexion passive range of motion (DPROM), isometric peak force of the lateral hip rotators, knee flexor/extensor peak force ratio (H:Q), the completion of the overhead deep squat), two functional tests (Margaria–Kalamen, Single Leg Triple Hop (SLTH)), and sex served as the predictor variables. Regression models to predict the GRFs normalized to the FFM (nGRFz, nGRFy) were generated. nGRFz was best predicted with a linear regression equation that included SLTH and DPROM (adjusted R² = 0.274; p = 0.001). nGRFy was best predicted with a linear regression equation that included H:Q, FFM, and DPROM (adjusted R² = 0.476; p < 0.001). Simple clinical measures and functional tests explain a small to moderate amount of the variance associated with the FFM normalized vertical and posterior GRFs in active college-age individuals.

Knee injury prevention in alpine skiing. A technological paradigm shift towards a mechatronic ski binding

BACKGROUND

Skiing can be beneficial for the sense of delight and wellbeing. Nonetheless, the risk of injury should not be ignored. The traditional ski binding, working solely on a mechanical principle, performs well with regards to a prevention of mid-shaft tibia fracture. However, with respect to knee injuries, it is not able to provide protection. Future concepts, such as mechatronic binding designs have the potential to decrease knee injuries that traditional bindings cannot prevent. In addition to mechanical loads, this kind of binding design uses additional parameters, e.g. knee kinematics and the skier's muscle state, to control the binding release.

METHODS

This paper provides a review about our knowledge of injury mechanisms in recreational alpine skiing and previous work regarding mechatronic ski binding concepts. Also, our own biomechanical approach towards a mechatronic ski binding is described. Four input variables for an algorithm are discussed with respect to existing sensor solutions and designs of our own. A concept for an algorithm, based on our current knowledge in injury mechanisms is presented.

CONCLUSIONS

Though first designs were described in the 80s, for decades the idea of a mechatronic ski binding was not further pursued by research. Technological improvements in the field of micro-electronics and wearable sensors, as well as decreasing costs of these devices, make a mechatronic concept feasible. Main challenge is still the missing knowledge about injury mechanisms in alpine skiing and hence the quantification of the influence of possible input variables for the mechatronic system on those injuries.

Assessment of luteinizing hormone receptor expression in structural support tissues of canine hip and femorotibial joints

OBJECTIVE

To determine whether luteinizing hormone receptors (LHRs) are expressed in canine femoral head subchondral bone (FHSB), hip joint round ligament (RL), cranial cruciate ligament (CCL), and femorotibial joint synovium (FJS) specimens.

SAMPLE

1 specimen each of the FHSB, RL, CCL, and FJS obtained from the left hind limbs of 19 fresh canine cadavers.

PROCEDURES

1 section of each FHSB, RL, CCL, and FJS specimen was processed with rabbit polyclonal IgG anti-human LHR antibody, and 1 section was treated with negative control reagents. Percentage immunoexpression of LHRs in FHSB and FJS sections was analyzed by assessment of 100 bone marrow cells or synoviocytes in 3 adjacent hpf (400×). In each RL and CCL section, immunoexpression of LHRs in fibrocytes was semiquantitatively analyzed on the basis of the mean of the product of percentage staining score (from 0 [no staining] to 3 [> 50% of cells stained]) and staining intensity score (from 0 [no staining] to 2 [moderate to strong staining]) for 3 adjacent hpf.

RESULTS

All tissues examined had variable LHR expression. Expression of LHRs in FHSB, CCL, or FJS specimens did not differ between sexes or between sexually intact and gonadectomized dogs. However, RL specimens from female dogs had significantly greater LHR expression scores, compared with findings for male dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that LHRs are expressed in structural support tissues of canine hip and femorotibial joints. Further research is required to determine the LHRs' function, mechanism of action, and potential contribution to the pathogenesis of hip dysplasia or CCL rupture in dogs.

Match and Training Injuries in Women's Rugby Union: A Systematic Review of Published Studies

BACKGROUND

There is a paucity of studies reporting on women's injuries in rugby union.

OBJECTIVE

The aim of this systematic review was to describe the injury epidemiology for women's rugby-15s and rugby-7s match and training environments.

METHODS

Systematic searches of PubMed, SPORTDiscus, Web of Science Core Collection, Scopus, CINAHL(EBSCO) and ScienceDirect databases using keywords.

