Anterior cruciate ligament deficiency causes brain plasticity: a functional MRI study

Cortical Motor Planning and Biomechanical Stability During Unplanned Jump-Landings in Males With ACL-Reconstruction

CONTEXT

Athletes with anterior cruciate ligament (ACL) reconstruction exhibit increased cortical motor planning during simple sensorimotor tasks compared to healthy controls. This may interfere with proper decision-making during time-constrained movements elevating the re-injury risk.

OBJECTIVE

To compare cortical motor planning and biomechanical stability during jump-landings between participants with ACL-reconstruction and healthy individuals.

DESIGN

Cross-sectional exploratory study.

SETTING

Laboratory patients or other participants: Ten males with ACL-reconstruction (28±4 yrs., 63±35 months post-surgery) and 17 healthy males (28±4 yrs.) completed pre-planned (landing leg shown before take-off; n=43±4) and unplanned (visual cue during flight; n=51±5) countermovement-jumps with single-leg-landings.

MAIN OUTCOME MEASURES

Movement-related cortical potentials (MRCP) and frontal theta frequency power before the jump were analyzed using electroencephalography. MRCP were subdivided into three successive 0.5 sec epochs (readiness potential 1 and 2; RP and negative slope; NS) relative to movement onset (higher values indicative of more motor planning). Theta power was calculated for the last 0.5 sec prior to movement onset (higher values indicative of more focused attention). Biomechanical landing stability was measured via vertical peak ground reaction force, time to stabilization, and center of pressure.

RESULTS

Both conditions evoked MRCP at all epochs in both groups. During the unplanned condition, the ACL-reconstructed group exhibited slightly, but not significantly higher MRCP (RP-1:p=0.651, d=0.44, RP-2:p=0.451, d=0.48; NS:p=0.482, d=0.41). The ACL-reconstructed group also showed slightly higher theta power values during the pre-planned (p=0.175, d=0.5) and unplanned condition (p=0.422, d=0.3) reaching small to moderate effect sizes. In none of the biomechanical outcomes, both groups differed significantly (p>0.05). No significant condition and group interactions occurred (p>0.05).

CONCLUSIONS

Our jump-landing task evoked MRCP. Although not significant between groups, the observed effect sizes provide first indication that males with ACL-reconstruction may persistently rely on more cortical motor planning associated with unplanned jump-landings. Confirmatory studies with larger sample sizes are warranted.

TRIAL REGISTRY

clinicalTrials.gov (NCT03336060).

Lateral ankle instability-induced neuroplasticity in brain grey matter: A voxel-based morphometry MRI study

OBJECTIVES

The deficits in sensory pathways caused by peripheral edema, pain, and inflammation of the damaged ligaments may induce maladaptive changes within the central nervous system. The purpose of this study was to determine whether patients with lateral ankle instability (LAI) exhibit morphological differences of brain grey matter when compared with healthy controls, and then assess the relationships between the observed differences and the characteristics of patients.

DESIGN

Cross-sectional.

METHODS

Thirty patients with LAI and 32 healthy controls without LAI underwent MRI scans using anatomical T1 sequences. A voxel-wise general linear model was used to compare the grey matter volume throughout the whole brain between patients and controls. Linear regression analyses were performed for the grey matter volume within the significant clusters to assess their relationship with age, sex, the existence of acute injury, pain level, sports activity level, and the duration of LAI within the patient group.

RESULTS

The grey matter volume of a cluster within the cerebellar vermis (Vermis_4_5 in automated anatomical labeling template) was significantly reduced in patients with LAI (Gaussian Random Field corrections with two-tailed p-cluster < 0.05 and p-voxel < 0.001). Multivariate linear regression analysis revealed that the duration of LAI tended to be passively associated with the grey matter volume of this LAI-related vermal cluster (p = 0.092).

CONCLUSIONS

Participants with LAI exhibited a reduced grey matter volume of a cluster within the cerebellar vermis compared with participants without LAI, and the degree of volume reduction tended to be positively associated with the duration of LAI.

Functional Cortical Connectivity Related to Postural Control in Patients Six Weeks After Anterior Cruciate Ligament Reconstruction

Whereas initial findings have already identified cortical patterns accompanying proprioceptive deficiencies in patients after anterior cruciate ligament reconstruction (ACLR), little is known about compensatory sensorimotor mechanisms for re-establishing postural control. Therefore, the aim of the present study was to explore leg dependent patterns of cortical contributions to postural control in patients 6 weeks following ACLR. A total of 12 patients after ACLR (25.1 ± 3.2 years, 178.1 ± 9.7 cm, 77.5 ± 14.4 kg) and another 12 gender, age, and activity matched healthy controls participated in this study. All subjects performed 10 × 30 s. single leg stances on each leg, equipped with 64-channel mobile electroencephalography (EEG). Postural stability was quantified by area of sway and sway velocity. Estimations of the weighted phase lag index were conducted as a cortical measure of functional connectivity. The findings showed significant group × leg interactions for increased functional connectivity in the anterior cruciate ligament (ACL) injured leg, predominantly including fronto-parietal [F _{(1, 22)} = 8.41, p ≤ 0.008, η² = 0.28], fronto-occipital [F _{(1, 22)} = 4.43, p ≤ 0.047, η² = 0.17], parieto-motor [F _{(1, 22)} = 10.30, p ≤ 0.004, η² = 0.32], occipito-motor [F _{(1, 22)} = 5.21, p ≤ 0.032, η² = 0.19], and occipito-parietal [F _{(1, 22)} = 4.60, p ≤ 0.043, η² = 0.17] intra-hemispherical connections in the contralateral hemisphere and occipito-motor [F _{(1, 22)} = 7.33, p ≤ 0.013, η² = 0.25] on the ipsilateral hemisphere to the injured leg. Higher functional connectivity in patients after ACLR, attained by increased emphasis of functional connections incorporating the somatosensory and visual areas, may serve as a compensatory mechanism to control postural stability of the injured leg in the early phase of rehabilitation. These preliminary results may help to develop new neurophysiological assessments for detecting functional deficiencies after ACLR in the future.

The Neuroplastic Adaptation Trident Model: A Suggested Novel Framework for ACL Rehabilitation

Anterior Cruciate Ligament (ACL) injuries are common in athletic populations and there are many factors that contribute to a return to play decision. Human movement is diverse and variable, and it is important for patients recovering from an ACL injury to develop a variety of movement strategies for athletic performance. Variability of movement during sport may help to decrease injury risk by preparing the individual to handle many different situations and improve problem solving. ACL injuries result in neurophysiological dysfunction due to a disruption of the afferent information from the native mechanoreceptors in the ligament. Following injury, the brain enters a neuroplastic state and can adapt and change positively or negatively based on the rehabilitation or lack thereof. This commentary presents a novel framework for rehabilitation called the Neuroplastic Adaptation Trident Model that takes into account respected methods for attempting to achieve positive neuroplastic changes. This structured framework provides clinicians with reproducible methods to employ as part of the rehabilitation process to maximize motor control and motor learning. Suggested dosage and implementation are proposed to lead to a consistent and gradually progressive challenge throughout the entire rehabilitation process that takes advantage of the time from surgery until return to play. The purpose of this clinical commentary is to describe the Neuroplastic Adaptation Trident model and provide examples for clinical implementation. This method should be studied further to determine true effectiveness; currently, it is presented as a theoretical model based on best current evidence regarding ACL injury and rehabilitation of neurophysiologic dysfunction.

LEVEL OF EVIDENCE

5.

Rupture, reconstruction, and rehabilitation: A multi-disciplinary review of mechanisms for central nervous system adaptations following anterior cruciate ligament injury

BACKGROUND

Despite surgical reconstruction and extensive rehabilitation, persistent quadriceps inhibition, gait asymmetry, and functional impairment remain prevalent in patients after anterior cruciate ligament (ACL) injury. A combination of reports have suggested underlying central nervous system adaptations in those after injury govern long-term neuromuscular impairments. The classic assumption has been to attribute neurophysiologic deficits to components of injury, but other factors across the continuum of care (e.g. surgery, perioperative analgesia, and rehabilitative strategies) have been largely overlooked.

OBJECTIVE

This review provides a multidisciplinary perspective to 1) provide a narrative review of studies reporting neuroplasticity following ACL injury in order to inform clinicians of the current state of literature and 2) provide a mechanistic framework of neurophysiologic deficits with potential clinical implications across all phases of injury and recovery (injury, surgery, and rehabilitation) RESULTS: Studies using a variety of neurophysiologic modalities have demonstrated peripheral and central nervous system adaptations in those with prior ACL injury. Longitudinal investigations suggest neurophysiologic changes at spinal-reflexive and corticospinal pathways follow a unique timecourse across injury, surgery, and rehabilitation.

