Quantifying Brain White Matter Microstructure of People with Lateral Ankle Sprain

Corticospinal tract alterations after ankle sprain in adolescence: Insights from the mouse model

Purpose

Lateral ankle sprains (LAS) are associated with corticospinal pathway deficits. Existing evidence is primarily based on cross-sectional investigations and noncausal speculations. This study aims to determine whether maladaptive corticospinal pathway alterations occur pre- and postligament transection in LAS mouse models. Additionally, this study explores whether the alterations are more pronounced in adolescent mice than adults.

Methods

Twenty-four 8-week-old adolescent and twenty-four 24-week-old adult mice were randomly assigned to lateral ankle ligament transection or sham surgery. Diffusion-weighted imaging of the corticospinal pathway was performed presurgery and 8 weeks postsurgery. Fractional anisotropy (FA) values, reflecting fiber integrity within the corticospinal subregions of the medulla, pons, midbrain, and cerebrum, were extracted.

Results

Overall, 41 mice completed repeated image acquisition. Before surgery, no significant group effects on FA within the four corticospinal subregions were detected in either adolescent or adult mice. Two months after surgery, the adolescent cohort displayed a significant reduction in FA in the medulla subregion following ankle ligament transection (β-baseline-adjusted ​= ​-0.083, 95% CI , -0.145 to -0.021, p-corrected ​= ​0.048). Conversely, no significant effects of ankle ligament transection on corticospinal FA were observed in the adult cohort.

Conclusion

The maladaptive alterations in the corticospinal tract could be observed in the adolescent LAS mouse model, characterized by reduced fiber integrity in the medulla subregion. While these results are derived from an animal model, they provide a foundation for future investigations into the mechanisms underlying neurological deficits following musculoskeletal injuries.

Future risk of falls induced by ankle-foot sprains history: An observational and mendelian randomization study

Background

Ankle-foot sprains are the most common musculoskeletal injuries, which can impair balance and theoretically increase the risk of falls, but still, there is a lack of evidence supporting the direct association between ankle-foot sprains and the future risk of falls.

Methods

UK Biobank cohort was utilized to measure the association between ankle-foot sprains and fall risk with covariates adjusted. Then, the two-sample Mendelian randomization (MR) analysis was applied based on the genetically predicated ankle-foot sprains from FinnGen to validate causal relationship. Finally, genetically predicated cerebellar neuroimaging features were used to explore the mediating role of maladaptive neuroplasticity between ankle-foot sprains and falls by two-step MR analyses.

Results

Patients with ankle-foot sprains history exhibited a slightly increased risk of falls than the matched controls before and after adjustment for covariates (odd ratio [OR] ranged from 1.632 to 1.658). Two-sample MR analysis showed that ankle-foot sprains led to a higher risk of falls (OR ​= ​1.036) and a lower fractional anisotropy of superior cerebellar peduncle (SCP) (left, β ​= ​-0.052; right, β ​= ​-0.053). A trend of mediating effect was observed for the fractional anisotropy of right SCP in the causal effects of ankle-foot sprains on falls (β ​= ​0.003).

Conclusion

The history of ankle-foot sprains is associated with a slightly increased risk of falls. These findings improve our understanding of the clinical consequences of ankle-foot sprains in terms of fall risk and suggest the importance of adopting more efficient strategies for managing residual functional deficits after the injuries.

Clinical Features Post-Anterior Cruciate Ligament Reconstruction Associated With Structural Alterations in the Corticospinal Tract

CONTEXT

Structural evidence for corticospinal tract (CST) abnormality in patients with anterior cruciate ligament reconstruction (ACLR) compared with healthy controls and the relationships between CST structure and clinical features of the patients (eg, objective sensorimotor outcomes and postoperative duration) are lacking.

OBJECTIVE

To investigate whether the structural features of the CST differ between patients with ACLR and healthy controls and are associated with clinical features in patients after ACLR.

DESIGN

Cross-sectional study.

SETTING

Sports medicine laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 26 patients who had undergone ACLR (age = 36.35 ± 6.39 years, height = 173.88 ± 5.97 cm, mass = 74.80 ± 10.61 kg) and 26 healthy controls (age = 32.85 ± 9.20 years, height = 173.35 ± 7.19 cm, mass = 72.88 ± 11.06 kg) participated.

MAIN OUTCOME MEASURE(S)

Using the CST as the region of interest, we performed diffusion tensor imaging to measure the microstructure of white matter tracts. Between-groups comparisons and correlation analyses with clinical features in patients with ACLR were performed.

RESULTS

Patients with ACLR had moderately lower fractional anisotropy (Cohen d = -0.666; 95% CI = -1.221, -0.104; P = .01), lower axial diffusivity (Cohen d = -0.526; 95% CI = -1.077, 0.030; P = .03), higher radial diffusivity (RD; Cohen d = 0.514; 95% CI = -0.042, 1.064; P = .04), and smaller Y-Balance Test anterior-reach distance (Cohen d = -0.743; 95% CI = -1.302, -0.177; P = .005) compared with healthy controls. The RD values were correlated with the postoperative duration (r = 0.623, P < .001) after controlling for age, sex, and body mass index in patients with ACLR.

CONCLUSIONS

Patients with ACLR had impaired integrity (lower fractional anisotropy values and higher RD values) in the CST contralateral to the ACLR injured limb in comparison with healthy controls. Decreased integrity (higher RD) of the CST in patients was associated with longer postoperative duration, which hinted that impaired structural integrity of the CST may be a maladaptive process of neuroplasticity in ACLR.

Corticospinal and intracortical excitability in individuals with anterior cruciate ligament injury and ligament reconstruction: a meta-analysis

BACKGROUND

Primary motor cortex (M1) organization and quadriceps femoris excitability may change after anterior cruciate ligament injury (ACLi) and anterior cruciate ligament reconstruction (ACLr), as demonstrated by transcranial magnetic stimulation (TMS) studies.

OBJECTIVE

To systematically review studies evaluating changes in quadriceps femoris corticospinal and intracortical excitability in subjects with ACLi and ACLr.

METHODS

Database searches were conducted in PubMed, Embase, Scopus, and ScienceDirect, with the last search performed on November 23, 2023. Newcastle-Ottawa Scale and a specific checklist for evaluating descriptions in studies using TMS assessment were used. Continuous variables were expressed as mean and standard deviation and represented by the estimated difference from the mean and 95% confidence interval (CI). Heterogeneity was assessed by Chi2 and I2 and the level of statistical significance was 5%.

