Mapping current research trends on anterior cruciate ligament injury risk against the existing evidence: In vivo biomechanical risk factors

Changes in Lower Limb Biomechanics Across Various Stages of Maturation and Implications for ACL Injury Risk in Female Athletes: a Systematic Review

BACKGROUND

Female athletes are four to six times more likely to sustain an anterior cruciate ligament (ACL) injury than male athletes. Jump-landing biomechanics are influenced by maturation, with post-pubertal female athletes at a heightened risk of ACL injuries.

OBJECTIVE

The aim of our systematic review was to identify and summarise the current evidence regarding the changes in kinematic and kinetic risk factors associated with ACL injuries during jump-landing tasks in female athletes at various stages of maturity.

METHODS

A systematic search was conducted in PubMed, CINAHL, Web of Science, SPORTDiscus, EMBASE and Scopus. Articles were included if they: (1) conducted the research on uninjured female athletes with no restriction on playing level/experience; (2) provided information regarding the stage of the maturity and the scale used for estimating the maturity status of the participants; and (3) reported a biomechanical risk factor associated with ACL injuries during jump-landing tasks across at least two different maturity groups (e.g. pre-pubertal vs post-pubertal).

RESULTS

Sixteen articles involving 2323 female athletes were included in our review. A total of 12 kinematic and 8 kinetic variables were identified across these studies. Of the 12 kinematic variables reported in our review, we found strong evidence for higher peak knee abduction angle in post-pubertal female individuals compared with pre-pubertal girls (p < 0.05). With regard to the 8 kinetic variables, we found strong evidence for lower relative peak vertical ground reaction force, higher external knee abduction moment and internal rotation moment in post-pubertal compared with pre-pubertal athletes. The strength of evidence for the remaining kinematic and kinetic variables ranged from conflicting to moderate and, in some instances, could not be determined.

CONCLUSIONS

Our study provides an overview of the changes in biomechanical risk factors in female athletes during jump-landing tasks at various stages of maturity. We found moderate-to-limited evidence for most kinematic and kinetic variables, highlighting the need for further research.

Fatigue-induced Landing Alterations in ACL Reconstructed Athletes after Return-to-Sport

At the time of return-to-sport, anterior cruciate ligament reconstructed athletes still show altered neuromechanics in their injured leg during single leg hopping tasks. Part of these alterations can be magnified when these athletes are fatigued. So far, little is known whether fatigue-induced landing alterations persist after return-to-sport. Therefore, the aim of this study was to evaluate whether these alterations persist in the six months following return-to-sport. Sixteen anterior cruciate ligament reconstructed athletes performed five unilateral hop tasks before and after a fatigue protocol. The hop tasks were executed at three different time points (return-to-sport, 3 and 6 months post-return-to-sport). A 2-by-3 repeated measures ANOVA was performed to evaluate whether fatigue-induced landing alterations persisted 3 and 6 months following return-to-sport. At 6 months following return-to-sport, fatigue still induces a reduction in hamstring medialis activation and an increase in the knee abduction moment during a vertical hop with 90-degree inward rotation. Most fatigue-induced landing alterations present at the time of return-to-sport normalize after resumption of sports activities. However, a larger knee abduction moment in the injured leg after resumption of sports activities can still be observed.

Change of Direction Biomechanics in a 180-Degree Pivot Turn and the Risk for Noncontact Knee Injuries in Youth Basketball and Floorball Players

BACKGROUND

Studies investigating biomechanical risk factors for knee injuries in sport-specific tasks are needed.

PURPOSE

To investigate the association between change of direction (COD) biomechanics in a 180-degree pivot turn and knee injury risk among youth team sport players.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 258 female and male basketball and floorball players (age range, 12-21 years) participated in the baseline COD test and follow-up. Complete data were obtained from 489 player-legs. Injuries, practice, and game exposure were registered for 12 months. The COD test consisted of a quick ball pass before and after a high-speed 180-degree pivot turn on the force plates. The following variables were analyzed: peak vertical ground-reaction force (N/kg); peak trunk lateral flexion angle (degree); peak knee flexion angle (degree); peak knee valgus angle (degree); peak knee flexion moment (N·m/kg); peak knee abduction moment (N·m/kg); and peak knee internal and external rotation moments (N·m/kg). Legs were analyzed separately and the mean of 3 trials was used in the analysis. Main outcome measure was a new acute noncontact knee injury.

RESULTS

A total of 18 new noncontact knee injuries were registered (0.3 injuries/1000 hours of exposure). Female players sustained 14 knee injuries and male players 4. A higher rate of knee injuries was observed in female players compared with male players (incidence rate ratio, 6.2; 95% CI, 2.1-21.7). Of all knee injuries, 8 were anterior cruciate ligament (ACL) injuries, all in female players. Female players displayed significantly larger peak knee valgus angles compared with male players (mean for female and male players, respectively: 13.9°± 9.4° and 2.0°± 8.5°). No significant associations between biomechanical variables and knee injury risk were found.

