Noncontact Anterior Cruciate Ligament Injury Research Articles

COMPARISON OF INTER-SESSION, INTRA-RATER AND INTER-RATER RELIABILITY OF SINGLE AND DOUBLE LEG LANDING ERROR SCORING SYSTEM USING DIFFERENT CALCULATION METHODS

INTRODUCTION & AIMS The Landing Error Scoring System (LESS) is used for screening noncontact anterior cruciate ligament (ACL) injury risk. The LESS is deemed a valid and reliable indicator of landing biomechanics that predict noncontact ACL injuries. We have sought to validate a Single-Leg Landing Error Scoring System (SLESS) against the established LESS. There are seven distinct calculation methods for final LESS scores, adding variability to the original version and the risk of misinterpreting results. This study used different calculation methods to investigate the inter-session, intra-rater and inter-rater reliability of the SLESS and LESS scores. METHODS Thirty-five team sports players performed four drop jump landing variations (dominant leg, non-dominant leg, double-leg and cognitive loading drill with double-leg) over three sessions. Sessions 1 and 2 were conducted on the same day, with Session 3 a week later. Video footage from frontal and sagittal views captured all landings. Three professionals scored recorded trials using standard SLESS and LESS protocols. One scorer assessed intra-session and inter-session reliability, while three evaluated inter-rater reliability. The final SLESS and LESS scores were calculated using original version/OG, average of 3 trials-AV, worst trial/WT, best score/BS, first trial/FT, last trial/LT, error present in at least two of three trials/TT). Reliability was assessed using intraclass correlation coefficient (ICC), standard error of measurement (SEM), and coefficient of variation (CV) with 95% confidence intervals. RESULTS The study observed acceptable inter-session reliability across single-leg and double-leg drop jump landing tasks using all seven calculation methods (SLESS: ICC=0.80-0.91, SEM=1.07-1.10, CV=6.5-10.1%; LESS: ICC=0.63-0.90, SEM=1.06-1.11, CV=5.7-11.5%). The study also demonstrated acceptable intra-rater reliability for all tasks using all calculation methods (SLESS: ICC=0.86-0.94, SEM=1.05-1.08, CV=5.0-8.5%; LESS: ICC=0.74-0.93, SEM=1.04-1.08, CV=4.2-8.5%). In addition, acceptable inter-rater reliability was shown for all tasks using all calculation methods (SLESS: ICC=0.69-0.83, SEM=1.11-1.18, CV=10.5-18.0%; LESS: ICC=0.54-0.82, SEM=1.10-1.20, CV=10.3-20.3%). CONCLUSION The study indicates the reliability of all seven calculation methods for SLESS and LESS scores. Precise specification of the chosen calculation method is crucial for practitioners and researchers.

Regenerative Anterior Cruciate Ligament Healing in Youth and Adolescent Athletes: The Emerging Age of Recovery Science

Anterior cruciate ligament (ACL) injuries mainly arise from non-contact mechanisms during sport performance, with most injuries occurring among youth or adolescent-age athletes, particularly females. The growing popularity of elite-level sport training has increased the total volume, intensity and frequency of exercise and competition loading to levels that may exceed natural healing capacity. Growing evidence suggests that the prevailing mechanism that leads to non-contact ACL injury from sudden mechanical fatigue failure may be accumulated microtrauma. Given the consequences of primary ACL injury on the future health and quality of life of youth and adolescent athletes, the objective of this review is to identify key “recovery science” factors that can help prevent these injuries. Recovery science is any aspect of sports training (type, volume, intensity, frequency), nutrition, and sleep/rest or other therapeutic modalities that may prevent the accumulated microtrauma that precedes non-contact ACL injury from sudden mechanical fatigue failure. This review discusses ACL injury epidemiology, current surgical efficacy, the native ACL vascular network, regional ACL histological complexities such as the entheses and crimp patterns, extracellular matrix remodeling, the concept of causal histogenesis, exercise dosage and ligament metabolism, central nervous system reorganization post-ACL rupture, homeostasis regulation, nutrition, sleep and the autonomic nervous system. Based on this information, now may be a good time to re-think primary ACL injury prevention strategies with greater use of modified sport training, improved active recovery that includes well-planned nutrition, and healthy sleep patterns. The scientific rationale behind the efficacy of regenerative orthobiologics and concomitant therapies for primary ACL injury prevention in youth and adolescent athletes are also discussed.

