Noncontact Anterior Cruciate Ligament Injury Research Articles

Elevated In Vivo ACL Strain Is Associated With a Straight Knee in Both the Sagittal and the Coronal Planes

Background: Noncontact anterior cruciate ligament (ACL) injuries typically occur during deceleration movements such as landing or cutting. However, conflicting data have left the kinematic mechanisms leading to these injuries unclear. Quantifying the influence of sagittal and coronal plane knee kinematics on in vivo ACL strain may help to elucidate noncontact ACL injury mechanisms. Purpose/Hypothesis: The purpose of this study was to measure in vivo sagittal and coronal plane knee kinematics and ACL strain during a single-leg jump. We hypothesized that ACL strain would be modulated primarily by motion in the sagittal plane and that limited coronal plane motion would be measured during this activity. Study Design: Descriptive laboratory study. Methods: Seventeen healthy participants (8 male/9 female) underwent magnetic resonance imaging (MRI) followed by high-speed biplanar radiography, obtained as participants performed a single-leg jump. Three-dimensional models of the femur, tibia, and associated ACL attachment site footprints were created from the MRIs and registered to the radiographs to reproduce the position of the knee during the jump. ACL strain, knee flexion/extension angles, and varus/valgus angles were measured throughout the jump. Spearman rank correlations were used to assess relationships between mean ACL strain and kinematic variables. Results: Mean ACL strain increased with decreasing knee flexion angle (ρ = −0.3; P = .002), and local maxima in ACL strain occurred with the knee in a straight position in both the sagittal and the coronal planes. In addition, limited coronal plane motion (varus/valgus angle) was measured during this activity (mean ± SD, −0.5°± 0.3°). Furthermore, we did not detect a statistically significant relationship between ACL strain and varus/valgus angle (ρ = −0.01; P = .9). Conclusion: ACL strain was maximized when the knee was in a straight position in both the sagittal and coronal planes. Participants remained in <1° of varus/valgus position on average throughout the jump. As a ligament under elevated strain is more vulnerable to injury, landing on a straight knee may be an important risk factor for ACL rupture. Clinical Relevance: These data may improve understanding of risk factors for noncontact ACL injury, which may be useful in designing ACL injury prevention programs.

Effect of foot strike patterns and cutting angles on knee kinematics and kinetics during side-cutting maneuvers

Purpose Cutting maneuvers are important actions in multidirectional sports but associated with noncontact anterior cruciate ligament (ACL) injuries. This study aimed to investigate the effect of different foot strike patterns and cutting angles on knee kinematics and kinetics. Methods Twenty healthy male team sports athletes performed cuts with maximum speed at three angles (45°, 90°, and 135°) with different foot strike patterns (rearfoot strike [RFS] and forefoot strike [FFS]). A three-dimensional motion capture system combined with a force plate was used to collect makers trajectory and ground reaction force (GRF). Vertical GRF, and knee joint angles and moments were compared among these cutting tasks. Results Regardless of foot strike patterns, increased knee flexion angle, knee valgus moment, and knee internal rotation moment were observed during cutting to sharper angles (p &lt; 0.001). At 90° and 135°, the FFS condition remained in a varus position and showed lower knee flexion moment than the RFS condition (p ≤ 0.004). However, no significant differences in knee kinematic and kinetic variables were found between foot strike patterns during cutting to 45°. Conclusions These findings suggest that sharper cutting angles potentially increase the risk of ACL injury. Compared with the RFS pattern, the FFS pattern induces a slight knee varus angle and a lower knee flexion moment at sharper angles, which might further reduce the load placed on the knee.

Does posterior tibial slope laterality exist? A matched cohort study between ACL-injured and non-injured knees

