Increased Visual Use in Chronic Ankle Instability: A Meta-analysis

Sensory Reweighting System Differences on Vestibular Feedback With Increased Task Constraints in Individuals With and Without Chronic Ankle Instability

CONTEXT

Chronic ankle instability (CAI) is associated with a less flexible and adaptable sensorimotor system. Thus, individuals with CAI may present an inadequate sensory reweighting system, inhibiting their ability to place more emphasis (upweight) on reliable sensory feedback to control posture. However, how individuals with CAI reweight sensory feedback to maintain postural control in bilateral and unilateral stances has not been established.

OBJECTIVES

To examine (1) group differences in how the sensory reweighting system changes to control posture in a simple double-limb stance and a more complex single-limb stance (uninjured limb and injured limb) under increased environmental constraints manipulating somatosensory and visual information for individuals with and without CAI and (2) the effect of environmental and task constraints on postural control.

DESIGN

Case-control study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 21 individuals with CAI (age = 26.4 ± 5.7 years, height = 171.2 ± 9.8 cm, mass = 76.6 ± 15.17 kg) and 21 individuals without CAI (control group; age = 25.8 ± 5.7 years, height = 169.5 ± 9.5 cm, mass = 72.4 ± 15.0 kg) participated.

MAIN OUTCOME MEASURE(S)

We examined the equilibrium scores based on the first 10 seconds of trials in which participants completed 6 environmental conditions of the Sensory Organization Test during 3 tasks (double-limb and single-limb [uninjured and injured] stances). Sensory reweighting ratios for sensory systems (somatosensory, vision, and vestibular) were computed from paired equilibrium scores based on the first 10 seconds of the trials.

RESULTS

We observed 3-factor interactions between groups, sensory systems, and tasks (F4,160 = 3.754, P = .006) and for group, task, and environment (F10,400 = 2.455, P = .007). The CAI group did not downweight vestibular feedback compared with the control group while maintaining posture on the injured limb (P = .03). The CAI group demonstrated better postural stability than the control group while standing with absent vision (ie, eyes closed), fixed surroundings, and a moving platform on the injured limb (P = .03).

CONCLUSIONS

The CAI group relied on vestibular feedback while maintaining better postural stability than the control group in injured-limb stance. Group differences in postural control depended on both environmental (absent vision and moving platform) and task (injured limb) constraints.

Do we underestimate the frequency of ankle sprains in running? A systematic review and meta-analysis

OBJECTIVE

To provide a systematic review and meta-analysis of the proportion of ankle sprains in running practices.

DESIGN

Systematic review and meta-analysis.

MAIN OUTCOME MEASURES

We calculated the weighted summary proportion and conducted meta-analyses for runners, considering levels (elite/recreational) and disciplines (distance, track, cross-country, trail, and orienteering).

RESULTS

32 studies were included in the systematic review and 19 were included in the meta-analysis with a level of quality ranging from poor to good. Proportion of ankle sprains in runners was 13.69% (95%CI = 7.40-21.54; I2 = 98.58%) in global, 12.20% (95%CI = 5.24-21.53; I2 = 89.31%) in elite, 19.40% (95%CI = 10.05-30.90; I2 = 99.09%) in recreational, 8.51% (95%CI = 4.22-14.12; I2 = 96.15%) in distance, 67.42% (95%CI = 0.50-82.85; I2 = 99.36%) in track, 27.07% (95%CI = 12.48-44.81; I2 = 97.97%) in cross-country, and 25.70% (95%CI = 19.87-32.14; I2 = 0.00) in orienteering.

CONCLUSIONS

Running practice results in significant proportion rate of ankle sprains. Recreational runners exhibit higher proportion than elite. Running disciplines, especially track, cross-country, and orienteering, influence reported ankle sprain rates, surpassing those of distance runners.

Strobe training as a visual training method that improves performance in climbing

Introduction

Strobe training is a form of visual training where the athlete has to practice during intermittently dark conditions. Strobe training improves visual, perceptual, and cognitive skills, which will enhance athletic performance. Strobe training can influence multiple training components in climbing: psychological, tactical, physical, and technical training.

Materials and methods

The study was conducted on 17 elite climbers from Romania (10 male and 7 female), representing the entire National Youth Climbing Team. The research group was divided into a control group (n = 8) and an experimental group (n = 9). The used instruments were the Cognitrom battery (for cognitive skills, such as spatial skills and reactivity), the Witty SEM system (for motor-cognitive skills, such as cognitive agility, visual processing speed, and visual memory), and the International Rock Climbing Research Association (IRCRA) performance-related test battery for climbers (climbing-specific motor skills). The experimental group had 20 strobe training sessions, which took place during one calendar year, as an additional session to their climbing schedule done with their principal trainer. The strobe session was once a week, depending on the periodization of the macrocycle (preparatory, competitional, and transition periods). The control group and the experimental group had similar climbing training sessions during the 1-year macrocycle in terms of intensity and volume of their training.

Results

Strobe training improved on-sight performance (d = 0.38) and red-point performance (d = 0.36). Strobe training improved the majority of cognitive skills [all spatial skills (d = 1.27 for mental image transformation; d = 1.14 for spatial orientation; d = 1.59 for image generation) and simple reaction time (d = 0.99)]. Strobe training improved all motor-cognitive skills (d = 0.16 for visual memory; d = 1.96 for visual memory errors; d = 1.39 for visual processing speed; d = 1.94 for visual processing errors; d = 1.30 for cognitive agility). Strobe training improved many climbing-specific parameters (flexibility and upper body strength) (d = 0.44 and d = 0.47 for flexibility parameters; d = 0.50 to 0.73 for upper body strength parameters).

Discussion

Strobe training is an effective training method for enhancing performance that should be used on more experienced climbers. It acts more on spatial skills, rather than on reactivity skills, developing the visual-motor coordination system. Strobe training has greater effects on climbers aged below 16 years, as youth athletes rely more on visual input compared to adults. The improvement in climbing-specific variables was due to the additional climbing session done weekly. Strobe training acts more on the cognitive component of training than on the motor component of training in climbing.

Study on the effect of blood flow restriction training combined with IASTAM on ankle strength and function intervention in athletes with chronic ankle instability in sport dance events

BACKGROUND

Athletes engaged in sports dance frequently encounter the potential for ankle injuries and instability, factors that may contribute to diminished training efficacy, compromised athletic performance, prolonged recuperation, and heightened susceptibility to recurring injuries.

OBJECTIVE

The objective of this study was to investigate the impact of an exercise intervention (comprising blood flow restriction training combined with low-load ankle muscle strength training and balance training) as well as instrument-assisted soft tissue mobilization (IASTM) on the foot and ankle function, strength, and range of motion in sports dance athletes exhibiting ankle instability (CAI).

METHODS

Thirty participants exhibiting ankle instability, restriction, or discomfort were recruited and randomly assigned to two groups: the Test group (comprising blood flow restriction training combined with IASTM, n = 15) and the traditional ankle strength training group (n = 15). The intervention spanned 4 weeks, with one session per week. Assessment of the Cumberland Ankle Instability Tool (CAIT), Foot and Ankle Ability Measure (FAAM), and ankle range of motion occurred at three time points: pre-intervention, immediately following the initial intervention, and after 4 weeks of intervention. Ankle strength testing was conducted solely before and after the intervention for comparative analysis.

RESULTS

There were no significant variances in baseline characteristics between the two intervention groups. In terms of CAIT scores, both groups exhibited notably higher scores following the initial intervention and after 4 weeks of intervention compared to pre-intervention (P < 0.05). The Test group displayed higher CAIT scores than the control group, signifying a more pronounced enhancement in ankle stability among patients in the Test group. Concerning FAAM scores, both groups significantly enhanced ankle function in CAI patients (P < 0.05), with the Test group demonstrating notably higher FAAM-SPORT scores than the control group (P < 0.05), indicating superior restoration of athletic capability in the Test group. As for improvements in ankle range of motion, both groups demonstrated significant enhancements compared to pre-intervention (P < 0.05). The Test group exhibited significantly superior improvements in dorsiflexion, eversion, and inversion range of motion compared to the control group (P < 0.05), while the control group did not exhibit significant enhancements in plantarflexion and eversion range of motion (P > 0.05). Both groups displayed enhanced ankle strength in CAI patients following the intervention (P < 0.05), with the Test group manifesting notably higher dorsiflexion and inversion strength than the control group (P < 0.05).

CONCLUSION

Both blood flow restriction training combined with IASTM and traditional ankle strength and stability training have shown significant improvements in stability, function, strength, and range of motion in CAI patients. Furthermore, the Test group exhibits superior efficacy in ankle stability, daily functional movement, dorsiflexion, and eversion range of motion compared to the control group.

CLINICAL TRIAL REGISTRATION

9 February 2024, ClinicalTrials.gov, ID; NCT06251414.

Postural control and trunk stability on sway parameters in adults with and without chronic low back pain

BACKGROUND

Postural sway changes often reflect functional impairments in adults with chronic low back pain (LBP). However, there is a gap in understanding how these individuals adapt their postural strategies to maintain stability.

PURPOSE

This study investigated postural sway distance and velocity, utilizing the center of pressure (COP) and center of gravity (COG), between adults with and without LBP during repeated unilateral standing trials.

METHODS

Twenty-six subjects with LBP and 39 control subjects participated in the study. Postural sway ranges, COP/COG sways, and sway velocities (computed by dividing path length by time in anteroposterior (AP) and mediolateral (ML) directions over 10 s) were analyzed across three unilateral standing trials.