RESULTS

Fourteen studies, comprising 381 individuals, using TMS were identified. Meta-analysis results showed significantly higher motor threshold (MT) in ACLi/ACLr individuals compared to healthy controls (p < .01, mean difference 6.72). Additionally, MTs were significantly higher on the uninjured side compared to healthy controls (p < .0001, mean difference 3.82). Motor-evoked potentials (MEP) amplitude was significantly higher on the uninjured side compared to the injured side (p < .00001, mean difference 0.01). Short-interval intracortical inhibition (SICI) amplitude was significantly lesser on the injured limb compared to the uninjured side (p < .00001, mean difference 0.50).

CONCLUSION

Quadriceps MT and SICI are altered in ACLi and ACLr populations, and minor alterations were identified in MEP, demonstrating brain changes related to anterior cruciate ligament injury and/or reconstruction.

Revealing the Progression of Pain Pathways and Identifying Chronification of Pain Predictors After an Isolated Lateral Ankle Sprain: Project RECOIL

Persistent pain is a common complaint among civilians and military personnel after a lateral ankle sprain (LAS). Most individuals who experience pain after an LAS self-report a moderate pain intensity level that interferes with activity. This pain experience is mostly described through study designs and outcomes that limit the understanding of the acute to chronic pain transition after an LAS. The purpose of this prospective study is to quantify the prevalence rate of chronic ankle pain at 6-months post-injury and identify susceptibility and resiliency factors that contribute to pain chronification after an LAS. The objective of this study will be accomplished through a two-site prospective cohort study design with data collected at four timepoints (<7 days post-LAS, 3-, 6-, and 12-months post-LAS). A target sample size of 200 men or women (100 per site) between 18 and 45 years of age who sustain an acute LAS within the previous 7-days will be enrolled. Participants will complete a series of standardized electronic surveys at each timepoint to self-report the presence of chronic ankle pain, healthcare utilization patterns, subsequent musculoskeletal injury, and new co-morbid conditions. Additionally, participants will complete validated patient-reported outcomes (PROs) electronically to characterize the pain burden and undergo quantitative sensory testing to assess mechanical pain sensitivity via pressure pain thresholds, pain facilitation via temporal summation, and pain inhibition via a conditioned pain modulation response at all timepoints. Lastly, clinician-based outcomes will be completed at 3-, 6-, and 12-months post-LAS to examine dynamic postural control, functional performance, and walking mechanics. We hypothesize that 30% of participants will self-report chronic ankle pain at 6-months post-injury. In addition, chronic pain at 6-months will be predicted by a combination of healthcare utilization patterns, prolonged levels of peripheral sensitization and pain facilitation, and worse functional performance and PROs.

Effects of kinesio taping on lower limb biomechanical characteristics during dynamic postural control tasks in individuals with chronic ankle instability

PURPOSE

Previous studies have demonstrated significant biomechanical differences between individuals with chronic ankle instability (CAI) and healthy controls during the Y-balance test. This study aimed to examine the effects of kinesio taping (KT) on lower limb biomechanical characteristics during the Y-balance anterior reach task in individuals with CAI.

METHODS

A total of 30 participants were recruited, comprising 15 individuals with CAI and 15 healthy controls. All participants were randomly assigned three taping conditions: no taping (NT), placebo taping (PT), and KT, followed by the Y-balance anterior reach task. Each condition was separated by one-week intervals. Kinematic and kinetic data of the lower limbs during the movement phase were collected using the Vicon motion capture system (Vicon, T40, 200 Hz) and two Kistler force platforms (Kistler, 1000 Hz).

RESULTS

KT significantly improved the Y-balance anterior reach distance (P = 0.003) and peak ankle eversion angle (P = 0.019) compared to NT. Additionally, KT resulted in increased peak knee flexion angle (P = 0.002, P = 0.011) and peak ankle dorsiflexion angle (P <0.001, P = 0.005) relative to both NT and PT. KT also significantly reduced mediolateral center of pressure (COP) displacement (P = 0.001) and average velocity of mediolateral COP displacement (P = 0.033) in comparison to NT. Furthermore, KT decreased mediolateral center of gravity displacement (P = 0.002, P = 0.003) relative to both NT and PT.

CONCLUSION

KT significantly improved abnormal ankle posture by promoting greater ankle dorsiflexion and eversion angles. Additionally, KT reduced mediolateral COP displacement and average velocity to improve postural stability. These changes may contribute to reduced risk of ankle sprains. Therefore, KT may serve as an effective tool for managing recurrent ankle sprains in individuals with CAI.

Neural structural alterations correlates of quadriceps muscle strength deficits in patients after anterior cruciate ligament reconstruction

Background

Persistent maladaptive changes of corticospinal tract (CST) and quadriceps strength deficits exist in patients with anterior cruciate ligament reconstruction (ACLR). This study aimed to investigate the relationships between the structural alterations of CST and quadriceps muscle strength deficits in patients with ACLR.

Methods

Twenty-nine participants who had undergone unilateral ACLR (29 males; age = 32.61 ± 6.72 years) were enrolled in a cross-sectional investigation. We chose CST as a region of interest and performed diffusion tensor imaging (DTI) that measured the microstructure of white matter tracts. Maximal voluntary isometric quadriceps muscle strength was assessed using a hand-held dynamometer. Simple and partial correlation analyses were performed between the DTI outcomes and quadriceps muscle strength deficits in patients with ACLR before and after controlling for age, sex, BMI, Tegner activity score, and graft type. Sub-group analyses were also performed to investigate the relationships between the DTI outcomes of CST structure and quadriceps muscle strength deficits according to the graft type before and after controlling for age, sex, BMI, and Tegner activity score.

Results

Lower limb symmetry index (LSI) of quadriceps muscle strength was associated with a higher ratio of radial diffusivity (RD, r = -0.379, p = 0.042) in corticospinal tracts of the injured hemisphere to those of the non-injured hemisphere in ACLR patients after controlling for age, BMI, Tegner activity score and graft type. In subgroup analyses of ACLR patients with hamstring autografts, we found that higher injured quadriceps muscle strength was associated with higher axial diffusivity (AD, r = 0.616, p = 0.033) of CST structure and lower LSI of quadriceps muscle strength was associated with higher ratio of mean diffusivity (MD, r = -0.682, p = 0.014) and RD (r = -0.759, p = 0.004) in corticospinal tracts of the injured hemisphere to those of the non-injured hemisphere in ACLR patients after controlling for age, BMI, Tegner activity score.