PurposeThe purpose of this study is to examine 1) the degree and frequency of laterality in posterior tibial slope (PTS) with control and anterior cruciate ligament (ACL) injury groups and 2) the laterality of PTS between sides of injury and dominant legs in patients with primary ACL injuries.MethodsA total of 187 consecutive patients with clinically diagnosed noncontact ACL injuries and an age- and sex-matched 1:1 control group were identified. PTS was measured using three different methods (aPTS = anterior PTS, mPTS = middle PTS, pPTS = posterior PTS) on a lateral knee radiograph. PTS of the left and right sides were compared between the patients in the control and ACL-injured groups, and between the injured and non-injured and dominant and non-dominant legs among the patients in the ACL-injured group. The patients with a difference in PTS of ≥ 3° in mPTS were selected. The percentages were compared between left and right between and among both groups, and between the injured and non-injured, and non-dominant and dominant leg, for the ACL group. Multiple regression analysis was performed to analyze the factors influencing the degree of mPTS.ResultsBoth control (Right vs Left: aPTS; 9.0 ± 2.5 vs 10.5 ± 3.0, mPTS; 6.6 ± 2.3 vs 8.1 ± 2.7, pPTS; 4.0 ± 2.4 vs 5.6 ± 2.8, respectively, p < 0.01) and ACL injury groups (Right vs Left: aPTS; 10.6 ± 3.0 vs 12.6 ± 2.9, mPTS; 7.6 ± 2.6 vs 9.5 ± 2.6, pPTS; 5.9 ± 3.0 vs 8.0 ± 3.0, respectively, p < 0.01) had a significantly greater PTS on the left than on the right side, and the ACL group had a significantly greater PTS than the control group on both the left and right sides. In the ACL group, PTS was greater on the injured and the non-dominant leg than on the non-injured and the dominant leg. The percentage of patients with a PTS difference of ≥ 3° was significantly greater on the left, injured, and non-dominant leg (95.3% vs 4.7%, 73.8% vs 26.2%, 86.1% vs 13.9%, respectively, p < 0.01). Only the left leg had a significant influence on PTS in the multivariate analysis.ConclusionThere was laterality in PTS within control and ACL injury groups, and this information is of benefit for effective treatment of ACL injuries.Level of evidenceLevel III.

Are COL22A1 Gene Polymorphisms rs11784270 and rs6577958 Associated with Susceptibility to a Non-Contact Anterior Cruciate Ligament Injury in Polish Athletes?

Understanding the risk factors and etiology of ACL ruptures (anterior cruciate ligament) is crucial due to the injury’s high occurrence, significant financial cost to the healthcare sector, and clinical consequences. In this study, we investigated the hypothesis that rs11784270 A/C and rs6577958 C/T SNPs (single gene polymorphism) within COL22A1 are associated with ACL ruptures (ACLR) in Polish soccer players. Methods: 228 athletes with ACLR (157 male, age 26 ± 4, 71 female, age 26 ± 6) and 202 control athletes (117 male, age 26 ± 6, 85 female, age 29 ± 2) engaged in the study. The buccal cell swabs were genotyped using TaqMan® pre-designed SNP genotyping assays, following the manufacturer’s recommendations. The R program and SNPassoc package were used to determine the genotype and allele frequency distributions under the various inheritance models (co-dominant, dominant, recessive, and over-dominant). Further, p-values of <0.05 were considered statistically significant. We found no association between the analyzed polymorphisms and the risk of non-contact ACL ruptures in any of the studied models. Although the genetic variants investigated in this study were not associated with the risk of non-contact ACL ruptures, we assumed that the COL22A1 gene remains a candidate for further investigations in musculoskeletal injuries.

An Anterior Cruciate Ligament (ACL) Injury Risk Screening and Reduction Program for High School Female Athletes: A Pilot Study.

Anterior cruciate ligament (ACL) injury causes physical, mental, and financial burdens. Therefore, it is imperative to screen, identify, and educate athletes who are at high-risk. The combination of screening and education could identify those at risk and potentially reduce future injuries. The purpose was to conduct a feasible community pre-season screening program for high school female athletes for the presence of known modifiable risk factors that predispose them to sustaining a non-contact ACL injury. Non-experimental prospective study. A convenience sample of 15 healthy female athletes were recruited from local high schools, consisting of 11 soccer players and four basketball players. A pre-season screening program was designed encompassing four stations that addressed modifiable neuromuscular and biomechanical risk factors including range of motion (ROM), jump-landing technique, strength, and balance. Athletes were categorized into high-risk versus low-risk groups based on cutoff scores previously established in the literature. Every athlete met the high-risk cutoff score for at least one extremity during the ROM screening, and some met high-risk cutoff scores for more than one ROM. Out of all four categories tested, lower extremity ROM demonstrated the greatest deficits. This study identified athletes as having multiple modifiable risk factors that can be addressed with training and exercises. This supports implementing a pre-season program aimed at screening for injury risk factors. Level 3.

