Leg kinematics and kinetics in landing from a single-leg hop for distance. A comparison between dominant and non-dominant leg

Ankle Biomechanics During Multidirectional Landings in Athletes With Chronic Ankle Instability

BACKGROUND

Assessing and understanding the control of the ankle during multidirectional jump landings in athletes with chronic ankle instability (CAI) would help health professionals develop interventions to reduce the risk of recurrent injuries. The aim of this study was to investigate the angle, angular velocity, and movements of the ankle joint, and the muscle activity of peroneus longus (PL), tibialis anterior (TA), and gastrocnemius (GAS) muscles during multidirectional landings in athletes with CAI.

METHODS

Nineteen athletes with CAI (≤25 Cumberland Ankle Instability Tool-Thai Score) participated. A Vicon Nexus motion analysis system synchronously collected data with an AMTI force plate and surface electromyography (EMG) to capture kinematics, kinetics, and muscle activity, respectively. Participants were asked to perform single-leg jump-landing tests in forward (0°), 30° diagonal, 60° diagonal, and lateral (90°) directions. Ankle joint kinematics, kinetics, and muscle activity of PL, TA, and GAS were analyzed. Repeated measure ANOVA (analysis of variance) and Friedman tests were used to analyze the main effects of the jump-landing direction.

RESULTS

Athletes with CAI exhibited significant differences in ankle angles, angular velocities, ankle movements, and average muscle activity of GAS between directions. Greatest average EMG of GAS muscle was observed during landing in the lateral direction compared with the forward and 30° diagonal directions.

CONCLUSION

Lateral and diagonal direction movements showed the greatest risks associated with recurrent ankle sprains. Impairments of neuromuscular control in both pre-landing and landing phases were observed in athletes with CAI when considered alongside previously published data.

LEVEL OF EVIDENCE

Laboratory-based observational study.

Effects of shoe collar height and limb dominance on landing knee biomechanics in female collegiate volleyball players

Volleyball-specific footwear with higher collar heights (a mid-cut shoe) are worn to restrict ankle motion. Reduced ankle dorsiflexion has been associated with increased frontal plane motion and injury risk at the knee. With the high frequency of unilateral landings in volleyball, the purpose of this study was to determine the effect of volleyball-specific shoes and limb dominance on knee landing mechanics in collegiate volleyball players. It was hypothesized that participants would exhibit smaller sagittal plane and greater frontal plane knee joint mechanics in mid-cut and dominant limb and that vertical and posterior directed ground reaction forces would be greater wearing mid-cut, yet similar between limbs. Seventeen female volleyball players performed unilateral landings on each limb in mid-cut and low-top volleyball shoes. For shoe main effects, smaller peak dorsiflexion angle and internal peak plantarflexion moment and greater peak medial ground reaction force were found in the mid-cut but with no impact on knee mechanics. For limb main effects, the internal peak knee abduction moment was greater in the dominant limb. Greater peak lateral ground reaction force was found in the interaction between the non-dominant limb and low-top. Further research is warranted to better understand shoe and limb impact in volleyball players.

Lower Extremity Kinematic Waveform Analysis During a Single Leg Drop Task - Including a Single Subject Design

BACKGROUND

Lower limb asymmetries may be associated with increased injury risk in an active female population. However, an appropriate method for determining these asymmetries has not been established.

HYPOTHESIS/PURPOSE

The purpose of the present study was to examine the single leg drop landing (SLD) kinematic waveforms of female recreational athletes for the pelvis, hip, and knee using statistical parametric mapping (SPM). It was hypothesized that individual bilateral differences would be masked by the group analysis.

STUDY DESIGN

Descriptive Laboratory Study.

METHODS

The current study examined the sagittal and frontal plane pelvis, hip, and knee kinematics of nine physically active females during a SLD. To better elucidate whether asymmetries were present between right and left limbs throughout the landing phase, data were analyzed with SPM. The time-series data were comprised from initial contact to the bottom of the landing. A single subject design was also included to account for potential interindividual variability.

RESULTS

At the group level there were no statistical differences between the right and left limbs of participants for all variables. The single subject design yielded at least two significant asymmetries for all participants. Six out of the nine participants had bilateral differences for all six kinematic time-series.

CONCLUSIONS

The lack of significant differences at the group level may have been masked by movement variability amongst participants. For example, when considering participants with significant differences for hip flexion, four participants had greater values on the left limb and three on the right. A similar observation was made for knee flexion where three participants had significantly greater kinematic values on the left versus four on the right. Until a method is developed to adequately dichotomize lower extremities during the SLD task, a single subject design strategy be used with group analysis when making bilateral comparisons.

LEVEL OF EVIDENCE

3.

Der Einfluss von lokaler Muskelermüdung und Fußaufsatztechnik auf die kinematischen Merkmale und die plantare Druckverteilung beim Laufen

Trotz zahlreicher Studien liegen keine eindeutigen Befunde vor, die eine bedeutsame Aussage darüber treffen, wie sich der Fußaufsatz durch eine muskuläre Ermüdung verändert. Bei Untersuchungen mit Laufermüdung kann nicht differenziert werden, welche kinematischen oder kinetischen Veränderungen ein unmittelbares Ergebnis der lokalen Muskelermüdung und variierten Geschwindigkeiten darstellen. Ziel der Studie war die Untersuchung der Wirkung der Fußaufsatztechnik und der lokalen Muskelermüdung der Plantar- und Dorsalflexoren auf die plantare Druckverteilung sowie ausgewählte kinematische Merkmale beim Laufen auf dem Laufband. An der Studie nahmen 26 freiwillige Vor- und Rückfußläufer*innen vergleichbaren Alters und vergleichbarer Körpermasse teil. Jede Gruppe absolvierte 2 Testabläufe mit einem zeitlichen Abstand von 3–7 Tagen. Die kinematische Datenerfassung erfolgte mithilfe eines 3-dimensionalen Mess- und Analysesystems während des Laufens auf dem Laufband. Das Ermüdungsprotokoll umfasste einen isometrischen Maximalkrafttest und einen isokinetischen Ausdauertest. Zur Überprüfung der Unterschiede wurde eine 2-faktorielle Varianzanalyse mit Messwiederholung berechnet. Die Kraftwerte der beiden Läufer*innengruppen wiesen signifikante Unterschiede bei den Plantarflexoren im Kraftausdauertest und beim Ermüdungsindex mit im Durchschnitt höheren Werten der Rückfußläufer*innen sowohl für das linke als auch das rechte Bein. Die Ergebnisse der Kraftwerte überraschen, denn aufgrund des Vorfußaufsatzes beim regelmäßigen Laufen sollten die Plantarflexoren dieser Läufer*innengruppe gut trainiert sein. Nach Ermüdung reduzierten sich die Druckmaxima unter den exponiert belasteten Fußzonen, d.h. unter dem Vorderfuß beim Vorfußaufsatz und unter der Ferse beim Rückfußaufsatz. Die beiden Läufer*innengruppen differierten im Fußwinkel bei Foot on mit höheren Werten der Vorfußläufer*innen. Der größere Fußwinkel der Vorfußläufer*innen verbessert die Schockabsorption und kann so das Verletzungsrisiko verringern. In einer weiteren Studie sollten gewohnheitsmäßige Barfußläufer*innen ausgewählt werden.