CONCLUSION

Clinicians should consider the unique injury, surgery, anesthesia, and rehabilitation on central nervous system adaptations. Therapeutic strategies across the continuum of care may be beneficial to mitigate maladaptive neuroplasticity in those after ACL injury.

Effects of neuromuscular training on knee proprioception in individuals with anterior cruciate ligament injury: a systematic review and GRADE evidence synthesis

OBJECTIVE

To systematically review and summarise the evidence for the effects of neuromuscular training compared with any other therapy (conventional training/sham) on knee proprioception following anterior cruciate ligament (ACL) injury.

DESIGN

Systematic Review.

DATA SOURCES

PubMed, CINAHL, SPORTDiscus, AMED, Scopus and Physical Education Index were searched from inception to February 2020.

ELIGIBILITY CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials investigating the effects of neuromuscular training on knee-specific proprioception tests following a unilateral ACL injury were included.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently screened and extracted data and assessed risk of bias of the eligible studies using the Cochrane risk of bias 2 tool. Overall certainty in evidence was determined using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool.

RESULTS

Of 2706 articles retrieved, only 9 RCTs, comprising 327 individuals with an ACL reconstruction (ACLR), met the inclusion criteria. Neuromuscular training interventions varied across studies: whole body vibration therapy, Nintendo-Wii-Fit training, balance training, sport-specific exercises, backward walking, etc. Outcome measures included joint position sense (JPS; n=7), thresholds to detect passive motion (TTDPM; n=3) or quadriceps force control (QFC; n=1). Overall, between-group mean differences indicated inconsistent findings with an increase or decrease of errors associated with JPS by ≤2°, TTDPM by ≤1.5° and QFC by ≤6 Nm in the ACLR knee following neuromuscular training. Owing to serious concerns with three or more GRADE domains (risk of bias, inconsistency, indirectness or imprecision associated with the findings) for each outcome of interest across studies, the certainty of evidence was very low.

CONCLUSIONS

The heterogeneity of interventions, methodological limitations, inconsistency of effects (on JPS/TTDPM/QFC) preclude recommendation of one optimal neuromuscular training intervention for improving proprioception following ACL injury in clinical practice. There is a need for methodologically robust RCTs with homogenous populations with ACL injury (managed conservatively or with reconstruction), novel/well-designed neuromuscular training and valid proprioception assessments, which also seem to be lacking.

PROSPERO REGISTRATION NUMBER

CRD42018107349.

Visual Perturbation to Enhance Return to Sport Rehabilitation after Anterior Cruciate Ligament Injury: A Clinical Commentary

Anterior cruciate ligament (ACL) tears are common traumatic knee injuries causing joint instability, quadriceps muscle weakness and impaired motor coordination. The neuromuscular consequences of injury are not limited to the joint and surrounding musculature, but may modulate central nervous system reorganization. Neuroimaging data suggest patients with ACL injuries may require greater levels of visual-motor and neurocognitive processing activity to sustain lower limb control relative to healthy matched counterparts. Therapy currently fails to adequately address these nuanced consequences of ACL injury, which likely contributes to impaired neuromuscular control when visually or cognitively challenged and high rates of re-injury. This gap in rehabilitation may be filled by visual perturbation training, which may reweight sensory neural processing toward proprioception and reduce the dependency on vision to perform lower extremity motor tasks and/or increase visuomotor processing efficiency. This clinical commentary details a novel approach to supplement the current standard of care for ACL injury by incorporating stroboscopic glasses with key motor learning principles customized to target visual and cognitive dependence for motor control after ACL injury.

LEVEL OF EVIDENCE

5.

Integrated 3D motion analysis with functional magnetic resonance neuroimaging to identify neural correlates of lower extremity movement

BACKGROUND

To better understand the neural drivers of aberrant motor control, methods are needed to identify whole brain neural correlates of isolated joints during multi-joint lower-extremity coordinated movements. This investigation aimed to identify the neural correlates of knee kinematics during a unilateral leg press task.

NEW METHOD

The current study utilized an MRI-compatible motion capture system in conjunction with a lower extremity unilateral leg press task during fMRI. Knee joint kinematics and brain activity were collected concurrently and averaged range of motion were modeled as covariates to determine the neural substrates of knee out-of-plane (frontal) and in-plane (sagittal) range of motion.

RESULTS

Increased out-of-plane (frontal) range of motion was associated with altered brain activity in regions important for attention, sensorimotor control, and sensorimotor integration (z >3.1, p < .05), but no such correlates were found with in-plane (sagittal) range of motion (z >3.1, p > .05). Comparison with Existing Method(s): Previous studies have either presented overall brain activation only, or utilized biomechanical data collected outside MRI in a standard biomechanics lab for identifying single-joint neural correlates.

CONCLUSIONS

The study shows promise for the MRI-compatible system to capture lower-extremity biomechanical data collected concurrently during fMRI, and the present data identified potentially unique neural drivers of aberrant biomechanics. Future research can adopt these methods for patient populations with CNS-related movement disorders to identify single-joint kinematic neural correlates that may adjunctively supplement brain-body therapeutic approaches.

The role of the dominant leg while assessing balance performance. A systematic review and meta-analysis

BACKGROUND

Good balance is a pre-requisite for various activities of daily life and sports. Physiotherapists thus regularly assess and train patient's balance capacities. In order to interpret the test results of unilateral balance tests, a comparison with normative data is common. In patients who had an injury or a surgery, the performance of the injured leg is often compared with performance of the non-injured leg. Nevertheless, it remains unclear if unilateral balance performance differs between the dominant and non- dominant legs. If so, this should take into consideration when interpreting test results.

RESEARCH QUESTION

This meta-analysis summarized the current evidence to determine if the balance performance of healthy adults was influenced by the leg's dominance.

METHODS

Articles were searched in PubMed, CINAHL, Cochrane and Embase. Data from studies meeting the pre-defined inclusion criteria were extracted in a standardized form. A meta-analysis was conducted using a random effect model.

RESULTS

Forty-six studies were included. Their data were allocated in 7 categories of balance tests. Significant differences between the dominant and the non-dominant legs were not found in any of the categories (surface stable, eyes open: -0.04, 95 % CI -0.12 to 0.05, surface stable eyes closed: -0.06, 95 % CI -0.22 to 0.11, surface unstable, eyes open: -0.15, 95 % CI -0.38 to 0.07, surface unstable, eyes closed: -0.06, 95 % CI -0.27 to 0.15, BESS (Balance Error Scoring System): 0.03, 95 % CI -1.09 to 1.14, SEBT (Star Excursion Balance Test)/YBT (Y Balance Test): 0.06, 95 % CI -0.04 to 0.16, jump: 0.04, 95 % CI -0.28 to 0.36).

SIGNIFICANCE

Results indicate that balance performance is not influenced by the leg's dominance. This means that performances of both legs can be used as reference. Evidence is strong for the one leg stance. However, future studies are needed to confirm our results for stabilization tasks after a jump landing.

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.

Athletes with an ACL reconstruction show a different neuromuscular response to environmental challenges compared to uninjured athletes

BACKGROUND

Evidence suggests that neuromuscular alterations in patients with an anterior cruciate ligament reconstruction (ACLR) are rooted in neurocognitive and proprioceptive deficits. The aim of this study was to assess neuromuscular control of athletes with ACLR under increased cognitive and environmental challenges.

RESEARCH QUESTION

Do athletes with ACLR show a different neuromuscular response to cognitive and environmental challenges relative to controls?

METHODS

Cross-sectional study. Twenty athletes who had an ACLR (age: 23.7 ± 4.3 years, 14 males, time post-surgery: 258.6 ± 54 days) and twenty uninjured controls (age: 21.4 ± 1.5 years, 14 males) performed a stepping down-task in four environmental conditions: no additional challenges, while performing a cognitive dual-task, while undergoing an unpredictable support surface perturbation, and with the cognitive dual-task and unpredictable perturbation combined. Muscle activations of the vastus medialis (VM), vastus lateralis, hamstrings medialis (HM), hamstrings lateralis (HL), gastrocnemius medialis, gastrocnemius lateralis (GL) and gluteus medius were recorded with surface EMG. A three-way ANOVA with main effects for group, dual-task and perturbation was used to compare muscle activations.