Conclusion

Decreased integrity (higher ratio of RD) of CST microstructure in ACLR patients was significantly associated with lower quadriceps limb symmetry index, which hinted that quadriceps muscle strength deficits of injured side may be a demyelinating process of CST microstructure in ACLR.

Is chronic pain caused by central sensitization? A review and critical point of view

Chronic pain causes disability and loss of health worldwide. Yet, a mechanistic explanation for it is still missing. Frequently, neural phenomena, and among them, Central Sensitization (CS), is presented as causing chronic pain. This narrative review explores the evidence substantiating the relationship between CS and chronic pain: four expert researchers were divided in two independent teams that reviewed the available evidence. Three criteria were established for a study to demonstrate a causal relationship: (1) confirm presence of CS, (2) study chronic pain, and (3) test sufficiency or necessity of CS over chronic pain symptoms. No study met those criteria, failing to demonstrate that CS can cause chronic pain. Also, no evidence reporting the occurrence of CS in humans was found. Worryingly, pain assessments are often confounded with CS measures in the literature, omitting that the latter is a neurophysiological and not a perceptual phenomenon. Future research should avoid this misconception to directly interrogate what is the causal contribution of CS to chronic pain to better comprehend this problematic condition.

Knee joint pathology and efferent pathway dysfunction: Mapping muscle inhibition from motor cortex to muscle force

BACKGROUND

Dysfunction in efferent pathways after knee pathology is tied to long-term impairments in quadriceps and hamstrings muscle performance, daily function, and health-related quality of life. Understanding the underlying etiology is crucial for effective treatment and prevention of poor outcomes, such as post-traumatic osteoarthritis or joint replacement.

OBJECTIVES

To synthesize recent evidence of efferent pathway dysfunction (i.e., motor cortex, motor units) among individuals with knee pathology.

DESIGN

Commentary.

METHOD

We summarize the current literature investigating the motor cortex, corticospinal tract, and motoneuron pool in individuals with three common knee pathologies: anterior cruciate ligament (ACL) injury, anterior knee pain (AKP), and knee osteoarthritis (OA). To offer a complete perspective, we draw from studies applying a range of neuroimaging and neurophysiologic techniques.

RESULTS

Adaptations within the motor cortices, corticospinal tract, and motoneuron pool are present in those with knee pathology and underline impairments in quadriceps and hamstrings muscle function. Each pathology has evidence of altered motor system excitability and reduced volitional muscle activation and force-generating capacity, but few impairments were common across ACL injury, AKP, and OA studies. These findings underscore the central role of the motor cortex and motor unit behavior in the long-term outcomes of individuals with knee pathology.

CONCLUSIONS

Adaptations in the efferent pathways underlie persistent muscle dysfunction across three common knee pathologies. This review provides an overview of these changes and summarizes key findings from neurophysiology and neuroimaging studies, offering direction for future research and clinical application in the rehabilitation of joint injuries.

Thin and Plain Supplementary Motor Area in Chronic Ankle Instability: A Volume- and Surface-Based Morphometric Study

CONTEXT

The supplementary motor area (SMA) is involved in the functional deficits of chronic ankle instability (CAI), but the structural basis of its abnormalities remains unclear.

OBJECTIVES

To determine the differences in volume- and surface-based morphologic features of the SMA between patients with CAI and healthy controls and the relationship between these features and the clinical features of CAI.

DESIGN

Cross-sectional study.

SETTING

Sports medicine laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 32 patients with CAI (10 women, 22 men; age = 32.46 ± 7.51 years) and 31 healthy controls (12 women, 19 men; age = 29.70 ± 8.07 years) participated.

MAIN OUTCOME MEASURE(S)

We performed T1-weighted structural magnetic resonance imaging of participants and calculated volume- and surface-based morphologic features of SMA subregions. These subregions included anterior and posterior subdivisions of the medial portion of Brodmann area 6 (6 ma and 6 mp, respectively) and supplementary and cingulate eye fields. Between-group comparisons and correlation analysis with clinical features of CAI were performed.

RESULTS

Moderately thinner 6 mp (motor-output site; Cohen d = -0.61; 95% CI = -1.11, -0.10; P = .02) and moderately plainer 6 ma (motor-planning site; Cohen d = -0.70; 95% CI = -1.20, -0.19; P = .01) were observed in the CAI than the control group. A thinner 6 mp was correlated with lower Foot and Ankle Ability Measure Activities of Daily Living subscale scores before (r = 0.400, P = .02) and after (r = 0.449, P = .01) controlling for covariates.

CONCLUSIONS

Patients with CAI had a thinner 6 mp and a plainer 6 ma in the SMA compared with controls. The thin motor-output site of the SMA was associated with ankle dysfunction in patients. This morphologic evidence of maladaptive neuroplasticity in the SMA might promote more targeted rehabilitation of CAI.

Differences in Cortical Activation During Dorsiflexion and Plantarflexion in Chronic Ankle Instability: A Task-fMRI Study

BACKGROUND

Chronic ankle instability is a common sports injury that often presents with increased plantarflexion and restricted dorsiflexion. The cumulative effect of peripheral injuries may induce neuroplasticity in the central nervous system. However, the relationship between dorsiflexion or plantarflexion and the central nervous system in patients with chronic ankle instability remains unknown.

QUESTIONS/PURPOSES

(1) Is there a difference in region and voxel (volume pixel) of cortical activation during plantarflexion and dorsiflexion between patients with chronic ankle instability and a control group with normal ankle function? (2) Is there a correlation between activation of sensorimotor-related brain regions and three clinical measurement scales of ankle function and disease severity in patients with chronic ankle instability?