Soccer and volleyball players do not land differently: implications for anterior cruciate ligament injury risk.

Non-contact anterior cruciate ligament injuries are common in soccer and volleyball, occurring during changes of direction and landings. This study aimed to investigate kinematic differences between soccer and volleyball players in single-planar and multiplanar landing tasks, simulating sport-specific injury mechanisms. Since the anterior cruciate ligament injury rate in soccer is higher than in volleyball, we hypothesized that volleyball players would adopt safer landing strategies, especially in single-planar landing tasks. Twenty-two soccer and 19 volleyball players performed single-leg drop landing, drop jump in vertical, 45°-medial and 45°-lateral directions. Box height and jump length were adapted to the subject's height and performance level, respectively. A 9-camera motion capture system provided lower limb kinematics. Two mixed multivariate analyses of covariance (sport, task, sex as covariate) were used to compare soccer and volleyball players' initial contact and peak kinematics (α=0.05). Task had significant effects on lower limb initial contact and peak angles, as expected. Sport and task × sport interaction had no significant effects on kinematics. Soccer and volleyball players' landing strategies were thus similar in each task, in opposition to initial hypotheses. We might speculate that the higher anterior cruciate ligament injury rate in soccer may be more related to non-predictable factors than the isolated landing kinematics.

Gender differences in the impact of anatomical factors on non-contact anterior cruciate ligament injuries: a magnetic resonance study

PurposeTo identify MRI-detected anatomical risk factors for non-contact anterior cruciate ligament (ACL) injuries across genders.MethodsA retrospective analysis was performed on 141 ACL-reconstructed patients (35 females, 106 males) and 142 controls (37 females, 105 males) from January 2020 to April 2022. Inclusion criteria were primary non-contact ACL injuries. The tibial plateau slope, lateral femoral condyle index, Insall-Salvati index, and patellar tendon angle were measured, using binary logistic regression for gender-specific risk evaluation.ResultsIncreased lateral tibial plateau slope, reduced intercondylar notch width index, lateral femoral condyle index, and patellar tendon angle correlated with ACL injuries in both genders. The Insall-Salvati index was a significant risk factor in females but not in males.ConclusionThis study identifies the lateral tibial plateau slope, notch width index, lateral femoral condyle index, and patellar tendon angle at near-extension as risk factors for ACL injuries in both genders, with the Insall-Salvati index also implicated in females.

The relationship between lateral femoral condyle ratio measured by MRI and anterior cruciate ligament injury.

Previous studies have shown that the lateral femoral condyle ratio (LFCR) measured by X-ray has a significant relationship with the anterior cruciate ligament (ACL) injury. However, few relevant studies have been performed on LFCR measured by magnetic resonance imaging (MRI). (1) To evaluate the relationship between LFCR measured by MRI and ACL injury or rerupture. (2) To compare the LFCR measured by MRI with existing bony morphological risk factors and screen out the most predictive risk factors for primary ACL injury or rerupture. Cohort study; Level of evidence, 3. Totally 147 patients who underwent knee arthroscopic surgery from 2015 to 2019 with minimum follow-up of 48months were retrospectively evaluated. Patients were placed into three groups: 1) the control group of patients with simple meniscus tears without ligament injury; 2) the primary noncontact ACL injury group; 3) ACL rerupture group (ACL reconstruction failure). The LFCR measured by MRI and other previous known risk factors associated with MRI (notch width index, medial tibial slope, lateral tibial slope, medial tibial depth, lateral tibial height) were performed to evaluate their predictive value for ACL injury and rerupture. All the risk factors with p < 0.01 according to univariate analysis were included in the logistic regression models. Receiver operating characteristic (ROC) curves were analyzed for sensitivity, specificity, cut-off, and area under the curve (AUC). Z tests were used to compare the AUC values. The LFCR measured by MRI was obviously higher in primary ACL injury group (0.628 ± 0.020) and in ACL rerupture group (0.625 ± 0.021) than that in the control group (0.593 ± 0.030). The best risk factor was the LFCR with a cut-off of 0.602 (AUC, 0.818; 95% CI, 0.748-0.878; sensitivity, 90%; specificity, 66%). When combined with lateral tibial slope (cutoff, 7°) and lateral tibial height (cutoff, 3.6mm), the diagnostic performance was improved significantly (AUC, 0.896; 95% CI, 0.890-0.950; sensitivity, 87%; specificity, 80%). The increased LFCR measured by MRI was associated with a significantly higher risk for ACL injury or rerupture. The combination of LFCR, lateral tibial slope and lateral tibial height were the most predictive risk factors. This may help clinicians identify susceptible individuals and allow precision approaches for better prevention, treatment and management of this disease.