RESULTS

Athletes with ACLR show larger HM (ES = 0.45) and HL activation (ES = 1.32) and lower VM activation (ES = 0.72), compared to controls. Athletes with ACLR show a significantly smaller increase in VM (ES = 0.69), VL (ES = 0.53) and GL activation (ES = 0.52) between perturbed and unperturbed tasks compared to controls. Furthermore, under cognitive loading a significantly larger decrease in HM activation (ES = 0.40) and (medial) co-contraction (ES = 0.75) was found in athletes with ACLR compared to controls.

SIGNIFICANCE

Athletes with ACLR show an altered neuromuscular response which might represent an arthrogenic muscle response. They show less additional adaptation to perturbed tasks compared to controls, potentially as result of altered proprioceptive input. Furthermore a larger influence of increased cognitive loading on the neuromuscular control was found in athletes with ACLR, indicating that also neurocognitive limitations may contribute to altered neuromuscular control.

DUAL-TASK ASSESSMENT IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY: A SYSTEMATIC REVIEW

Background

Several systematic reviews have evaluated the role of dual-task assessment in individuals with concussion. However, no systematic reviews to date have investigated dual-task protocols with implications for individuals with anterior cruciate ligament (ACL) injury or ACL reconstruction (ACLR).

Purpose

To systematically review the evidence on dual-task assessment practices applicable to those with ACL deficiency/ACLR, specifically with the aim to identify motor-cognitive performance costs.

Study Design

Systematic review.

Methods

A systematic literature review was undertaken on those with ACL-deficient or ACL-reconstructed knees performing dual-task activities. The following databases were searched from inception to June 8, 2018 including CINAHL, PsychInfo, PubMed, SPORTDiscus, Web of Science, and gray literature. Three primary search categories (knee, cognition, and motor task) were included. Only one reviewer independently performed the database search, data extraction, and scored each article for quality. All studies were assessed for quality and pertinent data were extracted, examined and synthesized.

Results

Ten studies were included for analysis, all of which were published within the prior ten years. Performance deficits were identified in those with either ACL deficiency or ACLR while dual-tasking, such as prioritization of postural control at the expense of cognitive performance, impaired postural control in single limb stance, greater number of cognitive errors, and increased step width coefficient of variation while walking. No studies examined those with prior ACL injury or ACLR during tasks that mimicked ACL injury mechanisms such as jump-landing or single-leg cutting.

Conclusion

The results of the current systematic review suggests that postural control, gait, and/or cognitive deficits exist when evaluated under a dual-task paradigm in those with ACL deficiency or ACLR. This systematic review highlights the need for future research on dual-task assessment for individuals who have sustained an ACL injury or undergone ACLR, specifically utilizing more difficult athletic movements.

Level of Evidence

Level 3a.

Can Neurocognitive Function Predict Lower Extremity Injuries in Male Collegiate Athletes?

The purpose of this study is to demonstrate whether neurocognitive evaluation can confirm the association between neurocognitive level and postural control and to analyze the relationship between neurocognitive level and acute musculoskeletal injury in male non-net sports athletes. Seventy-seven male non-net sports athletes participated in this study. The Standardized Assessment of Concussion (SAC), Landing Error Scoring System (LESS), Balance Error Scoring System (BESS), and Star Excursion Balance Test (SEBT) were used for testing; we collected data related to injury history for six months after testing. Pearson's correlation analysis, logistic regression, and the independent sample t-test were used for statistical analysis. The correlation between SAC and SEBT results was weak to moderate (p < 0.05). Eleven of the seventy-seven participants experienced acute lower limb injuries. SAC, LESS, BESS, and SEBT results have no effect on the occurrence of acute lower extremity injuries (p > 0.05) and were not statistically different between the injured and non-injured groups (p > 0.05). Therefore, using the SAC score alone to determine the risk factor of lower extremity injuries, except in the use of assessment after a concussion, should be cautioned against.

Changes in motor-flexibility following anterior cruciate ligament reconstruction as measured by means of a leg-amplitude differentiation task with haptic and visual feedback

BACKGROUND

In the current study changes in lower-limb motor flexibility of patients undergoing Anterior Cruciate Ligament Reconstruction were evaluated in relation to fear of harm.

METHODS

Fourteen patients were measured pre- and post-surgery, and data were compared to those of a single measurement in fifteen controls. Lower-limb motor-flexibility was assessed in treadmill-walking and a cyclic leg-amplitude differentiation task augmented with haptic or visual feedback. Flexibility was captured by determining the between-leg coordination-variability (SD of relative phase) and each leg's temporal variability (sample entropy). Patients were post hoc divided into a higher-fear-group (pre-surgery: n = 6, post-surgery: n = 7) and a lower-fear-group (pre-surgery: n = 6, post-surgery: n = 7) by means of a median split of their scores on a self-reported fear of harm scale. Differences in flexibility-measures between the higher-fear-group and the lower-fear-group were also assessed.

FINDINGS

No pre- and post-surgery differences, nor differences with the control group, were found in motor-flexibility during treadmill-walking but the post-surgery higher-fear-group did show lower values of SD relative phase. In the leg-amplitude differentiation task the SD of the relative phase decreased but sample entropy increased post-surgery towards levels of the control-group. The pre-surgery higher-fear-group showed lower values of sample entropy in visual conditions.

INTERPRETATION

While gait kinematics may not show motor-flexibility changes following anterior cruciate ligament reconstruction, a leg-amplitude differentiation task does show such changes. Differentiating patients on a fear-of-harm scale revealed subtle differences in motor-flexibility. Challenging patients with non-preferred movements such as amplitude differentiation may be a promising tool to evaluate motor-flexibility following ACLR.

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

After anterior cruciate ligament (ACL) injury and reconstruction, biomechanical and neuromuscular control deficits persist and 25% of those who have experienced an ACL injury will experience a second ACL rupture in the first year after returning to sports. There remains a need for improved rehabilitation and the ability to detect an individual's risk of secondary ACL rupture. Nonlinear analysis metrics, such as the largest Lyapunov exponent (LyE) can provide new biomechanical insight in this population by identifying how movement patterns evolve over time. The purpose of this study was to determine how ACL injury, ACL reconstruction (ACLR), and participation in high-performance athletics affect control strategies, evaluated through nonlinear analysis, produced during a novel task that simulates forces generated during cutting movements. Uninjured recreational athletes, those with ACL injury who have not undergone reconstruction (ACLD [ACL deficient]), those who have undergone ACL reconstruction, and high-performance athletes completed a task that simulates cutting forces. The LyE calculated from forces generated during this novel task was greater (ie, force control was diminished) in the involved limb of ACLD and ACLR groups when compared with healthy uninjured controls and high-performance athletes. These data suggest that those who have experienced an ACL injury and subsequent reconstructive surgery exhibit poor force control when compared with both uninjured controls and high-performance athletes. Clinical significance: significantly larger LyE values after ACL injury and reconstruction when compared with healthy athletes suggest a continuing deficit in force control not addressed by current rehabilitation protocols and evaluation metrics that could contribute to secondary ACL rupture.

Leg-amplitude differentiation guided by haptic and visual feedback to detect alterations in motor flexibility due to Total Knee Replacement

Following total knee replacement (TKR), patients often persist in maladaptive motor behavior which they developed before surgery to cope with symptoms of osteoarthritis. An important challenge in physical therapy is to detect, recognize and change such undesired movement behavior. The goal of this study was to measure the differences in clinical status of patients pre-TKR and post-TKR and to investigate if differences in clinical status were accompanied by differences in the patients'' motor flexibility. Eleven TKR participants were measured twice: pre-TKR and post-TKR (twenty weeks after TKR). In order to infer maladaptation, the pre-TKR and post-TKR measurements of the patient group were separately compared to one measurement in a control group of fourteen healthy individuals. Clinical status was measured with the Visual Analogue Scale (VAS) for pain and knee stiffness and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Furthermore, Lower-limb motor flexibility was assessed by means of a treadmill walking task and a leg-amplitude differentiation task (LAD-task) supported by haptic or visual feedback. Motor flexibility was measured by coordination variability (standard deviation (SD) of relative phase between the legs) and temporal variability (sample entropy) of both leg movements. In the TKR-group, the VAS-pain and VAS- stiffness and the subscales of the KOOS significantly decreased after TKR. In treadmill walking, lower-limb motor flexibility did not significantly change after TKR. Between-leg coordination variability was significantly lower post-TKR compared to controls. In the LAD-task, a significant decrease of between-leg coordination variability between pre-TKR and post-TKR was accompanied by a significant increase in temporal variability. Post-TKR-values of lower-limb flexibility approached the values of the control group. The results demonstrate that a clinically relevant change in clinical status, twenty weeks after TKR, is not accompanied by alterations in lower-limb motor flexibility during treadmill walking but is accompanied by changes in motor flexibility towards the level of healthy controls during a LAD-task with visual and haptic feedback. Challenging patients with non-preferred movements such as amplitude differentiation may be a promising tool in clinical assessment of motor flexibility following TKR.