METHODS

Between December 2020 and May 2022, we treated 400 patients who had chronic ankle instability. Ten percent (40 patients; mean ± standard deviation age 29 ± 7 years; 17 male patients) were randomly selected to participate in this study. We recruited 42 volunteers with normal ankle function (mean age 28 ± 5 years; 21 male participants) matched by age and education level. A total of 2.5% (1 of 40) of patients with bilateral chronic ankle instability and 30% (12 of 40) with left-sided chronic ankle injury did not meet our inclusion criteria and were excluded from the study. The control group underwent MRI with good image quality. Finally, 27 patients with chronic ankle instability (mean age 26 ± 5 years; 10 male patients) and 42 participants with normal ankle function were enrolled. Ankle function and disease severity were assessed using three clinical scales: the Cumberland Ankle Instability Tool, Karlsson-Peterson Ankle Function Score, and the American Orthopedic Foot and Ankle Society Score. A uniplanar and nonweightbearing ankle dorsiflexion-plantarflexion paradigm (a recognized model or pattern) was performed using a short-block design during the functional MRI scan. This experimental design included a series of on-off periods consisting of movement and a rest period. From 15° of plantarflexion to 15° of dorsiflexion, the manipulator allowed 30° of ankle rotation. The cerebral excitability patterns between patients with chronic ankle instability and controls were analyzed using t-tests. We retained voxels with p values less than 0.05 in a voxel-level family-wise error correction. Clusters with voxel numbers greater than 10 were retained. The Cohen d coefficient was used to calculate between-group effect sizes. Spearman analysis was performed to explore the correlation between activation regions and the three clinical assessment scales.

RESULTS

In the patient group, cortical activation was greater during plantarflexion than during dorsiflexion, which was different from that in the control group. The between-group comparison showed that patients with chronic ankle instability had reduced activation in the ipsilateral precuneus (cluster size = 35 voxels [95% CI -0.23 to 0.07]; p < 0.001) during dorsiflexion, whereas during plantarflexion, chronic ankle instability caused increased activation in the ipsilateral superior temporal gyrus (cluster size = 90 voxels [95% CI -0.73 to -0.13]; p < 0.001), precuneus (cluster size = 18 voxels [95% CI -0.56 to -0.19]; p < 0.001), supplementary motor area (cluster size = 57 voxels [95% CI -0.31 to 0.00]; p < 0.001), superior frontal gyrus (cluster size = 43 voxels [95% CI -0.82 to -0.29]; p < 0.001), medial part of the superior frontal gyrus (cluster size = 39 voxels [95% CI 0.41 to 0.78]; p < 0.001), and contralateral postcentral gyrus (cluster size = 100 voxels [95% CI -0.32 to 0.02]; p < 0.001). Patients with chronic ankle instability showed a large effect size compared with controls (Cohen d > 0.8). During plantarflexion, the number of activated voxels in the supplementary motor area had a modest, positive correlation with the Karlsson-Peterson Ankle Function Score (r = 0.52; p = 0.01), and the number of activated voxels in the primary motor cortex (M1) and primary sensory cortex (S1) had a weak, positive correlation with the American Orthopedic Foot and Ankle Society Score in patients with chronic ankle instability (M1: r = 0.45; p = 0.02, S1: r = 0.49; p = 0.01).

CONCLUSION

Compared with volunteers with normal ankle function, patients with chronic ankle instability had increased cortical activation during plantarflexion and decreased cortical activation during dorsiflexion. We analyzed the central neural mechanisms of chronic ankle instability in patients with sports injuries and provided a theoretical basis for the development of new central and peripheral interventions in the future.

CLINICAL RELEVANCE

Because there was a positive correlation between the neural activity in sensorimotor-related regions during plantarflexion and clinical severity, clinicians might one day be able to help patients who have chronic ankle instability with neuromuscular rehabilitation by applying electrical stimulation to specific targets (such as S1M1 and the supplementary motor area) or by increasing activation of sensorimotor neurons through ankle movement.

Contralateral thalamocortical connectivity is related to postural control in the uninvolved limb of older adults with history of ankle sprain

BACKGROUND

Sensorimotor brain connectivity is often overlooked when determining relationships between postural control and motor performance following musculoskeletal injury. Thalamocortical brain connectivity is of particular interest as it represents the temporal synchrony of functionally and anatomically linked brain regions. Importantly, adults over the age of 60 are especially vulnerable to musculoskeletal injury due to age-related declines in postural control and brain connectivity.

RESEARCH QUESTION

Is there a relationship between thalamocortical connectivity and static postural control in older adults with a history of LAS?

METHODS

Data were analyzed from twenty older adults (mean age = 67.0 ± 4.3 yrs; 13 females) with a history of LAS. The sensorimotor network (SMN) was identified from resting-state MRI data, and a priori thalamic and postcentral gyri regions of interest were selected in order to determine left and right hemisphere thalamocortical connectivity. Balance was assessed for the involved and non-involved limbs via center of pressure velocity (COPV) in the medial-lateral (ML) and anterior-posterior (AP) directions.

RESULTS

Contralateral thalamocortical connectivity was significantly associated with COPV_ML COPV_ML (r = -0.474, P = 0.05) and COPV_AP (r = -0.622, P = 0.008) in the non-involved limb. No significant association was observed between involved limb balance and contralateral thalamocortical connectivity (COPV_ML: r = -0.08, P = 0.77; COPV_AP: r = 0.12, P = 0.63).

SIGNIFICANCE

A significant relationship between thalamocortical connectivity and static postural control was observed in the non-involved, but not the involved limb in older adults with a history of LAS. Findings suggest that thalamocortical connectivity may lead to or be the product of LAS.

Postural Control Deficits During Static Single-leg Stance in Chronic Ankle Instability: A Systematic Review and Meta-Analysis

CONTEXT

Postural control deficits arising from injured ankles are central to chronic ankle instability (CAI) and its persistent symptoms. This is usually measured by recording the center of pressure (CoP) trajectory during static single-leg stance using a stable force plate. However, existing studies have produced conflicting results on whether this mode of measurement adequately reveals the postural deficits in CAI.

OBJECTIVE

To determine whether postural control during static single-leg stance is impaired in CAI patients when compared with uninjured healthy controls.

DATA SOURCES

Literature databases, PubMed, Embase, Web of Science, Cochrane Library, Scopus, CINAHL, and SPORTDiscus, were searched from inception to April 1, 2022, using ankle-, injury-, and posture-related terms.

STUDY SELECTION

Two authors independently performed the step-by-step screening of article titles, abstracts, and full texts to select peer-reviewed studies investigating CoP trajectory during static single-leg stance using a stable force plate in CAI patients and healthy controls. A total of 13,637 studies were reviewed, and 38 studies (0.003%) met the selection criteria.

STUDY DESIGN

Meta-analyses of descriptive epidemiological study.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

CoP parameters, sway directions, visual condition, and numerical data (means and standard deviations) were extracted.

RESULTS

The injured ankles of CAI patients had higher standard deviations of sway amplitude in both anterior-posterior and medial-lateral directions (standardized mean difference [SMD] = 0.36 and 0.31, respectively) under conditions of open eyes than controls. Higher mean sway velocity in anterior-posterior, medial-lateral, and total directions (SMD = 0.41, 0.37, and 0.45, respectively) with closed eyes was also found.