The effect of theta burst stimulation over the primary motor cortex on experimental hamstring pain: A randomised, controlled study

Theta burst stimulation (TBS) over the primary motor cortex (M1) is an emerging technique that may have utility in the treatment of musculoskeletal pain. However, previous work exploring the analgesic effects of noninvasive brain stimulation has been limited largely to the arm or hand, despite 80% of acute musculoskeletal injuries occurring in the lower limb. This is a pertinent point, given the functional and neurophysiological differences between upper and lower limb musculature, as well as evidence suggesting that reorganization of corticomotor pathways is region-specific. This study investigated the effect of excitatory TBS on pain, function, and corticomotor organization during experimentally induced lower limb pain. Twenty-eight healthy participants attended 2 experimental sessions. On Day 0, participants completed 10 sets of 10 maximal eccentric contractions of the right hamstring muscles to induce delayed onset muscle soreness. Four consecutive blocks of either active or sham TBS were delivered on Day 2. Measures of mechanical sensitivity, pain (muscle soreness, pain intensity, pain area) function (single-leg hop distance, maximum voluntary isometric contraction, lower extremity functional scale), and corticomotor organization were recorded before and after TBS on Day 2. Pain and function were also assessed daily from Days 2 to 10. Active TBS reduced mechanical sensitivity compared to sham stimulation (P = .01). Corticomotor organization did not differ between groups, suggesting that improvements in mechanical sensitivity were not mediated by changes in M1. Subjective reports of pain intensity and function did not change following active TBS, contrasting previous reports in studies of the upper limb. PERSPECTIVE: M1 TBS reduces mechanical sensitivity associated with experimentally induced hamstring pain. Though further work is needed, these findings may hold important implications for those seeking to expedite recovery or reduce muscle sensitivity following hamstring injury.

Relationship of Quantitative Measures of Jumping Performance with Gross Motor Development in Typically Developed Preschool Children

Jumping is a key movement developing in the preschool period, but limited studies have reported the determinants of jumping performance and its relationship with gross motor development. This study aimed to determine the correlations among jumping performance, quantitative parameters of jumping, and gross motor development in preschool children. Twenty-one preschool children were recruited from one kindergarten, and fifteen of them with complete data were further analyzed. The quantitative parameters of standing long jump (SLJ) and standing vertical jump (SVJ) were measured using a video-based motion capture system. The gross motor development was measured using the Preschooler Gross Motor Quality Scale (PGMQ). The Spearman’s rho value and a linear regression model were used to determine the relationships among the jumping performance, the quantitative measures, and the total PGMQ scores. The results indicate that the jumping performances were significantly correlated with the takeoff velocity, which was predicted by trunk inclination before takeoff in SLJ and by the ranges of trunk inclination during jumping in SVJ. Regression analysis showed that the preschool children with higher normalized jump height had better gross motor development, and that the jump performance and the gross motor development were directly or indirectly predicted by the slope of the hip-to-ankle angle plot during pre-takeoff. In conclusion, this study identifies key components of jumping in jumping performance and gross motor development in preschool children for physical education.

Patellofemoral and tibiofemoral joint loading during a single-leg forward hop following ACL reconstruction

Altered biomechanics are frequently observed following anterior cruciate ligament reconstruction (ACLR). Yet, little is known about knee-joint loading, particularly in the patellofemoral-joint, despite patellofemoral-joint osteoarthritis commonly occurring post-ACLR. This study compared knee-joint reaction forces and impulses during the landing phase of a single-leg forward hop in the reconstructed knee of people 12-24 months post-ACLR and uninjured controls. Experimental marker data and ground forces for 66 participants with ACLR (28 ± 6 years, 78 ± 15 kg) and 33 uninjured controls (26 ± 5 years, 70 ± 12 kg) were input into scaled-generic musculoskeletal models to calculate joint angles, joint moments, muscle forces, and the knee-joint reaction forces and impulses. The ACLR group exhibited a lower peak knee flexion angle (mean difference: -6°; 95% confidence interval: [-10°, -2°]), internal knee extension moment (-3.63 [-5.29, -1.97] percentage of body weight × participant height (body weight [BW] × HT), external knee adduction moment (-1.36 [-2.16, -0.56]% BW × HT) and quadriceps force (-2.02 [-2.95, -1.09] BW). The ACLR group also exhibited a lower peak patellofemoral-joint compressive force (-2.24 [-3.31, -1.18] BW), net tibiofemoral-joint compressive force (-0.74 [-1.20, 0.28] BW), and medial compartment force (-0.76 [-1.08, -0.44] BW). Finally, only the impulse of the patellofemoral-joint compressive force was lower in the ACLR group (-0.13 [-0.23, -0.03] body weight-seconds). Lower compressive forces are evident in the patellofemoral- and tibiofemoral-joints of ACLR knees compared to uninjured controls during a single-leg forward hop-landing task. Our findings may have implications for understanding the contributing factors for incidence and progression of knee osteoarthritis after ACLR surgery.

Fatigue and recovery have different effects on knee biomechanics of drop vertical jump between female collegiate and recreational athletes

Background

Although fatigue is known as one of the risk factors for noncontact anterior cruciate ligament injury, the effects of fatigue and recovery can be different based on the level of competition. However, it is unknown whether female recreational athletes are susceptible to fatigue or not, compared to female collegiate athletes with greater physical activity. The purpose of the present study was to examine and clarify the effects of fatigue and recovery on knee biomechanics of the drop vertical jump (DVJ) in female recreational athletes compared to female collegiate athletes.

Methods

Fifteen female collegiate athletes and ten female recreational athletes were enrolled in the current study. All subjects were basketball players and Tegner activity scales were level 9 and 7, respectively. They performed DVJ before and after the fatigue protocol. Three-dimensional knee kinematics and kinetics were collected during landing phase of DVJ. The data after the fatigue protocol (first, second, and third DVJs) were compared with those before the protocol using one-way repeated measures of analysis of variance in each group.

Results

Fatigue caused significant increase of knee abduction angle at initial contact (IC) and peak abduction moments within 40 ms from IC in female recreational athletes, whereas no increases of these parameters were observed in female collegiate athletes. Moreover, recovery from fatigue seemed to be more slowly in female recreational athletes than in female collegiate athletes as smaller knee flexion moment was observed even in post-fatigue third DVJ only for female recreational athletes.

Conclusions

Effects of fatigue on DVJ were significantly greater and continued for a longer duration in female recreational athletes compared to female collegiate athletes.

Six methods for classifying lower-limb dominance are not associated with asymmetries during a change of direction task

Quantifying asymmetries between dominant and non-dominant limbs is a common research objective aimed at identifying systematic differences between limbs and establishing normative ranges of asymmetry. Multiple methods for classifying limb dominance exist, and it is unclear how different methods relate to directional asymmetries during change of direction (CoD). This study aimed to determine whether different methods of classifying limb dominance, including a novel CoD task-specific method, identified significant inter-limb asymmetries during a 90° CoD task. Fifty participants completed a testing battery consisting of jumping, hopping, CoD, and isokinetic dynamometry. Limb dominance was classified for each participant according to preferred kicking limb, vertical jump height, horizontal hop distance, initial force plate contact during landing, max isokinetic knee extensor strength, and turning velocity. Asymmetries in whole-body and joint-level mechanics were defined using each method. No method for classifying limb dominance was associated with consistent inter-limb biomechanical asymmetries during CoD, and no method was related to any other method. The magnitude of asymmetry relative to the magnitude of absolute asymmetry present within the cohort suggests that using these tasks to classify the dominant limb in this CoD is akin to assigning dominance to a randomly selected limb. Previous observations of group symmetry during CoD may be statistical artifacts as opposed to a true indication of normative movement. Until an appropriate means of classifying limbs during CoD is established, quantifying normative asymmetry based on limb dominance should be done with caution.

Characteristics of ground reaction force and frontal body movement during failed trials of single-leg lateral drop jump-landing task

Background

/objectives: For biomechanical studies using jump-landing tasks, many researchers set the criteria for judging success or failure of the trial. Failed trials are usually removed from the analysis. However, the kinetics and kinematics during tasks included in failed trials might be important for understanding the mechanisms and risk factors of non-contact sports injuries. However, few studies have attempted to analyze failed trials. Therefore, the main objective of this study was to investigate the characteristics associated with ground reaction force (GRF) and two-dimensional frontal body movements during a failed trial of single-leg lateral drop jump-landing.

Methods

Ten healthy women and 16 healthy men participated in this study. Spearman's rank correlation coefficients were calculated using the total number of failed trials and GRF data of successful trials. The association between frontal body movement and kinetics data was identified using correlation analyses. Wilcoxon signed-rank tests were performed to compare the GRF data of successful trials and failed trials of the same subject. Additionally, a two-way repeated measure analysis of variance was used to determine significant interactions of each trial and time after initial contact in the frontal body movement.