Neural activity for hip-knee control in those with anterior cruciate ligament reconstruction: A task-based functional connectivity analysis

Anterior cruciate ligament injury may induce neurophysiological changes for sensorimotor control. Neuroimaging investigations have revealed unique brain activity patterns for knee movement following injury, indicating potential neural mechanisms underlying aberrant neuromuscular control that may contribute to heightened risk of secondary injury, altered movement patterns and poor patient outcomes. However, neuroimaging paradigms thus far have been limited to single joint, single motion knee tasks. Therefore, we sought to overcome prior limitations to understand the effects of injury on neural control of lower extremity movement by employing a multi-joint motor paradigm and determining differences in neural activity between ACL-reconstructed (ACLr) individuals relative to healthy matched controls. Fifteen patients with left anterior cruciate ligament reconstruction and fifteen matched healthy controls participated in this study. Neural activity was examined using functional magnetic resonance imaging during a block-designed knee-hip movement paradigm (similar to a supine heel-slide). Participants for each group were monitored and task performance was controlled via a metronome to ensure the same spatial-temporal parameters. We observed that those with ACL reconstruction displayed increased activation within the intracalcarine cortex, lingual gyrus, occipital fusiform gyrus, lateral occipital cortex, angular gyrus, and superior parietal lobule relative to controls. A follow-up task-based functional connectivity analyses using seed regions identified from the group analysis revealed connectivity among fronto-insular-temporal and sensorimotor regions within the ACLr participants. The results of this fMRI investigation suggest ACLr individuals require increased activity and connectivity in areas responsible for visual-spatial cognition and orientation, and attention for hip and knee motor control.

Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury

Athletes who wish to resume high-level activities after an injury to the anterior cruciate ligament (ACL) are often advised to undergo surgical reconstruction. Nevertheless, ACL reconstruction (ACLR) does not equate to normal function of the knee or reduced risk of subsequent injuries. In fact, recent evidence has shown that only around half of post-ACLR patients can expect to return to competitive level of sports. A rising concern is the high rate of second ACL injuries, particularly in young athletes, with up to 20% of those returning to sport in the first year from surgery experiencing a second ACL rupture. Aside from the increased risk of second injury, patients after ACLR have an increased risk of developing early onset of osteoarthritis. Given the recent findings, it is imperative that rehabilitation after ACLR is scrutinized so the second injury preventative strategies can be optimized. Unfortunately, current ACLR rehabilitation programs may not be optimally effective in addressing deficits related to the initial injury and the subsequent surgical intervention. Motor learning to (re-)acquire motor skills and neuroplastic capacities are not sufficiently incorporated during traditional rehabilitation, attesting to the high re-injury rates. The purpose of this article is to present novel clinically integrated motor learning principles to support neuroplasticity that can improve patient functional performance and reduce the risk of second ACL injury. The following key concepts to enhance rehabilitation and prepare the patient for re-integration to sports after an ACL injury that is as safe as possible are presented: (1) external focus of attention, (2) implicit learning, (3) differential learning, (4) self-controlled learning and contextual interference. The novel motor learning principles presented in this manuscript may optimize future rehabilitation programs to reduce second ACL injury risk and early development of osteoarthritis by targeting changes in neural networks.

Corticospinal tract structure and excitability in patients with anterior cruciate ligament reconstruction: A DTI and TMS study

BACKGROUND

Underlying neural factors contribute to poor outcomes following anterior cruciate ligament reconstruction (ACLR). Neurophysiological adaptations have been identified in corticospinal tract excitability, however limited evidence exists on neurostructural changes that may influence motor recovery in ACLR patients.

OBJECTIVE

To 1) quantify hemispheric differences in structural properties of the corticospinal tract in patients with a history of ACLR, and 2) assess the relationship between excitability and corticospinal tract structure.

METHODS

Ten participants with ACLR (age: 22.6 ± 1.9 yrs; height: 166.3 ± 7.5 cm; mass: 65.4 ± 12.6 kg, months from surgery: 70.0 ± 23.6) volunteered for this cross-sectional study. Corticospinal tract structure (volume; fractional anisotropy [FA]; axial diffusivity [AD]; radial diffusivity [RD]; mean diffusivity [MD]) was assessed using diffusion tensor imaging, and excitability was assessed using transcranial magnetic stimulation (motor evoked potentials normalized to maximal muscle response [MEP]) for each hemisphere. Hemispheric differences were evaluated using paired samples t-tests. Correlational analyses were conducted on structural and excitability outcomes.

RESULTS

The hemisphere of the ACLR injured limb (i.e. hemisphere contralateral to the ACLR injured limb) demonstrated lower volume, lower FA, higher MD, and smaller MEPs compared to the hemisphere of the non-injured limb, indicating disrupted white matter structure and a reduction in excitability of the corticospinal tract. Greater corticospinal tract excitability was associated with larger corticospinal tract volume.

CONCLUSIONS

ACLR patients demonstrated asymmetry in structural properties of the corticospinal tract that may influence the recovery of motor function following surgical reconstruction. More research is warranted to establish the influence of neurostructural measures on patient outcomes and response to treatment in ACLR populations.

Functional Brain Plasticity Associated with ACL Injury: A Scoping Review of Current Evidence

Anterior cruciate ligament (ACL) injury is a common problem with consequences ranging from chronic joint instability to early development of osteoarthritis. Recent studies suggest that changes in brain activity (i.e., functional neuroplasticity) may be related to ACL injury. The purpose of this article is to summarize the available evidence of functional brain plasticity after an ACL injury. A scoping review was conducted following the guidelines of the Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The terms “brain,” “activity,” “neuroplasticity,” “ACL,” “injury,” and “reconstruction” were used in an electronic search of articles in PubMed, PEDro, CINAHL, and SPORTDiscus databases. Eligible studies included the following criteria: (a) population with ACL injury, (b) a measure of brain activity, and (c) a comparison to the ACL-injured limb (contralateral leg or healthy controls). The search yielded 184 articles from which 24 were included in this review. The effect size of differences in brain activity ranged from small (0.05, ACL-injured vs. noninjured limbs) to large (4.07, ACL-injured vs. healthy control). Moreover, heterogeneity was observed in the methods used to measure brain activity and in the characteristics of the participants included. In conclusion, the evidence summarized in this scoping review supports the notion of functional neuroplastic changes in people with ACL injury. The techniques used to measure brain activity and the presence of possible confounders, as identified and reported in this review, should be considered in future research to increase the level of evidence for functional neuroplasticity following ACL injury.

Study protocol: a single-blind, multi-center, randomized controlled trial comparing dynamic intraligamentary stabilization, internal brace ligament augmentation and reconstruction in individuals with an acute anterior cruciate ligament rupture: LIBRƎ study

Background

The current gold standard for the treatment of an anterior cruciate ligament (ACL) rupture is reconstruction with tendon graft. Recently, two surgical ACL repair techniques have been developed for treating an acute ACL rupture: Dynamic Intraligamentary Stabilization (DIS, Ligamys®) and Internal Brace Ligament Augmentation (IBLA, InternalBrace™). We will conduct a single-blind, multi-center, randomized controlled trial which compares DIS, IBLA and reconstruction for relative clinical efficacy and economic benefit.

Methods

Subjects, aged 18–50 years, with a proximal, primary and repairable ACL rupture will be included. DIS is preferably performed within 4 weeks post-rupture, IBLA within 12 weeks and reconstruction after 4 weeks post-rupture. Patients are included in study 1 if they present within 0–4 weeks post-rupture and surgery is feasible within 4 weeks post-rupture. Patients of study 1 will be randomized to either DIS or IBLA. Patients are included in study 2 if they present after 4 weeks post-rupture and surgery is feasible between 5 and 12 weeks post-rupture. Patients of study 2 will be randomized to either IBLA or reconstruction. A total of 96 patients will be included, with 48 patients per study and 24 patients per study arm. Patients will be followed-up for 2 years. The primary outcome is change from baseline (pre-rupture) in International Knee Documentation Committee score to 6 months post-operatively. The main secondary outcomes are the EQ-5D-5 L, Tegner score, Lysholm score, Lachman test, isokinetic and proprioceptive measurements, magnetic resonance imaging outcome, return to work and sports, and re-rupture/failure rates. The statistical analysis will be based on the intention-to-treat principle. The economic impact of the surgery techniques will be evaluated by the cost-utility analysis. The LIBRƎ study is to be conducted between 2018 and 2022.