The Predicted Position of the Knee Near the Time of ACL Rupture Is Similar Between 2 Commonly Observed Patterns of Bone Bruising on MRI

Background: Bone bruises observed on magnetic resonance imaging (MRI) can provide insight into the mechanisms of noncontact anterior cruciate ligament (ACL) injury. However, it remains unclear whether the position of the knee near the time of injury differs between patients evaluated with different patterns of bone bruising, particularly with regard to valgus angles. Hypothesis: The position of the knee near the time of injury is similar between patients evaluated with 2 commonly occurring patterns of bone bruising. Study Design: Descriptive laboratory study. Methods: Clinical T2- and T1-weighted MRI scans obtained within 6 weeks of noncontact ACL rupture were reviewed. Patients had either 3 (n = 20) or 4 (n = 30) bone bruises. Patients in the 4–bone bruise group had bruising of the medial and lateral compartments of the femur and tibia, whereas patients in the 3–bone bruise group did not have a bruise on the medial femoral condyle. The outer contours of the bones and associated bruises were segmented from the MRI scans and used to create 3-dimensional surface models. For each patient, the position of the knee near the time of injury was predicted by moving the tibial model relative to the femoral model to maximize the overlap of the tibiofemoral bone bruises. Logistic regressions (adjusted for sex, age, and presence of medial collateral ligament injury) were used to assess relationships between predicted injury position (quantified in terms of knee flexion angle, valgus angle, internal rotation angle, and anterior tibial translation) and bone bruise group. Results: The predicted injury position for patients in both groups involved a flexion angle <20°, anterior translation >20 mm, valgus angle <10°, and internal rotation angle <10°. The injury position for the 3–bone bruise group involved less flexion (odds ratio [OR], 0.914; 95% CI, 0.846-0.987; P = .02) and internal rotation (OR, 0.832; 95% CI, 0.739-0.937; P = .002) as compared with patients with 4 bone bruises. Conclusion: The predicted position of injury for patients displaying both 3 and 4 bone bruises involved substantial anterior tibial translation (>20 mm), with the knee in a straight position in both the sagittal (<20°) and the coronal (<10°) planes. Clinical Relevance: Landing on a straight knee with subsequent anterior tibial translation is a potential mechanism of noncontact ACL injury.

The Effect of Two Types of Foot Orthoses on the Knee Valgus Angle Within Single-Leg Landing: Implications for ACL Damage Hazard Decrease

Background: Non-contact anterior cruciate ligament (ACL) injuries commonly occur when athletes land in high risk positions such as knee valgus. The impact of foot orthoses during exercises that recreate a non-contact ACL harm system (i.e., landing) in any case will be obscured. Objectives: The purpose of the current study research was to evaluate the effect of two foot orthoses (semi-hard foot orthoses and hard foot orthoses) on knee valgus angle during single-leg drop landing. Methods: Twenty male leisure volleyball gamers performed landing in one-leg step from 30 cm height in 3 conditions (without foot orthoses, mid-hard foot orthoses, and hard foot orthoses). A motion capture system was used to measure lower extremity kinematics. Two risk factors of ACL injury, maximum knee valgus angle (KVA), and maximum knee flexion was measured. ANOVA was used for statistical analysis (P &lt; 0.05). Results: With mid-hard foot, orthoses provide the maximum level of knee flexion and the minimum level of knee valgus during single-leg drop landing. Conclusions: It may be concluded showed that foot orthoses affect knee kinematics. More knee flexion and less knee valgus brought about by mid-hard foot orthoses can reduce injuries of the anterior cruciate ligament (ACL).

Can different training methods reduce the kinematic risk factors of ACL injuries in children?

According to the research, a lack of neuromuscular control is a major cause of non-contact anterior cruciate ligament (ACL) injury during locomotion. This study aimed to determine the influence of various prescriptive and Constrained Led Approach (CLA) training approaches on lower extremity kinematics and stride length in children aged 3–5 years old while walking and running. Thirty-six children with a mean age of 4.79 years were separated into three groups: 1- prescriptive training group (n = 10), 2- CLA training group (n = 11), and 3- Control group (n = 10). The kinematics of the hip, knee and ankle joints in the sagittal plane at the moment of heel contact and toe-off were recorded before and after six weeks of intervention. According to the MANOVA, there was no statistically significant difference between the two training techniques in the joint angles at heel contact and toe-off during walking and running after intervention (p ≥ 0.05). However, there was a significant difference in the kinematic characteristics of walking and running between the training and the control groups (p ≤ 0.05). The two training techniques showed a statistically significant difference in stride length during running (p ≤ 0.05). The results indicated that prescriptive and CLA training are effective at altering the kinematics and distance factors underlying children's walking and running abilities.