RESULTS

Ten articles addressing the incidence of injury in women's rugby union players were retrieved and included. The pooled incidence of injuries in women's rugby-15s was 19.6 (95% CI 17.7-21.7) per 1000 match-hours (h). Injuries in women's rugby-15s varied from 3.6 (95% CI 2.5-5.3) per 1000 playing-h (including training and games) to 37.5 (95% CI 26.5-48.5) per 1000 match-h. Women's rugby-7s had a pooled injury incidence of 62.5 (95% CI 54.7-70.4) per 1000 player-h and the injury incidence varied from 46.3 (95% CI 38.7-55.4) per 1000 match-h to 95.4 (95% CI 79.9-113.9) per 1000 match-h. The tackle was the most commonly reported injury cause with the ball carrier recording more injuries at the collegiate [5.5 (95% CI 4.5-6.8) vs. 3.5 (95% CI 2.7-4.6) per 1000 player-game-h; χ²₍₁₎ = 6.7; p = 0.0095], and Women's Rugby World Cup (WRWC) [2006: 14.5 (95% CI 8.9-23.7) vs. 10.9 (95% CI 6.2-19.2) per 1000 match-h; χ²₍₁₎ = 0.6; p = 0.4497; 2010: 11.8 (95% CI 6.9-20.4) vs. 1.8 (95% CI 0.5-7.3) per 1000 match-h; χ²₍₁₎ = 8.1; p = 0.0045] levels of participation. Concussions and sprains/strains were the most commonly reported injuries at the collegiate level of participation.

DISCUSSION

Women's rugby-7s had a higher un-pooled injury incidence than women's rugby-15s players based on rugby-specific surveys and hospitalisation data. The incidence of injury in women's rugby-15s and rugby-7s was lower than men's professional rugby-15s and rugby-7s competitions but similar to male youth rugby-15s players. Differences in reporting methodologies limited comparison of results.

CONCLUSION

Women's rugby-7s resulted in a higher injury incidence than women's rugby-15s. The head/face was the most commonly reported injury site. The tackle was the most common cause of injury in both rugby-7s and rugby-15s at all levels. Future studies are warranted on injuries in women's rugby-15s and rugby-7s.

PROSPERO REGISTRATION NUMBER

CRD42018109054 (last updated on 17 January 2019).

A prospective study of sport injuries in youth females

OBJECTIVES

To examine sports and physical education (PE) injury rates in youth females during a school year and to investigate if an association exists between injury and phase of the menstrual cycle.

DESIGN

Prospective cohort.

SETTING

An online questionnaire was used to record training and competition exposure and self-reported injuries for 30-weeks.

PARTICIPANTS

103 PE students (12-15 years) from a girls' secondary school.

MAIN OUTCOME MEASURES

Injury rates and prevalence of acute, gradual onset/overuse and substantial injuries.

RESULTS

On average, girls trained 3.4 h/week and competed 1 h/week. During the study, 74 participants reported 595 injuries. The average weekly prevalence of all injuries was 20.7% (95% CI: 20.0-21.3), of which 8.6% (95% CI: 8.3-9.0) were acute injuries and 12.0% (95% CI: 11.4-12.6) were gradual onset/overuse injuries. The overall rate of sport and PE injuries was 10.4 injuries/1000 h of exposure. The most common acute injury involved the ankle (35%) while the most common gradual onset/overuse injury involved the knee (51%). There was no significant association between the stage of the menstrual cycle and the likelihood of injury (P = 0.18).

CONCLUSION

The high number of injuries in this population of girls suggests preventative measures, particularly targeting the lower extremity, are needed.

Comparison of some intrinsic risk factors of shoulder injury in three phases of menstrual cycle in collegiate female athletes

OBJECTIVES

present study aims to investigate the changes in the shoulder joint stability factors during the menstrual cycle.

DESIGN

cross-sectional study; SETTING: laboratory.

PARTICIPANTS

15 healthy collegiate female athletes with normal menstrual cycles.

MAIN OUTCOME MEASURES

shoulder strength, proprioception, laxity and functional stability were the primary outcomes. Participants were assessed in three phases (mense, ovulation, midluteal (day 21) by 4 different categories of tests, each designed for a different factor. Shapiro-Wilk Test was used to determine normality of data, ANOVA and Friedman Test were used to compare results. Significance level and alpha were considered 95 percent and ≥0.05, respectively. Data shown a relation between proprioception, strength and menstrual cycle.