RESULTS

A significant group interaction in sway range difference was observed following repeated trials (F = 5.90, p = 0.02). For COG sway range, significant group interactions were demonstrated in both directions (F = 4.28, p = 0.04) and repeated trials (F = 5.79, p = 0.02). The LBP group demonstrated reduced ML sway velocities in the first (5.21 ± 2.43 for the control group, 4.16 ± 2.33 for the LBP group; t = 1.72, p = 0.04) and second (4.87 ± 2.62 for the control group, 3.79 ± 2.22 for the LBP group; t = 1.73, p = 0.04) trials.

CONCLUSION

The LBP group demonstrated decreased ML sway velocities to enhance trunk stability in the initial two trials. The COG results emphasized the potential use of trunk strategies in augmenting postural stability and optimizing neuromuscular control during unilateral standing.

Accuracy to identify young adults with chronic ankle instability using a virtual reality - Balance error scoring system: A cross-sectional study

INTRODUCTION

The Balance Error Scoring System (BESS) assesses the ability to control postural stability by performing 3 different stances on two-type surfaces during closed eyes. Virtual reality technology combined with the BESS test (VR-BESS) may be used to disrupt visual inputs instead of closing the eyes, which may improve the sensitivity of diagnosing patients with chronic ankle instability (CAI).

OBJECTIVE

This study aimed to evaluate the accuracy to identify individuals with CAI of the VR-BESS test comparing with the original BESS test.

METHODS

The BESS and VR-BESS tests were administered to 68 young adults (34 participants with CAI and 34 without CAI). Frontal and lateral video views were used to measure the participant's performance errors. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was computed to determine the diagnostic test's overall accuracy.

RESULTS

The total score of the BESS test and the VR-BESS test were statistically significant in comparison to the AUC of no discrimination at 0.5, with AUC values of 0.63 and 0.64, respectively. The cut-off scores for the BESS and VR-BESS tests were 12 and 15, respectively. There was no significant difference between the ROC curves of the BESS and the VR-BESS test for identifying individuals with CAI.

CONCLUSION

The BESS and VR-BESS tests may be utilized interchangeably to identify individuals with CAI.

Understanding the effects of a sudden directional shift in somatosensory feedback and increasing task complexity on postural adaptation in individuals with and without chronic ankle instability

BACKGROUND

Individuals with chronic ankle instability (CAI) present somatosensory dysfunction following an initial ankle sprain. However, little is known about how individuals with CAI adapt to a sudden sensory perturbation of instability with increasing task and environmental constraints to maintain postural stability.

METHODS

Forty-four individuals with and without unilateral CAI performed the Adaptation Test to a sudden somatosensory inversion and plantarflexion perturbations (environment) in double-, injured-, and uninjured- limbs. Mean sway energy scores were analyzed using 2 (group) × 2 (somatosensory perturbations) × 3 (task) repeated measures analysis of variance.

RESULTS

There were significant interactions between the group, environment, and task (P=.025). The CAI group adapted faster than healthy controls to a sudden somatosensory inversion perturbation in the uninjured- (P=.002) and injured- (P<.001) limbs, as well as a sudden somatosensory plantarflexion perturbation in the double- (P=.033) and uninjured- (P=.035) limbs. The CAI and healthy groups presented slower postural adaptation to a sudden inversion perturbation than a sudden somatosensory plantarflexion perturbation in double-limb (P<.001). Whereas both groups demonstrated faster postural adaptation to a sudden somatosensory inversion perturbation compared to somatosensory plantarflexion perturbation while maintaining posture in the injured- (P<.001) and uninjured- (P<.001) limbs. The CAI and healthy groups adapted faster to a sudden somatosensory inversion perturbation in the injured- (P<.001) and uninjured- (P<.001) limbs than in double-limb, respectively.

DISCUSSION

Postural adaptation in individuals with and without CAI depended on environmental (somatosensory perturbations) and task constraints. The CAI group displayed comparable and faster postural adaptation to a sudden somatosensory inversion and plantarflexion in double-, injured-, and uninjured- limbs, which may reflect a centrally mediated alteration in neuromuscular control in CAI.

Deficits in neurocognitive performance in patients with chronic ankle instability during a neurocognitive balance task - A retrospective case-control study

OBJECTIVES

To assess the neurocognitive performance while maintaining balance of patients experiencing CAI compared to healthy controls. In patients with CAI, the affected limb was also compared to the contralateral limb.

DESIGN

A retrospective case-control study.

SETTING

Laboratory study.

PARTICIPANTS

We included 27 patients with CAI and 21 healthy controls.

METHODS

The study consisted of two sessions, namely familiarisation and experimentation, which were scheduled with a gap of at least one week between them. During the experimental trial, both groups performed the Y-Balance Test and Reactive Balance Test once on each limb.

MAIN OUTCOME MEASURES

The main outcome measures are accuracy and visuomotor response time (VMRT) calculated via video-analysis and with the Fitlight™-hardware and software respectively during the Reactive Balance Test (RBT).

RESULTS

No data was excluded from the final analysis. Patients with CAI exhibited significantly lower accuracy than healthy controls, with a mean difference of 8.7% (±3.0)%. There were no differences for VMRT between groups. Additionally, no significant differences were observed between the affected and contralateral limb of the patient group for both accuracy and VMRT.

CONCLUSIONS

Patients with CAI showed lower accuracy, but similar VMRT compared to healthy controls during a neurocognitive balance task, indicating impaired neurocognitive function. Patients exhibit comparable speed to healthy individuals when completing neurocognitive balance tasks, yet they display a higher frequency of accuracy errors in accurately perceiving their environment and making decisions under time constraints. Future research should gain more insights in which other cognitive domains are affected in patients with CAI for a better grasp of this condition's underlying mechanism.

Test-retest, intra- and inter-rater reliability of the reactive balance test in patients with chronic ankle instability

Introduction

The Reactive Balance Test (RBT) could be a valuable addition to research on chronic ankle instability (CAI) and clinical practice, but before it can be used in clinical practice it needs to be reliable. It has already been proven reliable in healthy recreational athletes, but not yet in patients with CAI who have shown persistent deficits in dynamic balance. The study aimed to determine the test-retest, intra-, and inter-rater reliability of the RBT in patients with CAI, and the test-retest and inter-rater reliability of the newly developed RBT score sheet.

Methods

We used a repeated-measures, single-group design to administer the RBT to CAI patients on three occasions, scored by multiple raters. We included 27 participants with CAI. The study used multiple reliability measures, including Pearson r, intra-class correlations (ICC), standard error of measurement (SEM), standard error of prediction (SEP), minimal detectable change (MDC), and Bland-Altman plots, to evaluate the reliability of the RBT's outcome measures (visuomotor response time and accuracy). It also assessed the test-retest and inter-rater reliability of the RBT score sheet using the same measures.

Results

The ICC measures for test-retest reliability were similar for accuracy (0.609) and VMRT (0.594). Intra-rater reliability had high correlations and ICCs for accuracy (r = 0.816, ICC = 0.815) and VMRT (r = 0.802, ICC = 0.800). Inter-rater reliability had a higher ICC for VMRT (0.868) than for accuracy (0.690).

Conclusion

Test-retest reliability was moderate, intra-rater reliability was good, and inter-rater reliability showed moderate reliability for accuracy and good reliability for VMRT. Additionally, the RBT shows robust SEM and mean difference measures. The score sheet method also demonstrated moderate test-retest reliability, while inter-rater reliability was good to excellent. This suggests that the RBT can be a valuable tool in assessing and monitoring balance in patients with CAI.

Correlations between plantar pressure and postural balance in healthy subjects and their comparison according to gender and limb dominance: A cross-sectional descriptive study

BACKGROUND

Lower extremity injuries rank among the most common injuries affecting young population, and numerous factors affect the outcomes of plantar pressure and balance assessment.

RESEARCH QUESTION

Does a correlation exist between plantar pressure and postural balance in healthy subjects and are there any difference in the results based on gender and limb dominance?

METHODS

This study involved thirty healthy recreationally active young adults (15 females, 15 males). Plantar pressures were analyzed using the MatScan Pressure Mat System, and postural balance was evaluated using Biodex Balance System. All assessments conducted under both static and dynamic conditions. Correlations were tested by Spearman Correlation Coefficient, and comparative tests were performed for gender and limb dominance.

RESULTS

Correlations were observed between plantar pressure parameters and balance scores, particularly in the dynamic conditions (p < 0.05). Gender-based differences were noted in plantar pressure parameters (p < 0.05), with females demonstrating improved balance stability scores. No significant differences were found based on limb dominance in plantar pressure and postural balance data (p > 0.05).

SIGNIFICANCE

This study provides valuable detailed insights into the existing literature concerning plantar pressure and postural balance assessments within the healthy population. A strong correlation was observed between plantar pressure and postural balance, and the comparisons of these assessments were affected by gender but not by limb dominance. These results could lead the way for better rehabilitation approaches by considering the correlations and differences across diverse populations.

