Noncontact Anterior Cruciate Ligament Injury Research Articles

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.

Real-time ground reaction force and knee extension moment estimation during drop landings via modular LSTM modeling and wearable IMUs.

This work investigates real-time estimation of vertical ground reaction force (vGRF) and external knee extension moment (KEM) during single- and double-leg drop landings via wearable inertial measurement units (IMUs) and machine learning. A real-time, modular LSTM-based model with four sub-deep neural networks was developed to estimate the vGRF and KEM from wearable IMUs. Sixteen subjects wore eight IMUs on the chest, waist, right and left thighs, shanks, and feet and performed drop landing trials. Ground embedded force plates and an optical motion capture system were used to capture lower extremity biomechanics for model training and evaluation. During single-leg drop landings, accuracy for the vGRF and KEM estimation was R2=0.88 ±0.12 and R2=0.84 ±0.14, respectively, and during double-leg drop landings, accuracy for the vGRF and KEM estimation was R2=0.85 ±0.11 and R2=0.84 ±0.12, respectively. The best vGRF and KEM estimations of the model with the optimal LSTM unit number (130) require eight IMUs placed on the eight selected locations during single-leg drop landings. During double-leg drop landings, the best estimation on a leg only needs five IMUs placed on the chest, waist, and the leg's shank, thigh, and foot. The proposed modular LSTM-based model with optimally-configurable wearable IMUs can accurately estimate vGRF and KEM in real-time with relatively low computational cost during single- and double-leg drop landing tasks. This investigation could potentially enable in-field, non-contact anterior cruciate ligament injury risk screening and intervention training programs.

Effect of a Neuromuscular Training on Knee Valgus, Range of Motion and Muscle Strength of Soccer Players With Dynamic Knee Valgus

Background and Aims The present study aims to investigate the effect of a neuromuscular training program on knee valgus angle, and range of motion (ROM) and muscle strength of hip and ankle in male adolescent football players with dynamic knee valgus (DKV). Valgus knee is one of the most common neuromuscular abnormalities that is involved in causing non-contact damage to the anterior cruciate ligament (ACL). Methods This is a quasi-experimental study. Participants were 25 adolescent male football players with DKV who were purposefully selected from Shahin Football Academy in Amol, Iran and randomly divided into two groups of control and training. The existence of DKV was assessed by Squats test and the valgus angle were assessed by jump-landing test and Kinovea software. The abduction and external rotation strength and ROM of hip and the dorsiflexion and plantarflexion strength and ROM of ankle were evaluated with Manual Muscle Testing and a goniometer, respectively. After performing the pre-test assessments, the subjects in the training group performed neuromuscular training for 8 weeks, while the control group also participated in the physical fitness program of Shahin Football Academy. At the end, assessments were performed again in two groups. To examine the differences, repeated measures analysis of variance and Bonferroni post hoc test were used in SPSS software, version 24. The significance level was set at 0.05. Results The results showed a significant difference in knee valgus angle (P=0.001), abduction ROM of hip (P=0.01), external rotation ROM of hip (P=0.01), dorsiflexion ROM of ankle with knee extension (P=0.001), dorsiflexion ROM of ankle with knee flexion (P=0.001), hip abduction strength (P=0.002), hip external rotation strength (P=0.01), and plantarflexion strength of ankle (P=0.03) between the control and training groups. However, the results showed no significant difference in plantarflexion ROM of ankle and dorsiflexion strength of ankle (P&gt;0.05). After one month, the results showed the sustainability of the effect of training on abduction and external rotation ROM of hip, dorsiflexion ROM of ankle with knee extension and flexion, and dorsiflexion and plantarflexion strength of ankle. Conclusion The neuromuscular training can reduce the risk of non-contact ACL injury in male football players with DKV by improving strength and ROM of hip and ankle.

Bone Morphological Characteristics as Risk Factors for Anterior Cruciate Ligament Injury: Comparison Between Contact and Noncontact Injury