Results

A total of 137 trials including successful and failed trials were recorded. There were 59 failed jump trials. There was a significant negative correlation between the number of failed jump trials and the elapsed time from initial contact to peak vertical GRF (peak vGRF time) during successful trials (r = -0.427). The majority of failed trials were judged to be due to rearfoot movement patterns (rearfoot medial slip or rearfoot lateral slip). During rearfoot medial slip, we observed shorter peak vGRF time, larger trunk medial motions, and larger hip adduction movements after landing than that during successful trials. During rearfoot lateral slip, we observed larger trunk lateral motions and hip abduction movements after landing than that during successful trials.

Conclusions

Athletes who frequently failed during single-leg lateral drop jump-landing had poor skills absorbing jump-landing impact, which is related to various sports injuries. It is possible to identify the risk factors for sports injuries by analyzing failure patterns.

Secondary consequences of juvenile idiopathic arthritis in children and adolescents with knee involvement: physical activity, adiposity, fitness, and functional performance

OBJECTIVE

Secondary consequences of juvenile idiopathic arthritis (JIA) may impact long-term health outcomes. This study examined differences in physical activity, cardiorespiratory fitness, adiposity, and functional performance in children and adolescents with JIA compared to their typically developing (TD) peers.

METHODS

Participants with JIA (n = 32; 10-20 years old) and their TD peers (n = 35) volunteered for assessments of: daily moderate-to-vigorous physical activity (MVPA, body-worn accelerometer); peak oxygen consumption (VO_{2 Peak}, incremental bike test); fat mass index (FMI, dual-energy X-ray absorptiometry); and triple-single-leg-hop (TSLH) distance. Statistical analyses were performed in R using four linear mixed-effect models with Bonferroni adjustment (⍺ = 0.0125). Fixed effects were group, sex, and age. Participant clusters based on sex and age (within 1.5 years) were considered as random effects.

RESULTS

Participants with JIA displayed lower mean daily MVPA than their TD peers [p = 0.006; β (98.75% CI); -21.2 (-40.4 to -2.9) min]. VO_{2 Peak} [p = 0.019; -1.4 (-2.5 to -0.2) ml/kg/min] decreased with age. Females tended to have lower V_{O2 Peak} [p = 0.045; -6.4 (-13.0 to 0.4) ml/kg/min] and greater adiposity [p = 0.071; 1.4 (-0.1 to 3.0) kg/m²] than males.

CONCLUSION

The findings support the need for strategies to promote MVPA participation in children and adolescents with JIA. Sex and age should be considered in research on the consequences of JIA.

Test-retest reliability of entire time-series data from hip, knee and ankle kinematics and kinetics during one-leg hops for distance: Analyses using integrated pointwise indices

Motion capture systems enable in-depth interpretations of human movements based on data from three-dimensional joint angles and moments. Such analyses carry important bearings for evaluation of movement control during for instance hop landings among sports-active individuals from a performance perspective but also in rehabilitation. Recent statistical development allows analysis of entire time-series of angle and moment during hops using functional data analysis, but the reliability of such multifaceted data is not established. We used integrated pointwise indices (intra-class correlation, ICC; standard error of measurement, SEM) to establish the test-retest reliability of three-dimensional hip, knee and ankle angle and moment curves during landings of one-leg hop for distance (OLHD) in 23 asymptomatic individuals aged 18-28. We contrasted these findings to reliability of discrete variables extracted at specific events (initial contact, peak value). We extended the calculations of ICC and SEM to handle unbalanced situations (varying number of repetitions) to include all available data. Hip and knee angle curves proved reliable with stable ICC curves throughout the landing, with integrated ICCs ≥ 0.71 for all planes except for knee internal/external rotation (ICC = 0.57). Hip and knee moment curves and ankle angle and moments were less reliable and less stable, particularly in the first ~ 10-25% of the landing (integrated ICCs 0.44-0.57). Curve data were generally not in agreement with the results for discrete event data, thus advocating analysis of curve data which contains more information. To conclude, hip and knee angle curve data during OLHD landings can reliably be evaluated, while moment curves necessitate careful consideration.

Analysis Choices Impact Movement Evaluation: A Multi-Aspect Inferential Method Applied to Kinematic Curves of Vertical Hops in Knee-Injured and Asymptomatic Persons

Three-dimensional human motion analysis provides in-depth understanding in order to optimize sports performance or rehabilitation following disease or injury. Recent developments of statistical methods for functional data allow for novel ways to analyze often complex biomechanical data. Even so, for such methods as well as for traditional well-established statistical methods, the interpretations of the results may be influenced by analysis choices made prior to the analysis. We evaluated the consequences of three such choices when comparing one-leg vertical hop (OLVH) performance in individuals who had ruptured their anterior cruciate ligament (ACL), to that of asymptomatic controls, and also athletes. Kinematic data were analyzed using a statistical approach for functional data, targeting entire curve data. This was done not only for one joint at a time but also for multiple lower limb joints and movement planes simultaneously using a multi-aspect methodology, testing for group differences while also accounting for covariates. We present the results of when an individual representative curve out of three available was either: (1) a mean curve (Mean), (2) a curve from the highest hop (Max), or (3) a curve describing the variability (Var), as a representation of performance stability. We also evaluated choice of sample leg comparison; e.g., ACL-injured leg compared to either the dominant or non-dominant leg of asymptomatic groups. Finally, we explored potential outcome effects of different combinations of included joints. There were slightly more pronounced group differences when using Mean compared to Max, while the specifics of the observed differences depended on the outcome variable. For Var there were less significant group differences. Generally, there were more disparities throughout the hop movement when comparing the injured leg to the dominant leg of controls, resulting in e.g., group differences for trunk and ankle kinematics, for both Mean and Max. When the injured leg was instead compared to the non-dominant leg of controls, there were trunk, hip and knee joint differences. For a more stringent comparison, we suggest considering to compare the injured leg to the non-dominant leg. Finally, the multiple-joint analyses were coherent with the single-joint analyses. The direct effects of analysis choices can be explored interactively by the reader in the Supplementary Material. To summarize, the choices definitively have an impact on the interpretation of a hop test results commonly used in rehabilitation following knee injuries. We therefore strongly recommend well-documented methodological analysis choices with regards to comparisons and representative values of the measures of interests.

Copers and Noncopers Use Different Landing Techniques to Limit Anterior Tibial Translation After Anterior Cruciate Ligament Reconstruction

Background:

At 1 year after anterior cruciate ligament reconstruction (ACLR), two-thirds of patients manage to return to sports (copers), whereas one-third of patients do not return to sports (noncopers). Copers and noncopers have different muscle activation patterns, and noncopers may not be able to control dynamic anterior tibial translation (ATTd) as well as copers.

Purpose/Hypothesis:

To investigate whether (1) there is a positive correlation between passive ATT (ATTp; ie, general joint laxity) and ATTd during jump landing, (2) whether ATTd is moderated by muscle activating patterns, and (3) whether there is a difference in moderating ATTd between copers and noncopers. We hypothesized that patients who have undergone ACLR compensate for ATTd by developing muscle strategies that are more effective in copers compared with noncopers.

Study Design:

Controlled laboratory study.

Methods:

A total of 40 patients who underwent unilateral ACLR performed 10 single-leg hops for distance with both legs. Lower body kinematic and kinetic data were measured using a motion-capture system, and ATTd was determined with an embedded method. Muscle activity was measured using electromyographic signals. Bilateral ATTp was measured using a KT-1000 arthrometer. In addition, the Beighton score was obtained.

Results:

There was no significant correlation between ATTp and ATTd in copers; however, there was a positive correlation between ATTp and ATTd in the operated knee of noncopers. There was a positive correlation between the Beighton score and ATTp as well as between the Beighton score and ATTd in both copers and noncopers in the operated knee. Copers showed a negative correlation between ATTd and gastrocnemius activity in their operated leg during landing. Noncopers showed a positive correlation between ATTd and knee flexion moment in their operated knee during landing.