Discussion

This LIBRƎ study protocol is the first study to compare DIS, IBLA and ACL reconstruction for relative clinical efficacy and economic benefit. The outcomes of this study will provide data which could aid orthopaedic surgeons to choose between the different treatment options for the surgical treatment of an acute ACL rupture.

Trial registration

This study is registered at ClinicalTrials.gov; NCT03441295. Date registered 13.02.2018.

One-leg rise performance and associated knee kinematics in ACL-deficient and ACL-reconstructed persons 23 years post-injury

BACKGROUND

Research indicates reduced knee function and stability decades after anterior cruciate ligament (ACL) injury. Assessment requires reliable functional tests that discriminate such outcomes from asymptomatic knees, while providing suitable loading for different populations. The One-leg rise (OLR) test is common in clinics and research but lacks scientific evidence for its implementation. Our cross-sectional study compared performance including knee kinematics of the OLR between ACL-injured persons in the very long term to controls and between legs within these groups, and assessed the within-session reliability of the kinematics.

METHODS

Seventy ACL-injured individuals (mean age 46.9 ± 5.4 years) treated with either reconstructive surgery and physiotherapy (ACL_R; n = 33) or physiotherapy alone (ACL_PT; n = 37), on average 23 years post-injury, and 33 age- and sex-matched controls (CTRL) attempted the OLR. Participants completed as many repetitions as possible to a maximum of 50 while recorded by motion capture. We compared between all groups and between legs within groups for total repetitions and decomposed the OLR into movement phases to compare phase completion times, maximum and range of knee abduction and adduction angles, and mediolateral knee control in up to 10 repetitions per participant.

RESULTS

ACL_PT performed significantly fewer OLR repetitions with their injured leg compared to the CTRL non-dominant leg (medians 15 and 32, respectively) and showed significantly greater knee abduction than ACL_R and CTRL (average 2.56°-3.69° depending on phase and leg). Distribution of repetitions differed between groups, revealing 59% of ACL_PT unable to complete more than 20 repetitions on their injured leg compared to 33% ACL_R and 36% CTRL for their injured and non-dominant leg, respectively. Within-session reliability of all kinematic variables for all groups and legs was high (ICC 3,10 0.97-1.00, 95% CI 0.95-1.00, SEM 0.93-1.95°).

CONCLUSIONS

Negative outcomes of OLR performance, particularly among ACL_PT, confirm the need to address aberrant knee function and stability even decades post-ACL injury. Knee kinematics derived from the OLR were reliable for asymptomatic and ACL-injured knees. Development of the OLR protocol and analysis methods may improve its discriminative ability in identifying reduced knee function and stability among a range of clinical populations.

Negative Emotion and Joint-Stiffness Regulation Strategies After Anterior Cruciate Ligament Injury

CONTEXT

Fear of reinjury after an anterior cruciate ligament (ACL) reconstruction (ACLR) may be associated with persistent deficits in knee function and subsequent injury. However, the effects of negative emotion on neuromuscular-control strategies after an ACL injury have remained unclear.

OBJECTIVE

To identify how negative emotional stimuli affect neural processing in the brain and muscle coordination in patients after anterior cruciate ligament reconstruction compared with healthy control participants.

DESIGN

Case-control study.

SETTING

Neuromechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty patients after unilateral anterior cruciate ligament reconstruction and 20 healthy recruits.

MAIN OUTCOME MEASURE(S)

Electrocortical θ (4-8 Hz) activity (event-related synchronization, % increased power relative to a nonactive baseline) at selected electrodes placed at the frontal (F3, Fz, F4) and parietal (P3, Pz, P4) cortices using electroencephalography, neurophysiological cardiac changes (beats/min), and subjective fear perceptions were measured, along with joint stiffness (Nm/°/kg) with and without an acoustic stimulus in response to 3 types of emotionally evocative images (neutral, fearful, and knee-injury pictures).

RESULTS

Both groups had greater frontoparietal θ power with fearful pictures (Fz: 35.9% ± 29.4%; Pz: 81.4% ± 66.8%) than neutral pictures (Fz: 24.8% ± 29.7%, P = .002; Pz: 64.2 ± 54.7%, P = .024). The control group had greater heart-rate deceleration with fearful (-4.6 ± 1.4 beats/min) than neutral (-3.6 ± 1.3 beats/min, P < .001) pictures, whereas the ACLR group exhibited decreased heart rates with both the fearful (-4.6 ± 1.3 beats/min) and injury-related (-4.4 ± 1.5 beats/min) pictures compared with neutral pictures (-3.4 ± 1.4 beats/min, P < .001). Furthermore, during the acoustic startle condition, fearful pictures increased joint stiffness (Nm/°/kg) in the ACLR group at the midrange (0°-20°: 0.027 ± 0.02) and long range (0°-40°: 0.050 ± 0.02) compared with the neutral pictures (0°-20°: 0.017 ± 0.01, P = .024; 0°-40°: 0.043 ± 0.02, P = .014).

CONCLUSIONS

Negative visual stimuli simultaneously altered neural processing in the frontoparietal cortices and joint-stiffness regulation strategies in response to a sudden perturbation. The adverse effects of fear on neuromuscular control may indicate that psychological interventions should be incorporated in neuromuscular-control exercise programs after ACL injury.

Motor imagery in high-functioning individuals with chronic anterior cruciate ligament deficiency: A cross-sectional study

BACKGROUND

There is increasing evidence that motor imagery performance (MIP) is impaired in conditions that have a component of movement dysfunction. However, MIP has not been investigated in people with chronic anterior cruciate ligament (ACL) deficiency who experience limited disability and function at high levels.

HYPOTHESIS

This study had three objectives: (1) to assess implicit MIP in individuals with a chronic ACL deficient (ACLD) knee compared with healthy controls (i.e., intact anterior cruciate ligament); (2) to determine if the location of ACL deficiency affects MIP (dominant versus non-dominant leg); and (3) to determine if impairment in MIP is specific to the side (injured versus non-injured) of ACL deficiency.

METHODS

Forty-five participants with chronic ACLD knee and 44 healthy controls completed a left/right judgement task of pictured knees using the "Recognise" app to evaluate implicit MIP. Accuracy and reaction time of judgements were compared between groups. Additionally, within the chronic ACLD knee group, we made comparisons between the dominant ACLD knee and non-dominant ACLD knee subgroups and between the injured knee and the non-injured knee of the ACLD group.

RESULTS

There were no differences in implicit MIP between the ACLD knee and the control group, the non-injured knee versus injured knee of the ACLD knee group, or the dominant ACLD knee versus non-dominant ACLD knee subgroups.

CONCLUSION

Implicit MIP is not disrupted in high functioning individuals with chronic ACLD knee.

Deficits in Quadriceps Force Control After Anterior Cruciate Ligament Injury: Potential Central Mechanisms

CONTEXT

Poor quadriceps force control has been observed after anterior cruciate ligament (ACL) reconstruction but has not been examined after ACL injury. Whether adaptations within the central nervous system are contributing to these impairments is unknown.

OBJECTIVE

To examine quadriceps force control in individuals who had sustained a recent ACL injury and determine the associations between cortical excitability and quadriceps force control in these individuals.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Eighteen individuals with a recent unilateral ACL injury (6 women, 12 men; age = 29.6 ± 8.4 years, height = 1.74 ± 0.07 m, mass = 76.0 ± 10.4 kg, time postinjury = 69.5 ± 42.5 days) and 18 uninjured individuals (6 women, 12 men; age = 29.2 ± 6.8 years, height = 1.79 ± 0.07 m, mass = 79.0 ± 8.4 kg) serving as controls participated.

MAIN OUTCOME MEASURE(S)

Quadriceps force control was quantified as the root mean square error between the quadriceps force and target force during a cyclical force-matching task. Cortical excitability was measured as the active motor threshold and cortical silent period. Outcome measures were determined bilaterally in a single testing session. Group and limb differences in quadriceps force control were assessed using mixed analyses of variance (2 × 2). Pearson product moment correlations were performed between quadriceps force control and cortical excitability in individuals with an ACL injury.