Background: Altered bone morphologies are considered risk factors for noncontact anterior cruciate ligament (ACL) injuries. Purpose/Hypothesis: This study aimed to investigate bone morphological characteristics as risk factors for ACL tears in contact injuries and compare these factors with those for noncontact ACL injuries. We hypothesized that altered bone morphologies would also be risk factors for contact ACL injury. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Enrolled were patients who underwent primary ACL reconstructions between January 2000 and December 2021 within 6 weeks after injury. Patients in the ACL group were classified according to injury mechanism (contact vs noncontact). During the same period, a control group of patients matched by age, height, and body mass index to the ACL group was selected. The lateral femoral condylar ratio (LFCR), notch width index (NWI), and lateral posterior tibial slope (PTS) were measured. Measured parameters were compared between the control, contact, and noncontact groups using analysis of variance. Results: There were 86 patients in the control group, 102 patients in the contact ACL group, and 105 patients in the noncontact ACL group. The demographic characteristics of the 3 groups did not differ significantly. The contact group had significantly higher LFCRs and lower NWIs compared with the control group ( P &lt; .001 and P = .001, respectively). The noncontact group had significantly higher LFCRs and PTSs and lower NWIs compared with the control group ( P = .031; P &lt; .001; and P &lt; .001, respectively). The noncontact group had significantly higher PTSs and lower NWIs compared with the contact group ( P = .003 and P =.014, respectively). In the contact group, the LFCR, PTS, and NWI were significant risk factors for ACL tears (odds ratio [OR], 1.25 [ P &lt; .001]; OR, 1.16 [ P = .008]; and OR, 1.27 [ P = .001], respectively), and in the noncontact group, the PTS and NWI were significant risk factors for ACL tears (OR, 1.20 [ P &lt; .001]; OR, 1.59 [ P &lt; .001], respectively). Conclusion: Altered bone morphological characteristics of the knee were found to be risk factors for ACL tears in contact injuries as well as noncontact injuries. Altered morphology has a more significant effect in noncontact ACL injuries.

Levels of ACL-straining activities increased in the six months prior to non-contact ACL injury in a retrospective survey: evidence consistent with ACL fatigue failure.

Introduction: Recent evidence has emerged suggesting that a non-contact anterior cruciate ligament (ACL) tear can result from repetitive submaximal loading of the ligament. In other words, when the intensity of ACL-straining athletic activities is increased too rapidly, microdamage can accumulate in the ligament beyond the rate at which it can be repaired, thereby leading to material fatigue in the ligament and its eventual failure. The objective of this survey-based exploratory study was to retrospectively determine whether the levels of various athletic activities performed by ACL-injured patients significantly changed during the 6months before injury. Methods: Forty-eight ACL-injured patients completed a survey to characterize their participation in various activities (weightlifting, sport-specific drills, running, jumping, cutting, pivoting/twisting, and decelerating) at three timepoints (1week, 3months, 6months) prior to ACL injury. Activity scores, which summarized the frequency and intensity of each activity, were calculated for each patient at each time interval. A series of linear mixed-effects regression models was used to test whether there was a significant change in levels of the various activities in the 6-month period leading up to ACL injury. Results: Patients who sustained a non-contact ACL injury markedly increased their sport-specific drills activity levels in the time leading up to injury (p = 0.098), while those patients who sustained a contact ACL injury exhibited no change in this activity during the same time period (p = 0.829). Levels of running, jumping, cutting, pivoting/twisting, and decelerating increased for non-contact ACL-injured patients but decreased for contact ACL-injured patients, though not significantly (p values > 0.10). Weightlifting activity significantly decreased leading up to injury among contact ACL-injured patients (p = 0.002). Discussion: We conclude that levels of ACL-straining athletic activities or maneuvers in non-contact ACL-injured patients markedly increased in the 6months leading up to their injury, providing evidence that changing levels of certain activities or maneuvers may play a role in ACL injury risk. This warrants further investigation of the hypothesis that too rapid an increase in activities or maneuvers known to place large loads on the ACL can cause microdamage to accumulate in the ligament, thereby leading to failure.

Correlation between spatial inclination of Blumensaat line and anterior cruciate ligament injury based on EOS biplanar 3D imaging system