Conclusion:

Copers used increased gastrocnemius activity to reduce ATTd, whereas noncopers moderated ATTd by generating a smaller knee flexion moment.

Clinical Relevance:

This study showed that copers used different landing techniques than noncopers. Patients who returned to sports after ACLR had sufficient plantar flexor activation to limit ATTd.

Limb dominance influences energy absorption contribution (EAC) during landing after anterior cruciate ligament reconstruction

OBJECTIVE

To determine the role of limb dominance on energy absorption contribution (EAC) during a jump landing (JL) task at return to sport (RTS) after ACL-R.

DESIGN

Cross-sectional study.

SETTING

Clinical Research Laboratory.

PARTICIPANTS

One hundred eight participants (age = 16.19 ± 1.74, Height = 172.25 ± 9.96 cm, Weight = 72.61 ± 15.48 kg).

MAIN OUTCOME MEASURES

Participants were grouped into two groups: those who injured their dominant limb ACL (D-ACL) and those who injured their non-dominant limb ACL (ND-ACL). A multiple analysis of variance (MANOVA) was used to assess for between group differences in EAC across the three joints.

RESULTS

In the surgical limb, D-ACL demonstrated smaller hip (D-ACL = 32.23 ± 10.44%, ND-ACL = 69.68 ± 8.51%, p < 0.008) and greater knee (D-ACL = 45.86 ± 10.36%, ND-ACL = 9.41 ± 5.68%, p < 0.008) EAC than ND-ACL. In the non-surgical limb, D-ACL demonstrated greater hip (D-ACL = 62.59 ± 9.03%, ND-ACL = 25.95 ± 7.15%, p < 0.008), and smaller knee (D-ACL = 13.79 ± 5.57%, ND-ACL = 58.01 ± 7.86%, p < 0.008), EAC than ND-ACL.

CONCLUSION

After ACL-R, eccentric loading strategies during a JL task at RTS are different depending upon limb dominance. D-ACL demonstrated a greater knee loading strategy on the surgical side compared to ND-ACL.

Lower Limb Asymmetry After Anterior Cruciate Ligament Reconstruction in Adolescent Athletes: A Systematic Review and Meta-Analysis

OBJECTIVES

To identify reported (1) common biomechanical asymmetries in the literature after anterior cruciate ligament (ACL) reconstruction in adolescents during landing and (2) timescales for asymmetry to persist postsurgery.

DATA SOURCES

We identified sources by searching the CINAHL, PubMed, Scopus, and SPORTDiscus electronic databases using the following search terms: asymmetry OR symmetry AND landing AND biomechanics OR kinematics OR kinetics.

STUDY SELECTION

We screened the titles and abstracts of 85 articles using our inclusion criteria. A total of 13 articles were selected for further analysis.

DATA EXTRACTION

Three reviewers independently assessed the methodologic quality of each study. We extracted the effect sizes directly from studies or calculated them for biomechanical variables assessing asymmetry between limbs of participants with ACL reconstruction. We conducted meta-analyses on variables that were assessed in multiple studies for both double- and single-limb landings.

DATA SYNTHESIS

Asymmetry was more commonly identified in kinetic than kinematic variables. Anterior cruciate ligament reconstruction appeared to have a large effect on asymmetry between limbs for peak vertical ground reaction force, peak knee-extension moment, and loading rate during double-limb landings, as well as mean knee-extension moment and knee energy absorption during both double- and single-limb landings.

CONCLUSIONS

Our findings suggested that return-to-sport criteria after ACL reconstruction should incorporate analysis of the asymmetry in loading experienced by each limb rather than movement patterns alone.

Instrumented triple single-leg hop test: A validated method for ambulatory measurement of ankle and knee angles using inertial sensors

BACKGROUND

Hop tests are commonly used in clinical environments to measure function after sport-related knee injuries. Joint angle measurement during hopping is feasible in research-based environments equipped with motion-capture systems. Employing these systems in clinical research settings is inefficient, given the associated cost, preparation time, and expertise required to administer and interpret the findings. Therefore, this study aimed to introduce a wearable system comprising three inertial measurement units for 3D joint angular measurement during horizontal hop tests, validate the joint angles against a camera-based system, and evaluate its applicability in clinical research environments.

METHODS

Ten able-bodied participants were outfitted with three inertial measurement units during triple single-leg hop trials. 3D knee and ankle angles were calculated using the strap-down integration method, and results were compared with camera-based joint angles. Additionally, knee and ankle range of motions (RoMs) during bilateral triple single-leg hop trials were compared for 22 participants with unilateral sport-related knee injuries and 10 uninjured participants.

FINDINGS

Estimated angles had root-mean-square and RoM error medians of less than 2.3 and 3.2 degrees for both joints, and correlation coefficients of above 0.92 when compared with the camera-based system, for all hop phases. Injured participants had smaller sagittal ankle RoM (P = .008) on their injured side, during the third hop. Concurrently, they demonstrated smaller knee RoM symmetry indices (P = .017) and injured knee sagittal RoMs (P = .009) compared to uninjured participants.

INTERPRETATION

The introduced system had appropriate accuracy to highlight post-injury modifications in hopping kinematics and reveal noteworthy differences in RoM of clinical samples.

Timing of Muscle Activation Is Altered During Single-Leg Landing Tasks After Anterior Cruciate Ligament Reconstruction at the Time of Return to Sport

OBJECTIVES

It is well known that alterations in landing mechanics persist for years after anterior cruciate ligament reconstruction (ACL-R). Nevertheless, existing literature is controversial in reporting successful or unsuccessful recovery of prelanding muscle activation timing after ACL-R. The study aimed at comparing myoelectric and kinematic patterns during landing tasks between ACL-R and healthy subjects.

DESIGN

Cross-sectional study.

SETTING

Institutional research laboratory.

PATIENTS AND INTERVENTION

Fifteen male athletes after ACL-R using patellar tendon and 11 using hamstrings autograft at the time of return to sport were recruited. Fifteen healthy athletes served as control group. Participants performed 4 different single-leg landing tasks arriving onto a force plate.

MAIN OUTCOME MEASURES

Electromyographic (EMG) activity of knee extensors and flexors, normalized vertical ground reaction force (vGRF), and knee angular displacement were recorded.

RESULTS

In all the tasks, preimpact EMG duration was longer in ACL-R (112 ± 28 ms in the knee extensors; 200 ± 34 ms in the knee flexors) compared with healthy participants (74 ± 19 ms in the knee extensors; 153 ± 29 ms in the knee flexors; P < 0.05). Initial contact (IC) and maximum postimpact knee angle were lower in ACL-R (9 ± 7 degrees at IC; 39 ± 12 degrees at maximum flexion) compared with healthy participants (17 ± 9 degrees at IC; 52 ± 15 degrees at maximum flexion; P < 0.05). Normalized vGRF was higher in ACL-R compared with healthy participants (3.4 ± 0.5 and 2.7 ± 0.6; P < 0.05).

CONCLUSIONS

At the time of return to sport, ACL-R subjects showed altered motor control strategies of single-leg landings. These alterations may lead to uncoordinated movement, hence increasing the risk of reinjury.

THE RELATIONSHIP BETWEEN Y-BALANCE TEST SCORES AND KNEE MOMENTS DURING SINGLE-LEG JUMP-LANDING IN NETBALL

Background

Using 3-dimensional motion analysis to derive knee moments that may contribute to non-contact anterior cruciate ligament (ACL) injuries during single-leg jump-landing is expensive and time consuming. Severe ACL injuries that are inappropriately rehabilitated can potentially end athletes' careers. Consequently, a quick-and-simple to administer screening tool that can be used to infer knee moments during single-leg jump-landing could be useful for regular screening of netballers' predispositions to increased knee loading during single-leg jump-landing.

Purpose

The purpose of this study was to investigate whether knee moments during weight-acceptance phase of a forward single-leg jump for maximal distance were correlated with reach scores in the Y-Balance Test (YBT).