Sensory conflicts through short, discrete visual input manipulations: Identification of balance responses to varied input characteristics

Human balance control relies on various sensory modalities, and conflict of sensory input may result in postural instability. Virtual reality (VR) technology allows to train balance under conflicting sensory information by decoupling visual from somatosensory and vestibular systems, creating additional demands on sensory reweighting for balance control. However, there is no metric for the design of visual input manipulations that can induce persistent sensory conflicts to perturb balance. This limits the possibilities to generate sustained sensory reweighting processes and design well-defined training approaches. This study aimed to investigate the effects that different onset characteristics, amplitudes and velocities of visual input manipulations may have on balance control and their ability to create persistent balance responses. Twenty-four young adults were recruited for the study. The VR was provided using a state-of-the-art head-mounted display and balance was challenged in two experiments by rotations of the visual scene in the frontal plane with scaled constellations of trajectories, amplitudes and velocities. Mean center of pressure speed was recorded and revealed to be greater when the visual input manipulation had an abrupt onset compared to a smooth onset. Furthermore, the balance response was greatest and most persistent when stimulus velocity was low and stimulus amplitude was large. These findings show clear dissociation in the state of the postural system for abrupt and smooth visual manipulation onsets with no indication of short-term adaption to abrupt manipulations with slow stimulus velocity. This augments our understanding of how conflicting visual information affect balance responses and could help to optimize the conceptualization of training and rehabilitation interventions.

Sensorimotor Dysfunction Following Anterior Cruciate Ligament Reconstruction- an Afferent Perspective: A Scoping Review

Background

Sensorimotor dysfunction is thought to occur following anterior cruciate ligament (ACL) injury which may have implications on future reinjury risk. Dysfunction has been demonstrated within the efferent component of the sensorimotor system. However, no reviews have examined the two main components of the afferent system: the visual and somatosensory systems.

Hypothesis/Purpose

This study aimed to report differences in function (central processing and local processing) within the (1) somatosensory and (2) visual systems between individuals following anterior cruciate ligament reconstruction (ACLR) and healthy controls (between-subject). The study also aimed to report differences in function within the two systems between the two limbs of an individual following ACLR (within-subject).

Study Design

Scoping review.

Methods

A search was conducted in PubMed, SPORTDiscus, CINAHL, Medline and Embase up until September 2021. Level I-IV studies assessing somatosensory and visual systems were included if they compared ACLR limbs to the uninjured contralateral limb (within-subject) or a healthy control limb (between-group). The function of somatosensory and visual systems was assessed across both central processing (processing of information in the central cortex) and local processing (all other assessments outside of central processing of information).

Results

Seventy studies were identified (52 somatosensory, 18 visual). Studies examining somatosensory central processing demonstrated significant differences; 66% of studies exhibited within-subject differences and 100% of the studies exhibited between-group differences. Studies examining local somatosensory processing had mixed findings; 40% of the 'joint position sense (JPS)' and 'threshold to detect motion (TTDM)' studies showed significant within-subject differences (JPS=0.8°-3.8° and TTDPM=0.2°-1.4°) and 42% demonstrated significant between-group differences (JPS=0.4°-5° and TTDPM=0.3°-2.8°). Eighty-three percent of visual central processing studies demonstrated significant dysfunction between-groups with no studies assessing within-subject differences. Fifty percent of the studies examining local visual processing demonstrated a significant between-group difference.

Conclusion

Significant differences in central processing exist within somatosensory and visual systems following ACLR. There is mixed evidence regarding local somatosensory and visual processing. Increased compensation by the visual system and local visual processing dysfunction may occur in conjunction with somatosensory dysfunction.

Balance, strength and physical activity after ankle sprain: Comparison between children with chronic ankle instability and copers

OBJECTIVE

The aim of this study was to compare muscle strength, balance, and physical activity between children with chronic ankle instability and copers.

DESIGN

Cross-sectional study.

SETTING

Pediatric Physical Therapy laboratory.

PARTICIPANTS

Children aged between 7 and 12 years old from regular schools who had a history of unilateral ankle sprain.

MAIN OUTCOME MEASURES

Lower extremity strength, Static and dynamic standing balance, and Level of physical activity.

RESULTS

Fifteen children with chronic ankle instability and 15 copers were recruited. Demographic data showed no differences between group except for sex and the Cumberland Ankle Instability Tool-Youth (CAITY) score. Children with CAI had a significantly lower score during the standing long jump test (p < 0.05), poorer performance of single leg stance test (p < 0.001) and Y-Balance test in the anterior, posteromedial, and posterolateral directions (p < 0.05) when compared to copers. Total METs per week was significantly higher in the copers (p < 0.05).

CONCLUSION

Children with chronic ankle instability exhibited weaker lower limb strength, poorer static and dynamic standing balance, and participate in less physical activity compared to those in a coper group which may have future negative health consequences. Knowledge about the differences between the two groups may provide guidance for physical educators and physical therapists. (200 words).

Postural control measured before and after simulated ankle inversion landings among individuals with chronic ankle instability, copers, and controls

BACKGROUND

Postural control measured during single-leg stance and single-leg hop stabilization has been used to estimate sensorimotor function in CAI individuals and copers. To date, studies have not used postural control tasks as a way of measuring responses to sudden changes in sensory information after simulated ankle inversion landings.

RESEARCH QUESTION

A cross-sectional study was performed to identify any differences in static and dynamic postural control before and after simulated ankle inversion landings among individuals with chronic ankle instability (CAI), copers, and healthy controls.

METHODS

Nineteen CAI individuals, 19 copers, and 19 controls participated in this study. Participants performed 3 static and dynamic balance tasks before and after simulated ankle inversion landings onto a 25° tilted platform from a height of 30 cm. The main outcome measures were the center of pressure (COP) velocity and range from the single-leg stance, as well as the dynamic postural stability index from the single-leg hop stabilization. The Wilcoxon signed-rank test was used to compare posttest and pretest differences in static and dynamic postural control between groups.

RESULTS

In the static postural control measures, the CAI group had a higher difference in COP velocity and COP range in the frontal plane (p < 0.05 and p < 0.05, respectively) than the coper group. In the dynamic postural control measures, the CAI group demonstrated a higher difference in the vertical stability index (p < 0.05) than the healthy control group.

SIGNIFICANCE

CAI individuals have persistent worse postural control after somatosensory modulation due to their inability to adapt to sudden somatosensory modulation. Relative to CAI individuals, copers may have different abilities not only the integration of somatosensory input about ankle inversion modulation, but also the adaptation of the entire motor control system, preventing recurrent ankle sprains after an initial LAS. Therefore, somatosensory modulation may be the indicator of understanding CAI and coper.

EMG Analysis During Static Balance in Chronic Ankle Instability, Coper and Controls

Patients with chronic ankle instability (CAI) consistently display postural control alterations, which may result from sensorimotor dysfunction. This study aimed to compare muscle activity in the lower extremity and postural control among individuals with CAI, copers and uninjured controls during a static balance test. A total of 57 physically active participants were categorized into three groups (CAI, copers and controls) and performed a single-leg balance test with two visual conditions: eyes open and eyes closed. Muscle activity in six lower extremity muscles and center of pressure (CoP) variables were recorded and analyzed. Patients with CAI exhibited greater muscle activity in the medial gastrocnemius and gluteus maximus compared to controls or copers, regardless of the visual condition. Copers displayed increased gluteus medius activity compared to controls. Additionally, all groups demonstrated increased muscle activity and CoP variables when visual feedback was disrupted. These findings suggest that patients with CAI may have less effective recruitment of motor units during static balance. On the other hand, greater muscle activity in the gluteus medius in copers may represent a coping mechanism to avoid further ankle injuries. Further research on muscle activity during dynamic postural control is warranted to explore sensorimotor alterations in patients with CAI.

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.

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.

The effects of kinesiophobia on postural control with chronic ankle instability

BACKGROUND

Patients with chronic ankle instability (CAI) often experience injury-related fear following ankle injuries, a condition known as kinesiophobia. Little research has investigated the impact of kinesiophobia in patients with CAI.

RESEARCH QUESTION

How does kinesiophobia impact the static and dynamic balance of individuals with CAI?

METHODS

Fifty patients with CAI were divided into 2 subgroups based on their responses to the Tampa Scale of Kinesiophobia: 25 with kinesiophobia (CAI-K) and 25 without kinesiophobia (CAI-N). These groups were compared to 20 control participants. All participants performed a single-leg balance test with eyes open (EO) and eyes closed (EC). They also performed the Y-balance test (YBT) with EO. Romberg ratios were calculated as EC/EO and used for statistical analysis.

RESULTS

No differences in static balance with EO and EC were found among three groups. However, the CAI-K group displayed a higher Romberg ratio in the mediolateral direction during static balance than both CAI-N and control groups. Additionally, both CAI-K and CAI-N groups displayed higher Romberg ratio in the anterior-posterior than controls. During YBT, the CAI-K group showed reduced reach distance in the anterior direction than CAI-N and control groups.

SIGNIFICANCE

The CAI-K group relies more on visual feedback during static balance in the mediolateral direction than CAI-N and control groups. Furthermore, the CAI-K group displayed less anterior reach distance during YBT compared to the CAI-N and control groups. Clinicians should consider both psychological and physical factors when designing rehabilitation programs.

Postural adaptations within normalized stability between older adults with and without chronic low back pain

BACKGROUND

Adaptations of dynamic balance performance are related to sway excursions in older adults with chronic low back pain (LBP). However, there is a lack of understanding on postural control within different thresholds of radius from the center of pressure (COP).

PURPOSE

This study was conducted to compare the normalized stability based on the time-in-boundary (TIB) during repeated unilateral limb standing trials between subjects with and without chronic LBP.

METHODS

There were 26 older adults with LBP and 39 control subjects who completed three trials of repeated unilateral limb standing on a force plat.

RESULTS

The TIB based on the seven thresholds was analyzed, and the groups demonstrated a significant interaction on thresholds for TIB (F = 8.76, p = 0.01). The TIB was significantly different in the 10 mm (F = 4.01, p = 0.04), 15 mm (F = 5.21, p = 0.03), and 20 mm (F = 4.48, p = 0.04) radius of thresholds only in the second trial. However, there was no group difference on TIB at the first and third trials due to potential compensatory and/or adaptive reactions to avoid fall risks.