Tibial Spine Height Measured by Radiograph Is a Risk Factor for Non-Contact Anterior Cruciate Ligament Injury in Males: A Retrospective Case-Control Study

Various anatomic abnormalities are implicated in non-contact anterior cruciate ligament (ACL) injury, but researchers rarely deal with the relation between tibial spine height and ACL injury. We conducted a retrospective case-control study to include 96 patients with and without non-contact ACL injuries. Tibial plateau width (TPW), medial and lateral tibial spine height (MTSH and LTSH), and tibial spine width (TSW) were measured by radiographs. The parameters were compared among subgroups. Binary regression mode, receiver operating characteristic curves, and the area under the curve (AUC) were used to evaluate the specific correlation of the parameters with ACL injury. As a result, we found that the ratio of LTSH/TPW was larger in ACL-injured patients than in ACL-intact controls (p = 0.015). In the study group, LTSH/TPW (p = 0.007) and MTSH/TPW (p = 0.002) were larger in males than in females. The ratio of LTSH/TPW had an AUC of 0.60 and a significant OR of 1.3 for ACL injury in males, but not in females. In conclusion, LTSH was larger in patients with ACL injury and is a risk factor for ACL injury in males. The impact of increased LTSH on the impingement between the grafts and lateral tibial spine during ACL reconstruction warrants further investigation.

Effect of combining eight weeks of neuromuscular training with dual cognitive tasks on landing mechanics in futsal players with knee ligament dominance defect: a randomized controlled trial

BackgroundThe performing of jump and landing in futsal simultaneous with divided attention is one of the most common mechanisms of non-contact anterior cruciate ligament (ACL) injury. Neuromuscular training has effectively reduced the risk of ACL injury, but the effect of neurocognitive training has received less attention. This study investigated the effect of combining 8 weeks of neuromuscular training with dual cognitive tasks on the landing mechanics of futsal players with knee ligament dominance defects.MethodsThirty male futsal players (mean ± SD: age: 21.86 ± 3.27 years) with knee ligament dominance defects were purposefully identified by the tuck jump test and were randomly divided into the intervention and the control group. The intervention group performed dual task (DT) training for three weekly sessions for 8 weeks and 60 min each, while the control group only did activities of daily living. During the drop vertical jump test, 2D landing kinematics in two moments of initial contact (IC) and full flexion (FF) were assessed. Data were analyzed by means of 2 × 2 repeated measures ANOVA followed by post hoc comparison (Bonferroni) at the significance level of (α ≤ 0.05).ResultsA significant improvement was observed in the intervention group compared to the control group for the dynamic knee valgus at IC (F1,28 = 6.33; P = 0.02, ES = 0.31) and FF (F1,28 = 13.47; P = 0.003, ES = 0.49), knee flexion at IC (F1,28 = 20.08; P = 0.001, ES = 0.41) and FF (F1,28 = 13.67; P = 0.001, ES = 0.32), ankle dorsiflexion at IC (F1,28 = 37.17; P = 0.001, ES = 0.72) and FF (F1,28 = 14.52; P = 0.002, ES = 0.50), and trunk flexion at FF (F1,28 = 20.48; P = 0.001, ES = 0.59) angles. Changes in the trunk flexion at IC (F1,28 = 0.54; P = 0.47, ES = 0.03) and trunk lateral flexion at IC (F1,28 = 0.006; P = 0.93, ES = 0.00) and FF (F1,28 = 2.44; P = 0.141, ES = 0.148) angles were not statistically significant.ConclusionsDT training compared to the control group improved landing mechanics in futsal players with knee ligament dominance defects.Trial registration: Current Controlled Trials using the IRCT website with ID number IRCT20210602051477N1 prospectively registered on 20/06/2021.

Dynamic knee valgus in anterior cruciate ligament non-contact injury and reinjury in professional female athletes. Determinant or not?