CONCLUSION

CAI patients had deficits of postural control during static single-leg stance, and these deficits were identified by the CoP trajectory. Further methodological explorations of CoP parameters and corresponding test conditions are required to enhance the sensitivity and reliability of postural deficit assessments in CAI using force plates.

Association of Diaphragm Contractility and Postural Control in a Chronic Ankle Instability Population: A Preliminary Study

BACKGROUND

Altered reorganization of the sensorimotor system after an initial lateral ankle sprain may lead to a chronic neuromuscular maladaptation in multiple body locations. Specifically, decreased diaphragm contractility has been observed in patients with chronic ankle instability (CAI). The diaphragm has an essential role in postural control. Decreased diaphragm contractility could associate with diminished postural control commonly observed in patients with CAI. However, no study has determined if diaphragm contractility contributes to postural control in a CAI population.

HYPOTHESIS

Decreased diaphragm contractility would be negatively associated with static postural control in patients with CAI.

STUDY DESIGN

Cross-sectional study design.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 15 participants with CAI participated voluntarily. An ultrasonography assessment was performed to quantify the right and left hemidiaphragm thickness at the end of resting inspiration and expiration in supine while breathing quietly. The degree of diaphragm contractility was calculated from the diaphragm thickness. Participants performed 3 eyes-open trials of a 20-second single-leg balance task on the involved limb. Static postural control measures included the center of pressure velocity (COPV) and mean of time-to-boundary (TTB) minima in the anteroposterior (AP) and mediolateral directions.

RESULTS

Moderate correlations of the right hemidiaphragm contractility were observed with COPV (ρ = -0.54) and TTB mean minima (ρ = 0.56) (P < 0.05) in the AP direction. The left hemidiaphragm contractility was moderately correlated with COPV (ρ = -0.56) and TTB mean minima (ρ = 0.60) (P < 0.05) in the AP direction.

CONCLUSION

Lower diaphragm contractility may be associated with diminished static postural control in the AP direction in patients with CAI.

CLINICAL RELEVANCE

This study highlights diaphragm contractility could be a potential connection with diminished static postural control in patients with CAI. Our data raise new avenues for future exploration including potential beneficial effects of implementation of diaphragm breathing exercises and techniques for restoring static postural control in patients with CAI.

What interventions can treat arthrogenic muscle inhibition in patients with chronic ankle instability? A systematic review with meta-analysis

PURPOSE

To identify, critically appraise, and synthesize the existing evidence regarding the effects of therapeutic interventions on arthrogenic muscle inhibition (AMI) in patients with chronic ankle instability (CAI).

MATERIALS AND METHODS

Two reviewers independently performed exhaustive database searches in Web of Science, PubMed, Medline, CINAHL, and SPORTDiscus.

RESULTS

Nine studies were finally included. Five types of disinhibitory interventions were identified: focal ankle joint cooling (FAJC), manual therapy, fibular reposition taping (FRT), whole-body vibration (WBV), and transcranial direct current stimulation (tDCS). There were moderate effects of FAJC on spinal excitability in ankle muscles (g = 0.55, 95% CI = 0.03-1.08, p = 0.040 for the soleus and g = 0.54, 95% CI = 0.01-1.07, p = 0.046 for the fibularis longus). In contrast, manual therapy, FRT, WBV were not effective. Finally, 4 weeks of tDCS combined with eccentric exercise showed large effects on corticospinal excitability in 2 weeks after the intervention (g = 0.99, 95% CI = 0.14-1.85 for the fibularis longus and g = 1.02, 95% CI = 0.16-1.87 for the tibialis anterior).

CONCLUSIONS

FAJC and tDCS may be effective in counteracting AMI. However, the current evidence of mainly short-term studies to support the use of disinhibitory interventions is too limited to draw definitive conclusions.

In Vivo Characterization of Cerebellar Peduncles in Chronic Ankle Instability: A Single and Multishell Diffusion-Weighted Imaging Study

BACKGROUND

Ankle sprain causes proprioceptor injuries and prolonged joint deafferentation, which might lead to maladaptive neuroplasticity in patients with chronic ankle instability (CAI), especially in the cerebellum. Previous studies have indicated the impairment of superior cerebellar peduncle (SCP), but the inferior cerebellar peduncle (ICP) and middle cerebellar peduncle (MCP) have not been fully analyzed.

HYPOTHESIS

The cerebellar peduncles of participants with CAI would have altered fractional anisotropy (FA) and orientation dispersion index (ODI) in comparison with healthy controls without ankle injury history. In addition, FA and ODI would be correlated with the duration or severity of the sensorimotor deficits in CAI.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A group of 27 participants with CAI and 26 healthy controls underwent diffusion-weighted imaging scanning, with the cerebellar peduncles as the regions of interest. The measures obtained by single-shell diffusion tensor imaging and the multishell neurite orientation dispersion and density imaging were used. Correlation analyses were performed to examine the potential relationship between the FA/ODI and both the normalized Y-balance scores and the durations of ankle instability.

RESULTS

The ipsilateral ICP of the injured ankle in participants with CAI showed significantly lower FA (Cohen d 95% CI, -1.33 to -0.21; P = 0.04) and marginally significant higher ODI (Cohen d 95% CI, 0.10 to 1.20, P = 0.08) when compared with the same measures in the control group, with the ODI being positively correlated with the duration of ankle instability (r = 0.42, P = 0.03).

CONCLUSION

The ICP in participants with CAI exhibited impaired integrity and a trend of abnormally organized neurites in comparison with a healthy control group.

CLINICAL RELEVANCE

The impairments of ICP might be an ongoing part of the pathological process of CAI, having the potential to become a target for the diagnostic evaluation of this clinical entity.

Organization of sensorimotor activity in anterior cruciate ligament reconstructed individuals: an fMRI conjunction analysis

Introduction

Anterior cruciate ligament reconstruction (ACLR) is characterized by persistent involved limb functional deficits that persist for years despite rehabilitation. Previous research provides evidence of both peripheral and central nervous system adaptations following ACLR. However, no study has compared functional organization of the brain for involved limb motor control relative to the uninvolved limb and healthy controls. The purpose of this study was to examine sensorimotor cortex and cerebellar functional activity overlap and non-overlap during a knee motor control task between groups (ACLR and control), and to determine cortical organization of involved and uninvolved limb movement between groups.