CONCLUSION

The LBP group lacked postural stability within the thresholds less than a 20 mm radius at the second trial of unilateral standing. The significant group interaction with the thresholds indicates an adaptation strategy on sway thresholds. This postural reaction from repeated trials should be considered with sway excursion adjustments and fall prevention in older adults with LB.

Balance and Muscle Synergies During a Single-Limb Stance Task in Individuals With Chronic Ankle Instability

The aim of this study was to investigate balance performance and muscle synergies during a Single-Limb Stance (SLS) task in individuals with Chronic Ankle Instability (CAI) and a group of healthy controls. Twenty individuals with CAI and twenty healthy controls were asked to perform a 30-second SLS task in Open-Eyes (OE) and Closed-Eyes (CE) conditions while standing on a force platform with the injured or the dominant limb, respectively. The activation of 13 muscles of the lower limb, hip, and back was recorded by means of surface electromyography. Balance performance was assessed by identifying the number and the duration of SLS epochs, and the Root-Mean-Square (RMS) in Antero-Posterior (AP) and Medio-Lateral (ML) directions of the body-weight normalized ground reaction forces. The optimal number of synergies, weight vectors, and activation coefficients were also analyzed. CAI group showed a higher number and a shorter duration of SLS epochs and augmented ground reaction force RMS in both AP and ML directions compared to controls. Both groups showed an increase in the RMS in AP and ML forces in CE compared to OE. Both groups showed 4 optimal synergies in CE, while controls showed 5 synergies in OE. CAI showed a significantly higher weight of knee flexor muscles in both OE and CE. In conclusion, muscle synergies analysis provided an in-depth knowledge of motor control mechanisms in CAI individuals. They showed worse balance performance, a lower number of muscle synergies in a CE condition and abnormal knee flexor muscle activation compared to healthy controls.

Cortical Activation During Single-Legged Stance in Patients With Chronic Ankle Instability

CONTEXT

Chronic ankle instability (CAI) has been considered a neurophysiological condition, with dysfunctional somatosensory and motor system excitability. However, few researchers have explored the changes in cortical activation during balance tasks of patients with CAI.

OBJECTIVE

To compare the cortical activity during single-legged stance among CAI, copers, and uninjured control participants and to compare dynamic balance across groups.

DESIGN

Cross-sectional study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 participants with CAI (median [interquartile range]; age = 34.5 [11.0] years, height = 170.0 [15.8] cm, mass = 67.0 [16.2] kg), 17 copers (age = 27.0 [14.0] years, height = 170.0 [9.5] cm, mass = 66.5 [16.5] kg), and 21 uninjured control participants (age = 25.0 [10.5] years, height = 170.0 [11.0] cm, mass = 64.0 [16.5] kg).

MAIN OUTCOME MEASURE(S)

Participants performed single-legged stance while cortical activation was tested with functional near-infrared spectroscopy. The peak oxyhemoglobin response of the activated cortex was calculated and compared across groups. The Y-Balance test outcomes and patient-reported outcomes were assessed and compared across groups.

RESULTS

The CAI group had worse Y-balance test and patient-reported outcomes than the coper and uninjured control groups. Differences in the peak oxyhemoglobin response were observed for the primary somatosensory cortex (S1; F2,57 = 4.347, P = .017, ηp2 = 0.132) and superior temporal gyrus (STG; F2,57 = 4.548, P = .015, ηp2 = 0.138). Specifically, copers demonstrated greater activation in S1 and STG than the CAI (d = 0.73, P = .034, and d = 0.69, P = .043, respectively) and uninjured control (d = 0.77, P = .036, and d = 0.88, P = .022, respectively) groups. No differences were found in the cortical activation between CAI and uninjured control participants.

CONCLUSIONS

Copers displayed greater cortical activation in S1 and STG than CAI and uninjured control participants. Greater activation in S1 and STG suggested a better ability to perceive somatosensory stimuli and may represent a compensatory mechanism that allows copers to maintain good functional ability after the initial severe ankle sprain.

Disrupted vision impairs force steadiness and accuracy in chronic ankle instability patients

The primary purpose of this study was to examine the effect of visual disruption on submaximal force steadiness and accuracy among three groups including chronic ankle instability (CAI) patients, lateral ankle sprain copers, and healthy controls. Twenty patients with CAI, 20 copers, and 20 matched-healthy controls volunteered to participate in the study. Submaximal force steadiness and accuracy for evertors, invertors, and hip abductors (10% and 20% of their maximal voluntary isometric contraction) were measured with an isokinetic dynamometer. All groups performed the tasks with and without stroboscopic glasses. The CAI group showed worse steadiness and accuracy in evertors with visual disruption compared to nonvisual disruption (p < 0.0001 and = 0.02, respectively). Relative to the control group, the CAI group showed worse force steadiness and accuracy in evertors (p < 0.0001, both), worse force accuracy in hip abductors (p = 0.02), and the coper group also showed worse accuracy in evertors (p = 0.02). Individuals with CAI demonstrated impaired force steadiness and accuracy in evertors and hip abductors compared to healthy controls. In addition, they tended to rely more on visual feedback during the force steadiness task than copers and healthy controls.

Effects of plantar-sensory treatments on postural control in chronic ankle instability: A systematic review and meta-analysis

OBJECTIVE

This study aimed to examine the effects of plantar-sensory treatments on postural control in individuals with chronic ankle instability (CAI).

METHODS

This study was registered in PROSPERO (registration number CRD42022329985) on May 14, 2022. An extensive search was performed in Pubmed, Embase, Cochrane, Web of Science, and Scopus to identify the potential studies on plantar-sensory treatments affecting postural control before May 2022. The methodological quality of involved studies was assessed using the scale of Physiotherapy Evidence Database (PEDro). The Cochrane Tool and the Risk of Bias in Non-randomized Studies of Interventions assessment tool were used to evaluate the risk of bias in randomised controlled trials (RCTs) and non-RCTs respectively. RevMan 5.4 was utilised to calculate the standardised mean difference (SMD), with 95% confidence interval (CI).

RESULTS

Eight RCTs with a mean PEDro rating of 6 and four non-RCTs with a mean PEDro rating of 4.75 were included in the quantitative analysis. The types of plantar-sensory treatments included plantar massage, whole-body vibration and textured surface-stimulation treatment. A significant effect of static balance with eyes open (SMD = -0.54; 95% CI: -0.81 to -0.27; p < 0.001) was found and subgroup analysis showed that plantar massage (SMD = -0.49; 95% CI: -0.84 to -0.14; p = 0.006) and whole-body vibration (SMD = -0.66; 95% CI: -1.12 to -0.19; p = 0.005) had positive effects. In the subgroup analysis of anterior dynamic balance, whole-body vibration revealed a significant increase (SMD = 0.60; 95% CI: 0.06-1.14; p = 0.03). The pooled results or subgroup analysis including eyes-closed static balance and other directions of dynamic balance indicated no significant difference (p > 0.05).

CONCLUSIONS

This meta-analysis indicated that plantar-sensory treatments could improve postural control in CAI, especially the treatments of plantar massage and long-term whole-body vibration.

Effects of foot intensive rehabilitation (FIRE) on clinical outcomes for patients with chronic ankle instability: a randomized controlled trial protocol

BACKGROUND

Lateral ankle sprains account for a large proportion of musculoskeletal injuries among civilians and military service members, with up to 40% of patients developing chronic ankle instability (CAI). Although foot function is compromised in patients with CAI, these impairments are not routinely addressed by current standard of care (SOC) rehabilitation protocols, potentially limiting their effectiveness. The purpose of this randomized controlled trial is to determine if a Foot Intensive REhabilitation (FIRE) protocol is more effective compared to SOC rehabilitation for patients with CAI.

METHODS

This study will use a three-site, single-blind, randomized controlled trial design with data collected over four data collection points (baseline and post-intervention with 6-, 12-, and 24-month follow-ups) to assess variables related to recurrent injury, sensorimotor function, and self-reported function. A total of 150 CAI patients (50 per site) will be randomly assigned to one of two rehabilitation groups (FIRE or SOC). Rehabilitation will consist of a 6-week intervention composed of supervised and home exercises. Patients assigned to SOC will complete exercises focused on ankle strengthening, balance training, and range of motion, while patients assigned to FIRE will complete a modified SOC program along with additional exercises focused on intrinsic foot muscle activation, dynamic foot stability, and plantar cutaneous stimulation.

DISCUSSION

The overall goal of this trial is to compare the effectiveness of a FIRE program versus a SOC program on near- and long-term functional outcomes in patients with CAI. We hypothesize the FIRE program will reduce the occurrence of future ankle sprains and ankle giving way episodes while creating clinically relevant improvements in sensorimotor function and self-reported disability beyond the SOC program alone. This study will also provide longitudinal outcome findings for both FIRE and SOC for up to two years. Enhancing the current SOC for CAI will improve the ability of rehabilitation to reduce subsequent ankle injuries, diminish CAI-related impairments, and improve patient-oriented measures of health, which are critical for the immediate and long-term health of civilians and service members with this condition. Trial Registration Clinicaltrials.gov Registry: NCT #NCT04493645 (7/29/20).