Dynamic Knee Valgus (DKV) is correlated with both, Anterior Cruciate Ligament (ACL) injury and hip and ankle disorders in female athletes and has a more significant prevalence compared with male athletes because of numerous factors. The aim of this study is to determine if the connexion between DKV, landing errors, and non-contact ACL injury and re-injury in high-performance, adult, female team sport athletes can be eliminated by changing the frontal plane movement pattern and the landing errors during the rehabilitation process (RHB), a process which was focussed on dynamic knee stability with multidimensional single-leg jump landing training, on 3D knee balance improvement and multistimulus perturbation challenges and tasks,+ eccentric &amp; concentric exercise, strength &amp; conditioning, aerobic training that lasted from 26 - 44 weeks. Assessing and eliminating-reducing DKV during the RHB is mandatory in lowering the re-rupture rates in female professional athletes after ACL surgery and in preventing opposite knee trauma.

Unanticipated fake-and-cut maneuvers do not increase knee abduction moments in sport-specific tasks: Implication for ACL injury prevention and risk screening.

Non-contact anterior cruciate ligament injuries typically occur during cutting maneuvers and are associated with high peak knee abduction moments (KAM) within early stance. To screen athletes for injury risk or quantify the efficacy of prevention programs, it may be necessary to design tasks that mimic game situations. Thus, this study compared KAMs and ranking consistency of female handball players in three sport-specific fake-and-cut tasks of increasing complexity. The biomechanics of female handball players (n = 51, mean ± SD: 66.9 ± 7.8 kg, 1.74 ± 0.06 m, 19.2 ± 3.4 years) were recorded with a 3D motion capture system and force plates during three standardized fake-and-cut tasks. Task 1 was designed as a simple pre-planned cut, task 2 included catching a ball before a pre-planned cut in front of a static defender, and task 3 was designed as an unanticipated cut with three dynamic defenders involved. Inverse dynamics were used to calculate peak KAM within the first 100 ms of stance. KAM was decomposed into the frontal plane knee joint moment arm and resultant ground reaction force. RANOVAs (α ≤ 0.05) were used to reveal differences in the KAM magnitudes, moment arm, and resultant ground reaction force for the three tasks. Spearman's rank correlations were calculated to test the ranking consistency of the athletes' KAMs. There was a significant task main effect on KAM (p = 0.02; = 0.13). The KAM in the two complex tasks was significantly higher (task 2: 1.73 Nm/kg; task 3: 1.64 Nm/kg) than the KAM in the simplest task (task 1: 1.52 Nm/kg). The ranking of the peak KAM was consistent regardless of the task complexity. Comparing tasks 1 and 2, an increase in KAM resulted from an increased frontal plane moment arm. Comparing tasks 1 and 3, higher KAM in task 3 resulted from an interplay between both moment arm and the resultant ground reaction force. In contrast to previous studies, unanticipated cutting maneuvers did not produce the highest KAMs. These findings indicate that the players have developed an automated sport-specific cutting technique that is utilized in both pre-planned and unanticipated fake-and-cut tasks.

Injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament injury: a systematic review of cluster randomised trials.

Do injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament (ACL) injuries in sport? Systematic review of (cluster) randomised trials with meta-analysis. Sporting participants of any age, sex or competition level. The experimental intervention was an injury prevention program that included plyometric exercises. The control intervention was the usual warm-up program, which did not include plyometric exercises. Exposure-based ACL injury rates. The initial search yielded 7,302 articles, of which nine met the inclusion criteria. All nine articles reported cluster randomised trials, providing data on 14,394 participants. The pooled results showed that injury prevention programs that include plyometric exercises reduce the risk of ACL injury by 60% per 1,000 hours of exposure compared with the control group, with an injury risk ratio (IRR) of 0.40 (95% CI 0.26 to 0.63). Data from subgroups of these trials estimated that this preventative effect may be stronger in males (IRR 0.21, 95% CI 0.07 to 0.62) and weaker in females (IRR 0.51, 95% CI 0.30 to 0.87), albeit with less precise estimates. Subgroup analysis also suggested a stronger effect on non-contact ACL injuries (IRR 0.34, 95% CI 0.18 to 0.65), whereas the effect on contact ACL injuries remained uncertain (IRR 0.59, 95% CI 0.15 to 2.30). Injury prevention programs that incorporate plyometric exercises substantially decrease the risk of ACL injuries more than warm-up programs that do not include plyometric exercises. The preventive effect appears to be stronger among males and in the prevention of ACL injuries that do not involve contact with another player. PROSPERO CRD42020196982.

