ACL injury and reconstruction affect control of ground reaction forces produced during a novel task that simulates cutting movements

Jumping into recovery: A systematic review and meta-analysis of discriminatory and responsive force plate parameters in individuals following anterior cruciate ligament reconstruction during countermovement and drop jumps

Purpose

Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post-ACLR during CMJ and/or DJ.

Methods

We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross-sectional papers comparing post-ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist.

Results

Thirty-three studies including 1185 (50.38%) participants post-ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single-leg CMJ, double-leg CMJ, single-leg DJ, and double-leg DJ. Jump height was reduced in both single (mean difference [MD] = -3.13; p < 0.01; 95% confidence interval [CI]: [-4.12, -2.15]) and double-leg (MD = -4.24; p < 0.01; 95% CI: [-5.14, -3.34]) CMJs amongst individuals with ACLR. Similarly, concentric impulse and eccentric/concentric impulse asymmetry could distinguish between ACLR (MD = 3.42; p < 0.01; 95% CI: [2.19, 4.64]) and non-ACLR (MD = 5.82; p < 0.01; 95% CI: [4.80, 6.80]) individuals. In double-leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = -0.10; p = 0.03; 95% CI: [-0.18, -0.01]) but higher in the uninvolved side (MD = 0.15; p < 0.01; 95% CI: [0.10, 0.20]) when compared to controls and demonstrated significant changes between 6 months and 3 years post-ACLR.

Conclusion

This study identified discriminative kinetic parameters when comparing individuals with and without ACLR and also monitored neuromuscular function post-ACLR. Due to heterogeneity, a combination of parameters may be required to better identify functional deficits post-ACLR.

Level of Evidence

Level III.

Does core stability training improve hopping performance and kinetic asymmetries during single-leg landing in anterior cruciate ligament reconstructed patients?

Safe return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR) surgery is important. Core stabilization is common within rehabilitation, but its influence on hopping performance and single-leg landing kinetics among athletes post-ACLR is unclear. Twenty-four male professional athletes who had ACL reconstruction surgery (time since surgery = 11.47 ± 1.55 months) were recruited and randomly assigned to exercise (n = 12) and control (n = 12) groups. Exercise group received an 8-week core stability exercise program. Limb symmetry index (LSI) for single-leg hop for distance (SLH) and triple hop (TRH) tests, and single-leg landing kinetics (multidirectional ground reaction forces) were measured pre- and post-intervention. In post-test, the participants in exercise group were more symmetrical in SLH (P = .04, CI = 0.01-7.68) and TRH (P = .01, CI = 0.28-11.1) distances. They also improved their LSI values for vertical ground reaction force (vGRF), though not significantly (P < .05). LSI for anteroposterior (a-p) and mediolateral (m-l) GRFs remained unchanged for participants of both groups. Our findings indicate the positive effect of core exercise on decreasing between-limb asymmetries during SLH and TRH tests. Our results demonstrate that despite lack of change in kinetics, functional performance is more symmetrical following core stability training.

A cross-sectional study to assess variability in knee frontal plane movement during single leg squat in patients with anterior cruciate ligament injury

BACKGROUND

Single leg squat (SLS) tests help predict anterior cruciate ligament injuries. However, the variability in joint movement during this test has not been fully investigated. The aim of this study was to examine the knee frontal plane movement variability during SLS in patients with anterior cruciate ligament (ACL) injury.

METHODS

In this cross-sectional study, we enrolled 56 patients with ACL injury (28 males; 28 females) and 46 healthy subjects (23 males; 23 females). All participants underwent SLS tests. All kinematic variables were joint angle of trunk, pelvis and lower limb, center of gravity (COG), center of pressure (COP). These data were obtained at the frontal plane and the coefficient of variation (CV) were calculated. Multiple comparisons were performed between healthy subjects and the injured leg and uninjured leg of patients with ACL injury. The correlation of the CV in knee varus/valgus range of motion (ROM) with the CV in other kinematic variables were investigated in patients with ACL injury.

RESULTS

Compared with healthy subjects, patients with ACL injury exhibited significantly larger the CV in knee varus/valgus ROM. A positive correlation was observed between the CV in knee varus/valgus ROM and the CV in pelvic lateral inclination ROM in patients with ACL injury.

CONCLUSIONS

Knee frontal plane movement variability during SLS may help evaluate the risk of ACL injury/re-injury. In addition, pelvic lateral inclination variability during SLS may need to be evaluated in conjunction with knee frontal plane movement variability.