Effectiveness of the SMART training intervention on ankle joint function in patients with first-time acute lateral ankle sprain: study protocol for a randomized controlled trial

BACKGROUND

The lateral ankle sprain (LAS) is the most common injury in the field of everyday and sports-related activities. There is a high rate of patients with LAS who will develop chronic ankle instability (CAI). A possible explanation for this high rate is an insufficient rehabilitation and/or a premature return to intense exercise and workloads. Currently, there are general rehabilitation guidelines for LAS but there is a lack of standardized evidenced-based rehabilitation concepts for LAS, which effectively reduce the high CAI rate. The primary aim of the study is to investigate the effectiveness of a 6-week sensorimotor training intervention (SMART-Treatment, SMART) in contrast to standard therapy (Normal Treatment, NORMT) after an acute LAS on perceived ankle joint function.

METHODS

This study will be a prospective, single-center, interventional randomized controlled trial with an active control group. Patients (14-41 years) with an acute LAS and a MRI confirmed lesion or rupture of at least one ankle ligament will be included. Exclusion criteria are acute concomitant injuries of the ankle, pre-injuries of the ankle, serious lower-extremity injuries of the last 6 months, lower-extremity surgery, and neurological diseases. The primary outcome measure will be the Cumberland Ankle Instability Tool (CAIT). Secondary outcomes include the Foot and Ankle Ability Measurement (FAAM), isokinetic and isometric strength diagnostics, joint repositioning sense, range of motion, measurements of postural control, gait and run analysis, and jump analysis. This protocol will follow the SPIRIT guidance.

DISCUSSION

Current management of LAS rehabilitation lacks since there is a high rate of patients developing a CAI. It has been shown that exercise therapy improves ankle function in acute LAS as well as in patients with CAI. It is further recommended to address specific impairment domains in ankle rehabilitation. However, empirical data for such a holistic treatment algorithm is missing. Therefore, this study has the potential to improve the healthcare for LAS patients and might be used for a future standardized evidence-based rehabilitation concept.

TRIAL REGISTRATION

"Prospectively registered" ISRCTN - ISRCTN13640422 17/11/2021; DRKS (German Clinical Trials Register) - DRKS00026049.

Another Look at Fatigued Individuals with and without Chronic Ankle Instability: Posturography and Proprioception

Fatigue can impair function of the three sensory systems (vestibular, visual, and somatosensory) that control postural balance. Yet impairment may be greater among individuals with than those without chronic ankle instability (CAI). The present study used posturography assessment to extend previous findings demonstrating reduced function of the three systems in CAI participants following fatigue. Our aim in this study was to examine the influence of anaerobic and aerobic protocols on the function of these three sensory systems in individuals with and without CAI. We assessed 60 healthy physical education students (Mage = 24.3, SD = 3.4) by a Tetrax® Posturography device for Stability-Index and Fourier-frequencies [low sway (F1) visual input, medium-low sway (F2-F4) vestibular input, medium-high sway (F5-F6) somatosensory input] and by the Active Movement Extent Discrimination Assessment (AMEDA) for active ankle somatosensory ability, before and after performing anaerobic or aerobic protocols. Among participants, 45% were identified with CAI. We found significant Time effect (pre-post), CAI effect, and CAI X Time interactions for Fourier frequencies, Stability-Index, and AMEDA scores, indicating greater pre-post deterioration for those with CAI compared to those without CAI (p < .05). CI (95%) showed that, although there was a Time effect for F1, F2-F4, and F5-F6, only F5-F6 frequencies (i.e., somatosensory input) showed the CAI effect and the Time X CAI interaction. Thus, participants with and without CAI showed reduced visual, vestibular, and somatosensory ability following fatigue. While we found greater deterioration in both passive and active somatosensory ability (F5-6 and AMEDA) among individuals with CAI compared with those with no-CAI, we recommend intervention programs for improving vestibular abilities following fatigue in both those with and without CAI.

Effects of virtual reality immersion on postural stability during a dynamic transition task

Dynamic postural stability paradigms with virtual reality (VR) provide a means to simulate real-world postural challenges and induce customised but controlled perturbations. The purpose of this study was to determine the effects of a VR unanticipated perceptual sport perturbation on postural stability compared to traditional methods. Sixteen individuals between the ages of 18-23 years (19.5 ± 1.4 years) with no history of injury within 12 months were recruited. A double-leg to single-leg transition task was performed on a force plate in one of the following conditions: eyes open (EO), eyes closed (EC), a sport video with a standard non-immersive computer monitor (SV), and VR. The VR and SV conditions used a pre-recorded tackle avoidance task video where participants shifted to a leg in the opposite direction of a simulated opponent, while EC and EO were completed with auditory prompts. Relative to the EO condition, EC and VR induced greater postural instability. The largest effect sizes were between VR and EO for path length (g = 3.57), mean velocity anterior-posterior centre of pressure (CoP) (g = 3.65), and mean velocity medial-lateral CoP (g = 3.27). By including VR, the difficulty of a clinically based postural stability task was increased to the level of EC while accounting for the sporting environment.

Effects of load carriage on measures of postural sway in healthy, young adults: A systematic review and meta-analysis

Load carriage (LC) is a contributing factor to musculoskeletal injury in many occupations. Given that falls are a common mechanism of injury for those frequently engaging in LC, understanding the effects of LC on postural stability (PS) is necessary. A systematic review and meta-analysis was conducted to examine effects of LC on PS. Sixteen and 9 studies were included in the qualitative and quantitative synthesis, respectively. In most studies, it was found that LC leads to a decrease in PS with significant effects on center of pressure (COP) sway area (standardized mean difference = 0.45; p < 0.005) and COP anterior-posterior excursion (standardized mean difference = 0.52; p < 0.05). Furthermore, load magnitude and load placement are factors which can significantly affect COP measures of PS. It is recommended to minimize load magnitude and equally distribute load when possible to minimize LC effects on PS. Future research should examine additional factors contributing to differences in individual PS responses to LC such as changes in muscle activation and prior LC experience.

Effects of visual deprivation on the injury of lower extremities among functional ankle instability patients during drop landing: A kinetics perspective

Background: The ankle is prone to injury during drop landing with usual residual symptoms, and functional ankle instability (FAI) is the most common. Vision guarantees the postural stability of patients with FAI, and visual deprivation (VD) increases their risk of injury when completing various movements. This study explored injury risk during drop landing in patients with FAI under VD through the kinetics of lower extremities. Methods: A total of 12 males with FAI participated in the study (age, 23.0 ± 0.8 years; height, 1.68 ± 0.06 m; weight, and 62.2 ± 10.4 kg) completed single-leg drop landings under visual presence (VP) and VD conditions. Ground reaction force (GRF), time to peak GRF, joint torque, and vertical length variation (ΔL) were measured. Results: Significant effects were detected in the group for time to peak lateral GRF (p = 0.004), hip extensor torque (p = 0.022), ankle plantarflexion torque (p < 0.001), ankle varus torque (p = 0.021), lower extremity stiffness (p = 0.035), and ankle stiffness (p < 0.001). Significant effects of conditions were detected for vertical GRF, time to peak vertical and lateral GRF, loading rate, hip extensor torque, knee extensor torque, hip varus torque, knee varus torque, lower extremity stiffness, and ankle stiffness (p < 0.05). ΔL was affected by VD with a significant difference (p < 0.001). Conclusion: In patients with FAI, an unstable extremity has a higher injury risk than a stable extremity, and VD increases such risk. However, because the influence of the central nervous system on hip strategy is also affected, the effect on the unstable extremity is more significant and more likely to result in injury. Deepening the squat range may be an effective preventive measure for reducing injury risk of unstable extremities during drop landing.

Intrinsic Risk Factors for Ankle Sprain Differ Between Male and Female Athletes: A Systematic Review and Meta-Analysis

Background

Ankle sprains remain prevalent across most team sports. However, despite divergent ankle sprain injury rates in male and female athletes, little is known about potential sex-specific risk factors for ankle sprain.

Objective

To systematically investigate the sex-specific risk factors for ankle sprain.

Methods

Combinations of the key terms were entered into PubMed, Web of Science, Embase and Cochrane Library databases, and prospective studies reporting ankle sprain risk factors in males or females were included for meta-analysis.

Results

Sixteen studies were eligible for inclusion, for a total of 3636 athletes (735 female) and 576 ankle sprains (117 female). Out of 21 prognostic factors, previous ankle sprain injury (odds ratio = 2.74, P < .001), higher body mass index (SMD = 0.50, P < 0.001), higher weight (SMD = 0.24, P = 0.02), lower isometric hip abduction strength (SMD = − 0.52, P < 0.0001) and lower dynamic balance performance (SMD = − 0.48 to − 0.22, P < 0.001–0.04) were identified as risk factors in male athletes. In female athletes, out of 18 factors eligible for meta-analysis, only lower concentric dorsiflexion strength was identified as a risk factor (SMD = − 0.48, P = 0.005).

Conclusion

This meta-analysis provides novel evidence for different risk factor profiles for ankle sprain injuries between female and male athletes. Further studies, particularly in female athletes, are needed to strengthen the evidence.

Effects of Conservative Interventions on Static and Dynamic Balance in Individuals With Chronic Ankle Instability: A Systematic Review and Meta-analysis

OBJECTIVE

To determine which conservative interventions are effective for static and dynamic balance in patients with chronic ankle instability (CAI).

DATA SOURCES

PubMed, Cochrane Library, Web of Sciences, and CINAHL databases were searched up to March 20, 2022.

STUDY SELECTION

Randomized controlled trials investigating the effects of conservative interventions on static and/or dynamic balance in patients with CAI compared with those of different conservative interventions or controls were included.