CONCLUSION

Female players were at increased risk of knee and ACL injury compared with male players. Female players performed the 180-degree pivot turn with significantly larger knee valgus compared with male players. However, none of the investigated variables was associated with knee injury risk in youth basketball and floorball players.

Trunk motion and anterior cruciate ligament injuries: a narrative review of injury videos and controlled jump-landing and cutting tasks

The aims of this narrative review were to summarise trunk motion and external trunk perturbation observed in anterior cruciate ligament (ACL) injury videos and to review the association between trunk motion and ACL loading variables in controlled jump-landing and cutting tasks in non-injured populations. Video analyses have shown limited trunk flexion and increased trunk lateral bending towards the injured leg are associated with increased risk of ACL injuries, while trunk axial rotation away from the injured leg is more frequent than rotation towards the injured leg. Contact with the trunk before and at the time of the injury is common and might increase the risk of ACL injury. Controlled jump-landing and cutting studies have shown that limited trunk flexion and increased trunk lateral bending are associated with increased ACL loading. However, the findings of trunk axial rotation are not consistent with most video analyses. Mid-flight external trunk perturbation could increase ACL loading variables for one leg and is consistent with the videos of trunk-contact ACL injuries. These findings may help understand the role of trunk motion on primary ACL injury mechanisms and improve ACL injury screening tasks and ACL injury prevention strategies with the consideration of trunk motion.

The Effect of Training Interventions on Change of Direction Biomechanics Associated with Increased Anterior Cruciate Ligament Loading: A Scoping Review

Change of direction (COD) manoeuvres are associated with anterior cruciate ligament (ACL) injury risk due to the propensity to generate large multiplanar knee joint loads. Given the short- and long-term consequences of ACL injury, practitioners are interested in methods that reduce knee joint loads and subsequent ACL loading. An effective strategy to reduce ACL loading is modifying an athlete’s movement mechanics to reduce knee joint loading. The purpose of this scoping review was to critically appraise and comprehensively synthesise the existing literature related to the effects of training interventions on COD biomechanics associated with increased knee joint loads and subsequent ACL loading, and identify gaps and recommend areas for future research. A review of the literature was conducted using Medline and Sport DISCUS databases. Inclusion criteria consisted of pre-post analysis of a COD task, a minimum 4-week training intervention, and assessments of biomechanical characteristics associated with increased ACL loading. Of the 1,027 articles identified, 22 were included in the scoping review. Based on current literature, balance training and COD technique modification are the most effective training modalities for reducing knee joint loading (small to moderate effect sizes). One study reported dynamic core stability training was effective in reducing knee joint loads, but further research is needed to definitively confirm the efficacy of this method. Perturbation-enhanced plyometric training, the F-MARC 11 + soccer specific warm-up, Oslo Neuromuscular warm-up, and resistance training are ineffective training modalities to reduce COD knee joint loads. Conflicting findings have been observed for the Core-Pac and mixed training programme. Consequently, practitioners should consider incorporating balance and COD technique modification drills into their athletes’ training programmes to reduce potentially hazardous knee joint loads when changing direction. However, training intervention studies can be improved by investigating larger sample sizes (> 20), including a control group, acknowledging measurement error when interpreting their findings, and considering performance implications, to confirm the effectiveness of training interventions and improve adherence.

The cumulative and residual changes in eccentric knee flexor strength indices following soccer-specific treadmill running: Novel considerations of angle specific torque

With potential implications for recovery and conditioning practices, the aim of this study was to assess the cumulative and residual response of angle specific eccentric knee flexor (eccKF) strength indices following soccer-specific activity. Thirteen semi-professional soccer players were therefore required to complete a 90-minute soccer-specific treadmill running. with eccKF isokinetic strength assessments completed pre-trial, immediately post-trial, and 48 hours post-trial. The strength assessments comprised the completion of 5 repetitions at angular velocities of 60 and 300 deg·s^-1. Isokinetic data was analysed for measures of peak torque (PT), angle of peak torque (APT), functional range (FR), and angle specific torque (AST). Significant post-trial impairments were observed for measures of slow velocity PT₆₀ (6.6%) and AST₃₀₀ (12.5%). Further significant differences were observed 48 hours post-trial for PT₃₀₀ (10.7%) and PT₆₀ (12.8%) PT, APT₆₀ (~15°), and AST₃₀₀ (>13.6%). These data have implications for post exercise recovery monitoring and the prescription of recovery modalities and conditioning practices in the 2 days following match-play. The AST and APT responses highlight the importance of analysis of the entire strength-angle curve and at a range of angular velocities.