Methods

Eighteen participants with left knee ACLR and 18 control participants performed a knee flexion/extension motor control task during functional magnetic resonance imaging (fMRI). A conjunction analysis was conducted to determine the degree of overlap in brain activity for involved and uninvolved limb knee motor control between groups.

Results

The ACLR group had a statistically higher mean percent signal change in the sensorimotor cortex for the involved > uninvolved contrast compared to the control group. Brain activity between groups statistically overlapped in sensorimotor regions of the cortex and cerebellum for both group contrasts: involved > uninvolved and uninvolved > involved. Relative to the control group, the ACLR group uniquely activated superior parietal regions (precuneus, lateral occipital cortex) for involved limb motor control. Additionally, for involved limb motor control, the ACLR group displayed a medial and superior shift in peak voxel location in frontal regions; for parietal regions, the ACLR group had a more posterior and superior peak voxel location relative to the control group.

Conclusion

ACLR may result in unique activation of the sensorimotor cortex via a cortically driven sensory integration strategy to maintain involved limb motor control. The ACLR group's unique brain activity was independent of strength, self-reported knee function, and time from surgery.

Effects of whole-body vibration on sensorimotor deficits and brain plasticity among people with chronic ankle instability: a study protocol for a single-blind randomized controlled trial

BACKGROUND

Chronic ankle instability (CAI) is a form of musculoskeletal disease that can occur after a lateral ankle sprain, and it is characterized by pain, recurrent ankle sprains, a feeling of "giving way" at the ankle joint, and sensorimotor deficits. There has been increasing evidence to suggest that plastic changes in the brain after the initial injury play an important role in CAI. As one modality to treat CAI, whole-body vibration (WBV) has been found to be beneficial for treating the sensorimotor deficits accompanying CAI, but whether these benefits are associated with brain plasticity remains unknown. Therefore, the current study aims to investigate the effect of WBV on sensorimotor deficits and determine its correlation with plastic changes in the brain.

METHODS

The present study is a single-blind randomized controlled trial. A total of 80 participants with CAI recruited from the university and local communities will be divided into 4 groups: whole-body vibration and balance training (WBVBT), balance training (BT), whole-body vibration (WBV), and control group. Participants will be given the WBV intervention (25-38 Hz, 1.3-2 mm, 3-time per week, 6-week) supervised by a professional therapist. Primary outcome measures are sensorimotor function including strength, balance, proprioception and functional performance. Brain plasticity will be evaluated by corticomotor excitability, inhibition, and representation of muscles, as measured by transcranial magnetic stimulation. Activation of brain areas will be assessed through functional near-infrared spectroscopy. Secondary outcome measures are self-reported functional outcomes involving the Cumberland Ankle Instability Tool and the Foot and Ankle Ability Measure. All tests will be conducted before and after the WBV intervention, and at 2-week follow-up. Per‑protocol and intention-to-treat analysis will be applied if any participants withdraw.

DISCUSSION

This is the first trial to investigate the role of brain plasticity in sensorimotor changes brought by WBV for individuals with CAI. As plastic changes in the brain have been an increasingly important aspect in CAI, the results of the current study can provide insight into the treatment of CAI from the perspective of brain plasticity.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2300068972); registered on 02 March 2023.

Brain Neuroplasticity Related to Lateral Ankle Ligamentous Injuries: A Systematic Review

BACKGROUND

Lateral ankle sprains are the most common ankle injuries in sports and have the highest recurrence rates. Almost half of the patients experiencing lateral ankle sprains develop chronic ankle instability. Patients with chronic ankle instability experience persistent ankle dysfunctions and detrimental long-term sequelae. Changes at the brain level are put forward to explain these undesirable consequences and high recurrence rates partially. However, an overview of possible brain adaptations related to lateral ankle sprains and chronic ankle instability is currently lacking.

OBJECTIVE

The primary purpose of this systematic review is to provide a comprehensive overview of the literature on structural and functional brain adaptations related to lateral ankle sprains and in patients with chronic ankle instability.

METHODS

PubMed, Web of Science, Scopus, Embase, EBSCO-SPORTDiscus and Cochrane Central Register of Controlled Trials were systematically searched until 14 December, 2022. Meta-analyses, systematic reviews and narrative reviews were excluded. Included studies investigated functional or structural brain adaptations in patients who experienced a lateral ankle sprain or with chronic ankle instability and who were at least 18 years of age. Lateral ankle sprains and chronic ankle instability were defined following the recommendation of the International Ankle Consortium. Three authors independently extracted the data. They extracted the authors' name, publication year, study design, inclusion criteria, participant characteristics, the sample size of the intervention and control groups, methods of neuroplasticity testing, as well as all means and standard deviations of primary and secondary neuroplasticity outcomes from each study. Data reported on copers were considered as part of the control group. The quality assessment tool for observational and cross-sectional studies was used for the risk of bias assessment. This study is registered on PROSPERO, number CRD42021281956.

RESULTS

Twenty articles were included, of which only one investigated individuals who experienced a lateral ankle sprain. In all studies combined, 356 patients with chronic ankle instability, 10 who experienced a lateral ankle sprain and 46 copers were included. White matter microstructure changes in the cerebellum have been related to lateral ankle sprains. Fifteen studies reported functional brain adaptations in patients with chronic ankle instability, and five articles found structural brain outcomes. Alterations in the sensorimotor network (precentral gyrus and supplementary motor area, postcentral gyrus and middle frontal gyrus) and dorsal anterior cingulate cortex were mainly found in patients with chronic ankle instability.

DISCUSSION

The included studies demonstrated structural and functional brain adaptations related to lateral ankle sprains and chronic ankle instability compared to healthy individuals or copers. These adaptations correlate with clinical outcomes (e.g. patients' self-reported function and different clinical assessments) and might contribute to the persisting dysfunctions, increased re-injury risk and long-term sequelae seen in these patients. Thus, rehabilitation programmes should integrate sensorimotor and motor control strategies to cope with neuroplasticity related to ligamentous ankle injuries.