Intrinsic Risk Factors for First-Time Noncontact ACL Injury: A Prospective Study of College and High School Athletes.

A comprehensive understanding of the intrinsic risk factors for anterior cruciate ligament (ACL) disruption is important for identifying individuals at increased risk for suffering this trauma and developing interventions to mitigate risk. A variety of risk factors predispose athletes to first-time, noncontact ACL injury and some of these differ between male and female athletes. Prospective cohort study with nested case-control sampling. Level 2. Sport teams at 28 high schools and 8 colleges were monitored prospectively over 4 years, and 109 of 130 athletes who suffered their first noncontact ACL injury participated in the study. At the time of injury, matched control subjects were randomly selected from among the case's teammates and a total of 227 athletes participated. Demographic characteristics, joint laxity, lower extremity alignment, strength, and personality characteristics were measured. The association of each risk factor with injury risk was assessed by conditional logistic regression. The risk factors that were associated with ACL injury in both male and female athletes included having a parent with prior ACL injury and increases of the following variables: body weight, anterior displacement of the tibia relative to the femur, genu recurvatum, and generalized joint laxity. Risk factors that are unique to female athletes included increased body mass index, increased trunk flexion strength, and prior non-ACL knee injury. The risk factors specific to male athletes were decreased standing quadriceps angle, decreased hip adduction strength, and chronic disease. A diverse set of risk factors predispose both male and female athletes to ACL injury, whereas others appear to be sex-specific. Different approaches for assessing risk and preventing ACL injury are needed for male and female athletes. In addition, personalized prevention strategies may be needed to target the specific characteristics that place an individual at increased risk of suffering this trauma.

Effects Of Fatigue On Lower Extremity Kinetics And Kinematics In Jump-stop Tasks

Non-contact anterior cruciate ligament (ACL) injury is common among athletes. Sudden deceleration in basketball competitions is closely related to non-contact ACL injury. Fatigue has also been considered one of potential injury risk factors according to epidemiological statistics. PURPOSE:To simulate the actual fatigue in basketball competitions and investigate the changes of injury-related lower extremity biomechanical characteristics. METHODS:Twelve male basketball players (age: 20.1 ± 0.6 years old; height: 1.8 ± 0.1 m; weight: 71.4 ± 13.5 kg) were recruited to executive a basketball-specific fatigue protocol. The fatigue protocol consists of a sequence including sprinting, cutting and consecutive vertical jumps. Participants repeated this sequence until they were unable to reach 80% of the maximal height. Participants were required to perform 6 trials of jump-stop tasks before and immediately after the fatigue protocol. Eight high-speed cameras (Motion Analysis Raptor- 4, USA) sampling at 200 Hz were used to collect joint angles. Two force plates (Kistler 9281CA, Switzerland) sampling at 1000 Hz were used to collect ground reaction forces. Joint net moment was calculated by inverse dynamics. All data was smoothed by 13.3 Hz Butterworth low-pass filter with Cortex 2.6. Paired t-test was performed (α =0.05) with SPSS 24.0. RESULTS:Knee flexion angle (73.52 ± 12.21, P = 0.034, Cohen’s d = 1.243) significantly increased post-fatigue at peak stance, so was the approach speed at initial contact (2.78 ± 0.51, P = 0.003, Cohen’s d = 1.333). A decreased hip abduction angle (-7.67 ± 8.57, P = 0.010, Cohen’s d = 0.577) was significantly observed post-fatigue at initial contact. Participants landed with increased vertical ground reaction force (0.245 ± 0.063(BW), P = 0.031, Cohen’s d = 0.667) in kinetics, but the posterior ground reaction force significantly decreased (0.005 ± 0.012(BW), P = 0.014, Cohen’s d = -0.6) at peak vertical ground reaction force. No fatigue-induced difference of lower extremity moment was found in this study. CONCLUSIONS:The influence of fatigue on both kinematics and kinetics of lower extremity during jump-stop tasks indicates an increased ACL injury risk. Research supported by the Education Social Science Foundation Project of the 13th Five-Year Plan of Education in China (BLA180218).

