Introduction. Perception of ACL injury prevention programs amongst professional netball players and coaches has not been studied. We investigated (1) level of awareness and experience of ACL injury prevention programs; (2) use of ACL injury prevention programs; and (3) barriers to implementing ACL injury prevention program in netball. Methodology. Female netball players representing Welsh senior and under-21 teams and elite and amateur coaches were invited electronically to this web-based study between 1st May–31st July 2021. Information on ACL injury susceptibility and seriousness, knowledge, experience, and implementation of ACL injury prevention programs were ascertained. Results. Twenty-eight players (77.8%) and 29 coaches (13.2%) completed the questionnaire. Seventeen (60.7%) players and 15 (51.7%) coaches reported female athletes were at greater risk for sustaining ACL injuries. Over 90% of respondents identified netball as high-risk, whilst 89% of players and 76% of coaches reported these injuries to be preventable. Two (7.1%) players and 6 (20.7%) coaches utilised ACL injury prevention programs with lack of time and engagement from coaches and players identified. Majority of respondents indicated that their club has neither promoted, advocated nor demonstrated exercises for ACL injury prevention. Over 90% of respondents would utilise such programs if it minimised players risk with appropriate training and information. Conclusion. Study highlights limited knowledge of female athletes’ increased susceptibility of ACL injuries with lack of communication and education of ACL injury prevention programs between sporting associations, coaches and players. Results demonstrate willingness of players and coaches to implement ACL injury prevention programs in Welsh netball

Purpose. Stress fractures (SFs) are highly prevalent in female athletes, especially runners (1337%), and result in pain and lost training time. There are numerous risk factors for SFs in athletes; however, the role of bone quality in the etiology of SFs is currently unknown. Therefore, our primary objective was to examine whether there are characteristic differences in bone quality and bone strength in female athletes with lower limb SFs using high-resolution peripheral quantitative computed tomography (HR-pQCT). A secondary objective was to compare muscle strength between SF subjects and controls. Method. Female athletes with (n=19) and without (n=19) lower limb SFs were recruited from the local community. All SFs were medically confirmed by a physician and subjects were assessed within 1–47 weeks (12.7 13.7) of diagnosis. Controls were age-, training volume- and sport-matched to SF athletes. Bone density and microarchitectural bone parameters such as cortical thickness and porosity, as well as trabecular thickness, separation and number of all subjects were assessed using HR-pQCT at two distal tibia scanning sites (distal, ultra-distal). Finite element (FE) analysis was employed to estimate bone strength and load sharing of cortical and trabecular bone from the HR-pQCT scans. Regional analysis was applied to the HR-pQCT scans to investigate site-specific bone differences between groups. Muscle torque was measured by a Biodex dynamometer as a surrogate of muscle strength. Independent sample t-tests and Mann-Whitney U-tests were used for statistical analyses (p < 0.05). Results. Significant differences and trends indicated compromised trabecular bone and slightly thicker cortices with fewer pores in SF subjects compared with controls. This was most pronounced in the posterior region of the distal tibia, which is the site of highest tensile stresses during running and a common SF site. FE analysis indicated significantly higher cortical loads (median 4.2% higher; p=0.03) in the distal tibia site (but not ultra-distal site) of SF subjects compared to controls. The SF group exhibited significantly reduced knee extension strength (median 18.3% lower; p=0.03) and a trend towards reduced plantarflexion (median 17.3% lower; p=0.24) and eversion strength (median 9.6% lower; p=0.49) compared to controls. Conclusion. This is the first study to compare bone microarchitectural quality and lower-limb muscle strength between female athletes with SFs and health controls. A reduced trabecular bone quality in SF subjects may result in an insufficient ability to absorb and distribute tibial loads. This, in turn, may lead to higher stresses in the cortex and a higher risk for SFs. Low muscle strength may increase SF risk by providing insufficient muscular support to counteract shear stresses associated with reaction forces during running. Further study is needed to determine whether a resistance-training program can improve bone quality and in turn, reduce SF risk