Study Design

Cross-sectional, Correlation.

Methods

Twenty-one female national-level netballers performed two and three successful trials on the YBT and forward single-leg jump-landing, respectively, with the non-dominant leg. A three-dimensional motion analysis system captured trunk and lower limb kinematics and ground reaction forces of the non-dominant leg during landing. Averages of peak knee flexion-extension, valgus-varus and internal-external rotation moments across jumps were calculated and correlations with peak directional reach scores were examined.

Results

A strong positive correlation existed between posteromedial reach with externally applied flexor moments (r = 0.56, p = ≤ 0.01). A moderate negative correlation existed between anterior reach distances with internal rotation moments (T _b = -0.32, p = 0.05). No correlation was found between valgus moments and YBT reaches.

Conclusions

The YBT shows potential to indicate externally applied flexion- and internal rotation moments during forward jump-landing on the non-dominant leg.

Level of Evidence

3.

Sagittal knee kinematics in relation with the posterior tibia slope during jump landing after an anterior cruciate ligament reconstruction

Purpose

An increased posterior tibia plateau angle is associated with increased risk for anterior cruciate ligament injury and re-rupture after reconstruction. The aims of this study were to determine whether the tibia plateau angle correlates with dynamic anterior tibia translation (ATT) after an anterior cruciate ligament reconstruction and whether the tibia plateau angle correlates with aspects of knee kinematics and kinetics during jump landing.

Methods

Thirty-seven patients after anterior cruciate ligament reconstruction with autograft hamstring tendon were included. Knee flexion angle and knee extension moment during single leg hops for distance were determined using a motion capture system and the dynamic ATT with its embedded method. The medial and lateral posterior tibia plateau angle were measured using MRI. Moreover, passive ATT was measured using the KT-1000 arthrometer.

Results

A weak negative correlation was found between the maximal dynamic ATT and the medial tibia plateau angle (p = 0.028, r = − 0.36) and between the maximal knee flexion angle and the lateral tibia plateau angle (p = 0.025, r = − 0.37) during landing. Patients with a smaller lateral tibia plateau angle show larger maximal knee flexion angle during landing than the patients with larger lateral tibia plateau angle. Also, the lateral tibia plateau angle is associated the amount of with muscle activity.

Conclusion

The posterior medical tibia plateau angle is associated with dynamic ATT. The maximal knee flexion angle and muscle activity are associated with the posterior lateral tibia plateau angle.

Level of evidence

III

Quantification of Triple Single-Leg Hop Test Temporospatial Parameters: A Validated Method using Body-Worn Sensors for Functional Evaluation after Knee Injury

Lower extremity kinematic alterations associated with sport-related knee injuries may contribute to an unsuccessful return to sport or early-onset post-traumatic osteoarthritis. Also, without access to sophisticated motion-capture systems, temporospatial monitoring of horizontal hop tests during clinical assessments is limited. By applying an alternative measurement system of two inertial measurement units (IMUs) per limb, we obtained and validated flying/landing times and hop distances of triple single-leg hop (TSLH) test against motion-capture cameras, assessed these temporospatial parameters amongst injured and uninjured groups, and investigated their association with the Knee Injury and Osteoarthritis Outcome Score (KOOS). Using kinematic features of IMU recordings, strap-down integration, and velocity correction techniques, temporospatial parameters were validated for 10 able-bodied participants and compared between 22 youth with sport-related knee injuries and 10 uninjured youth. With median (interquartile range) errors less than 10(16) ms for flying/landing times, and less than 4.4(5.6)% and 2.4(3.0)% of reference values for individual hops and total TSLH progression, differences between hopping biomechanics of study groups were highlighted. For injured participants, second flying time and all hop distances demonstrated moderate to strong correlations with KOOS Symptom and Function in Daily Living scores. Detailed temporospatial monitoring of hop tests is feasible using the proposed IMUs system.

Dynamic Leap and Balance Test: Ability to Discriminate Balance Deficits in Individuals With Chronic Ankle Instability

Context: The Dynamic Leap Balance Test (DLBT) is a new dynamic balance task that requires serial changes in base of support with alternating limb support and recovery of dynamic stability, as compared with the Y modification of the Star Excursion Balance Test (Y-SEBT), which assesses dynamic stability over an unchanging base of support. Objectives: To assess the dynamic balance performance in 2 different types of dynamic balance tasks, the DLBT and the SEBT, in subjects with unilateral chronic ankle instability (CAI) when compared with matched controls. The authors hypothesized that the DLBT score would significantly differ between the CAI involved and uninvolved limbs (contralateral and healthy matched) and demonstrate a modest (r = .50) association with the SEBT scores. Design: Case-control. Setting: Controlled laboratory. Participants: A total of 36 physically active adults, 18 with history of unilateral CAI and 18 without history of ankle injury, were enrolled in the study. CAI subjects were identified using the Identification of Functional Ankle Instability questionnaire. Interventions: The DLBT and the SEBT were performed in a randomized order on a randomly selected limb in CAI and healthy subjects. Main Outcome Measures: Time taken to complete the DLBT and the reach distances performed on the SEBT were compared between the CAI and the healthy subjects. Results: There were no statistically significant differences (P < .05) in SEBT reach distances between groups. The DLBT time was greater (P < .01) for unstable ankles compared with the stable ankle. The authors found no correlation (P > .05) between DLBT time and any of the SEBT reach distances suggesting that the DLBT provides unique information in the assessment of patients with CAI. Conclusion: The DLBT challenges the ability to maintain postural control in CAI subjects differently than the SEBT. There is a need of more dynamic balance assessment tools that are functional and clinically relevant.

Neurocognitive challenged hops reduced functional performance relative to traditional hop testing

OBJECTIVE

Determine the relationship between four foundational single-leg hop tests and respective neurocognitive single-leg hop tests.

DESIGN

Cross-sectional; SETTING: University gymnasium.

PATIENTS OR OTHER PARTICIPANTS

Twenty-two participants (9 Male, 13 Female, 20.9 ± 2.5 years, 171.2 ± 11.7 cm, 70.3 ± 11.0 kg) were recruited. Maximum distance was measured for three hop tests (single-leg hop, single-leg crossover hop, single-leg triple hop) and fastest time was measured for the fourth (single-leg 6-m hop) for traditional and neurocognitive conditions.

MAIN OUTCOME MEASURES

Pearson correlations were conducted to assess the relationship between the new neurocognitive hop and the analogous traditional hop. One repeated measures MANOVA was conducted for each leg to determine the difference in hop performance between hop conditions (traditional and neurocognitive) for the dependent variables. Alpha level was set at α < 0.05.

RESULTS

Correlations ranged from 0.86 to 0.92 between traditional and neurocognitive hop tests. The repeated measures MANOVA was significant for condition for both legs (p < 0.05). Specifically, the crossover hop (average percent decrease 10.37%), triple hop (average percent decrease 7.13%), and 6-m hop (average percent decrease 81.67%) were statistically different between traditional and neurocognitive conditions (p < 0.05).

CONCLUSION

The addition of neurocognitive reactive and anticipatory components to simulate more sport specific scenarios may improve functional testing for return to sport.

Horizontal jumping biomechanics among elite female handball players with and without anterior cruciate ligament reconstruction: an ISU based study

Background

Handball is a strenuous body-contact team sport that places high loads on the knee joint. Anterior cruciate ligament (ACL) tear is one of the most devastating injuries that any handball player can suffer, and female athletes are at particular risk due to their intrinsic anatomical, hormonal, neuromuscular and biomechanical characteristics. The purpose of this study was to analyze the horizontal jumping biomechanics of female elite handball players with or without previous ACL reconstruction.

Methods

Twenty-one female participants (6 with previous ACL reconstruction and 15 uninjured controls) were recruited. Two horizontal hopping tasks were evaluated using inertial sensor unit (ISU)-based technology to assess jumping biomechanics through a direct mechanics-based approach.