RESULTS

shoulder strength was significantly increased in ovulation phase compared to other phases (p < 0.5) (effect size >0.14). Proprioception was significantly decreased in luteal phase than in mense and ovulation phases (p < 0.5) (effect size >0.14). Finally, ligament laxity and functional stability showed no change in all phases (p < 0.5).

CONCLUSION

Menstrual cycle and sexual hormones affect muscle strength and proprioception of shoulder joint, but have no effect on ligament laxity and functional stability.

Changes in Knee Vastii Muscle Activity in Women with Patellofemoral Pain Syndrome During the Menstrual Cycle

BACKGROUND

Changes in hormonal levels during the menstrual cycle are known to affect muscle electromyographic (EMG) activity, but no studies have investigated the effect of hormonal changes on the EMG activity of muscles around the knee in patients with patellofemoral pain syndrome (PFPS).

OBJECTIVE

To evaluate the EMG activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles during toe rise and heel rock tasks in different phases of the menstrual cycle in women with PFPS.

DESIGN

Cross sectional study.

SETTING

Rehabilitation Research Center at the School of Rehabilitation Sciences of Shiraz University of Medical Sciences.

PARTICIPANTS

Ten women with PFPS between 18 and 40 years of age.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

The VL/VMO amplitude ratio and differences between onset (onset VL-onset VMO) of vastii muscle activity were measured in the affected limb during rise and rock tasks in the follicular and ovulatory phases of the menstrual cycle. The signals were analyzed with MATLAB software.

RESULTS

During both tasks, there were no significant changes in onset differences in vastii muscles between the ovulatory and follicular phases. However, the amplitude ratio (VL/VMO) was significantly lower in the ovulatory phase compared to the follicular phase (P = .035 for rise tasks and .010 for rock tasks).

CONCLUSION

The menstrual cycle may affect some EMG parameters. These factors can be taken into account when planning sports and rehabilitation training programs.

Alpine Skiing Injuries

Context:

Alpine skiing is a popular sport worldwide but has significant risk for injury. The epidemiology of skiing-related injuries has been described, which has led to the identification of risk factors for specific types of injuries.

Evidence Acquisition:

Pertinent literature from peer-reviewed publications was reviewed.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

The adoption of international standards for ski-boot-binding systems has changed the profile of skiing-related injuries over time, as has the widespread use of helmets. An understanding of mechanisms of injury, risk factors, and preventative measures may decrease the incidence of skiing-related injuries.

Conclusion:

Advances in standards for skiing equipment have been effective at decreasing both the frequency and severity of skiing-related injuries, but additional efforts are required to improve the safety of the sport.

Effect of Estrogen on Musculoskeletal Performance and Injury Risk

Estrogen has a dramatic effect on musculoskeletal function. Beyond the known relationship between estrogen and bone, it directly affects the structure and function of other musculoskeletal tissues such as muscle, tendon, and ligament. In these other musculoskeletal tissues, estrogen improves muscle mass and strength, and increases the collagen content of connective tissues. However, unlike bone and muscle where estrogen improves function, in tendons and ligaments estrogen decreases stiffness, and this directly affects performance and injury rates. High estrogen levels can decrease power and performance and make women more prone for catastrophic ligament injury. The goal of the current work is to review the research that forms the basis of our understanding how estrogen affects muscle, tendon, and ligament and how hormonal manipulation can be used to optimize performance and promote female participation in an active lifestyle at any age.

Epidemiology of Injuries in Women Playing Competitive Team Bat-or-Stick Sports: A Systematic Review and a Meta-Analysis

BACKGROUND

Team bat-or-stick sports, including cricket, softball and hockey, are popular among women. However, little is known about the injury profile in this population.

OBJECTIVE

The aim was to describe the incidence, nature and anatomical location of injuries in bat-or-stick sports played by women in a competitive league.

METHODS

This review was prospectively registered (PROSPERO CRD42015026715). CINAHL, MEDLINE, PsycINFO, PubMed, SPORTDiscus were systematically searched from January 2000 to September 2016, inclusive. Peer-reviewed original research articles reporting the incidence, nature and anatomical location of injuries sustained by women aged 18 + years in competitive bat-or-stick sports were included. Two meta-analyses based on injury incidence proportions (injury IP) and injury rates per 1000 person-days of athletic exposure (AE) were performed.