RESULTS

Individuals with an ACL injury exhibited greater total force-matching error with their involved (standardized mean difference [SMD] = 0.8) and uninvolved (SMD = 0.9) limbs than did controls (F_1,27 = 11.347, P = .03). During the period of descending force, individuals with an ACL injury demonstrated greater error using their involved (SMD = 0.8) and uninvolved (SMD = 0.8) limbs than uninjured individuals (F_1,27 = 4.941, P = .04). Greater force-matching error was not associated with any cortical excitability measures (P > .05).

CONCLUSIONS

Quadriceps force control was impaired bilaterally after recent ACL injury but was not associated with selected measures of cortical excitability. The findings highlight a need to incorporate submaximal-force control tasks into rehabilitation and "prehabilitation," as the deficits were present before surgery.

Hypoesthesia after anterior cruciate ligament reconstruction: The relationship between proprioception and vibration perception deficits in individuals greater than one year post-surgery

BACKGROUND

While surgical reconstruction restores mechanical stability following anterior cruciate ligament (ACL) rupture, many experience early-onset osteoarthritis despite surgery. Neurophysiological changes are hypothesized to contribute to knee osteoarthritis progression. Proprioceptive deficits have been reported following ACL injury/reconstruction; however, vibration perception threshold (VPT) has been less studied. This study explored relationships between pain, VPT, proprioception, function, and strength following ACL-reconstruction.

METHODS

Twenty individuals (27 ± 6 years; 10 males) (standard deviation) status-post ACL-reconstruction were compared with a control group. Measurements included VPT, proprioception (threshold to detect passive movement), pain, function (Knee Outcome Survey (KOS)) and isometric quadriceps strength. Group differences were assessed using Mann-Whitney U tests, side-to-side differences with Wilcoxon Signed Rank tests, and associations evaluated using Spearman correlations.

RESULTS

The ACL-reconstruction group had minor functional deficits (15 ± 11%) and resting pain (1.8 ± 1.7). Impaired VPT and proprioception (hypoesthesia) were demonstrated on surgical compared to contralateral and control limbs (p ≤ 0.008). Proprioception was significantly different between contralateral and control knees, but not VPT. Surgical knee proprioceptive deficits and VPT deficits were positively correlated (ρ = 0.462, p = 0.047) but not in controls (ρ = -0.042, p = 0.862). Strength was negatively correlated to pain (ρ = -0.589; p = 0.006), but not to KOS scores, proprioception or VPT (p ≥ 0.099).

CONCLUSION

Proprioceptive deficits following ACL injury have been ascribed to loss of afferent input from the torn ligament. Alternatively, multi-modality as well as contralateral sensory deficits suggest a spinal/supraspinal source of neurophysiological findings which may predispose to early osteoarthritis.

LEVEL OF EVIDENCE

III.

Neuroplastic changes in anterior cruciate ligament reconstruction patients from neuromechanical decoupling

The purpose of this study was to identify how the brain simultaneously perceives proprioceptive input during joint loading in anterior cruciate ligament reconstruction (ACLR) patients, when compared to healthy controls. Seventeen ACLR patients (ACLR) and seventeen controls (CONT) were tested for the somatosensory cortical activation using electroencephalography (EEG) while measuring knee laxity using a knee arthrometer. The relationship between cortical activation and joint laxity within group was also examined. The ACLR patients had increased cortical activation (36.4% ± 11.5%) in the somatosensory cortex during early loading (ERD1) to the injured limb compared to the CONT's matched limb (25.3% ± 13.2%, P = 0.013) as well as compared to the noninjured limb (25.1% ± 14.2%, P = 0.001). Higher somatosensory cortical activity during midloading (ERD2) to the ACLR knee positively correlated with knee laxity (mm) during early loading (LAX1, r = 0.530), midloading (LAX2, r = 0.506), total anterior loading (LAXA, r = 0.543), and total antero-posterior loading (LAXT, r = 0.501), while the noninjured limb revealed negative correlations between ERD1 and LAXA (r = -0.534) as well as between ERD2 and LAX2 (r = -0.565). ACLR patients demonstrate greater brain activation during joint loading in the injured knees when compared to healthy controls' matched knees as well as contralateral healthy knees, while the CONT group shows similar brain activation patterns during joint loading between limbs. These different neural activation strategies may indicate neuromechanical decoupling following an ACL reconstruction and evidence of altered sensorimotor perception and control of the knee (neuroplasticity), which may be critical to address after surgery for optimal neuromuscular control and patients' outcomes.

Neurophysiological correlates of motor planning and movement initiation in ACL-reconstructed individuals: a case-control study

INTRODUCTION

Current evidence suggests that the loss of mechanoreceptors after anterior cruciate ligament (ACL) tears might be compensated by increased cortical motor planning. This occupation of cerebral resources may limit the potential to quickly adapt movements to unforeseen external stimuli in the athletic environment. To date, studies investigating such neural alterations during movement focused on simple, anticipated tasks with low ecological validity. This trial, therefore, aims to investigate the cortical and biomechanical processes associated with more sport-related and injury-related movements in ACL-reconstructed individuals.

METHODS AND ANALYSIS

ACL-reconstructed participants and uninjured controls will perform repetitive countermovement jumps with single leg landings. Two different conditions are to be completed: anticipated (n=35) versus unanticipated (n=35) successful landings. Under the anticipated condition, participants receive the visual information depicting the requested landing leg prior to the jump. In the unanticipated condition, this information will be provided only about 400 msec prior to landing. Neural correlates of motor planning will be measured using electroencephalography. In detail, movement-related cortical potentials, frequency spectral power and functional connectivity will be assessed. Biomechanical landing quality will be captured via a capacitive force plate. Calculated parameters encompass time to stabilisation, vertical peak ground reaction force, and centre of pressure path length. Potential systematic differences between ACL-reconstructed individuals and controls will be identified in dependence of jumping condition (anticipated/ unanticipated, injured/uninjured leg and controls) by using interference statistics. Potential associations between the cortical and biomechanical measures will be calculated by means of correlation analysis. In case of statistical significance (α<0.05.) further confounders (cofactors) will be considered.

ETHICS AND DISSEMINATION

The independent Ethics Committee of the University of Frankfurt (Faculty of Psychology and Sports Sciences) approved the study. Publications in peer-reviewed journals are planned. The findings will be presented at scientific conferences.

TRIAL STATUS

At the time of submission of this manuscript, recruitment is ongoing.

TRIAL REGISTRATION NUMBER

NCT03336060; Pre-results.

Left Right Judgement Task and Sensory, Motor, and Cognitive Assessment in Participants with Wrist/Hand Pain

The Left Right Judgement Task (LRJT) involves determining if an image of the body part is of the left or right side. The LRJT has been utilized as part of rehabilitation treatment programs for persons with pain associated with musculoskeletal injuries and conditions. Although studies often attribute changes and improvement in LRJT performance to an altered body schema, imaging studies suggest that the LRJT implicates other cortical regions. We hypothesized that cognitive factors would be related to LRJT performance of hands and feet and that sensory, motor, and pain related factors would be related to LRJT in the affected hand of participants with wrist/hand pain. In an observational cross-sectional study, sixty-one participants with wrist/hand pain participated in a study assessing motor imagery ability, cognitive (Stroop test), sensory (Two-Point Orientation Discrimination, pressure pain thresholds), motor (grip strength, Purdue Pegboard Test), and pain related measures (West Haven Yale Multidimensional Pain Inventory) as well as disability (Disability of the Arm, Shoulder and Hand). Multiple linear regression found Stroop test time and motor imagery ability to be related to LRJT performance. Tactile acuity, motor performance, participation in general activities, and the taking of pain medications were predictors of LRJT accuracy in the affected hand. Participants who took pain medications performed poorly in both LRJT accuracy (p=0.001) and reaction time of the affected hand (p=0.009). These participants had poorer cognitive (p=0.013) and motor function (p=0.002), and higher pain severity scores (p=0.010). The results suggest that the LRJT is a complex mental task that involves cognitive, sensory, motor, and behavioural processes. Differences between persons with and without pain and improvement in LRJT performance may be attributed to any of these factors and should be considered in rehabilitation research and practice utilizing this task.