Altered gut microbiota richness in individuals with a history of lateral ankle sprain

This study aimed to examine differences in the intestinal microbiota diversity in individuals with and without a history of a lateral ankle sprain (LAS). Fifty male college student athletes with (n=32) and without (n=18) a LAS history participated in this study. Faecal samples were collected in the morning after awakening during an off-season, and faecal microbiota were characterized via bacteria 16S rRNA amplicon sequencing. Alpha-diversity metrics and ß-diversity indices were calculated to assess the gut microbiota diversity. The LAS-history group significantly had lower Chao1 (p=0.020) and abundance-based coverage estimators (p=0.035) indices compared to the control group. Gut microbiota composition was not significantly different between athletes with a LAS history and controls (R2 =0.01, p 0.414). Athletes with a history of LASs had significantly higher proportions of Bacteroides Fragilis (p=0.024) and Ruminococcus Gnavus (p=0.021) compared with controls. The gut microbiota of athletes with a LAS history had less richness compared to controls, indicating potential associations between a LAS and the gut microbiota. This study highlights the potential link of a LAS to global health. This study may help raise awareness of strategies to prevent long-term health-related negative consequences in people suffering from LASs.

Yoga as a balance intervention for middle-age and older adults with history of lateral ankle sprain: An exploratory study

INTRODUCTION

Balance deficiencies are common among aging adults. Musculoskeletal injuries such as lateral ankle sprains (LAS) also contribute to compromised balance; potentially amplifying the postural insufficiencies in these age groups with a history of LAS. Yoga has emerged as an effective balance training intervention for aging adults; but limited application exists in these age cohorts with LAS history. This study may provide important guidance for the implementation of this intervention in these populations.

METHODS

In this cohort design study, middle-age and older adults with a history of LAS completed an 8-week beginner-level yoga class. Balance was measured before and after the yoga intervention statically (force plate) and dynamically (star excursion balance test [SEBT]) using single-limb balance tasks.

RESULTS

Following the yoga intervention, older adults improved static postural control in the anterior-posterior direction, as well as dynamic postural control in selected reach directions of the SEBT relative to the middle-age adults.

CONCLUSION

This is an important step in exploring how to help the aging population that likely has amplifications in balance deficiencies due to a common musculoskeletal injury, LAS. While more work is needed to determine how to optimize and document balance improvements in aging adults with LAS history, yoga appears to be a promising form of intervention, particularly for older adults.

Time-loss and recurrence of lateral ligament ankle sprains in male elite football: A systematic review and meta-analysis

A literature search was conducted to systematically review and meta-analyze time-loss and recurrence rate of lateral ankle sprains (LAS) in male professional football players. Six electronic databases (PubMed, Scopus, Web of Science, PEDRO, CINAHL, and Cochrane) were searched independently, separately both for time-loss and recurrence from inception until April 30, 2021. In addition, reference lists were screened manually to find additional literature. Cohort studies, case reports, case-control studies and RCT in English language of male professional football players (aged more than 16 years) for which data on time-loss or recurrence rates of LAS were available were included. A total of 13 (recurrence) and 12 (time-loss) studies met the inclusion criteria. The total sample size of the recurrence studies was 36,201 participants (44,404 overall initial injuries; 7944 initial ankle sprain [AS] injuries, 1193 recurrent AS injuries). 16,442 professional football players (4893 initial AS injuries; 748 recurrent AS injuries) were meta-analyzed. A recurrence rate of 17.11% (95% CI: 13.31-20.92%; df = 12; Q = 19.53; I² = 38.57%) based on the random-effects model was determined. A total of 7736 participants were part of the time-loss studies (35,888 total injuries; 4848 total ankle injuries; 3370 AS injuries). Out of the 7736 participants, 7337 participants met the inclusion criteria with a total of 3346 AS injuries. The average time-loss was 15 days (weighted mean: 15.92; median: 14.95; min: 9.55; max: 52.9). We determined a priori considerable heterogeneity (CI: 18.15-22.08; df = 11; Q = 158; I² = 93%), so that the data on time-loss are only presented descriptively. There is an average time-loss of 15 days per LAS and a recurrence rate of 17%. LAS is one of the most common types of injury with higher recurrence rates than ACL injuries (9%-12%) in professional football players. Nevertheless, the focus of research in recent years has been mostly on ACL injuries. However, the high recurrence rates and long-term consequences show the necessity for research in the field of LAS in elite football. Yet, heterogeneous data lead to difficulties concerning the aspect of comparability.

Low Regional Homogeneity of Intrinsic Cerebellar Activity in Ankle Instability: An Externally Validated rs-fMRI Study

PURPOSE

Joint deafferentation after post-ankle sprain ligament healing can disrupt sensory input from the ankle and induce maladaptive neuroplasticity, especially in the cerebellum. This study aimed to determine whether the regional homogeneity of intrinsic cerebellar activity differs between patients with ankle instability and healthy controls without a history of ankle injury.

METHODS

The current study used a primary data set of 18 patients and 22 healthy controls and an external UK Biobank data set of 16 patients with ankle instability and 69 healthy controls for a cross-database, cross-sectional investigation. All participants underwent resting-state functional magnetic resonance imaging to calculate their regional homogeneity (ReHo) value. Between-group comparisons of the sensorimotor-related subregions of the cerebellum were first performed in the primary data set to identify low cerebellar ReHo in patients with multiple comparison corrections, and the surviving subregions were then externally validated in the UK Biobank data set. Correlation analyses between the ReHo values and clinical features were also performed.

RESULTS

The ReHo value of cerebellar lobule VIIIb was significantly lower in the ankle instability group than in the controls (0.170 ± 0.016 vs 0.184 ± 0.019 in the primary data set, 0.157 ± 0.026 vs 0.180 ± 0.042 in the UK Biobank data set). The ReHo values of this subregion showed a significant positive correlation with the Cumberland Ankle Instability Tool scores in the ankle instability group (r = 0.553, P-corrected = 0.0348).

CONCLUSIONS

Patients with ankle instability had lower intraregional coherence in cerebellar lobule VIIIb than that of controls, which was also positively correlated with the intensity of self-reported ankle instability.

Longitudinal neuroplasticity after ankle sprain in mice: A voxel-based morphometry study on 11.7T MRI

Lateral ankle sprains (LAS) might lead to joint sensory deafferentation, which induces maladaptive neuroplasticity, especially the morphological atrophy of the cerebellar vermis. However, longitudinal evidence on the causality of injury and neural differences is still lacking. To this end, this study aimed to determine whether the morphology of the central nervous system would be altered before and after ligament transection in LAS mouse models. A total of 40 C57BL/6 mice were randomly divided among the LAS, Sham and Blank groups. We repeatedly performed the balance beam test and neural voxel-based morphometry (VBM) measurements using an 11.7 T magnetic resonance imaging before and 2 months after the surgery. The results showed that for balance outcomes, the LAS group had a significantly longer time and more slips of the balance beam tests compared with the Sham and Blank groups at 2 months after surgery, with no significant difference among the three groups before surgery. Regarding the VBM analysis, the LAS group showed significantly lower VBM values in the central lobule III of the cerebellar vermis and medial amygdalar nucleus (MEA) compared with the Sham and Blank groups after surgery, with no significant difference among the three groups before surgery. In conclusion, lateral ligament injuries might lead to morphological atrophy of the cerebellar vermis in animal models, which might pave the way for the pathological process of ankle instability after LAS.