A quick, portable and reliable tool for predicting ACL injury could be an invaluable instrument for athletes, coaches, and clinicians. The gold standard, Vicon motion analysis, despite having a high sensitivity and risk specificity, is not practical for coaches or clinicians to use on a routine basis for assessing athletes. The present study validated the Kinect device to the currently used method of chart review in predicting athletes at high risk. A total of 114 participants were recruited from both the men and women McGill Varsity Sports Program. 69 males and 45 female athletes were evaluated to assess the specificity and sensitivity of the Kinect device in predicting athletes at high risk of injury. Each athlete performed three-drop vertical jumps off of a 31cm box and the data was recorded and risk score was generated. Generation of this data is done by our uniquely programmed software that measures landing angles at different time frames and compares live results to previously known data of injured athletes. A chart review was then performed by a clinician, blinded to these risk scores, to risk stratify the same athletes as high or low risk of ACL injury based on their medical charts. Data reviewed incorporated pre-season physical exams along with documented known risk factors for ACL injury, including previous knee injuries, family history of ACL injury, gender, sport, and BMI. Positive risk factors were assigned one point while negative risk factors assigned zero points. The Kinect device, powered by our software, identified 40 athletes as having a high-risk score (> 55%), and subsequently, five (4.39%) sustained an ACL injury by the end of their respective sport seasons. Two male and two female basketball players along with one male soccer player sustained non-contact ACL injuries. Given that all five of the injured athletes were in the cohort of 40 identified as high risk by the Kinect, this yielded a sensitivity of 100% for the device. As for the specificity, the Kinect computed 35 false positives, yielding a specificity of 68% for the duration of the study. The medical chart review identified 36 athletes as high risk and 60 as being low risk of ACL injury. Four of the athletes that sustained an ACL injury were in the group of 36 identified as high risk by the clinician. However, one of the five participants who sustained an ACL injury was not captured by the medical chart assessment, yielding a sensitivity of 80% and a specificity of 65% for the clinician. When it comes to injury prediction, it is preferred to have a high sensitivity even if the specificity is slightly lower as this ensures that all athletes who are at risk will be captured. Our data demonstrated that the chart analysis provided one false negative and led to missing one high-risk athlete who ended up sustaining an ACL injury. Based on the comparison of sensitivity and specificity, the Kinect system provides a slightly better predictive analysis for predicting ACL injury compared to chart review

Limb symmetry on a battery of functional tests is becoming more common as a clinical rehabilitation tool serving as a proxy assessment for readiness to return to sport following anterior cruciate ligament reconstruction (ACLR). The predictive capability of each included test for determining the likelihood of a second ACL injury is not well known. This study combines 14 established functional tests into a comprehensive return-to-sport assessment (RTSA). Study purpose: to determine if any of the functional tests were independently related to a second ACL injury occurring after the patient was cleared for return to sport. The RTSA was administered to 226 individuals after primary, unilateral ACLR who were followed for at least 24 months (51% female; mean ± SD age, 18.9 ± 4.0 years at RTSA, 9.4 ± 2.4 months post-surgery). The RTSA included 14 tests that involved calculation of Limb Symmetry Indices (LSI): leg press [LP], eccentric hamstring strength [HS], hip adductor strength [HA], Y Balance Test (anterior [YANT], posteromedial [YPM], posterolateral [YPL]), single hop [SH], triple hop [TH], crossover hop [CH], 6 meter timed hop [TiH], lateral hop [LH], medial hop [MH], vertical jump [VJ], single leg squat [SLS]. LSI averaged values of three trials for each leg for LP, HS, HA, SH, TH, CH, TiH, LH, MH, VJ, and SLS. The lowest bilateral difference across three trials was used for YANT, YPM, and YPL. Logistic regression using backward elimination was used to predict the odds of a second non-contact ACL injury using the RTSA, sex, age, and months post-surgery at RTSA as the independent variables. Twenty-five (11%) patients returned to have a subsequent ACL surgery. Twenty of the 25 experienced a second non-contact ACL injury (70% female; 10 ipsilateral, 10 contralateral). Of the 14 female athletes, there were eight contralateral and six ipsilateral tears. In males, there were two contralateral and four ipsilateral tears. The mean time from surgery to injury was 20.5 ± 9.8 months. Age (OR; 95%CI: 0.75; 0.58, 0.92), LP (0.97; 0.93, 0.99), YANT (1.21; 1.02, 1.43), and TiH (1.10; 1.01, 1.20) were found to be significantly associated with the odds of re-injury. Age, YANT, and the LSI of LP and TiH have a statistically significant impact on the odds of a second ACL injury after ACL reconstruction. YANT has an OR of 1.21, indicating that a 1cm increase in asymmetry will increase the likelihood of re-injury by 21%, holding all else constant. A 1% increase in the TiH LSI results in a 10% increase in the odds of re-injury. The risk of re-injury decreases as age increases. The OR for LP symmetry was near 1.0 and therefore may not have a clinically relevant effect on re-injury risk. Although LSI is a straightforward, quantitative measure, clinicians should not solely rely on it as a proxy for recovery of knee function. Many tests are available for clinical assessments, but this study found only a few of the tests to have significant associations with a subsequent ACL injury following return to play after ACL reconstruction