Cognitive Performance and Locomotor Adaptation in Persons With Anterior Cruciate Ligament Reconstruction

Background. Persons with anterior cruciate ligament reconstruction (ACLR) show deficits in gait and neuromuscular control following rehabilitation. This altered behavior extends to locomotor adaptation and learning, however the contributing factors to this observed behavior have yet to be investigated. Objective. The purpose of this study was to assess differences in locomotor adaptation and learning between ACLR and controls, and identify underlying contributors to motor adaptation in these individuals. Methods. Twenty ACLR individuals and 20 healthy controls (CON) agreed to participate in this study. Participants performed four cognitive and dexterity tasks (local version of Trail Making Test, reaction time test, electronic pursuit rotor test, and the Purdue pegboard). Three-dimensional kinematics were also collected while participants walked on a split-belt treadmill. Results. ACLR individuals completed the local versions of Trails A and Trails B significantly faster than CON. During split-belt walking, ACLR individuals demonstrated smaller step length asymmetry during EARLY and LATE adaptation, smaller double support asymmetry during MID adaptation, and larger stance time asymmetry during DE-ADAPT compared with CON. Conclusions. ACLR individuals performed better during tasks that required visual attention and task switching and were less perturbed during split-belt walking compared to controls. Persons with ACLR may use different strategies than controls, cognitive or otherwise, to adapt locomotor patterns.

Visual-Motor Control of Drop Landing After Anterior Cruciate Ligament Reconstruction

CONTEXT

  Visual feedback is crucial in the control of human movement. When vision is obstructed, alterations in landing neuromuscular control may increase movements that place individuals at risk for injury. Anterior cruciate ligament (ACL) injury may further alter the motor-control response to alterations in visual feedback. The development of stroboscopic glasses that disrupt visual feedback without fully obscuring it has enabled researchers to assess visual-motor control during movements that simulate the dynamic demands of athletic activity.

OBJECTIVE

  To investigate the effect of stroboscopic visual-feedback disruption (SVFD) on drop vertical-jump landing mechanics and to determine whether injury history influenced the effect.

DESIGN

  Cohort study.

SETTING

  Movement-analysis laboratory.

PATIENTS OR OTHER PARTICIPANTS

  A total of 15 participants with ACL reconstruction (ACLR; 7 men, 8 women; age = 21.41 ± 2.60 years, height = 1.72 ± 0.09 m, mass = 69.24 ± 15.24 kg, Tegner Activity Scale score = 7.30 ± 1.30, time since surgery = 36.18 ± 26.50 months, hamstrings grafts = 13, patellar tendon grafts = 2) and 15 matched healthy control participants (7 men, 8 women; age = 23.15 ± 3.48 years, height = 1.73 ± 0.09 m, mass = 69.98 ± 14.83 kg, Tegner Activity Scale score = 6.77 ± 1.48).

INTERVENTION(S)

  Drop vertical-jump landings under normal and SVFD conditions.

MAIN OUTCOME MEASURE(S)

  The SVFD effect for knee sagittal- and frontal-plane excursions, peak moments, and vertical ground reaction force were calculated during landing and compared with previously established measurement error and between groups.

RESULTS

  The SVFD altered knee sagittal-plane excursion (4.04° ± 2.20°, P = .048) and frontal-plane excursion (1.98° ± 1.53°, P = .001) during landing above within-session measurement error. Joint-moment difference scores from full vision to the SVFD condition were not greater than within-session error. We observed an effect of ACLR history only for knee flexion (ACLR group = 3.12° ± 3.76°, control group = -0.84° ± 4.45°; P = .001). We did not observe an effect of side or sex.

CONCLUSIONS

  The SVFD altered sagittal- and frontal-plane landing knee kinematics but did not alter moments. Anterior cruciate ligament reconstruction may induce alterations in sagittal-plane visual-motor control of the knee. The group SVFD effect was on a level similar to that of an in-flight perturbation, motor-learning intervention, or plyometric-training program, indicating that visual-motor ability may contribute to knee neuromuscular control on a clinically important level. The individual effects of the SVFD indicated possible unique sensorimotor versus visual-motor movement strategies during landing.

Altered lower extremity joint mechanics occur during the star excursion balance test and single leg hop after ACL-reconstruction in a collegiate athlete

The effects of ACL-reconstruction on lower extremity joint mechanics during performance of the Star Excursion Balance Test (SEBT) and Single Leg Hop (SLH) are limited. The purpose of this study was to determine if altered lower extremity mechanics occur during the SEBT and SLH after ACL-reconstruction. One female Division I collegiate athlete performed the SEBT and SLH tasks, bilaterally, both before ACL injury and 27 months after ACL-reconstruction. Maximal reach, hop distances, lower extremity joint kinematics and moments were compared between both time points. Musculoskeletal simulations were used to assess muscle force production during the SEBT and SLH at both time points. Compared to the pre-injury time point, SEBT reach distances were similar in both limbs after ACL-reconstruction except for the max anterior reach distance in the ipsilateral limb. The athlete demonstrated similar hop distances, bilaterally, after ACL-reconstruction compared to the pre-injury time point. Despite normal functional performance during the SEBT and SLH, the athlete exhibited altered lower extremity joint mechanics during both of these tasks. These results suggest that measuring the maximal reach and hop distances for these tasks, in combination with an analysis of the lower extremity joint mechanics that occur after ACL-reconstruction, may help clinicians and researchers to better understand the effects of ACL-reconstruction on the neuromuscular system during the SEBT and SLH.

Brain Activity Changes in Somatosensory and Emotion-Related Areas With Medial Patellofemoral Ligament Deficiency

BACKGROUND

Patellar instability with medial patellofemoral ligament (MPFL) deficiency is a common sports injury among young people. Although nonoperative and surgical treatment can provide stability of the patella, patients often have anxiety related to the knee. We speculate that neural dysfunction may be related to anxiety in these patients; however, the mechanism in the brain that generates this anxiety remains unknown.

QUESTIONS/PURPOSES

(1) How does brain activity in patients with MPFL deficiency change in the areas related to somatic sensation against lateral shift of the patella? (2) How does patella instability, which can lead to continuous fear or apprehension for dislocation, influence brain activity in the areas related to emotion?

METHODS

Nineteen patients with MPFL deficiency underwent surgical reconstruction in our hospital from April 2012 to March 2014. Excluding seven patients with osteochondral lesions, 12 patients (five males and seven females; mean age, 20 years) with MPFL deficiency were sequentially included in this study. Eleven control subjects (four males and seven females; mean age, 23 years) were recruited from medical students who had no history of knee injury. Diagnosis of the MPFL deficiency was made with MR images, which confirmed the rupture, and by proving the instability with a custom-made biomechanical device. Brain activity during passive lateral stress to the patella was assessed by functional MRI. Functional and anatomic images were analyzed using statistical parametric mapping. Differences in functional MRI outcome measures from the detected activated brain regions between the patients with MPFL deficiency and controls were assessed using t tests.

RESULTS

Intergroup analysis showed less activity in several sensorimotor cortical areas, including the contralateral primary somatosensory areas (% signal change for MPFL group 0.49% versus 1.1% for the control group; p < 0.001), thalamus (0.2% versus 0.41% for the MPFL versus control, respectively; p < 0.001), ipsilateral thalamus (0.02% versus 0.27% for the MPFL versus control, respectively; p < 0.001), and ipsilateral cerebellum (0.82% versus 1.25% for the MPFL versus control, respectively; p < 0.001) in the MPFL deficiency group than in the control group. In contrast, the MPFL deficiency group showed more activity in several areas, including the contralateral primary motor area (1.06% versus 0.6% for the MPFL versus control, respectively; p < 0.001), supplementary motor area (0.89% versus 0.52% for the MPFL versus control, respectively; p < 0.001), prefrontal cortex (1.09% versus 1.09% for the MPFL versus control, respectively; p < 0.001), inferior parietal lobule (0.89% versus 0.62% for the MPFL versus control, respectively; p < 0.001), anterior cingulate cortex (0.84% versus 0.08% for the MPFL versus control, respectively; p < 0.001), visual cortex (0.86% versus 0.14% for the MPFL versus control, respectively; p < 0.001), vermis (1.18% versus 0.37% for the MPFL versus control, respectively; p < 0.001), and ipsilateral prefrontal cortex (1.1% versus 0.75% for the MPFL versus control, respectively; p < 0.001) than did the control group.

CONCLUSIONS

Less activity in the contralateral somatosensory cortical areas suggested that MPFL deficiency may lead to diminished somatic sensation against lateral shift of the patella. In contrast, increased activity in the anterior cingulate cortex, prefrontal cortex, and inferior parietal lobule may indicate anxiety or fear resulting from patellar instability, which is recognized as an aversion similar to that toward chronic pain.

CLINICAL RELEVANCE

This study suggests that specific brain-area activity is increased in patients with MPFL deficiency relative to that in controls. Further longitudinal research to assess brain activity and proprioception between patients pre- and postreconstructive knee surgery may reveal more regarding how patella instability is related to brain function. We hope that based on such research, a neural approach to improve patella-instability-related brain function can be developed.