Changes in balance due to mild lateral ankle sprain measured by parts of the JESS-Score: a case report

BACKGROUND

By chance, one participant of a norm value study concerning the Jenaer-Standing-Stability-Score (JESS-Score) could be measured before and after a lateral ankle sprain (LAS, Grade I). Therefore, a complete comparison of the initial function, the situation after the LAS and even after additional therapy with focus on balance and postural control, was possible.

CASE PRESENTATION

A 34-year-old woman, working as medical doctor was measured her standing stability by use of the JESS-Score. A few weeks after, she experienced a mild LAS. There was no physical therapy in the first 3 months after the LAS. In the following, the patient received 7 sessions of physical therapy with focus on balance and postural control. The 2 used parts of the stability assessment (JESS-Score: 1-unipedal stance test; 2-target-step-test) changed in the course of time. Before the ankle sprain both tests on balance and postural control reached the standard value and were inconspicuous. There was no medically prescribed therapy due to the LAS, based on the minor complaints. However, after the LAS the number of deviating test items increased and was even 6 weeks and 3 months after the LAS inconsistent. Only after additional physiotherapy, the score result improved to the initial situation again.

CONCLUSIONS

It is assumable that LAS is associated with postural deterioration. Therefore, the effect of exercises focussing on postural control and balance after lateral ankle sprain, even if only mild, should be investigated. Some items of the JESS-Score seem to be sensitive for evaluating changes concerning the balance ability.

Mechanisms of Arthrogenic Muscle Inhibition

CONTEXT

Arthrogenic muscle inhibition (AMI) continues to be a limiting factor in joint rehabilitation as the inability to volitionally activate muscle significantly dampens recovery. New evidence acquired at higher brain centers and in clinical populations continues to reshape our perspective of what AMI is and how to treat it. This review aims to stimulate discussion about the far-reaching effects of AMI by exploring the interconnected pathways by which it evolves.

OBJECTIVES

To discuss how reflexive inhibition can lead to adaptations in brain activity, to illustrate how changes in descending motor pathways limit our ability to contract muscle following injury, and to summarize the emerging literature on the wide-reaching effects of AMI on other interconnected systems.

DATA SOURCES

The databases PubMed, SPORTDiscus, and Web of Science were searched for articles pertaining to AMI. Reference lists from appropriate articles were cross-referenced.

CONCLUSION

AMI is a sequential and cumulative neurological process that leads to complex clinical impairments. Originating with altered afferent information arising from an injured joint, patients experience changes in afferent information, reflexive muscle inhibition, deficiencies in somatosensation, neuroplastic compensations in higher brain centers, and ultimately decreased motor output to the muscle surrounding the joint. Other aspects of clinical function, like muscle structure and psychological responses to injury, are also impaired and influenced by AMI. Removing, or reducing, AMI should continue to be a focus of rehabilitation programs to assist in the optimization of health after joint injury.

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.

Ankle Stability and Movement Coordination Impairments: Lateral Ankle Ligament Sprains Revision 2021

This revised clinical practice guideline (CPG) addresses the distinct but related lower extremity impairments of those with a first-time lateral ankle sprain (LAS) and those with chronic ankle instability (CAI). Depending on many factors, impairments may continue following injury. While most individuals experience resolution of symptoms, complaints of instability may continue and are defined as CAI. The aims of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. J Orthop Sports Phys Ther 2021;51(4):CPG1-CPG80. doi:10.2519/jospt.2021.0302.

Postural control is altered in females with excessive medial knee displacement

Knee valgus motion observed during landing tasks has been proposed as a predictor of future knee injury. It mainly involves excess motion in the frontal plane and is known to be greater in individuals with excessive medial knee displacement (MKD). This affects postural control during sports manoeuvres. Previous sports medicine-related research suggests that the nature of these fluctuations provide rich and more sensitive information to identify risk of (re)injury. We aimed to investigate the fluctuations of the centre of pressure (CoP) in individuals with and without excessive MKD. Twenty females (12 controls; 8 excessive MKD) were instructed to perform single-leg landing tasks from three different directions. The participants landed on a force plate and stayed still for 20 seconds. The fluctuations of the anterior-posterior and medial-lateral directions of the CoP were determined through the calculation of Sample Entropy. Mixed-model ANOVAs (3 [Landing Direction] x 2 [Group]) were used. We have found that only the entropy of the medial-lateral direction was different between groups. Individuals with excessive MKD exhibited an increase in entropy values, indicating greater randomness in CoP fluctuations. This suggests a decreased ability to adapt to environmental demands that likely result in an increased risk of injury.

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.

Changes in Spinal and Corticospinal Excitability in Patients with Chronic Ankle Instability: A Systematic Review with Meta-Analysis

The objective of this systematic review with meta-analysis was to determine alterations in spinal and corticospinal excitability of ankle muscles in patients with chronic ankle instability (CAI) compared to uninjured controls. Independent researchers performed comprehensive literature searches of electronic databases and included studies that compared groups with and without CAI and investigated neural excitability with Hoffmann reflex (H-reflex) and/or transcranial magnetic stimulation (TMS). A fixed-effect meta-analysis was conducted to determine group differences for (1) soleus and fibularis maximal H-reflex (Hmax)/maximal M-wave (Mmax)-ratios, and (2) soleus and fibularis longus cortical motor thresholds (CMTs). Seventeen studies were included in the current meta-analysis. They showed that the Hmax/Mmax-ratios of the soleus and the fibularis longus in the CAI group were significantly lower than those in the uninjured control group (soleus: d = −0.41, p < 0.001; fibularis longus: d = −0.27, p = 0.04). There was no evidence for changes in the CMT. This systematic review is the first to demonstrate evidence that patients with CAI present decreased spinal reflex excitability in the soleus and fibularis longus. However, there is no evidence of changes in supraspinal excitability when considering only the CMT. The latter result needs to be interpreted with caution as all except one study demonstrate some changes at the supraspinal level with CAI.