Age-related differences in torque in angle-specific and peak torque hamstring to quadriceps ratios in female soccer players from 11 to 18 years old: Α Cross-sectional study

The aim of this study was to evaluate and compare the hamstring (H) and quadriceps (Q) strength, bilateral difference and balance ratios in female soccer players. Ninety-three athletes from three age groups: under 13 (U13), 15 (U15) and 18 (U18) participated in the study performing isokinetic tests to measure peak torque, total work, average power and torque at 30º of thigh muscles. Conventional strength balance ratios, angle-specific balance ratio and bilateral strength difference were evaluated. There was bilateral strength difference for extensor muscles total work (p = 0.02) in U13 and flexor muscles peak torque (p = 0.02) in U15. All variables were superior in U15 than U13 (p <.05). There was no strength difference between U15 and U18. Balance ratios did not differ between sides or age groups. The study showed that although peak torque values were higher in U15 than in U13, balance ratios were similar.

Effects of ankle dorsiflexion limitation on lower limb kinematic patterns during a forward step-down test: A reliability and comparative study

BACKGROUND

Altered lower limb movement patterns (LLMP) during the forward step down (FSD) test have been studied in people suffering from knee instability. However, ankle dorsiflexion range of motion (ADROM) seems to be related to LLMP but no causal inference has been defined between those variables.

OBJECTIVE

Our goals were to evaluate (1) psychometric quality of the FSD test in healthy people and (2) the influence of experimental restricted ADROM on LLMP.

METHODS

Kinematics were measured by a motion capture system. Angular displacement and speed were calculated as well as center of mass (COM) and knee linear displacement. Forty-two healthy participants; firstly, performed the test three times to assess reliability, and secondly the same test in an experimental condition limiting the ADROM.

RESULTS

Reliability was excellent for all parameters (ICC: 0.75-0.99, SEM%: 2.0-34.0%). ADROM limitation significantly decreased Knee flexion range of motion (ROM) (-3.8∘), increased Hip flexion ROM (6∘), Hip adduction ROM (6.1∘), Pelvis drop ROM (3.5∘), Pelvic rotation ROM (3.1∘). No significant effect was found for Hip rotation ROM.

CONCLUSIONS

LLMP was affected by this experimental ADROM limitation in healthy people. As this limitation is often encountered in post-traumatic ankle sprain patients, clinicians should consider this point during FSD assessment test.

Is knee neuromuscular activity related to anterior cruciate ligament injury risk? A pilot study

BACKGROUND

There is limited evidence on neuromuscular risk factors for anterior cruciate ligament (ACL) injuries, with most work mainly focusing on hamstrings and quadriceps muscle strength. This prospective pilot study explored if neuromuscular activation patterns of the quadriceps and hamstrings during a drop vertical jump influence ACL injury risk.

METHODS

Forty-six female athletes performed a drop vertical jump at baseline. Injuries were monitored throughout a one-year follow-up. Neuromuscular activation patterns of the vastus medialis, vastus lateralis, hamstrings medialis and hamstrings lateralis, and selected landing kinematic and kinetic profiles (knee flexion, knee abduction and hip flexion angles, and knee abduction moments), were compared between athletes who sustained a non-contact ACL injury and those who remained injury free. Electromyogram vector fields were created to represent neuromuscular activation patterns of muscle pairs around the knee joint rather than only considering individual muscle activations, and compared using Statistical Parametric Mapping.

RESULTS

Four athletes sustained an ACL injury. Significantly greater {hamstrings medials, hamstrings lateralis}, {vastus lateralis, hamstrings lateralis} and {hamstrings lateralis, vastus medialis} activations, mainly due to greater hamstrings lateralis activation, were found in the injured group around peak loading and just before take-off (P < 0.001). No group differences were found in knee flexion, knee abduction and hip flexion angles, or knee abduction moments.

CONCLUSIONS

This pilot study revealed initial evidence that athletes already showed altered neuromuscular activation patterns prior to sustaining an ACL injury, namely increased lateral and posterior muscle activations.

The Effect of Angle and Velocity on Change of Direction Biomechanics: An Angle-Velocity Trade-Off