Comparing a Portable Motion Analysis System against the Gold Standard for Potential Anterior Cruciate Ligament Injury Prevention and Screening.

Knee kinematics during a drop vertical jump, measured by the Kinect V2 (Microsoft, Redmond, WA, USA), have been shown to be associated with an increased risk of non-contact anterior cruciate ligament injury. The accuracy and reliability of the Microsoft Kinect V2 has yet to be assessed specifically for tracking the coronal and sagittal knee angles of the drop vertical jump. Eleven participants performed three drop vertical jumps that were recorded using both the Kinect V2 and a gold standard motion analysis system (Vicon, Los Angeles, CA, USA). The initial coronal, peak coronal, and peak sagittal angles of the left and right knees were measured by both systems simultaneously. Analysis of the data obtained by the Kinect V2 was performed by our software. The differences in the mean knee angles measured by the Kinect V2 and the Vicon system were non-significant for all parameters except for the peak sagittal angle of the right leg with a difference of 7.74 degrees and a p-value of 0.008. There was excellent agreement between the Kinect V2 and the Vicon system, with intraclass correlation coefficients consistently over 0.75 for all knee angles measured. Visual analysis revealed a moderate frame-to-frame variability for coronal angles measured by the Kinect V2. The Kinect V2 can be used to capture knee coronal and sagittal angles with sufficient accuracy during a drop vertical jump, suggesting that a Kinect-based portable motion analysis system is suitable to screen individuals for the risk of non-contact anterior cruciate ligament injury.

Statistical shape analysis and computational modeling reveal novel relationships between tibiofemoral bony geometry and knee mechanics in young, female athletes

Young female athletes participating in sports requiring rapid changes of direction are at heightened risk of suffering traumatic knee injury, especially noncontact rupture of the anterior cruciate ligament (ACL). Clinical studies have revealed that geometric features of the tibiofemoral joint are associated with increased risk of suffering noncontact ACL injury. However, the relationship between three-dimensional (3D) tibiofemoral geometry and knee mechanics in young female athletes is not well understood. We developed a statistically augmented computational modeling workflow to determine relationships between 3D geometry of the knee and tibiofemoral kinematics and ACL force in response to an applied loading sequence of compression, valgus, and anterior force, which is known to load the ACL. This workflow included 3D characterization of tibiofemoral bony geometry via principal component analysis and multibody dynamics models incorporating subject-specific knee geometries. A combination of geometric features of both the tibia and the femur that spanned all three anatomical planes was related to increased ACL force and to increased kinematic coupling (i.e., anterior, medial, and distal tibial translations and internal tibial rotation) in response to the applied loads. In contrast, a uniplanar measure of tibiofemoral geometry that is associated with ACL injury risk, sagittal plane slope of the lateral tibial plateau subchondral bone, was not related to ACL force. Thus, our workflow may aid in developing mechanics-based ACL injury screening tools for young, active females based on a unique combination of bony geometric features that are related to increased ACL loading.

Decreased sagittal slope of the medial tibial spine and deep concavity of the lateral tibial spine are risk factors for noncontact anterior cruciate ligament injury.