Dual Tasking May Increase ACL Injury Risk By Decreasing Knee Flexion Angle During Jump Landing

Non-contact anterior cruciate ligament (ACL) injuries are common among young athletes playing team sports. They must coordinate cognitive and motor processes to adapt an appropriate response to visual stimuli. It is unclear how divided attention to distractors impacts landing mechanics and ACL injury risk factors. PURPOSE: To investigate effects of dual tasking on ACL injury risk factors during jump landing using the Eriksen Flanker task. METHODS: Fourteen healthy females (age: 21 ± 2 years, mass: 64 ± 7 kg, height: 1.7 ± 0.1 m) participated in the study. They stood on a portable force platform (28 cm tall), jumped diagonally at a 60° angle to their right, landed on two in-ground force platforms and performed a second jump to their right or left at a 60° angle. The direction of the second jump appeared on a screen in front of the participant. The signal was either shown before movement (baseline) or during the flight phase of the first jump (dual task). The signal for the dual task conditions showed five arrows and participants jumped in the direction of the middle one. The four other arrows either pointed to the same direction as the middle arrow (congruent) or in the opposite direction (incongruent). Knee flexion angles, knee valgus angles, and external knee valgus moments were determined during the first 100 ms of landing. Repeated measures ANOVA was used to test for main effects of jump direction, dual task condition and interactions. RESULTS: There were significant main effects of jump direction, dual task condition, and their interaction for initial and peak knee flexion angles (p ≤ 0.009). Initial knee flexion angle (10.5 ± 5.1°vs. 14.5 ± 6.6°, p = 0.01) and peak knee flexion angle (56.2 ± 5.1° vs. 60.3 ± 5.9°, p = 0.003) were significantly lower during dual tasking when jumping to the right. There were no significant differences between the congruent and incongruent dual tasks or when jumping to the left. CONCLUSION: Initial and peak knee flexion angles were decreased when the visual stimuli was presented mid-flight rather than at the beginning of the jump when jumping to the right (lateral to the knee). However, the incongruent Flanker task did not significantly affect knee flexion angle. Further research focusing on mid-flight decision making with a more challenging incongruent visual stimuli that mimics dynamic team sports is merited.

Transfer of post-trial feedback on impacts during drop landings in female athletes

ABSTRACT Increased vertical ground reaction force (vGRF) and dynamic knee valgus contribute to non-contact anterior cruciate ligament (ACL) injuries. We examined feedback’s influence during landing and transfer to a game-specific drill, measured by deceleration. Thirty-one female athletes performed 30 drop landings with augmented feedback and dual-task conditions, with a game-specific drill before and after. Differences were shown across time (baseline, feedback, post-feedback) and between conditions (with or without dual-task) in peak vGRF and knee to ankle ratio (K:A ratio). K:A ratio is the ratio of the frontal plane distance between the knees relative to the frontal plane distance between the ankles. This measure serves as a surrogate for knee valgus where a ratio closer to 1 indicates less knee valgus. There were reductions in peak vGRF (p < 0.05) and improvements in K:A ratio (p < 0.05) across time, improvements in K:A ratio across time and by condition (p < 0.05), and reduction in deceleration during landing in a game-specific drill (p < 0.05). Feedback may improve landing mechanics and transfer to a game-specific drill that can influence ACL injury in sport.

Osteoporosis in Light of a New Mechanism Theory of Delayed Onset Muscle Soreness and Non-Contact Anterior Cruciate Ligament Injury.

Osteoporosis is a disorder, with a largely unknown pathomechanism, that is often marked as a “silent thief”, because it usually only becomes undisguised when fractures occur. This implies that the pathological damage occurs earlier than the sensation of pain. The current authors put forward a non-contact injury model in which the chronic overloading of an earlier autologously microinjured Piezo2 ion channel of the spinal proprioceptor terminals could lead the way to re-injury and earlier aging in a dose-limiting and threshold-driven way. As a result, the aging process could eventually lead the way to the metabolic imbalance of primary osteoporosis in a quad-phasic non-contact injury pathway. Furthermore, it is emphasised that delayed onset muscle soreness, non-contact anterior cruciate injury and osteoporosis could have the same initiating proprioceptive non-contact Piezo2 channelopathy, at different locations, however, with different environmental risk factors and a different genetic predisposition, therefore producing different outcomes longitudinally. The current injury model does not intend to challenge any running pathogenic theories or findings, but rather to highlight a principal injury mechanism.