DATA EXTRACTION

Two independent reviewers extracted the data. Certainty of the evidence was assessed using the GRADE approach.

DATA SYNTHESIS

Forty-eight studies (1906 participants) were included. Whole-body vibration training (WBVT) was significantly more effective than controls for both static (standardized mean difference, 1.13; 95% confidence interval [CI], 0.58-1.68; moderate-certainty evidence) and dynamic balance (0.56; CI, 0.24-0.88; low-certainty evidence). Balance training (BT) and joint mobilization were significantly more effective than controls for dynamic balance (0.77; CI, 0.41-1.14; and 0.75; CI, 0.35-1.14, respectively), but not for static balance (very low to low-certainty evidence). Adding other interventions to BT had no significant effect on either type of balance compared with that of BT alone (moderate to low-certainty evidence). Strength training (ST) and taping had no significant effect on either type of balance (very low- to low-certainty evidence). Multimodal interventions were significantly effective in improving dynamic balance (0.76; CI, 0.32-1.20; low-certainty evidence). Adding transcranial direct current stimulation to ST was significantly more effective for dynamic balance than ST (0.81; CI, 0.08-1.53; moderate-certainty evidence). The effects on balance were not significantly different among BT, ST, and WBVT (very low- to low-certainty evidence).

CONCLUSIONS

The significantly effective interventions reviewed may be treatment options for balance impairments associated with CAI. However, interventions should be chosen carefully, as much of the certainty of evidence is very low to low.

Regional brain atrophy in patients with chronic ankle instability: A voxel-based morphometry study

The objective of this study was to investigate whether brain volume changes occur in patients with chronic ankle instability (CAI) using voxel-based morphometry and assessing correlations with clinical tests. Structural magnetic resonance imaging data were prospectively acquired in 24 patients with CAI and 34 healthy controls. CAI symptoms and pain intensity were assessed using the Foot and Ankle Ability Measure (FAAM), Cumberland Ankle Instability Tool (CAIT), American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, and visual analog scale (VAS). The gray matter volume (GMV) of each voxel was compared between the two groups while controlling for age, sex, weight, and education level. Correlation analysis was performed to identify associations between abnormal GMV regions and the FAAM score, AOFAS score, VAS score, disease duration, and body mass index. Patients with CAI exhibited reduced GMV in the right precentral and postcentral areas, right parahippocampal area, left thalamus, left parahippocampal area, and left postcentral area compared to that of healthy controls. Furthermore, the right parahippocampal (r = 0.642, p = 0.001), left parahippocampal (r = 0.486, p = 0.016), and left postcentral areas (r = 0.521, p = 0.009) were positively correlated with disease duration. The left thalamus was positively correlated with the CAIT score and FAAM activities of daily living score (r = 0.463, p = 0.023 and r = 0.561, p = 0.004, respectively). A significant positive correlation was found between the local GMV of the right and left parahippocampal areas (r = 0.487, p = 0.016 and r = 0.763, p < 0.001, respectively) and the AOFAS score. Neural plasticity may occur in the precentral and postcentral areas, parahippocampal area, and thalamus in patients with CAI. The patterns of structural reorganization in patients with CAI may provide useful information on the neuropathological mechanisms of CAI.

Adaptations of postural sway dynamics and cortical response to unstable stance with stroboscopic vision in older adults

Background: Stroboscopic vision (SV), intermittent visual blocking, has recently been incorporated into postural training in rehabilitation. This study investigated interactions of postural fluctuation dynamics and cortical processing for the elderly during stabilometer stance with SV.

Methods: Thirty-five healthy elderly maintained an upright stance on a stabilometer. Along with postural fluctuation dynamics, EEG relative power and EEG-EEG connectivity were used to contrast neuromechanical controls of stabilometer stance with SV and full-vision.

Results: Compared with the full-vision, SV led to greater postural fluctuations with lower sample entropy and mean frequency (MF). SV also reduced regional power in the mid-frontal theta cluster, which was correlated to SV-dependent changes in the size of postural fluctuations. SV also enhanced the alpha band supra-threshold connectivity in the visual dorsal and frontal–occipital loops of the right hemisphere, and the supra-threshold connectivity from Fp2 positively related to variations in the MF of postural fluctuations.

Conclusion: SV adds challenge to postural regulation on the stabilometer, with the increasing regularity of postural movements and fewer corrective attempts to achieve the postural goal. The elderly shift over-reliance on visual inputs for posture control with more non-visual awareness, considering deactivation of the dorsal visual stream and visual error processing.

Is Kinesio Taping Effective for Sport Performance and Ankle Function of Athletes with Chronic Ankle Instability (CAI)? A Systematic Review and Meta-Analysis

Background and Objectives: Ankle injuries are the most common type of injury in healthy active individuals. If not treated properly, recurrent sprains can lead to a condition of chronic ankle instability (CAI). The aim of the present review is to evaluate the effects of Kinesio Taping (or KT) on sports performances and ankle functions in athletes with CAI. Materials and Methods: This systematic review with meta-analysis was carried out following the criteria of the Prisma Statement system (registered on Open Science Framework, number: 10.17605/OSF.IO/D8QN5). For the selection of the studies, PubMed, Scopus and Web of Science were used as databases in which the following string was used: (“kinesiology tape” OR “tape” OR “taping” OR “elastic taping” OR “kinesio taping” OR “neuro taping”) AND (unstable OR instability) AND (ankle OR (ankle OR “ankle sprain” OR “injured ankle” OR “ankle injury”)). The Downs and Black Scale was used for the quality analysis. The outcomes considered were gait functions, ROM, muscle activation, postural sway, dynamic balance, lateral landing from a monopodalic drop and agility. Effect sizes (ESs) were synthesised as standardized mean differences between the control and intervention groups. Calculation of the 95% confidence interval (CI) for each ES was conducted according to Hedges and Olkin. Results: In total, 1448 articles were identified and 8 studies were included, with a total of 270 athletes. The application of the tape had a significant effect size on gait functions, ROM, muscle activation and postural sway. Conclusions: The meta-analysis showed a significant improvement in gait functions (step velocity, step and stride length and reduction in the base of support in dynamics), reduction in the joint ROM in inversion and eversion, decrease in the muscle activation of the long peroneus and decrease in the postural sway in movement in the mid-lateral direction. It is possible to conclude that KT provides a moderate stabilising effect on the ankles of the athletes of most popular contact sports with CAI.

Uneven treadmill training for rehabilitation of lateral ankle sprains and chronic ankle instability: a pragmatic randomized controlled trial (Preprint)

Background

Lateral ankle sprains (LASs) are common injuries among military service members. Approximately 40% of individuals with an LAS progress to develop chronic ankle instability (CAI), a condition that results in substantial mechanical and neurophysiological impairment and activity limitation. Since proprioceptive and balance training improve functional outcomes and prevent secondary injury following LAS, they are recommended in clinical practice. Uneven treadmills are an innovative modality that challenge the sensorimotor system while performing an ecologically valid task simulating environments frequently encountered by service members with LAS and CAI.

Objective

The aim of this study is to evaluate whether the inclusion of uneven treadmill training in standard rehabilitation can improve clinical, functional, biomechanical, and patient-reported outcomes compared with the standard of care alone in service members with LAS and CAI. The prophylactic effects of treatment on secondary injury and identification of any contributing or mediating factors that influence outcomes following treatment will also be evaluated. We hypothesize that service members receiving uneven treadmill training will demonstrate greater improvements in clinical and instrumented measures of impairment, patient-reported function, and lower risk of injury recurrence than the control group immediately post and 18 months following treatment.

Methods

A multisite, parallel randomized clinical trial will be performed among service members aged 18-49 years being treated for LAS and CAI in military treatment facilities in the United States. Participants randomly assigned and allocated to receive the experimental intervention will be provided up to 12 sessions of training on an uneven terrain treadmill over a 6-week treatment course to supplement standard rehabilitation care. Treatment intensity of the rehabilitation exercises and treadmill training will be progressed on the basis of patient-perceived intensity and treatment responses. Outcome measures will include patient-reported outcomes, functional assessments, performance measures, and biomechanical measures. Investigators collecting outcome measures will be blinded to treatment allocation. Reinjury rates and patient-reported outcomes of function will be tracked over 18 months following treatment.

Results

The project was funded in September 2020. Patient recruitment began in November 2021, with 3 participants enrolled as of February 2022. Dissemination of the main study findings is anticipated in 2024.

Conclusions

This study will assess the impact of an innovative uneven-terrain treadmill on treatment outcomes in the rehabilitation of service members with LAS and CAI. The results of this study will be used to inform rehabilitation practices and to potentially improve functional outcomes and secondary prevention in this patient population.

Trial Registration

ClinicalTrials.gov NCT04999904; https://clinicaltrials.gov/ct2/show/NCT04999904?term=NCT04999904

International Registered Report Identifier (IRRID)

DERR1-10.2196/38442

Altered Visual Reliance Induced by Stroboscopic Glasses during Postural Control

Little is known about how disrupted vision affects visual reliance during postural control. postural control. Twenty-four physically active adults volunteered to participate in the study. Static postural control was quantified with center of pressure measures during a one-legged balance test with four different visual inputs (eyes-open (EO), high frequency of strobe vision (HSV), low frequency of strobe vision (LSV), and eyes-closed (EC)) and on two different surfaces (firm and foam). Dynamic postural control was calculated by the dynamic postural stability index and the Y-Balance test for three different visual inputs (EO, HSV, and LSV) and the two different surfaces. Romberg ratios (HSV/EO, LSV/EO, and EC/EO) were then calculated and used for statistical analysis to assess visual contribution during postural control. In the results, Romberg ratios were higher when people were on the foam surface than the firm surface in center of pressure total path in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Similarly, Romberg ratios were higher on the foam surface than the firm surface in dynamic stability index in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Stroboscopic glasses could alter visual reliance when the somatosensory system is disturbed by a foam pad during both static and dynamic postural control. Clinicians could use the glasses to manipulate visual reliance during dynamic balance training for patients with musculoskeletal injuries.