This study aimed to assess the relationship between the geometric features of tibial eminence and susceptibility to noncontact anterior cruciate ligament (ACL) injuries. Patients with unilateral noncontact knee injuries between 2015 and 2021 were consecutively enroled in this study. Based on knee magnetic resonance imaging (MRI) and arthroscopic visualisation, patients were categorised into the case group (ACL rupture) and control group (ACL intact). Using MRI, the geometric features of tibial eminence were characterised by measuring the sagittal slopes, depth of concavityand coronal slopes of the inclined surfaces of the tibial spines. Univariate and multivariate logistic regressions were conducted to explore independent associations between quantified geometric indices of tibial eminence and the risk of noncontact ACL injuries. This study included 187 cases and 199 controls. A decreased sagittal slope of the medial tibial spine (MTSSS) (combined group: odds ratio [OR]: 0.87 [0.82, 0.92], p < 0.001; females: OR: 0.88 [0.80, 0.98], p = 0.020; males: OR: 0.87 [0.81, 0.93], p < 0.001) and an increased depth of concavity in the lateral tibial spine (LTSD)(combined group: OR: 1.51 [1.24, 1.85], p < 0.001; females: OR: 1.65 [1.12, 2.43], p = 0.012; males: OR: 1.44 [1.11, 1.89], p = 0.007) were independent risk factors for noncontact ACL injuries. Moreover, a steeper coronal slope of the inclined surface of the medial tibial spine was a significant predictor of noncontact ACL injuries for males (MTSCS: OR: 1.04 [1.01, 1.08], p = 0.015) but not for females. Geometric features of tibial eminence, particularly a decreased MTSSS and an increased LTSD, were identified as independent risk factors for noncontact ACL injuries. These findings will help clinicians identify individuals at high risk of ACL injury and facilitate the development of targeted prevention strategies. Level III.

Decreased moment of inertia of the lower limb facilitates a rapid hip internal rotation in a simulated foot impact maneuver. A laboratory-controlled biomechanical study for a precursor mechanism of noncontact anterior cruciate ligament injury.

Anterior cruciate ligament injury frequently occurs in the deceleration with the knee-extended position. In addition, a rapid hip internal rotation is concomitantly observed. However, how the extended knee position induces the hip internal rotation is unclear. Sixteen healthy participants performed the simulated foot impact task on the experimental chair. To vary the knee flexion angle, the following four-foot placement positions relative to the pelvis segment, i.e.: 1) near; 2) middle; 3) far; and 4) far + heel strike, were tested. The reflective marker positions and the ground reaction force (GRF) data were collected. The moment of inertia of the entire lower limb around its long axis as well as the peak hip internal rotation angular velocity were calculated and compared among four conditions (Wilcoxon Signed-Rank Test with Bonferroni correction, P<0.0083). As the knee extended from the near to far + heel strike condition, the moment of inertia of the entire lower limb significantly decreased and hip internal rotation angular velocity significantly increased (P<0.001). The extended knee position with far foot placement from torso reduces the inertial resistance of the entire lower limb around its long axis and is vulnerable to the hip internal rotation.

The Relationship Between Isometric Hip Strength and Incidence of Noncontact Anterior Cruciate Ligament Injuries in Female Athletes: A Critically Appraised Topic

Clinical Scenario: Noncontact anterior cruciate ligament (ACL) injuries are prevalent among athletes in multiplanar sports, especially females. Hip strength may contribute to the incidence of these injuries due to dynamic movement patterns at the knee. Clinical Question: Does hip strength impact the incidence of noncontact ACL injuries in female athletes? Summary of Key Findings: A literature search was conducted on the relationship between hip strength and noncontact ACLs. Three prospective studies measuring isometric hip strength and recording the number of noncontact ACL injuries that occurred within a time period were included. One study demonstrated lower isometric hip adductor-to-abductor ratio was associated with noncontact ACL injuries. Two studies demonstrated those with noncontact ACL injuries had greater isometric hip abduction strength. Clinical Bottom Line: Evidence suggests that greater isometric hip strength and low hip adductor-to-abductor strength ratio may be a risk factor that is associated with noncontact ACL injuries in females. Future research should investigate the impact of hip strength on the incidence of noncontact ACL injuries, across all genders. Strength of Recommendation: Based on the Center of Evidence-Based Medicine, these studies provide Level 3 evidence that hip strength is associated with the risk of noncontact ACL injuries in females.

Association of Increased Lateral Femoral Condylar Ratio With Lateral Meniscus Posterior Root Tear in Noncontact ACL Injury.