Results

The athletes with previous ACL reconstruction demonstrated a significant (P < 0.05) reduction in the unilateral triple hop for distance compared with the healthy controls. Furthermore, during the initial propulsive phase of the unilateral cross-over hop, the control participants generated significantly (P < 0.05) higher force values in the mediolateral direction (the X axis) with their dominant limb compared with the ACL-reconstructed (ACL-R) limb of previously injured participants.

Conclusions

Three-dimensional horizontal jumping biomechanics analyses using ISU-based technologies could provide clinicians with more accurate information regarding the horizontal jumping biomechanical patterns among elite handball female athletes. Furthermore, several mechanical alterations could still be observed among those players who had undergone previous ACL reconstruction, even when several years have passed since the original ACL injury.

Statistical Parametric Mapping as a Measure of Differences Between Limbs: Applications to Clinical Populations

In healthy individuals, symmetrical lower-extremity movement is often assumed and calculated using discrete points during various tasks. However, measuring overall movement patterns using methods such as statistical parametric mapping (SPM) may allow for better interpretation of human movement. This study demonstrated the ability of SPM to assess interlimb differences in lower-extremity movement during 2 example tasks: running and landing. Three-dimensional motion analysis was used to determine sagittal and frontal plane lower-extremity joint angles in (1) young and older individuals during running and (2) patients with anterior cruciate ligament reconstruction and uninjured control athletes during landing. Interlimb differences within each group were compared using SPM and paired t tests on peak discrete angles. No differences between limbs were found between young and older runners using SPM. Peak ankle eversion and plantar flexion angles differed between limbs in young and older runners. Sagittal plane hip angle varied between limbs in uninjured control athletes. Frontal plane ankle angle and sagittal plane knee and hip angles differed between limbs in patients with anterior cruciate ligament reconstruction using SPM and discrete analysis. These data suggest that SPM can be useful to determine clinically meaningful interlimb differences during running and landing in multiple populations.

Horizontal jumping biomechanics among elite male handball players with and without anterior cruciate ligament reconstruction. An inertial sensor unit-based study

OBJECTIVES

Anterior cruciate ligament (ACL) tears are one of the most devastating injuries that any handball player can suffer during landing and pivoting actions. The aim of this study was to analyze the horizontal jumping biomechanics among male elite handball players with or without previous ACLR.

DESIGN

Descriptive study.

SETTING

Spanish elite male handball players.

PARTICIPANTS

Twenty-six male participants (6 ACL-R and 20 uninjured controls) were recruited.

MAIN OUTCOME MEASURES

Two horizontal hopping tasks were evaluated using an inertial sensor unit (ISU)-based technology to assess jumping biomechanics through a direct mechanics-based approach.

RESULTS

Non-significant differences were found in relation to any of the biomechanical or performance related analyzed variables.

CONCLUSIONS

Previously ACL-R elite male handball players who have returned to the top level of sports participation do not seem to possess lasting biomechanical and/or performance deficits 6 years after the original surgical ligament repair.

Limb-dominance and gender differences in the ground reaction force during single-leg lateral jump-landings

[Purpose] The purpose of this study was to examine limb-dominance and gender differences in the magnitude of the ground reaction force during single-leg lateral jump-landings. We hypothesized that the peak ground reaction force would be larger in the non-dominant leg compared to that in the dominant leg and would be larger in females compared to that in men. [Subjects and Methods] Fifteen females and 15 males performed jump-landings sideways from a height of 20 cm, with a lateral distance of 60 cm. Vertical and medial ground reaction forces were measured, and the elapsed time from the initial contact to the peak ground reaction force was determined. The loading rate was calculated as the peak ground reaction force divided by the elapsed time from the initial contact to the peak ground reaction force. [Results] The vertical and medial peak ground reaction forces during single-leg lateral jump-landings were larger in females compared to that in males. In addition, the medial peak ground reaction force was larger for the non-dominant leg compared to that for the dominant leg. [Conclusion] The results suggest that in rehabilitation and conditioning settings, evaluations and instructions regarding attenuation are especially important for females and the non-dominant leg.

Altered movement during single leg hop test after ACL reconstruction: implications to incorporate 2-D video movement analysis for hop tests

PURPOSE

There is a lack of objective factors which can be used in guiding the return to sport (RTS) decision after an anterior cruciate ligament reconstruction (ACLR). The purpose of the current study was to conduct qualitative analysis of the single leg hop (SLH) in patients after ACLR with a simple and clinical friendly method and to compare the possible difference in movement pattern between male and female patients.

METHODS

Sixty-five patients performed the single leg hop (SLH) test at 6.8 ± 1.0 months following isolated ACLR. Digital video camcorders recorded frontal and sagittal plane views of the patient performing the SLH. Knee flexion at initial contact (IC), peak knee flexion, knee flexion range of motion (RoM), and knee valgus RoM were calculated. In addition, limb symmetry index (LSI) scores were calculated.

RESULTS

No differences were found in movement pattern between males and females. Movement analysis revealed that males had a decrease in knee flexion at IC (p = 0.018), peak knee flexion (p = 0.002), and knee flexion RoM (p = 0.017) in the injured leg compared to the non-injured leg. Females demonstrated a decrease in peak knee flexion (p = 0.011) and knee flexion RoM (p = 0.023) in the injured leg compared to the non-injured leg. Average LSI scores were 92.4% for males and 94.5% for females.

CONCLUSIONS

Although LSI scores were > 90%, clinical relevant altered movement patterns were detected in the injured leg compared to the non-injured leg. Caution is warranted to solely rely on LSI scores to determine RTS readiness.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION

The University of Groningen, ID 2012.362.

LEVEL OF EVIDENCE

III.

Single-Leg Hop Test Performance and Isokinetic Knee Strength After Anterior Cruciate Ligament Reconstruction in Athletes

Background:

Isokinetic strength and hop tests are commonly used to assess athletes’ readiness to return to sport after knee surgery.

Purpose/Hypothesis:

The purpose of this study was to investigate the results of single-leg hop and isokinetic knee strength testing in athletes who underwent anterior cruciate ligament reconstruction (ACLR) upon returning to sport participation as well as to study the correlation between these 2 test batteries. The secondary purpose was to compare the test results by graft type (patellar tendon or hamstring). It was hypothesized that there would be no statistically significant limb difference in either isokinetic knee strength or single-leg hop tests, that there would be a moderate to strong correlation between the 2 test batteries, and that there would be no significant difference between graft types.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Twenty-nine high school and collegiate athletes who underwent ACLR participated in this study. At the time of return to full sport participation, a series of hop tests and knee extension/flexion isokinetic strength measurements were conducted. The results were analyzed using analysis of variance and Pearson correlation (r).

Results:

The timed 6-m hop test was the only hop test that showed a significant difference between the involved and uninvolved limbs (2.3 and 2.2 seconds, respectively; P = .02). A significant difference between limbs in knee strength was found for flexion peak torque/body weight at 180 deg/s (P = .03), flexion total work/body weight at 180 deg/s (P = .04), and flexion peak torque/body weight at 300 deg/s (P = .03). The strongest correlation between the hop tests and knee strength was found between the total distance of the hop tests and flexion total work/body weight at 300 deg/s (r = 0.69) and between the timed 6-m hop test and flexion peak torque/body weight at 300 deg/s (r = –0.54). There was no statistically significant difference in hop test performance or isokinetic knee strength between graft types.

Conclusion:

The single-leg hop tests and isokinetic strength measurements were both useful for a bilateral comparison of knee functional performance and strength. Knee flexion strength deficits and flexion-to-extension ratios seemed to be correlated with single-leg hop test performance. There was no difference in postoperative hop test performance or knee strength according to graft type.

Associations between ankle dorsiflexion range of motion and foot and ankle strength in young adults

[Purpose] This study assessed the relationships between the ankle dorsiflexion range of motion and foot and ankle strength. [Subjects and Methods] Twenty-nine healthy (young adults) volunteers participated in this study. Each participant completed tests for ankle dorsiflexion range of motion, hallux flexor strength, and ankle plantar and dorsiflexor strength. [Results] The results showed (1) a moderate correlation between ankle dorsiflexor strength and dorsiflexion range of motion and (2) a moderate correlation between ankle dorsiflexor strength and first toe flexor muscle strength. Ankle dorsiflexor strength is the main contributor ankle dorsiflexion range of motion to and first toe flexor muscle strength. [Conclusion] Ankle dorsiflexion range of motion can play an important role in determining ankle dorsiflexor strength in young adults.