RESULTS

A total of 37 studies satisfied the inclusion criteria, and five had low risk of bias. The weighted injury IP was 0.42 [95% confidence interval (CI) 0.39-0.45]. The weighted injury rate was 6.12 (95% CI 6.05-6.18) overall, and greater in games [15.79 (95% CI 15.65-15.93)] than in practice [3.07 (95% CI 2.99-3.15)]. The ankle was the most commonly injured anatomical location, followed by the hand (including wrist and fingers), knee and head. Soft tissue and ligament injuries were most common types of injuries.

CONCLUSION

Injury prevention in women's sports is a novel and emerging field of research interest. This review highlights that injury incidence is high among female bat-or-stick players, but little information is known about direct causal mechanisms. This review clearly establishes the need for enhancements to injury data collection. Without this information, it will not be possible to develop evidence-based injury prevention interventions.

Effect of Exercise on Ovulation: A Systematic Review

BACKGROUND

Infertility has been described as a devastating life crisis for couples, and has a particularly severe effect on women, in terms of anxiety and depression. Anovulation accounts for around 30% of female infertility, and while lifestyle factors such as physical activity are known to be important, the relationship between exercise and ovulation is multi-factorial and complex, and to date there are no clear recommendations concerning exercise regimes.

OBJECTIVES

The objective of this review was to systematically assess the effect of physical activity on ovulation and to discuss the possible mechanisms by which exercise acts to modulate ovulation in reproductive-age women. This was done with a view to improve existing guidelines for women wishing to conceive, as well as women suffering from anovulatory infertility.

SEARCH METHODS

The published literature was searched up to April 2016 using the search terms ovulation, anovulatory, fertility, sport, physical activity and exercise. Both observational and interventional studies were considered, as well as studies that combined exercise with diet. Case studies and articles that did not report anovulation/ovulation or ovarian morphology as outcomes were excluded. Studies involving administered drugs in addition to exercise were excluded.

RESULTS

In total, ten interventions and four observational cohort studies were deemed relevant. Cohort studies showed that there is an increased risk of anovulation in extremely heavy exercisers (>60 min/day), but vigorous exercise of 30-60 min/day was associated with reduced risk of anovulatory infertility. Ten interventions were identified, and of these three have studied the effect of vigorous exercise on ovulation in healthy, ovulating women, but only one showed a significant disruption of ovulation as a result. Seven studies have investigated the effect of exercise on overweight/obese women suffering from polycystic ovary syndrome (PCOS) or anovulatory infertility, showing that exercise, with or without diet, can lead to resumption of ovulation. The mechanism by which exercise affects ovulation is most probably via modulation of the hypothalamic-pituitary-gonadal (HPG) axis due to increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. In heavy exercisers and/or underweight women, an energy drain, low leptin and fluctuating opioids caused by excess exercise have been implicated in HPA dysfunction. In overweight and obese women (with or without PCOS), exercise contributed to lower insulin and free androgen levels, leading to the restoration of HPA regulation of ovulation.

CONCLUSIONS

Several clear gaps have been identified in the existing literature. Short-term studies of over-training have not always produced the disturbance to ovulation identified in the observational studies, bringing up the question of the roles of longer term training and chronic energy deficit. We believe this merits further investigation in specific cohorts, such as professional athletes. Another gap is the complete absence of exercise-based interventions in anovulatory women with a normal body mass index (BMI). The possibly unjustified focus on weight loss rather than the exercise programme means there is also a lack of studies comparing types of physical activity, intensity and settings. We believe that these gaps are delaying an efficient and effective use of exercise as a therapeutic modality to treat anovulatory infertility.

Gender and age based differences in behavioural patterns following anterior cruciate ligament injury

ACL injury can be clinically diagnosed prior to imaging, and therefore understanding any symptomatology differences between age-groups and genders is critical. Data gathered from 341 patients with ACL injuries over six years showed no gender-based difference in ability to continue playing sport post-injury. Fewer males required crutches (37.2% vs. 49.5%, p = 0.04) and more males returned to sports prior to treatment (24.4% vs. 14.1%, p = 0.04). There was no age based difference in play continuation post-injury, however more elderly patients fell post-injury (<30 y: 91.9%, 30 y 83.8%, p = 0.02). Therefore, there are few differences in behavioural patterns following ACL injury based on age or sex.