In the setting of anterior cruciate ligament (ACL) injury, lateral meniscus posterior root tears (LMPRTs) are less readily diagnosed on preoperative magnetic resonance imaging (MRI). Therefore, to predict LMPRTs in ACL injuries, it is necessary to understand the risk factors associated with them. The purpose of this study was to investigate the association of lateral femoral condylar ratio (LFCR) with LMPRTs in ACL injuries. It was hypothesized that an increased LFCR would be associated with LMPRTs in noncontact ACL injuries. Cohort study; Level of evidence, 3. Enrolled were consecutive patients who underwent primary acute (<6 weeks from injury) ACL reconstruction after noncontact injury and had LMPRT confirmed on preoperative MRI and arthroscopically (combined group; n = 62) as well as patients who underwent isolated acute ACL reconstruction (isolated group; n = 80) who were matched to the combined group by age, height, and body mass index (BMI). All patients underwent surgery between January 1999 and November 2021. LFCR and posterior tibial slope (PTS) were measured and compared between the isolated and combined groups. The area under the receiver operating characteristic curve (AUC) was calculated to determine the cutoff for detecting increased risk of LMPRTs. The demographic characteristics of the 2 groups did not differ significantly, nor did the PTS. The LFCR was a significant factor (odds ratio [OR], 1.23; P = .001) associated with LMPRT. Patient age, height, BMI, and PTS were not associated with LMPRT. The AUC (0.66; 95% CI, 0.57-0.75) for LFCR had a sensitivity of 39% and specificity of 90% to predict LMPRT. The calculated cutoff associated with an increased risk for LMPRT when compared with the isolated group was 67.0% (OR, 4.98; 95% CI, 2.10-11.79). Increased LFCR was associated with the presence of LMPRTs in patients with acute ACL injuries. The LFCR may provide surgeons with additional information regarding the risk of having a concomitant LMPRT when planning ACL reconstructions.

Increased knee torsional misalignment associated with femoral torsion is related to non-contact anterior cruciate ligament injury: a case-control study.

Altered axial biomechanics of the knee are recognized as a risk factor for non-contact anterior cruciate ligament (ACL) injury. However, the relationship of knee and segmental torsion to non-contact ACL and combined anterolateral ligament (ALL) injury is unclear. This study aims to determine the relationship of knee and segmental torsion to non-contact ACL injury and to explore their relationship with ALL injuries. We divided 122 patients with arthroscopically confirmed non-contact ACL injuries into an ACL injury group (isolated ACL injury, 63 patients) and an ACL + ALL injury group (ACL combined with ALL injury,59 patients). Additionally, 90 normal patients with similar age, gender and body mass index (BMI) were matched as a control group. The tibial tubercle-trochlear groove (TT-TG) distance, distal femoral torsion (DFT), posterior femoral condylar torsion (PFCT) and proximal tibial torsion (PTT) were measured using magnetic resonance imaging (MRI). We assessed the differences between the groups using an independent samples t test and utilized receiver operating characteristic (ROC) curves to determine the cut-off value for the increased risk of ACL injury. In patients with ACL injury, the measurements of the TT-TG (11.8 ± 3.1mm), DFT (7.7° ± 3.5°) and PFCT (3.6° ± 1.3°) were significantly higher compared to the control group (9.1 ± 2.4mm, 6.3° ± 2.7° and 2.8° ± 1.3°, respectively; P < 0.05), but the PTT did not differ between the two groups. The TT-TG, DFT and PFCT were not significantly larger in patients combined with ALL injury. ROC curve analysis revealed ACL injury is associated with TT-TG, DFT and PFCT. Knee torsional alignment is associated with ACL injury, predominantly in the distal femur rather than the proximal tibia. However, its correlation with ALL injury remains unclear. These findings may help identify patients at high risk for non-contact ACL injury and inform the development of targeted prevention and treatment strategies.

Deceleration Profiles Between the Penultimate and Final Steps of Planned and Reactive Side-Step Cutting.