The effect of leg dominance and landing height on ACL loading among female athletes

Female athletes are more prone to anterior cruciate ligament (ACL) injury. A neuromuscular imbalance called leg dominance may provide a biomechanical explanation. Therefore, the purpose of this study was to compare the side-to-side lower limb differences in movement patterns, muscle forces and ACL forces during a single-leg drop-landing task from two different heights. We hypothesized that there will be significant differences in lower limb movement patterns (kinematics), muscle forces and ACL loading between the dominant and non-dominant limbs. Further, we hypothesized that significant differences between limbs will be present when participants land from a greater drop-landing height. Eight recreational female participants performed dominant and non-dominant single-leg drop landings from 30 to 60cm. OpenSim software was used to develop participant-specific musculoskeletal models and to calculate muscle forces. We also predicted ACL loading using our previously established method. There were no significant differences between dominant and non-dominant leg landing except in ankle dorsiflexion and GMED muscle forces at peak GRF. Landing from a greater height resulted in significant differences among most kinetics and kinematics variables and ACL forces. Minimal differences in lower-limb muscle forces and ACL loading between the dominant and non-dominant legs during single-leg landing may suggest similar risk of injury across limbs in this cohort. Further research is required to confirm whether limb dominance may play an important role in the higher incidence of ACL injury in female athletes with larger and sport-specific cohorts.

Do ground reaction forces during unilateral and bilateral movements exhibit compensation strategies following ACL reconstruction?

PURPOSE

The aims of the study were (1) to evaluate the leg asymmetry assessed with ground reaction forces (GRFs) during unilateral and bilateral movements of different knee loads in anterior cruciate ligament (ACL) reconstructed patients and (2) to investigate differences in leg asymmetry depending on the International Knee Documentation Committee Subjective Form (IKDC) in order to identify potential compensation strategies.

METHODS

The knee function of 50 ACL reconstructed (patella tendon) patients was examined at 31 ± 7 months after the surgery. GRFs were quantified during the sit-to-stand and stand-to-sit test, the step-up and step-down test, and the two- and one-leg vertical jump. Further, the IKDC score, the anterior-posterior knee laxity, and the concentric torque of the quadriceps and hamstring muscles were evaluated.

RESULTS

Differences between the operated and non-operated leg were found in the knee laxity, the quadriceps torque, and GRFs. The patients with low IKDC scores demonstrated greater leg asymmetries in GRFs compared to the patients with high IKDC scores.

CONCLUSIONS

ACL reconstructed patients showed GRF asymmetries during unilateral and bilateral movements of different knee loads. Three compensation strategies were found in patients with low subjective knee function: (1) a reduced eccentric load, (2) an inter-limb compensation during bilateral movements, and (3) the avoidance of high vertical impact forces. These compensation strategies may be indicative of a protective adaptation to avoid excessive ACL strain. GRF measurements are practicable and efficient tools to identify individual compensation strategies during early rehabilitation.

Bracing of the Reconstructed and Osteoarthritic Knee during High Dynamic Load Tasks

PURPOSE

Lateral compartment osteoarthritis accompanied by abnormal knee biomechanics is frequently reported in individuals with knee osteoarthritis after anterior cruciate ligament reconstruction (ACLR). The aim of this study was to evaluate changes in knee biomechanics produced by an adjusted and unadjusted varus knee brace during high dynamic loading activities in individuals with lateral knee osteoarthritis after ACLR and valgus malalignment.

METHODS

Nineteen participants who had undergone ACLR 5 to 20 yr previously and had symptomatic and radiographic lateral knee osteoarthritis with valgus malalignment were assessed. Quantitative motion analysis experiments were conducted during hopping, stair ascent, and descent under three test conditions: (i) no brace, (ii) unadjusted brace with sagittal plane support and neutral frontal plane alignment, and (iii) adjusted brace with sagittal plane support and varus realignment (valgus to neutral). Sagittal, frontal, and transverse plane knee kinematics, external joint moment, and angular impulse data were calculated.

RESULTS

Relative to an unbraced knee, braced conditions significantly increased knee flexion and adduction angles during hopping (P = 0.003 and P = 0.005; respectively), stair ascent (P = 0.003 and P < 0.001, respectively), and descent (P = 0.009 and P < 0.001, respectively). In addition, the brace conditions increased knee flexion (P < 0.001) and adduction (P = 0.001) angular impulses and knee stiffness (P < 0.001) during hopping, as well as increased knee adduction moments during stair ascent (P = 0.008) and flexion moments during stair descent (P = 0.006). There were no significant differences between the adjusted and the unadjusted brace conditions (P > 0.05).

CONCLUSION

A knee brace, with or without varus alignment, can modulate knee kinematics and external joint moments during hopping, stairs ascent, and descent in individuals with predominant lateral knee osteoarthritis after ACLR. Longer-term use of a brace may have implications in slowing osteoarthritis progression.

Knee Muscular Control During Jump Landing in Multidirections

BACKGROUND

Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks.

OBJECTIVES

The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direction jump landing.

MATERIALS AND METHODS

Eighteen male athletes performed the jump-landing test in four directions: forward (0°), 30° diagonal, 60° diagonal, and lateral (90°). Muscles tested were vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), and biceps femoris (BF). A Vicon(TM) 612 workstation collected the kinematic data. An electromyography was synchronized with the Vicon(TM) Motion system to quantify dynamic muscle function. Repeated measure ANOVA was used to analyze the data.

RESULTS

Jump-landing direction significantly influenced (P < 0.05) muscle activities of VL, RF, and ST and knee flexion excursion. Jumpers landed with a trend of decreasing knee flexion excursion and ST muscle activity 100 ms before foot contact progressively from forward to lateral directions of jump landing.

CONCLUSIONS

A higher risk of knee injury might occur during lateral jump landing than forward and diagonal directions. Athletes should have more practice in jump landing in lateral direction to avoid injury. Landing technique with high knee flexion in multi-directions should be taught to jumpers for knee injury prevention.

Influence of sex and limb dominance on lower extremity joint mechanics during unilateral land-and-cut manoeuvres

Limb dominance theory suggests that females tend to be more one-leg dominant and exhibit greater kinematic and kinetic leg asymmetries than their male counterparts, contributing to the increased risk of anterior cruciate ligament injury among female athletes. Thus, the purpose of this study was to examine the influences of sex and limb dominance on lower extremity joint mechanics during unilateral land-and-cut manoeuvres. Twenty-one women and 21 men completed land-and-cut manoeuvres on their dominant limb as well as their nondominant limb. Three-dimensional kinematics and kinetics were calculated bilaterally for the entire stance phase of the manoeuvre. Women performed land-and-cut manoeuvres with altered hip motions and loads as well as greater knee abduction at touchdown compared to men. Dominant limb land-and-cut manoeuvres where characterised by decreased hip flexion at touchdown as well as decreased hip flexion and adduction range of motion compared to nondominant land-and-cuts regardless of sex. The observed sex differences are consistent with previous research regarding mechanisms underlying the sex disparity in anterior cruciate ligament injury rates. However, observed differences regarding limb dominances appear somewhat arbitrary and did not suggest that the dominant or nondominant limb would be at increased risk of anterior cruciate ligament injury.

One-leg hop kinematics 20 years following anterior cruciate ligament rupture: Data revisited using functional data analysis

BACKGROUND

Despite interventions, anterior cruciate ligament ruptures can cause long-term deficits. To assist in identifying and treating deficiencies, 3D-motion analysis is used for objectivizing data. Conventional statistics are commonly employed to analyze kinematics, reducing continuous data series to discrete variables. Conversely, functional data analysis considers the entire data series.