An Increased Lateral Femoral Condyle Ratio Is a Risk Factor for Anterior Cruciate Ligament Injury

BACKGROUND

The purpose of this study was to examine the relationship between distal femoral morphology and anterior cruciate ligament (ACL) injury, ACL reconstruction (ACLR) failure, and contralateral ACL injury. It was hypothesized that increased posterior femoral condylar depth, quantified as the lateral femoral condyle ratio, would correlate with increased risk of primary ACL injuries, ACLR failures, and contralateral ACL injuries.

METHODS

The charts of consecutive patients who underwent arthroscopic knee surgery at an academic medical center from 2012 to 2016 with minimum follow-up of 24 months were retrospectively reviewed. Patients were stratified into 4 groups: (1) a control group of patients with no ACL injury, (2) patients with primary ACL injury, (3) patients with failed ACLR, and (4) patients with previous ACL injury and subsequent contralateral ACL injury. With use of lateral radiographs, the ratio of posterior femoral condylar depth to total condylar length was defined as the lateral femoral condyle ratio. Differences between study groups were identified with use of analysis-of-variance (ANOVA) and post-hoc testing with significance set at p < 0.05. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cutoff for detecting increased risk of ACL injury.

RESULTS

Two hundred patients met the inclusion criteria. The mean lateral femoral condyle ratios (and standard deviations) were 61.2% ± 2.4% in the control group, 64.2% ± 3.8% in the primary ACL injury group, 64.4% ± 3.6% in the failed ACLR group, and 66.9% ± 4.3% in the contralateral ACL injury group. Patients who had a primary ACL injury, failed ACLR, or contralateral ACL injury had significantly higher ratios compared with the control group (p < 0.008). ROC curve analysis demonstrated that a lateral femoral condyle ratio of >63% was associated with an increased risk for ACL injury, with a sensitivity of 77% and a specificity of 72%.

CONCLUSIONS

The data from this study show that increased posterior femoral condylar depth, quantified as the lateral femoral condyle ratio, is associated with an increased risk of ACL injury, including primary and contralateral ACL injuries. The data from this study may help clinicians to identify patients at a greater risk of ACL injury.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Minimizing Injury and Maximizing Return to Play: Lessons from Engineered Ligaments

Musculoskeletal injuries account for more than 70% of time away from sports. One of the reasons for the high number of injuries and long return to play is that we have only a very basic understanding of how our training alters tendon and ligament (sinew) structure and function. Sinews are highly dense tissues that are difficult to characterize both in vivo and in vitro. Recently, engineered ligaments have been developed in vitro using cells from human anterior cruciate ligaments or hamstring tendons. These three-dimensional tissues can be grown in a laboratory, treated with agents thought to affect sinew physiology, and then mechanically tested to determine their function. Using these tissues, we have learned that sinews, like bone, quickly become refractory to an exercise stimulus, suggesting that short (<10 min) periods of activity with relatively long (6 h) periods of rest are best to train these tissues. The engineered sinews have also shown how estrogen decreases sinew function and that a factor released following intense exercise increases sinew collagen synthesis and function. Last, engineered sinews are being used to screen possible nutritional interventions that may benefit tendon or ligament function. Using the data derived from these tissue-engineered sinews, new nutritional and training regimes are being designed and tested with the goal of minimizing injury and accelerating return to play.

Modeling Individual Cyclic Variation in Human Behavior

Cycles are fundamental to human health and behavior. Examples include mood cycles, circadian rhythms, and the menstrual cycle. However, modeling cycles in time series data is challenging because in most cases the cycles are not labeled or directly observed and need to be inferred from multidimensional measurements taken over time. Here, we present Cyclic Hidden Markov Models (CyH-MMs) for detecting and modeling cycles in a collection of multidimensional heterogeneous time series data. In contrast to previous cycle modeling methods, CyHMMs deal with a number of challenges encountered in modeling real-world cycles: they can model multivariate data with both discrete and continuous dimensions; they explicitly model and are robust to missing data; and they can share information across individuals to accommodate variation both within and between individual time series. Experiments on synthetic and real-world health-tracking data demonstrate that CyHMMs infer cycle lengths more accurately than existing methods, with 58% lower error on simulated data and 63% lower error on real-world data compared to the best-performing baseline. CyHMMs can also perform functions which baselines cannot: they can model the progression of individual features/symptoms over the course of the cycle, identify the most variable features, and cluster individual time series into groups with distinct characteristics. Applying CyHMMs to two real-world health-tracking datasets-of human menstrual cycle symptoms and physical activity tracking data-yields important insights including which symptoms to expect at each point during the cycle. We also find that people fall into several groups with distinct cycle patterns, and that these groups differ along dimensions not provided to the model. For example, by modeling missing data in the menstrual cycles dataset, we are able to discover a medically relevant group of birth control users even though information on birth control is not given to the model.