Noncontact anterior cruciate ligament injury often occurs during rapid deceleration and change-of-direction maneuvers. These activities require an athlete to generate braking forces to slow down the center of mass and change direction in a dynamic environment. During preplanned cutting, athletes can use the penultimate step for braking before changing direction, resulting in less braking demand during the final step. During reactive cutting, athletes use different preparatory movement strategies during the penultimate step when planning time is limited. However, possible differences in the deceleration profile between the penultimate and final steps of preplanned and reactive side-step cuts remain unknown. To comprehensively evaluate deceleration during the penultimate and final steps of preplanned and reactive cutting. Cross-sectional study. Laboratory. Thirty-six women (age = 20.9 ± 1.7 years, height = 1.66 ± 0.07 m, mass = 62.4 ± 8.7 kg). Participants completed 90° side-step cutting maneuvers under preplanned and reactive conditions. Approach velocity, velocity at initial contact, and cutting angle were compared between conditions. Stance time, deceleration time, and biomechanical indicators of deceleration were assessed during the penultimate and final steps of preplanned and reactive 90° cuts. Separate repeated-measures analysis-of-variance models were used to assess the influence of step, condition, and their interaction on the biomechanical indicators of deceleration. Approach velocity (P = .69) and velocity at initial contact of the penultimate step (P = .33) did not differ between conditions. During reactive cutting, participants achieved a smaller cutting angle (P < .001). We identified a significant step-by-condition interaction for all biomechanical indicators of deceleration (P values < .05). A lack of planning time resulted in less penultimate step braking and greater final step braking during reactive cutting. As a result, participants exhibited a decreased cutting angle and longer stance time during the final step of reactive cutting. Improving an athlete's ability to respond to an external stimulus may facilitate a more effective penultimate step braking strategy that decreases the braking demand during the final step of reactive cutting.

Lower Extremity Reaction Time in Individuals With Contact Versus Noncontact Anterior Cruciate Ligament Injuries After Reconstruction.

Deficits in perceptual-motor function, like visuomotor reaction time (VMRT), are risk factors for primary and secondary anterior cruciate ligament (ACL) injury. Noncontact ACL injuries have been associated with slower reaction time, but whether this association exists for patients with contact ACL injuries is unknown. Exploring differences in VMRT among individuals with contact versus noncontact ACL injuries may provide a more comprehensive understanding of modifiable risk factors. To compare lower extremity VMRT (LEVMRT) in individuals with contact or noncontact ACL injuries after ACL reconstruction (ACLR). Cross-sectional study. Research laboratory. A total of 36 participants with primary, unilateral ACLR completed an LEVMRT assessment (contact ACL injury = 20 [56%], noncontact ACL injury = 16 [44%]). The LEVMRT was assessed bilaterally and collected using a series of wireless light discs deactivated by individuals with their feet. The ACLR-active LEVMRT (ie, ACLR limb is deactivating lights) and ACLR-stable LEVMRT were compared using separate analyses of covariance to determine the association with contact or noncontact injury using time since surgery as a covariate. After controlling for time since surgery, a difference and large effect size between groups was found for the ACLR-stable LEVMRT (P = .010; η2 = 0.250) but not for the ACLR-active (P = .340; η2 = 0.065) condition. The contact group exhibited slower ACLR-stable LEVMRT (521.7 ± 59.3 milliseconds) than the noncontact group (483.4 ± 83.9 milliseconds). Individuals with contact ACL injury demonstrated a slower LEVMRT while their ACLR limb was stabilizing. The group differences during the ACLR-stable LEVMRT task might indicate deficits in perceptual-motor function when the surgical limb maintains postural control during a reaction time task. After ACLR, individuals with contact injuries may need additional motor learning interventions to enhance perceptual-motor functioning.

Lower hamstring to quadriceps muscle strength ratio and lower body weight as factors associated with noncontact anterior cruciate ligament injury in male American football players: A prospective cohort study

BackgroundPrevious studies have aimed to determine the use of certain risk factors in predicting the occurrence of noncontact anterior cruciate ligament (ACL) injuries. Unfortunately, evidence regarding noncontact ACL injuries in male American football players is limited. This prospective cohort study aimed to identify intrinsic risk factors for noncontact ACL injury among male American football players. MethodsThis study evaluated 152 male American football players in Japan for potential noncontact ACL injury risk factors during a preseason medical assessment, including anthropometric, joint laxity, and flexibility, muscle flexibility, muscle strength, and balance measurements. A total of 25 variables were examined. Participants were monitored during each season for noncontact ACL injury, as diagnosed by physicians. ResultsNoncontact ACL injuries occurred in 11 knees of 11 players (prevalence; 7.1 %). Injured players were significantly more likely to have lightweight (P = 0.049). No statistically significant between-group differences were found for any other variables. Participants with a lower hamstring to quadriceps (H/Q) ratio (P = 0.04) were more likely to sustain noncontact ACL injuries. ConclusionLower H/Q ratio and lower body weight were significantly associated with new-onset noncontact ACL injury in male American football players. These findings will help develop strategies to prevent noncontact ACL injuries in male American football players.