Optical flow balance perturbations alter gait kinematics and variability in chronic ankle instability patients

BACKGROUND

Individuals with chronic ankle instability (CAI) have known balance impairments thought to be the result of an inability to reweight sensory information. CAI patients place greater emphasis on visual information during single-limb stance than healthy controls but this evidence is based on removing visual information during static conditions.

RESEARCH QUESTION

Does perturbed optical flow effect step kinematics and variability in those with CAI differently than healthy controls? What is the relationship among ankle laxity, plantar cutaneous sensation, and susceptibility to perturbed optical flow in those with CAI?

METHODS

17 CAI patients and 17 healthy individuals participated in a crossover experimental study. Participants walked on a treadmill at 1.25 m/s while watching a speed-matched virtual hallway with and without continuous mediolateral (ML) optical flow perturbations. Three-dimensional pelvic and foot kinematics were recorded at 100 Hz for at least 300 consecutive steps in each condition. Step width (SW) and step length (SL) values were calculated from consecutive heel positions. Gait variability was characterized as the standard deviation of step width (SWV), step length (SLV), and ML sacrum motion (SMV) across all steps performed in each condition.

RESULTS

The CAI group exhibited a greater change in SWV (p = 0.037), SLV (p = 0.040), and ML SMV (p = 0.047) from the perturbed to unperturbed conditions relative to the healthy controls. A condition main effect was also noted for SW (p < 0.001) and SL (p < 0.001) as ML optical flow perturbations resulted in significant changes in SW and SL relative to the normal walking condition.

SIGNIFICANCE

Walking with ML optical flow perturbations induced greater variability changes in those with CAI relative to controls. When combined with the existing literature, this finding suggests that CAI individuals have a greater reliance on visual information in both static and dynamic (i.e. walking gait) conditions relative to healthy individuals.

Effects of Stroboscopic Vision on Postural Control in Individuals With and Without Chronic Ankle Instability

Objectives: Patients with chronic ankle instability (CAI) tend to increase their reliance on visual information, perhaps to compensate for proprioceptive deficits which appear after lateral ankle sprains. However, little is known about how limited visual feedback would alter static postural control in patients with CAI compared with copers and controls. The purpose of this study was to identify the effects of reduced visual feedback via stroboscopic glasses on static balance among CAI, coper, and uninjured control participants. Design: Controlled trial in a laboratory setting. Methods: Nineteen patients with CAI, 19 copers, and 19 controls participated in this study. Each participant performed a single-leg balance test with eyes open, stroboscopic vision, and eyes closed. Two-way analysis of variance (group × condition) was used to examine the differences between condition (eyes open, stroboscopic vision, and eyes closed) and group (CAI, coper, and control). Results: There were no significant interactions for static balance. Although there were no group effects among 3 groups for all static postural control measures, visual condition main effects were present (P < .01) for each dependent variable. Across all groups, anterior–posterior and mediolateral center of pressure path length and center of pressure velocity with stroboscopic vision were greater than the condition with eyes open (P < .01) and less than with eyes closed (P < .01). Conclusions: Stroboscopic glasses could be cost effective visual disruption equipment during static postural control regardless of ankle injury history. However, incorporating static balance with limited visual information via stroboscopic glasses could not display the differences in visual reliance in individuals with and without CAI.

The Intelligent Phenotypic Plasticity Platform (IP3) for Precision Medicine-Based Injury Prevention in Sport

The best predictor of future injury is previous injury and this has not changed in a quarter century despite the introduction of evidence-based medicine and associated revisions to post-injury treatment and care. Nearly nine million sports-related injuries occur annually, and the majority of these require medical intervention prior to clearance for the athlete to return to play (RTP). Regardless of formal care, these athletes remain two to four times more likely to suffer a second injury for several years after RTP. In the case of children and young adults, this sets them up for a lifetime of negative health outcomes. Thus, the initial injury is the tipping point for a post-injury cascade of negative sequelae exposing athletes to more physical and psychological pain, higher medical costs, and greater risk of severe long-term negative health throughout their life. This chapter details the technologies and method that make up the automated Intelligent Phenotypic Plasticity Platform (IP3)-a revolutionary new approach to the current standard of post-injury care that identifies and targets deficits that underly second injury risk in sport. IP3 capitalizes on the biological concept of phenotypic plasticity (PP) to quantify an athlete's functional adaptability across different performance environments, and it is implemented in two distinct steps: (1) phenomic profiling and (2) precision treatment. Phenomic profiling indexes the fitness and subsequent phenotypic plasticity of an individual athlete, which drives the personalization of the precision treatment step. IP3 leverages mixed-reality technologies to present true-to-life environments that test the athlete's ability to adapt to dynamic stressors. The athlete's phenotypic plasticity profile is then used to drive a precision treatment that systematically stresses the athlete, via a combination of behavioral-based and genetic fuzzy system models, to optimally enhance the athlete's functional adaptability. IP3 is computationally light-weight and, through the integration with mixed-reality technologies, promotes real-time prediction, responsiveness, and adaptation. It is also the first ever phenotypic plasticity-based precision medicine platform, and the first precision sports medicine platform of any kind.

Effects of balance training with stroboscopic glasses on postural control in chronic ankle instability patients

Individuals with chronic ankle instability (CAI) are believed to rely more on visual information during postural control due to impaired proprioceptive function, which may increase the risk of injury when their vision is limited during sports activities.

OBJECTIVES

To compare (1) the effects of balance training with and without stroboscopic glasses on postural control and (2) the effects of the training on visual reliance in patients with CAI.

DESIGN

A randomized controlled clinical trial.

METHODS

Twenty-eight CAI patients were equally assigned to one of 2 groups: strobe or control group. The strobe group wore stroboscopic glasses during a 4-week balance training. Static postural control, a single-leg hop balance test calculated by Dynamic Postural Stability Index (DPSI), and the Y-Balance test (YBT) were measured. During the tests, there were different visual conditions: eyes-open (EO), eyes-closed (EC), and strobe vision (SV). Romberg ratios were then calculated as SV/EO, and EC/EO and used for statistical analysis.

RESULTS

The strobe group showed a higher pretest-posttest difference in velocity in the medial-lateral direction and vertical stability index under SV compared with the control group (p < .05). The strobe group showed higher differences in EC/EO for velocity in the medial-lateral and anterior-posterior directions, and 95% confidence ellipse area (p < .05), and in SV/EO for velocity in the medial-lateral, 95% confidence ellipse area, and YBT-anterior direction (p < .05).

CONCLUSION

The 4-week balance training with stroboscopic glasses appeared to be effective in improving postural control and altering visual reliance in patients with CAI.

Slower visuomotor reaction time in division-I collegiate athletes with a history of ankle sprain

The purpose of this study was to compare visuomotor reaction time (VMRT) in collegiate athletes based on ankle sprain history. Participants included athletes with ankle sprain history (n = 18) and athletes with no ankle sprain history (n = 33). Participants completed an upper-extremity VMRT task which was comprised of eight wireless light-emitting diode sensors. The difference between reaction time (sec) and the number of "Hits" and "Misses" were compared between groups. The ankle sprain history group had significantly slower VMRT compared to the no ankle sprain history group with moderate effect sizes. However, there was no difference in the number of "Hits" or "Misses" between groups, despite observing moderate effect sizes. This result suggests that VMRT may be a potential target for prevention and rehabilitation strategies in individuals with ankle sprains. However, further research is needed to better understand the role of VMRT on the risk of ankle sprains.

Balance is impaired in symptomatic ankle osteoarthritis: A cross-sectional study

BACKGROUND

Ankle osteoarthritis (OA) is associated with several physical impairments but investigations into balance impairments in this population are limited. Understanding balance impairments in ankle OA may help inform the management of this condition.

RESEARCH QUESTION

Does balance overall performance differ between individuals with symptomatic radiographic ankle OA, asymptomatic radiographic ankle OA and healthy controls? Are there any differences in mediolateral or anteroposterior balance, or confidence to perform balance tasks between these groups?

METHODS

Ninety-six volunteers (31 symptomatic radiographic ankle OA, 41 asymptomatic radiographic ankle OA and 24 healthy controls) completed six static balance tasks: bilateral stance on a firm surface, bilateral stance on foam, and tandem stance, all performed with eyes open and closed. Centre of pressure (COP) data were collected using force plates. Confidence to perform each balance task was collected using an 11-point numerical rating scale.

RESULTS

Compared to controls, participants with symptomatic radiographic ankle OA had greater COP area when standing on a firm surface, foam and in tandem with eyes closed (all p < 0.05) and greater total COP sway in both firm surface and tandem stance conditions (p < 0.04). Participants with symptomatic ankle OA had greater COP area (p < 0.04) and total COP sway (p = 0.01) than those with asymptomatic ankle OA during tandem stance. Total COP sway and area were similar between asymptomatic ankle OA and control participants. Some differences in mediolateral and anteroposterior balance were identified between groups. Individuals with symptomatic ankle OA had lower confidence to perform the tandem stance eyes closed task compared to controls.