Performance: Bridging the Gap After ACL Surgery

PURPOSE OF REVIEW

The purpose of this paper is to identify strategies for a successful transition to sports in patients following rehabilitation for ACL reconstruction surgery (ACLR).

RECENT FINDINGS

Recent research continues to demonstrate a relatively low rate of return to previous level of play among athletes following ACLR combined with a significant risk of injury to either the ipsi or the contralateral ACL. Recent research also demonstrates a growing use of a varied battery of assessments to determine readiness to return to sport as well as a lack of consensus on the ideal rehabilitation program, the criteria for clearance for return to play (both in time from surgery and functional milestones), and the nature of a conditioning program designed specifically for transitioning the cleared athlete back to competition. Due to the lack of consensus and consistency regarding rehabilitation protocols and criteria for clearance to play after ACLR, deficits in strength, neuromuscular control, and psychological readiness may exist in "cleared" athletes. These deficits may not only negatively impact sports performance but also raise the risk of re-injury. Programs designed to successfully return an athlete to previous level of play should include not only strength and conditioning aimed at restoring fitness that was compromised as a result of the injury but also include attention to psychological readiness and address deficits in neuromuscular control. Problems that exist following ACLR cannot be solved by one professional; successful rehabilitation and return to play require a coordinated effort among the surgeon, physical therapist, athletic trainer, and fitness professional. Future research is needed to determine the optimal strategy to restore the neuromuscular control, functional strength, and psychological readiness necessary for a successful return to competition following ACLR.

Visual Utilization During Postural Control in Anterior Cruciate Ligament- Deficient and -Reconstructed Patients: Systematic Reviews and Meta-Analyses

OBJECTIVE

To determine whether anterior cruciate ligament-deficient (ACL-D) individuals and individuals with a reconstructed anterior cruciate ligament (ACL-R) rely more heavily on visual information to maintain postural control.

DATA SOURCES

PubMed, CINAHL, and SPORTDiscus databases were searched from their earliest available date to May 24, 2016, using a combination of keywords.

STUDY SELECTION

Articles were included if they reported any instrumented static single-leg balance outcome in both a patient and control sample. The means and SDs of these outcomes must have been reported with both eyes open and eyes closed.

DATA EXTRACTION

Sample sizes, means, and SDs of single-leg balance measures for each group's eyes open and eyes closed testing conditions were extracted. The methodological quality of included studies was independently evaluated by multiple authors using an adapted version of the Quality Index.

DATA SYNTHESIS

Effect sizes were calculated by dividing the differences in change between eyes closed and eyes open in the ACL-D and control group and the ACL-R and control group by the pooled SD from the eyes closed trials for each analysis. Significant differences between the ACL-D and control group (effect size, -1.66; 95% confidence interval [CI], -2.90 to -.41) were noted. The ACL-R and control group were not different (effect size, -.61; 95% CI, -2.17 to .95).

CONCLUSIONS

ACL-D individuals but not individuals with ACL-R demonstrate a greater reliance on visual information during single-leg stance compared with healthy individuals.

Permanent knee sensorimotor system changes following ACL injury and surgery

The cruciate ligaments are components of the knee capsuloligamentous system providing vital neurosensory and biomechanical function. Since most historical primary ACL repair attempts were unsuccessful, reconstruction has become the preferred surgery. However, an increased understanding of the efficacy of lesion-site scaffolding, innovative suturing methods and materials, and evolving use of biological healing mediators such as platelet-rich plasma and stem cells has prompted reconsideration of what was once believed to be impossible. A growing number of in vivo animal studies and prospective clinical studies are providing increasing support for this intervention. The significance of ACL repair rather than reconstruction is that it more likely preserves the native neurosensory system, entheses, and ACL footprints. Tissue preservation combined with restored biomechanical function increases the likelihood for premorbid neuromuscular control system and dynamic knee stability recovery. This recovery should increase the potential for more patients to safely return to sports at their desired intensity and frequency. This current concepts paper revisits cruciate ligament neurosensory and neurovascular anatomy from the perspective of knee capsuloligamentous system function. Peripheral and central nerve pathways and central cortical representation mapping are also discussed. Surgical restoration of a more physiologically sound knee joint may be essential to solving the osteoarthritis dilemma. Innovative rehabilitative strategies and outcome measurement methodologies using more holistic and clinically relevant measurements that closely link biomechanical and neurosensory characteristics of physiological ACL function are discussed. Greater consideration of task-specific patient physical function and psychobehavioral links should better delineate the true efficacy of all ACL surgical and non-surgical interventions. Level of evidence IV.

Anterior cruciate ligament reconstruction does not induce further gamma loop abnormalities on the intact side of the quadriceps femoris: A longitudinal study

This study aimed to investigate the effect of surgery on the gamma loop of the quadriceps on the side with an intact knee in patients with anterior cruciate ligament (ACL) injuries. We compared longitudinally the response of alpha motor neurons to vibration stimulation of the quadriceps on the side with an intact knee before and after ACL reconstruction. To evaluate alpha motor neuron response, we measured the maximal knee extension strength and integrated electromyography of the vastus medialis, vastus lateralis, and rectus femoris. After obtaining pre-vibration data from each subject, vibration stimulation was applied to the infrapatellar tendon, and the same measurements were performed immediately after stimulation. The results of this study showed that the response to prolonged vibration stimulation on the intact side of the quadriceps did not differ pre- and post-surgery. As vibration stimuli normally elicit a decrease in alpha motor neuron activity in normal individuals, abnormal responses to prolonged vibration stimulation of the quadriceps on the side with an intact knee might be observed in patients with ACL injuries. The abnormality of the gamma loop of the quadriceps on the side with an intact knee was probably induced by the rupture. Based on these results, we conclude that surgery does not induce further gamma loop abnormalities on the intact side of the quadriceps.

Improving ACL Reconstruction Outcomes

Anterior cruciate ligament (ACL) reconstruction is a common and predominantly successful surgical intervention. But are there specific preoperative patient characteristics or intraoperative surgeon decisions that lead to better or worse outcomes? And can understanding brain function changes of patients after ACL reconstruction reveal insights into the ways that postsurgical rehabilitation can be improved to further enhance outcomes? These intriguing and clinically applicable questions are addressed in this webinar titled "Improving ACL Reconstruction Outcomes," hosted jointly by JOSPT and JBJS. The webinar is based on 2 published research articles-one from JBJS and the other from JOSPT. Participants in this continuing education activity are asked to read both articles carefully before watching the webinar. JBJS co-author Kurt Spindler, MD, discusses findings from a longitudinal analysis that identified certain baseline patient characteristics and intraoperative choices that predicted higher and lower SF-36 Physical Component scores after ACL reconstruction. JOSPT co-author Dustin Grooms, PhD, ATC, shares recently published results of a controlled laboratory study that employed functional MRI to investigate brain-activation differences between patients who did and did not undergo ACL reconstruction. Moderated by Kevin Wilk, PT, DPT, FAPTA, a leading authority on rehabilitation of sports injuries, the webinar includes additional insights from expert commentators Eric McCarty, MD, and Karin Grävare Silbernagel, PT, PhD, ATC.

Neuroplasticity Associated With Anterior Cruciate Ligament Reconstruction

Study Design Controlled laboratory study. Background Anterior cruciate ligament (ACL) injury may result in neuroplastic changes due to lost mechanoreceptors of the ACL and compensations in neuromuscular control. These alterations are not completely understood. Assessing brain function after ACL injury and anterior cruciate ligament reconstruction (ACLR) with functional magnetic resonance imaging provides a means to address this gap in knowledge. Objective To compare differences in brain activation during knee flexion/extension in persons who have undergone ACLR and in matched controls. Methods Fifteen participants who had undergone left ACLR (38.13 ± 27.16 months postsurgery) and 15 healthy controls matched on age, sex, height, mass, extremity dominance, education level, sport participation, and physical activity level participated. Functional magnetic resonance imaging data were obtained during a unilateral knee motor task consisting of repeated cycles of knee flexion and extension. Results Participants who had undergone ACLR had increased activation in the contralateral motor cortex, lingual gyrus, and ipsilateral secondary somatosensory area and diminished activation in the ipsilateral motor cortex and cerebellum when compared to healthy matched controls. Conclusion Brain activation for knee flexion/extension motion may be altered following ACLR. The ACLR brain activation profile may indicate a shift toward a visual-motor strategy as opposed to a sensory-motor strategy to engage in knee movement. Level of Evidence Cohort, level 3. J Orthop Sports Phys Ther 2017;47(3):180-189. Epub 5 Nov 2016. doi:10.2519/jospt.2017.7003.