To explore correlation between femoral mechanical axis and Blumensaat line (FMBL) angle of knee joint (angle between Blumensaat line and femoral mechanical axis), α angle (angle between Blumensaat line and axis of distal femur in sagittal plane) on EOS biplane imaging and non-contact anterior cruciate ligament(ACL) injury, and evaluate angle for its accuracy in predicting the populations prone to non-contact ACL injury. From February 2018 to October 2020, EOS imaging and clinical data from 88 patients (176 knees) with unilateral non-contact ACL injury were retrospectively analyzed, including 53 males and 35 females, aged from 18 to 45 years old with an average of (30.3±6.2) years old, 48 patients on the left side and 40 patients on the right side. The patients were divided into ACL-affected group and ACL-health group according to side of ACL injuries, and 51 patients (51 knees) with non-ACL identified from EOS database were included in normal control group, including 28 males and 23 females, aged from 20 to 44 years old with an average of (31.6±5.5) years old, 26 patients on the left side and 25 patients on the right side. Full-length EOS imaging of skeleton extremitatis inferioris among three groups were reconstructed to 3D images of skeletal system with EOS software, and then FMBL angle and α angle were measured on the images. Univariate binary Logistic regression analysis was performed to determine the influence of the univariate(FMBL angle or α angle) on ACL status(normal or torn). And the angle cutoff value for univariate was selected based on receiver operating characteristics curve (ROC) to got the best accuracy. There was no statistically significant difference in age, gender and side distribution between ACL-injured group and normal control group(P>0.05). Statistical analyses (one-way ANOVA) indicated no significant difference in FMBL angle between ACL-injured knee group (32.8±2.3)° and ACL-injured contralateral knee group(32.5±2.3)°(P>0.05), but the values between two groups were significantly lower than that in normal control group (37.0±2.0)°(P<0.001). There was no statistically significant difference in α angle among three groups (P>0.05). Univariate binary Logistic regression analysis demonstrated that FMBL angle was risk factor for non-contact ACL injury[OR=0.433, 95%CI(0.330, 0.569), P<0.001]. The area under ROC curve for FMBL angle was 0.909[95%CI(0.861, 0.958), P<0.001], and the sensitivity and specificity were 70.5% and 98.0% respectively, cut-off value was 33.7°. FMBL angle formed by Blumensaat line and femoral mechanical axis is one of the risk factors for non-contact ACL injury and has good predictive accuracy. The general population with FMBL angle below 33.7° may be increased risk for ACL injury.

The Effect of a Knee Brace on Muscle Forces during Single-Leg Landings at Two Heights

Single-leg landing is one of the maneuvers that has been linked to non-contact anterior cruciate ligament (ACL) injuries, and wearing knee braces has been shown to reduce ACL injury incidence. The purpose of this study was to determine whether wearing a knee brace has an effect on muscle force during single-leg landings at two heights through musculoskeletal simulation. Eleven healthy male participants, some braced and some non-braced were recruited to perform single-leg landings at 30 cm and 45 cm. We recorded the trajectories and ground reaction forces (GRF) using an eight-camera motion capture system and a force platform. The captured data were imported into the generic musculoskeletal model (Gait2392) in OpenSim. Static optimization was used to calculate the muscle forces. The gluteus minimus, rectus femoris, vastus medialis, vastus lateralis, vastus medialis medial gastrocnemius, lateral gartrocnemius, and soleus muscle forces were all statistically significant different between the braced and non-braced participants. Simultaneously, increasing the landing height significantly affected the gluteus maximums, vastus medialis, and vastus intermedia muscle forces. Our findings imply that wearing a knee brace may alter muscle forces during single-leg landings, preventing ACL injuries. Additionally, research demonstrates that people should avoid landing from heights due to the increased risk of knee injuries.

Examining the Distribution of Bone Bruise Patterns in Contact and Noncontact Acute Anterior Cruciate Ligament Injuries

Background: Bone bruises are commonly seen on magnetic resonance imaging (MRI) in acute anterior cruciate ligament (ACL) injuries and can provide insight into the underlying mechanism of injury. There are limited reports that have compared the bone bruise patterns between contact and noncontact mechanisms of ACL injury. Purpose: To examine and compare the number and location of bone bruises in contact and noncontact ACL injuries. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Three hundred twenty patients who underwent ACL reconstruction surgery between 2015 and 2021 were identified. Inclusion criteria were clear documentation of the mechanism of injury and MRI within 30 days of the injury on a 3-T scanner. Patients with concomitant fractures, injuries to the posterolateral corner or posterior cruciate ligament, and/or previous ipsilateral knee injury were excluded. Patients were stratified into 2 cohorts based on a contact or noncontact mechanism. Preoperative MRI scans were retrospectively reviewed by 2 musculoskeletal radiologists for bone bruises. The number and location of the bone bruises were recorded in the coronal and sagittal planes using fat-suppressed T2-weighted images and a standardized mapping technique. Lateral and medial meniscal tears were recorded from the operative notes, while medial collateral ligament (MCL) injuries were graded on MRI. Results: A total of 220 patients were included, with 142 (64.5%) noncontact injuries and 78 (35.5%) contact injuries. There was a significantly higher frequency of men in the contact cohort compared with the noncontact cohort (69.2% vs 54.2%, P = .030), while age and body mass index were comparable between the 2 cohorts. The bivariate analysis demonstrated a significantly higher rate of combined lateral tibiofemoral (lateral femoral condyle [LFC] + lateral tibial plateau [LTP]) bone bruises (82.1% vs 48.6%, P < .001) and a lower rate of combined medial tibiofemoral (medial femoral condyle [MFC] + medial tibial plateau [MTP]) bone bruises (39.7% vs 66.2%, P < .001) in knees with contact injuries. Similarly, noncontact injuries had a significantly higher rate of centrally located MFC bone bruises (80.3% vs 61.5%, P = .003) and posteriorly located MTP bruises (66.2% vs 52.6%, P = .047). When controlling for age and sex, the multivariate logistical regression model demonstrated that knees with contact injuries were more likely to have LTP bone bruises (OR, 4.721 [95% CI, 1.147-19.433], P = .032) and less likely to have combined medial tibiofemoral (MFC + MTP) bone bruises (OR, 0.331 [95% CI, 0.144-0.762], P = .009) compared with those with noncontact injuries. Conclusion: Significantly different bone bruise patterns were observed on MRI based on ACL injury mechanism, with contact and noncontact injuries demonstrating characteristic findings in the lateral tibiofemoral and medial tibiofemoral compartments, respectively.