Constant performance in balance and proprioception tests across the menstrual cycle - a pilot study in well trained female ice hockey players on hormonal contraception

INTRODUCTION

It has yet to be explained why female athletes appear to suffer more often from non-contact ligament injuries during the first half of the menstrual cycle. Fluctuations in balance, caused by impaired proprioception due to increased fluid retention, may be relevant factors contributing to this anomaly in distribution. The aim of this study was therefore to uncover relationships between dynamic stability, proprioception and fluid retention in association with the menstrual cycle as a possible explanation for the observed changes in injury rates.

METHODS

Nine healthy, female, well trained ice hockey players on hormonal contraception with regular cycles were tested at least twelve times during one menstrual cycle. Bioimpedance analysis was applied to investigate body composition and fluid distribution. A joint position sense test was performed to characterize changes in proprioception, while unexpected perturbations on a balance board were used to obtain measures for dynamic postural control.

RESULTS

No distinct changes in proprioception, dynamic stability and fluid retention were identified across the menstrual cycle in this population. Weak correlations were found between parameters for dynamic stability and proprioception.

CONCLUSION

Variations in proprioception, dynamic stability and fluid retention seem unlikely to be major contributors to injury risk peaks, at least in this population of healthy trained athletes using hormonal contraception.

AS DIFERENTES FASES DO CICLO MENSTRUAL NÃO INFLUENCIAM O RENDIMENTO DE ATLETAS DE NADO SINCRONIZADO

RESUMO Introdução: O conhecimento referente à influência das fases do ciclo menstrual no desempenho ainda é inconclusivo. Objetivo: Analisar o desempenho físico e técnico de atletas de nado sincronizado em três diferentes fases do ciclo menstrual. Métodos: Seis atletas de nível nacional (idade: 17,6 ± 6,15) com ciclo menstrual normal foram avaliadas, considerando as seguintes fases do ciclo menstrual, folicular (F), ovulatória (O) e lútea (L). Foram avaliados os parâmetros antropométricos, neuromotores, o deslocamento vertical, alçada de eggbeater e o desempenho na rotina técnica. Resultados: Não foram encontradas alterações de parâmetros antropométricos, força dos membros superiores (F; O; L); abdominal (F; O; L) e flexibilidade (F; O; L). Nos testes específicos, tanto deslocamento vertical, alçada de eggbeater (F; O; L) e desempenho técnico (F: 77 ± 4, O: 80 ± 5, L: 77 ± 4; pontos) não se alteraram ao longo das fases do ciclo menstrual. Conclusão: Os dados do presente estudo indicam que as fases do ciclo menstrual não exercem influência direta no desempenho de atletas de nado sincronizado.

Compositional mapping of the mature anterior cruciate ligament-to-bone insertion

The anterior cruciate ligament (ACL)-to-bone interface constitutes a complex, multi-tissue structure comprised of contiguous ligament, non-mineralized fibrocartilage, mineralized fibrocartilage, and bone regions. This composite structure enables load transfer between structurally and functionally dissimilar tissues and is critical for ligament homeostasis and joint stability. Presently, there is a lack of quantitative understanding of the matrix composition and organization across this junction, especially after the onset of skeletal maturity. The objective of this study is to characterize the adult bovine ACL-to-bone interface using Fourier transform infrared spectroscopic imaging (FTIRI), testing the hypothesis that regional changes in collagen, proteoglycan, and mineral distribution, as well as matrix organization, persist at the mature insertion. It was observed that while collagen content increases continuously across the adult interface, collagen alignment decreases between ligament and bone. Proteoglycans were primarily localized to the fibrocartilage region and an exponential increase in mineral content was observed between the non-mineralized and mineralized regions. These observations reveal significant changes in collagen distribution and alignment with maturity, and these trends underscore the role of physiologic loading in postnatal matrix remodeling. Findings from this study provide new insights into interface organization and serve as benchmark design criteria for interface regeneration and integrative soft tissue repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2513-2523, 2017.