Which assessments are used to analyze neuromuscular control by electromyography after an anterior cruciate ligament injury to determine readiness to return to sports? A systematic review

BACKGROUND

Adequate neuromuscular control of the knee could be one element to prevent secondary injuries after an anterior cruciate ligament (ACL) injury. To assess neuromuscular control in terms of time, amplitude and activity, electromyography (EMG) is used. However, it is unclear which assessments using EMG could be used for a safe return to sports (RTS). Therefore, we aimed to summarize EMG-related assessments for neuromuscular control of the knee in adult patients after an ACL injury to decide upon readiness for RTS.

METHODS

This systematic review followed guidelines of Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane recommendations. MEDLINE/PubMed, EMBASE, CINAHL, Cochrane Library, Physiotherapy Evidence Database (PEDro), SPORTDiscus and the Web of Science were searched from inception to March 2019 and updated in November 2020. Studies identifying electromyographic assessments for neuromuscular control during dynamic tasks in adult, physically active patients with an anterior cruciate ligament injury were eligible and qualitatively synthesized. Two independent reviewers used a modified Downs and Black checklist to assess risk of bias of included studies.

RESULTS

From initially 1388 hits, 38 mainly cross-sectional, case-controlled studies were included for qualitative analysis. Most studies provided EMG outcomes of thigh muscles during jumping, running or squatting. Outcomes measures described neuromuscular control of the knee in domains of time, amplitude or activity. Risk of bias was medium to high due to an unclear description of participants and prior interventions, confounding factors and incompletely reported results.

CONCLUSIONS

Despite a wide range of EMG outcome measures for neuromuscular control, none was used to decide upon return to sports in these patients. Additional studies are needed to define readiness towards RTS by assessing neuromuscular control in adult ACL patients with EMG. Further research should aim at finding reliable and valid, EMG-related variables to be used as diagnostic tool for neuromuscular control. Moreover, future studies should aim at more homogenous groups including adequately matched healthy subjects, evaluate gender separately and use sport-specific tasks. Registration The protocol for this systematic review was indexed beforehand in the International Prospective Register of Systematic Reviews (PROSPERO) and registered as CRD42019122188.

Different unilateral force control strategies between athletes and non-athletes

This study investigated continuous visuomotor tracking capabilities between athletes and non-athlete controls using isometric force control paradigm. Nine female athletes and nine female age-matched controls performed unilateral hand-grip force control tasks with their dominant and non-dominant hands at 10% and 40% of maximal voluntary contraction (MVC), respectively. Three conventional outcome measures on force control capabilities included mean force, force accuracy, and force variability, and we additionally calculated two nonlinear dynamics variables including force regularity using sample entropy and force stability using maximal Lyapunov exponent. Finally, we performed correlation analyses to determine the relationship between nonlinear dynamics variables and conventional measures for each group. The findings indicated that force control capabilities as indicated by three conventional measures were not significantly different between athlete and non-athlete control groups. However, the athletes revealed less force regularity and greater force stability across hand conditions and targeted force levels than those in non-athlete controls. The correlation analyses found that increased force regularity (i.e., less sample entropy values) at 10% of MVC and decreased force regularity (i.e., greater sample entropy values) at 40% of MVC were significantly related to improved force accuracy and variability for the athlete group, and these patterns were not observed in the non-athlete control group. These findings suggested that the athletes may use different adaptive force control strategies as indicated by nonlinear dynamics tools.

Kinetic measurement system use in individuals following anterior cruciate ligament reconstruction: a scoping review of methodological approaches

Purpose

Our primary objectives were to (1) describe current approaches for kinetic measurements in individuals following anterior cruciate ligament reconstruction (ACLR) and (2) suggest considerations for methodological reporting. Secondarily, we explored the relationship between kinetic measurement system findings and patient-reported outcome measures (PROMs).

Methods

We followed the PRISMA extension for scoping reviews and Arksey and O’Malley’s 6-stage framework. Seven electronic databases were systematically searched from inception to June 2020. Original research papers reporting parameters measured by kinetic measurement systems in individuals at least 6-months post primary ACLR were included.

Results

In 158 included studies, 7 kinetic measurement systems (force plates, balance platforms, pressure mats, force-measuring treadmills, Wii balance boards, contact mats connected to jump systems, and single-sensor insoles) were identified 4 main movement categories (landing/jumping, standing balance, gait, and other functional tasks). Substantial heterogeneity was noted in the methods used and outcomes assessed; this review highlighted common methodological reporting gaps for essential items related to movement tasks, kinetic system features, justification and operationalization of selected outcome parameters, participant preparation, and testing protocol details. Accordingly, we suggest considerations for methodological reporting in future research. Only 6 studies included PROMs with inconsistency in the reported parameters and/or PROMs.

Conclusion

Clear and accurate reporting is vital to facilitate cross-study comparisons and improve the clinical application of kinetic measurement systems after ACLR. Based on the current evidence, we suggest methodological considerations to guide reporting in future research. Future studies are needed to examine potential correlations between kinetic parameters and PROMs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00397-0.