Background The minimum size required for a successful quadrupled hamstring autograft ACL reconstruction remains controversial. The risks of ACL re-tear in younger patients who tend to participate in a higher level of sports activity, and female athletes who have numerous predisposing factors, are poorly defined. Purpose To identify risk factors for graft re-tears within 2 years of ACL surgery. The hypotheses are that female sex, a smaller size graft, and younger patients will increase the odds of failure. Study Design Cohort Study. Level of evidence, 3. A cohort of 503 athletes undergoing primary, autograft hamstring ACL reconstruction, performed by a single surgeon using the same surgical technique and rehabilitation protocol, between September-December 2012, was followed for a total duration of 2 years. Return to play was allowed between 6 and 12 months post-surgery upon completion of functional testing. Exclusion criteria included infections, revisions, double bundle techniques, multi-ligament injuries, non-compliance, BTB/allografts/hybrid grafts. Primary outcome consisted of binary data (ACL graft re-tear or no tear) as measured on physical exam (Lachman and pivot shift) and MRI. Multivariate logistic regression statistical analysis with model fitting was used to investigate the predictive value of sex, age, and graft size on ACL re-tear. Secondary sensitivity analyses were performed on the adolescent subgroup, age and graft size as categorical variables, and testing for interactions among variables. Sample size was calculated based on the rule of 10 events per independent variable for logistic regression. The mean age of the 503 athletes was 27.5 (SD 10.6; range = 12–61). There were 235 females (47%) and 268 males (53%) with a 6 % rate of re-tears (28 patients; 17 females). Mean graft size was 7.9 (SD 0.6; range = 6–10). Univariate analyses of graft size, sex, and age only in the model showed that younger age (odds ratio [OR] = 0.86; 95% confidence interval [CI] = 0.80–0.93; P = .001] and smaller graft size (OR = 0.36; 95% CI = 0.18–0.70; P = .003) were significantly predictive of re-tear. Female sex was correlated with re-tear but was not significant (OR = 1.8; 95% CI = 0.84–3.97; P = .13). Multivariate analysis with all 3 variables in the model showed similar significant results. Graft size < 8 mm (OR = 2.95; 95% CI = 1.33–6.53; P = .008) and age < 25 (OR = 7.01; 95% CI = 2.40–20.53; P = .001) were significantly predictive of re-tear. Entire model was statistically significant (Omnibus test P = .001; Hosmer-Lemeshow statistic P = .68; Receiver Operating Curve [ROC] = 0.8). Surgeons should counsel their patients who are female, younger than 25 and with a graft size less than 8 mm accordingly and consider modifying their surgical or rehabilitation techniques to mitigate these re-tear risks

Purpose. Alpine skiing is associated with large skeletal loads with distinct patterns of loading rate and direction, and alpine skiers were previously found to have a robust bone structure compared to normally active controls. However, it is not known whether the mechanical stimuli experienced by skiers are also associated with enhanced bone microarchitecture and strength. Thus, the purpose of this study was to use high-resolution peripheral quantitative computed tomography (HR-pQCT) to compare bone macro- and microarchitecture and bone strength between elite alpine skiers and normally active controls. Method. Participants included 7 female and 12 male members of the Canadian Alpine Ski Team, and 10 female and 16 male normally active control subjects. A whole body dual energy X-ray absorptiometry (DXA) scan was performed to measure lean mass and percent body fat. HR-pQCT (XtremeCT, Scanco) was used to assess bone macro- and microarchitecture including total, cortical and trabecular bone area, total and cortical bone mineral density (BMD), and bone volume ratio (BV/TV) of the dominant distal tibia and radius. Finite element analysis was applied to the HR-pQCT scans to estimate bone strength (failure load, N). Analysis of covariance (ANCOVA) was used to compare outcomes between groups adjusting for body weight (tibia) and height (tibia and radius). Results. Bone area of the distal radius was significantly greater in female (30%, p<.001) and male (21%, p=.003) skiers compared with controls. Similarly, distal radius failure load was greater in female (37%, p=.001) and male (42%, p<.001) skiers. Higher BV/TV was apparent in the distal tibia of the male (18%, p=.005) and female skiers (19%, p=.012) and at the radius for the male skiers (19%, p=.02) compared with controls. High BV/TV is associated with a higher trabecular area at the distal tibia for the female athletes (14%, p=.06) and the distal radius for male athletes (32%, p=.002). Distal tibia failure load was higher in male (18%, p<.001) and female skiers (22%, p=.012) compared with controls. Distal tibia failure load remained significantly higher for the male athletes even after adjusting for lean mass. Conclusion. Compared to controls, skiers have larger bone areas at the radius in men and women, and at the tibia in women. Trabecular bone volume is augmented in skiers compared with controls, even after adjusting for height and weight. After adjusting for lean mass, group differences in bone strength were still apparent at the distal tibia in men, suggesting that direct mechanical input associated with alpine skiing affects bone microarchitecture. In conclusion a larger bone size and greater trabecular bone volume may represent skeletal adaptations to the extreme mechanical environment experienced during competitive skiing, and likely contribute to the greater bone strength observed in skiers compared with controls at both skeletal sites