Use of a Novel Multimodal Imaging Technique to Model In Vivo Quadriceps Force and ACL Strain During Dynamic Activity

Background: Quadriceps loading of the anterior cruciate ligament (ACL) may play a role in the noncontact mechanism of ACL injury. Musculoskeletal modeling techniques are used to estimate the intrinsic force of the quadriceps acting at the knee joint. Purpose/Hypothesis: The purpose of this paper was to develop a novel musculoskeletal model of in vivo quadriceps force during dynamic activity. We used the model to estimate quadriceps force in relation to ACL strain during a single-leg jump. We hypothesized that quadriceps loading of the ACL would reach a local maximum before initial ground contact with the knee positioned in extension. Study Design: Descriptive laboratory study. Methods: Six male participants underwent magnetic resonance imaging in addition to high-speed biplanar radiography during a single-leg jump. Three-dimensional models of the knee joint, including the femur, tibia, patellofemoral cartilage surfaces, and attachment-site footprints of the patellar tendon, quadriceps tendon, and ACL, were created from the magnetic resonance imaging scans. The bone models were registered to the biplanar radiographs, thereby reproducing the positions of the knee joint at the time of radiographic imaging. The magnitude of quadriceps force was determined for each knee position based on a 3-dimensional balance of the forces and moments of the patellar tendon and the patellofemoral cartilage contact acting on the patella. Knee kinematics and ACL strain were determined for each knee position. Results: A local maximum in average quadriceps force of approximately 6500 N (8.4× body weight) occurred before initial ground contact. ACL strain increased concurrently with quadriceps force when the knee was positioned in extension. Conclusion: This novel participant-specific modeling technique provides estimates of in vivo quadriceps force during physiologic dynamic loading. A local maximum in quadriceps force before initial ground contact may tension the ACL when the knee is positioned in extension. Clinical Relevance: These data contribute to understanding noncontact ACL injury mechanisms and the potential role of quadriceps activation in these injuries.

The injury mechanism correlation between MRI and video-analysis in professional football players with an acute ACL knee injury reveals consistent bone bruise patterns

PurposeTo analyze the MRI features, in particular bone bruises pattern, of Anterior Cruciate Ligament (ACL) injured footballers, and to correlate them with the characteristics of injury mechanism and situation obtained from direct video footage.MethodsNineteen professional football (soccer) players that sustained ACL injury while playing during an official match of First League Championship were included in the study. The video of injury was obtained from the Television broadcast. Knee Magnetic Resonance (MRI) was obtained within 7 days from the injury. BB and meniscal lesions were analyzed on MRI, while a video-analysis of mechanisms of ACL injury and injury dynamic were assessed from the videos.ResultsThe most commonly involved Bone Bruise areas in the knee were the Posterior Lateral Tibial Plateau (LTp) in 16 cases (84%) and the Central Lateral Femoral Condyle (LFc) in 11 cases (58%). Three patients (16%) had bone bruise in the Posterior Medial Tibial Plateau (MTp) while none (0%) had bone bruise in the Medial Femoral Condyle. Based on the bone bruise pattern, 11 (58%) had simultaneous LFc and LTp and were defined “Typical” while 8 (42%) had other locations or no bone bruise and were defined “Atypical”. 9 out of 11 injuries (82%) of athletes with “Typical” pattern occurred with a “Pivoting” action”, in contrast to only 1 case (12%) in those with “Atypical” bone bruise pattern (p = 0.0055).The most common situational mechanism pattern on video analysis was “pressing” (n = 7) accounting for the 47% of the “indirect” ACL injuries. In terms of movement pattern, ten injuries (52%) occurred during a “Pivoting” movement (7 pressing, 1 dribbling, 1 tackled, 1 goalkeeping), whereas the remaining were classified as “Planting” in four cases, “Direct Blow” in four cases and “Landing”.ConclusionA well-defined and consistent bone bruise pattern involving the posterior tibial plateau and central femoral condyle of lateral compartment is present in footballers that sustained non-contact and indirect ACL injuries during pivoting with sudden change of direction/deceleration, while heterogeneous patterns were present in those with direct contact or injury mechanisms involving high horizontal velocity.Level of evidenceLevel IV.