METHODS

Here, we employ functional data analysis to examine and compare the entire time-domain of knee-kinematic curves from one-leg hops between and within three groups. All subjects (n=95) were part of a long-term follow-up study involving anterior cruciate ligament ruptures treated ~20 years ago conservatively with physiotherapy only or with reconstructive surgery and physiotherapy, and matched knee-healthy controls.

FINDINGS

Between-group differences (injured leg, treated groups; non-dominant leg, controls) were identified during the take-off and landing phases, and in the sagittal (flexion/extension) rather than coronal (abduction/adduction) and transverse (internal/external) planes. Overall, surgical and control groups demonstrated comparable knee-kinematic curves. However, compared to controls, the physiotherapy-only group exhibited less flexion during the take-off (0-55% of the normalized phase) and landing (44-73%) phase. Between-leg differences were absent in controls and the surgically treated group, but observed during the flight (4-22%, injured leg>flexion) and the landing (57-85%, injured leg<internal rotation) phases in the physiotherapy-only group.

INTERPRETATION

Functional data analysis identified specific functional knee-joint deviations from controls persisting 20 years post anterior cruciate ligament rupture, especially when treated conservatively. This approach is suggested as a means for comprehensively analyzing complex movements, adding to previous analyses.

Analysis of Jumping-Landing Manoeuvers after Different Speed Performances in Soccer Players

Purpose

Running at high speed and sudden change in direction or activity stresses the knee. Surprisingly, not many studies have investigated the effects of sprinting on knee’s kinetics and kinematics of soccer players. Hence, this study is aimed to investigate indices of injury risk factors of jumping-landing maneuvers performed immediately after sprinting in male soccer players.

Methods

Twenty-three collegiate male soccer players (22.1±1.7 years) were tested in four conditions; vertical jump (VJ), vertical jump immediately after slow running (VJSR), vertical jump immediately after sprinting (VJFR) and double horizontal jump immediately after sprinting (HJFR). The kinematics and kinetics data were measured using Vicon motion analyzer (100Hz) and two Kistler force platforms (1000Hz), respectively.

Results

For knee flexion joint angle, (p = 0.014, η = 0.15) and knee valgus moment (p = 0.001, η = 0.71) differences between condition in the landing phase were found. For knee valgus joint angle, a main effect between legs in the jumping phase was found (p = 0.006, η = 0.31), which suggests bilateral deficit existed between the right and left lower limbs.

Conclusion

In brief, the important findings were greater knee valgus moment and less knee flexion joint angle proceeding sprint (HJFR & VJFR) rather than no sprint condition (VJ) present an increased risk for knee injuries. These results seem to suggest that running and sudden subsequent jumping-landing activity experienced during playing soccer may negatively change the knee valgus moment. Thus, sprinting preceding a jump task may increase knee risk factors such as moment and knee flexion joint angle.

A kinematic and kinetic analysis of spinal region in subjects with and without recurrent low back pain during one leg standing

BACKGROUND

The purpose of this study was to evaluate the relationship between normalized kinematic and kinetic stability indices for spinal regions with eyes-open and eyes-closed conditions during non-dominant leg standing between subjects with recurrent low back pain and control subjects.

METHODS

The kinematic stability index for the spinal regions (core spine model, lumbar spine, lower and upper thorax) and the kinetic stability index from force plate were measured. All participants were asked to maintain non-dominant leg standing with the dominant hip and knee flexed approximately 90 degrees for 25 seconds. Forty-two participants enrolled in the study, including 22 subjects with low back pain (12 male, 10 female) and 20 control subjects (12 male, 8 female).

FINDINGS

For the kinematic index for stability, the visual condition (F=30.06, p=0.0001) and spinal region (F=10.82, p=0.002) were statistically significant. The post hoc test results indicated a significant difference in the lumbar spine compared with the upper and lower thorax and the core spine model. The kinetic stability (average [standard deviation]) during the eyes-closed condition significantly decreased in the low back pain group (t=-3.24, p=0.002).

INTERPRETATION

The subjects with recurrent low back pain demonstrated higher lumbar spine stability in eyes-open condition. This higher stability of the lumbar spine might be due to a possible pain avoiding strategy from the standing limb. The low back pain group also significantly decreased kinetic stability during the eyes-closed condition. Clinicians need to consider both kinetic and kinematic indices while considering visual condition for lumbar spine stability in subjects with recurrent low back pain.

Acceleration and Orientation Jumping Performance Differences Among Elite Professional Male Handball Players With or Without Previous ACL Reconstruction: An Inertial Sensor Unit-Based Study

BACKGROUND

Handball is one of the most challenging sports for the knee joint. Persistent biomechanical and jumping capacity alterations can be observed in athletes with an anterior cruciate ligament (ACL) injury. Commonly identified jumping biomechanical alterations have been described by the use of laboratory technologies. However, portable and easy-to-handle technologies that enable an evaluation of jumping biomechanics at the training field are lacking.

OBJECTIVE

To analyze unilateral/bilateral acceleration and orientation jumping performance differences among elite male handball athletes with or without previous ACL reconstruction via a single inertial sensor unit device.

DESIGN

Case control descriptive study.

SETTING

At the athletes' usual training court.

PARTICIPANTS

Twenty-two elite male (6 ACL-reconstructed and 16 uninjured control players) handball players were evaluated.

METHODS

The participants performed a vertical jump test battery that included a 50-cm vertical bilateral drop jump, a 20-cm vertical unilateral drop jump, and vertical unilateral countermovement jump maneuvers.

MAIN OUTCOME MEASUREMENTS

Peak 3-dimensional (X, Y, Z) acceleration (m·s(-2)), jump phase duration and 3-dimensional orientation values (°) were obtained from the inertial sensor unit device. Two-tailed t-tests and a one-way analysis of variance were performed to compare means. The P value cut-off for significance was set at P < .05.

RESULTS

The ACL-reconstructed male athletes did not show any significant (P < .05) residual jumping biomechanical deficits regarding the measured variables compared with players who had not suffered this knee injury. A dominance effect was observed among non-ACL reconstructed controls but not among their ACL-reconstructed counterparts (P < .05).

CONCLUSIONS

Elite male handball athletes with previous ACL reconstruction demonstrated a jumping biomechanical profile similar to control players, including similar jumping performance values in both bilateral and unilateral jumping maneuvers, several years after ACL reconstruction. These findings are in agreement with previous research showing full functional restoration of abilities in top-level male athletes after ACL reconstruction, rehabilitation and subsequent return to sports at the previous level.

Lower extremity neuromuscular compensations during instrumented single leg hop testing 2-10 years following ACL reconstruction

BACKGROUND

This study compared lower extremity EMG activation and sagittal plane kinematics of subjects at a minimum of 2 years post-successful ACL reconstruction and rehabilitation during instrumented single leg hop testing.

METHODS

Comparisons were made based on subject responses to the following question, "compared to prior to your knee injury how capable are you now in performing sports activities"? Group 1=very capable, Group 2=capable, and Group 3=not capable. In addition to EMG (1000 Hz) and kinematic (60 Hz) data, subjective knee function, internal health locus of control, sports activity characteristics (intensity, frequency) pre-knee injury, and at follow-up were also compared.

RESULTS

Group 3 had lower perceived knee function, decreased perceived sports intensity, and more subjects with decreased sports activity intensity by two levels compared to pre-injury values. Perceived function scores, anterior laxity measurements and grades were similar between groups. During single leg hop propulsion and landing Group 1 (very capable) had greater involved lower extremity gluteus maximus and medial hamstring activation amplitudes than Group 3 (not capable). Perceived sports capability was related to better subjective knee function, and higher perceived sports activity intensity.

CONCLUSION

Neuromuscular compensations suggesting a hip bias with increased gluteus maximus and medial hamstring activation were identified at the involved lower extremity among most subjects who perceived high perceived sports capability compared to pre-injury status. These compensations may be related to a permanent neurosensory deficit, and its influence on afferent pathway changes that influence CNS sensorimotor re-organization.