Using an Affordable Motion Capture System to Evaluate the Prognostic Value of Drop Vertical Jump Parameters for Noncontact ACL Injury

Background: Knee kinematic parameters during a drop vertical jump (DVJ) have been demonstrated to be associated with increased risk of noncontact anterior cruciate ligament (ACL) injury. However, standard motion analysis systems are not practical for routine screening. Affordable and practical motion sensor alternatives exist but require further validation in the context of ACL injury risk assessment. Purpose/Hypothesis: To prospectively study DVJ parameters as predictors of noncontact ACL injury in collegiate athletes using an affordable motion capture system (Kinect; Microsoft). We hypothesized that athletes who sustained noncontact ACL injury would have larger initial and peak contact coronal abduction angles and smaller peak flexion angles at the knee during a DVJ. Study Design: Case-control study; Level of evidence, 3. Methods: 102 participants were prospectively recruited from a collegiate varsity sports program. A total of 101 of the 102 athletes (99%) were followed for an entire season for noncontact ACL injury. Each athlete performed 3 DVJs, and the data were recorded using the motion capture system. Initial coronal, peak coronal, and peak sagittal angles of the knee were identified by our software. Results: Five of the 101 athletes sustained a noncontact ACL injury. Peak coronal angles were significantly greater and peak sagittal flexion angles were significantly smaller in ACL-injured athletes (P = .049, P = .049, respectively). Receiver operating characteristic (ROC) analysis demonstrated an area under the curve of 0.88, 0.92, and 0.90 for initial coronal, peak coronal, and peak sagittal angle, respectively. An initial coronal angle cutoff of 2.96° demonstrated 80% sensitivity and 72% specificity, a peak coronal angle cutoff of 6.16° demonstrated 80% sensitivity and 72% specificity, and a peak sagittal flexion cutoff of 93.82° demonstrated 80% sensitivity and 74% specificity on the study cohort. Conclusion: Increased peak coronal angle and decreased peak sagittal angle during a DVJ were significantly associated with increased risk for noncontact ACL injury. Based on ROC analysis, initial coronal angle showed good prognostic ability, whereas peak coronal angle and peak sagittal flexion provided excellent prognostic ability. Affordable motion capture systems show promise as cost-effective and practical options for large-scale ACL injury risk screening.

The Association Between Functional Movement Screen Scores and Knee Valgus Moments During Unplanned Sidestep Cutting in Netball.

Regular employment of three-dimensional (3D) motion analyses to assess and monitor knee valgus moments; a contributor to non-contact anterior cruciate ligament (ACL) injury; during unplanned sidestep cutting (USC) is costly and time-consuming. An alternative quick-to-administer assessment tool to infer an athlete's risk for this injury could allow prompt and targeted interventions to mitigate this risk. This study investigated whether peak knee valgus moments (KVM) during weight-acceptance phase of an unplanned sidestep cut were correlated with composite and component scores of the Functional Movement Screen (FMS™). Cross-sectional, Correlation. Thirteen female national-level netballers performed six movements of the FMS™ protocol and three trials of USC. A 3D motion analysis system captured lower limb kinetics and kinematics of each participant's non-dominant leg during USC. Averages of peak KVM across USC trials were calculated and examined for correlations with composite and component scores of the FMS™. No correlations were found between FMS™ composite or any of its component scores with peak KVM during USC. The current FMS™ did not show any correlations with peak KVM during USC on the non-dominant leg. This suggests that the FMS™ has limited utility in screening for non-contact ACL injury risks during USC. 3.