Gaze Accuracy Differences During Single-Leg Balance Following Anterior Cruciate Ligament Reconstruction

CONTEXT

Individuals following anterior cruciate ligament reconstruction (ACLR) demonstrate altered postural stability and functional movement patterns. It is hypothesized that individuals following ACLR may compensate with sensory adaptations with greater reliance on visual mechanisms during activities. It is unknown if visual compensatory strategies are implemented to maintain postural stability during functional tasks.

OBJECTIVE

To examine visual gaze accuracy during a single-leg balance task in individuals following ACLR compared with healthy, active controls.

DESIGN

Case control.

SETTING

Controlled laboratory.

PARTICIPANTS

A total of 20 individuals (10 ACLR and 10 healthy controls) participated in the study.

DATA COLLECTION AND ANALYSIS

Visual gaze patterns were obtained during 20-second single-leg balance trials while participants were instructed to look at presented targets. During the Stationary Target Task, the visual target was presented in a central location for the duration of the trial. The Moving Target Task included a visual target that randomly moved to 1 of 9 target locations for a period of 2 seconds. Targets were stratified into superior, middle, and inferior levels for the Moving Target Task.

RESULTS

The Stationary Target Task demonstrated no differences in visual error between groups (P = .89). The Moving Target Task demonstrated a significant interaction between group and target level (F2,36 = 3.76, P = .033). Individuals following ACLR demonstrated greater visual error for the superior targets (ACLR = .70 [.44] m, healthy = .41 [.21] m, Cohen d = 0.83 [0.06 to 1.60]) and inferior targets (ACLR = .68 [.25] m, healthy = .33 [.16] m, Cohen d = 1.67 [0.81 to 2.52]).

CONCLUSION

Individuals following ACLR demonstrate greater visual error during settings of high or low visual stimuli compared with healthy individuals to maintain single-limb postural stability. This population may rely on visual input to compensate for the somatosensory changes following injury.

Neuromuscular function in anterior cruciate ligament reconstructed patients at long-term follow-up

BACKGROUND

The permanence of neuromuscular adaptations following anterior cruciate ligament reconstruction is not known. The aim of this study was to compare bilateral muscle co-contraction indices, time to peak ground reaction force, and timing of muscle onset between anterior cruciate ligament reconstruction subjects 10-15 years post reconstruction with those of matched uninjured controls during a one-leg hop landing.

METHODS

Nine healthy controls and 9 reconstruction subjects were recruited. Clinical and functional knee exams were administered. Lower limb co-contraction indices, time to peak ground reaction force, and muscle onset times were measured bilaterally. Differences in clinical and functional outcomes were assessed with unpaired t-tests, and mixed model repeated measures were used to examine effects of group, limb and interaction terms in electromyography measures.

FINDINGS

89% of control knees were clinically "normal", whereas only 33% of reconstructed knees were "normal". Anterior cruciate ligament-reconstructed subjects tended to achieve shorter functional hop distances but demonstrated symmetrical lower limb electromyography measures that were no different from those of controls' with the exception that biceps femoris activation was delayed bilaterally prior to ground contact but was greater during the injury risk phase of landing.

INTERPRETATION

With the exception of hamstring activation, lower limb electromyography measures were largely similar between ligament-reconstructed and matched control subjects, which was in contrast to the clinical findings. This result brings into question the significance of neuromuscular function at this long-term follow-up but raises new questions regarding the role of symmetry and pre-injury risk.

Filtering affects the calculation of the largest Lyapunov exponent

The calculation of the largest Lyapunov exponent (LyE) requires the reconstruction of the time series in an N-dimensional state space. For this, the time delay (Tau) and embedding dimension (EmD) are estimated using the Average Mutual Information and False Nearest Neighbor algorithms. However, the estimation of these variables (LyE, Tau, EmD) could be compromised by prior filtering of the time series evaluated. Therefore, we investigated the effect of filtering kinematic marker data on the calculation of Tau, EmD and LyE using several different computational codes. Kinematic marker data were recorded from 37 subjects during treadmill walking and filtered using a low pass digital filter with a range of cut-off frequencies (23.5-2Hz). Subsequently, the Tau, EmD and LyE were calculated from all cut-off frequencies. Our results demonstrated that the level of filtering affected the outcome of the Tau, EmD and LyE calculations for all computational codes used. However, there was a more consistent outcome for cut-off frequencies above 10 Hz which corresponded to the optimal cut-off frequency that could be used with this data. This suggested that kinematic data should remain unfiltered or filtered conservatively before calculating Tau, EmD and LyE.