The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in early phase of cutting maneuvers in female athletes

BackgroundCombined knee valgus and tibial internal rotation (VL + IR) moments have been shown to stress the anterior cruciate ligament (ACL) in several in vitro cadaveric studies. To utilize this knowledge for non-contact ACL injury prevention in sports, it is necessary to elucidate how the ground reaction force (GRF) acting point (center of pressure (CoP)) in the stance foot produces combined knee VL + IR moments in risky maneuvers, such as cuttings. However, the effects of the GRF acting point on the development of the combined knee VL + IR moment in cutting are still unknown. MethodsWe first established the deterministic mechanical condition that the CoP position relative to the tibial rotational axis differentiates the GRF vector's directional probability for developing the combined knee VL + IR moment, and theoretically predicted that when the CoP is posterior to the tibial rotational axis, the GRF vector is more likely to produce the combined knee VL + IR moment than when the CoP is anterior to the tibial rotational axis. Then, we tested a stochastic aspect of our theory in a lab-controlled in vivo experiment. Fourteen females performed 60° cutting under forefoot/rearfoot strike conditions (10 trials each). The positions of lower limb markers and GRF data were measured, and the knee moment due to GRF vector was calculated. The trials were divided into anterior- and posterior-CoP groups depending on the CoP position relative to the tibial rotational axis at each 10 ms interval from 0 to 100 ms after foot strike, and the occurrence rate of the combined knee VL + IR moment was compared between trial groups. ResultsThe posterior-CoP group showed significantly higher occurrence rates of the combined knee VL + IR moment (maximum of 82.8%) at every time point than those of the anterior-CoP trials, as theoretically predicted by the deterministic mechanical condition. ConclusionThe rearfoot strikes inducing the posterior CoP should be avoided to reduce the risk of non-contact ACL injury associated with the combined knee VL + IR stress.

Investigating the Role of Proximal Femoral Morphology in Noncontact ACL Injuries: A Comparative Study

Background: Non-contact anterior cruciate ligament (ACL) injury is a common and debilitating injury among athletes, with high recurrence rates and long-term consequences. Identifying individuals at risk of ACL injury can help prevent or reduce the severity of these injuries. The present study aimed to assess the alpha angle (AA) in ACL rupture patients in both the injured (ipsilateral) and non-affected (contralateral) extremities, compared to a control group. Methods and Results: This case-control study included 105 subjects (78.1% male and 21.9% female) aged between 15 and 45 years of both sexes involved in sports. The case group consisted of 54 patients with sport-related, noncontact ACL ruptures identified by MRI. Fifty-one patients, 10(19.6%) of whom were female, with no ACL rupture, were included in the study as a control group. Hip radiographs were taken in all the subjects using the modified Dunn View with the patient in the supine position, hip flexed 45o and abducted 20o. OsiriX software was used to obtain the measurements. Most injuries were caused by football (58.1%), followed by jumping sports (23.8%) and skiing (18.1%). The mean AA was 49.27 o (SD=4.93) for subjects without ACL rupture and 54.84o (SD=6.17) for subjects with ACL rupture, and the difference was statistically significant (P&lt;0.001). Results also showed a statistically significant difference in the AA on the ipsilateral (54.84o [SD=6.17]) and contralateral (49.48o [SD=7.04]) hips of the case subjects (P&lt;0.001). The logistic regression analysis indicated a statistically significant difference in AA between the case and control groups and between hips of the same subject with an OR of 1.12 (P=0.041) and 1.2 (P=0.000), respectively. Conclusion: Alterations in proximal femur morphology should be considered a potential risk factor for ACL injury, and AA can be a significant predictor of ACL injury. We recommend that young athletes actively participating in sports have their hip AA measured so those with higher AA can follow special prevention programs.

The effects of sex hormones during the menstrual cycle on knee kinematics.