Changes of direction (CODs) are key manoeuvres linked to decisive moments in sport and are also key actions associated with lower limb injuries. During sport athletes perform a diverse range of CODs, from various approach velocities and angles, thus the ability to change direction safely and quickly is of great interest. To our knowledge, a comprehensive review examining the influence of angle and velocity on change of direction (COD) biomechanics does not exist. Findings of previous research indicate the biomechanical demands of CODs are 'angle' and 'velocity' dependent and are both critical factors that affect the technical execution of directional changes, deceleration and reacceleration requirements, knee joint loading, and lower limb muscle activity. Thus, these two factors regulate the progression and regression in COD intensity. Specifically, faster and sharper CODs elevate the relative risk of injury due to the greater associative knee joint loading; however, faster and sharper directional changes are key manoeuvres for successful performance in multidirectional sport, which subsequently creates a 'performance-injury conflict' for practitioners and athletes. This conflict, however, may be mediated by an athlete's physical capacity (i.e. ability to rapidly produce force and neuromuscular control). Furthermore, an 'angle-velocity trade-off' exists during CODs, whereby faster approaches compromise the execution of the intended COD; this is influenced by an athlete's physical capacity. Therefore, practitioners and researchers should acknowledge and understand the implications of angle and velocity on COD biomechanics when: (1) interpreting biomechanical research; (2) coaching COD technique; (3) designing and prescribing COD training and injury reduction programs; (4) conditioning athletes to tolerate the physical demands of directional changes; (5) screening COD technique; and (6) progressing and regressing COD intensity, specifically when working with novice or previously injured athletes rehabilitating from an injury.

Sagittal Plane Hip, Knee, and Ankle Biomechanics and the Risk of Anterior Cruciate Ligament Injury: A Prospective Study

Background:

Stiff landings with less knee flexion and high vertical ground-reaction forces have been shown to be associated with an increased risk of anterior cruciate ligament (ACL) injury. The literature on the association between other sagittal plane measures and the risk of ACL injuries with a prospective study design is lacking.

Purpose:

To investigate the relationship between selected sagittal plane hip, knee, and ankle biomechanics and the risk of ACL injury in young female team-sport athletes.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 171 female basketball and floorball athletes (age range, 12-21 years) participated in a vertical drop jump test using 3-dimensional motion analysis. All new ACL injuries, as well as match and training exposure data, were recorded for 1 to 3 years. Biomechanical variables, including hip and ankle flexion at initial contact (IC), hip and ankle ranges of motion (ROMs), and peak external knee and hip flexion moments, were selected for analysis. Cox regression models were used to calculate hazard ratios (HRs) with 95% CIs. The combined sensitivity and specificity of significant test variables were assessed using a receiver operating characteristic (ROC) curve analysis.

Results:

A total of 15 noncontact ACL injuries were recorded during follow-up (0.2 injuries/1000 player-hours). Of the variables investigated, landing with less hip flexion ROM (HR for each 10° increase in hip ROM, 0.61 [95% CI, 0.38-0.99]; P < .05) and a greater knee flexion moment (HR for each 10-N·m increase in knee moment, 1.21 [95% CI, 1.04-1.40]; P = .01) was significantly associated with an increased risk of ACL injury. Hip flexion at IC, ankle flexion at IC, ankle flexion ROM, and peak external hip flexion moment were not significantly associated with the risk of ACL injury. ROC curve analysis for significant variables showed an area under the curve of 0.6, indicating a poor combined sensitivity and specificity of the test.

Conclusion:

Landing with less hip flexion ROM and a greater peak external knee flexion moment was associated with an increased risk of ACL injury in young female team-sport players. Studies with larger populations are needed to confirm these findings and to determine the role of ankle flexion ROM as a risk factor for ACL injury. Increasing knee and hip flexion ROMs to produce soft landings might reduce knee loading and risk of ACL injury in young female athletes.

Normalization influences knee abduction moment results: Could it influence ACL-injury research, too?

OBJECTIVES

Normalization of joint moments to reduce anthropometric influences prior to making group comparisons is a widely-accepted practice. However, a seminal prospective study reported greater non-normalized knee abduction moment (KAM) in nine females who subsequently sustained an ACL injury. It is not clear if this finding may have been influenced by the fact that the ACL-injured females were on average 3.6cm taller and 2.4kg heavier than uninjured females.

DESIGN

Cross-sectional.

METHODS

Peak KAM was identified in thirty-six females completing jump landings. A custom software program randomly divided participants into two groups that were compared on: (1) non-normalized KAM, (2) KAM normalized to body mass, and (3) KAM normalized to body height times weight a total of 500,000 times and the results categorically coded for statistical significance (α≤0.05). For the 10,591 iterations in which one group was 3-4cm taller and 2-3kg heavier, the agreement between results obtained using non-normalized versus normalized data were assessed using non-parametric analyses.

RESULTS

Despite moderate-strong agreement between the results obtained using non-normalized and normalized data (Κ=0.614-0.744), a significant effect of normalization on the interpretation of group differences in peak KAM was identified (p<0.001). In 30.4-41.9% of the cases in which non-normalized KAM was deemed significantly different between groups, no group differences were identified when using normalized KAM.

CONCLUSIONS

While it is unlikely the magnitude of the difference in non-normalized KAM identified prospectively in ACL-injured females was attributable solely to anthropometric differences, caution should be exercised when evaluating research findings reporting non-normalized KAM.