The effects of the menstrual cycle and sex hormones on knee kinematics remain unclear. The purpose of the study was to investigate the effects of the menstrual cycle and serum sex hormone concentrations on knee kinematic parameters of the 90°cutting in female college soccer athletes. Three female college soccer teams (53 subjects) participated in the study. During the first menstrual cycle, a three-step method was used to exclude subjects with anovulatory and luteal phase-deficient (LPD) (12 subjects). The subjects' menstrual cycle was divided into the menstrual phase, late-follicular phase, ovulatory phase, and mid-luteal phase (group 1, 2, 3, 4). In each phase of the second menstrual cycle, we used a portable motion analysis system to enter the teams and tested the sex hormones concentrations and knee kinematics parameters in three universities in turn. We found that subjects had a lower maximum knee valgus in group 4 compared with other groups. This meant that subjects had a lower biomechanical risk of non-contact anterior cruciate ligament (ACL) injury in the mid-luteal phase. There was no significant correlation between serum estrogen, progesterone concentration, and knee kinematic parameters. This meant that sex hormones did not have a protective effect. Future studies need to incorporate more factors (such as neuromuscular control, etc.) to investigate.

Cyclic loading induces anabolic gene expression in ACLs in a load-dependent and sex-specific manner.

Anterior cruciate ligament (ACL) injuries are historically thought to be a result of a single acute overload or traumatic event. However, recent studies suggest that ACL failure may be a consequence of fatigue damage. Additionally, the remodeling response of ACLs to fatigue loading is unknown. Therefore, the objective of this study was to investigate the remodeling response of ACLs to cyclic loading. Furthermore, given that women have an increased rate of ACL rupture, we investigated whether this remodeling response is sex specific. ACLs were harvested from male and female New Zealand white rabbits and cyclically loaded in a tensile bioreactor mimicking the full range of physiological loading (2, 4, and 8 MPa). Expression of markers for anabolic and catabolic tissue remodeling, as well as inflammatory cytokines, was quantified using quantitative reverse transcriptionpolymerase chain reaction. We found that the expression of markers for tissue remodeling of the ACL is dependent on the magnitude of loading and is sex specific. Male ACLs activated an anabolic response to cyclic loading at 4 MPa but turned off remodeling at 8 MPa. These data support the hypothesis that noncontact ACL injury may be a consequence of failed tissue remodeling and inadequate repair of microtrauma resulting from elevated loading. Compared to males, female ACLs failed to increase anabolic gene expression with loading and exhibited higher expression of catabolic genes at all loading levels, which may explain the increased rate of ACL tears in women. Together, these data provide insight into load-induced ACL remodeling and potential causes of tissue rupture.

MMP3 single-nucleotide polymorphisms are associated with noncontact ACL injuries in competing high-level athletes.

Matrix metalloproteinases (MMPs) play an important role in matrix remodeling, as well as in ligament integrity. Anterior cruciate ligament (ACL) rupture is a severe and frequent knee injury in sports. The aim of this study was to investigate polymorphisms within the MMP3 gene with the predisposition for noncontact ACL rupture in the Croatian professional athletes. One hundred eighty-seven (95 with ACL rupture occurring through a noncontact mechanism and 92 asymptomatic controls) unrelated Caucasians were recruited between 2016 and 2017. All participants were genotyped for three single-nucleotide polymorphisms (SNP) within the MMP3 gene: rs591058 C/T, rs650108 A/G, and rs679620 G/A using the pyrosequencing method. For all three investigated SNPs, genotype frequencies have significantly differed between cases and controls. The MMP3 rs591058 TT (p = 0.0012, odds ratio [OR] = 38.541, 95% confidence interval [CI] = 1.7024-8.7254), rs650108 GG (p = 0.0051, OR = 23.338, 95% CI = 1.2899-4.2226) and rs679620 AA (p = 0.0030, OR = 34.750, 95% CI = 1.5266-7.9101) genotypes, as well as haplotype variant T-G-A (p = 0.0104, OR = 1.71, 95% CI = 1.13-2.59) were significantly overrepresented in cases compared to controls. These results support association between functional variants within the MMP3 gene and the risk of ACL rupture. Still, further research is needed to corroborate these results in a larger population.