SIGNIFICANCE

Balance impairments and decreased balance confidence were identified in those with symptomatic radiographic ankle OA compared to asymptomatic individuals with and without radiographic ankle OA. This suggests that balance deficits in ankle OA may be related to symptoms, rather than radiographic evidence of disease.

Disrupted somatosensory input alters postural control strategies during the Star Excursion Balance Test (SEBT) in healthy people

BACKGROUND

Chronic adaptations, including persistent sensorimotor deficits, remain in individuals with a history of ankle instability, resulting in altered postural control strategies during functional tasks such as gait, running, or landing. However, we do not know the contribution of the altered somatosensory input on postural control strategies during a dynamic balance task such as the Star Excursion Balance Test (SEBT).

RESEARCH QUESTION

The purpose of this study was to characterize postural control strategies with and without disrupted somatosensory input during a dynamic balance task in people without chronic ankle sprain.

METHODS

This study was a crossover study design. Twenty healthy young adults (10 men, 10 women; age = 23.9 ± 3.0 years, height = 174.2 ± 7.4 cm, mass = 71.2 ± 16.7 kg) performed the posteromedial reach test during the SEBT while standing on the ground and on foam. We measured the maximum reach distance (MRD); joint angles of the ankle, knee, hip, and trunk in the sagittal, frontal, and transverse planes; and position and displacement of the center of mass (COM) and center of pressure (COP) during the posteromedial reach task.

RESULTS

The MRD was shorter when standing on the foam than on the ground (p < 0.001). There was a condition by phase interaction for ankle dorsiflexion; tibia internal rotation; and trunk flexion (p < 0.001; p = 0.03; p = 0.01, respectively). The COM and COP were positioned more laterally on the foam (p < 0.001). The COM and COP anterior-posterior displacements were more anterior during the foam condition (p = 0.017).

SIGNIFICANCE

By using a foam pad to disrupt somatosensory information, participants demonstrated altered strategies to control the joint kinematics, COM, and COP, as a function of posteromedial distance. Ankle and trunk movement strategies may influence the posteromedial reach distance. This model may simulate changes that occur with chronic ankle instability.

Lateral Ankle Sprain and Subsequent Ankle Sprain Risk: A Systematic Review

OBJECTIVE

To evaluate the evidence regarding the association between lateral ankle sprain (LAS) history and the subsequent LAS risk, as well as sex differences in the observed associations.

DATA SOURCES

PubMed, CINAHL, and SPORTDiscus were searched through July 2020 for articles on LAS history and incidence during the study period.

STUDY SELECTION

Studies were included if they were prospective in nature and the authors reported the number of participants with and those without a history of LAS at study initiation as well as the number of participants in each group who sustained an LAS during the investigation.

DATA EXTRACTION

Data were study design parameters as well as the number of participants with and those without an LAS history and the number of subsequent LASs that occurred in both groups. Risk ratios (RRs) with 95% CIs compared the risk of LAS during the study period between those with and those without an LAS history for each investigation.

DATA SYNTHESIS

A total of 19 studies involving 6567 patients were included. The follow-up periods ranged from 14 weeks to 2 years. Assessment scores indicated the studies were of moderate to high quality. A significantly higher risk of LAS during the study period was observed among those with a history of LAS in 10 of 15 studies (RR range = 1.29-6.06). Similar associations were seen in 4 of 6 studies of all-male samples (RR range = 1.38-8.65) and 1 of 4 studies with an all-female sample (RR = 4.28).

CONCLUSIONS

Strong evidence indicates that a previous LAS increased the risk of a subsequent LAS injury. Men with a history of LAS appeared to be at a higher risk of sustaining a subsequent LAS, but women were not. However, further data are needed to draw definitive conclusions from the limited number of sex-specific studies.

The effects of visual feedback disruption on postural control with chronic ankle instability

OBJECTIVES

The purpose of this study was to identify the effects of reduced visual feedback via stroboscopic glasses on dynamic postural control among chronic ankle instability (CAI), lateral ankle sprain (LAS) coper and uninjured control participants.

DESIGN

Controlled trial in a laboratory setting.

METHODS

Twenty CAI patients, 20 copers, and 20 controls participated in this study. Each participant performed a single-leg hop stabilization test with eyes open (EO) and stroboscopic vision (SV). Two-way ANOVAs (group × condition) were used to examine the differences between group (CAI, coper, and control) and condition (EO and SV).

RESULTS

There was a significant group by condition interaction for DPSI scores. CAI patients displayed increased DPSI scores with SV compared to EO (p < 0.01), and CAI patients had increased DPSI scores only with SV when compared with controls. All participants displayed decreased dynamic postural control under the SV condition compared to the EO condition (p < 0.01) regardless of ankle group.

CONCLUSIONS

CAI patients rely more on visual feedback during dynamic postural control than copers and controls. However, they may not be as able to compensate for the disrupted visual feedback during a dynamic task. Regardless of ankle injury history, stroboscopic glasses could be cost-effective visual disruption devices during a dynamic balance task.

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.

Progressive Visual Occlusion and Postural Control Responses in Individuals With and Without Chronic Ankle Instability

CONTEXT

Prophylactic and rehabilitative balance training is needed to maximize postural control and develop appropriate sensory organization strategies. Partially occluding vision during functional exercise may promote appropriate sensory organization strategies, but little is known about the influence of partially occluded vision on postural control in those with and without a history of musculoskeletal injury.

OBJECTIVE

To determine the effect of increasing levels of visual occlusion on postural control in a heterogeneous sample of those with and without chronic ankle instability (CAI). The secondary objective was to explore postural control responses to increasing levels of visual occlusion among those with unilateral and bilateral CAI relative to uninjured controls.

DESIGN

Cross-sectional.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-five participants with unilateral CAI, 10 with bilateral CAI, and 16 participants with no history of lower extremity injury.

MAIN OUTCOME MEASURES

All participants completed four 3-minute postural control assessments in double-limb stance under the following 4 visual conditions: (1) eyes open, (2) low occlusion, (3) high occlusion, and (4) eyes closed. Low- and high-occlusion conditions were produced using stroboscopic eyewear. Postural control outcomes included time-to-boundary minima means in the anteroposterior (TTB-AP) and mediolateral directions (TTB-ML). Repeated-measures analysis of variances tested the effects of visual condition on TTB-AP and TTB-ML.

RESULTS

Postural control under the eyes-open condition was significantly better (ie, higher) than the limited visual occlusion and eyes-closed conditions (P < .001) for TTB-AP and TTB-ML. For TTB-AP only, partially occluded vision resulted in better postural control than the eyes-closed condition (P ≤ .003).

CONCLUSIONS

Partial and complete visual occlusion impaired postural control during dual-limb stance in a heterogeneous sample of those with and without CAI. Stroboscopic eyewear appears to induce postural control impairments to the same extent as complete visual occlusion in the mediolateral direction.

Short-Term Effects of Balance Training with Stroboscopic Vision for Patients with Chronic Ankle Instability: A Single-Blinded Randomized Controlled Trial

Chronic Ankle Instability (CAI) is one of the most common musculoskeletal dysfunctions. Stroboscopic vision (SV) training has been deemed to enhance somatosensorial pathways in this population group; nevertheless, until recently no studies have addressed the additional effects of this treatment option to the traditional therapeutic approach.

METHODS

To evaluate the effectiveness of a partial visual deprivation training protocol in patients with CAI, a randomized controlled trial was carried out. Patients with CAI (n = 73) were randomized into either a balance training, SV training, or a control (no training) group. For participants assigned into training groups, they received 18 training sessions over 6 weeks. The primary outcome was dynamic balance as measured by the Star Excursion Balance Test assessed at baseline and after 6 weeks of intervention. Secondary outcome measures included ankle dorsiflexion range of motion, self-reported instability feeling, and ankle functional status.

RESULTS

Better scores in stroboscopic training and balance training groups in all outcome measures were observed in comparison with the control group with moderate to large effect sizes. Stroboscopic training was more effective than neuromuscular training in self-reported instability feeling (cohen's d = 0.71; p = 0.042) and anterior reach distance of the star excursion balance test (cohen's d = 1.23; p = 0.001).

CONCLUSIONS

Preliminary findings from the effects of SV Stroboscopic training in patients with CAI, suggest that SV may be beneficial in CAI rehabilitation.

Submaximal Force Steadiness and Accuracy in Patients With Chronic Ankle Instability

CONTEXT

Patients with chronic ankle instability (CAI) have demonstrated sensorimotor impairments. Submaximal force steadiness and accuracy measure sensory, motor, and visual function via a feedback mechanism, which helps researchers and clinicians comprehend the sensorimotor deficits associated with CAI.

OBJECTIVE

To determine if participants with CAI experienced deficits in hip and ankle submaximal force steadiness and accuracy compared with healthy control participants.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-one patients with CAI and 21 uninjured individuals.

MAIN OUTCOME MEASURE(S)

Maximal voluntary isometric contraction (MVIC) and force steadiness and accuracy (10% and 30% of MVIC) of the ankle evertors and invertors and hip abductors were assessed using the central 10 seconds (20%-87% of the total time) of the 3 trials.

RESULTS

Relative to the control group, the CAI group demonstrated less accuracy of the invertors (P < .001). Across all motions, the CAI group showed less steadiness (P < .001) and less accuracy (P < .01) than the control group at 10% of MVIC. For MVIC, the CAI group displayed less force output in hip abduction than the uninjured group (P < .0001).

CONCLUSIONS

Patients with CAI were unable to control ongoing fine force (10% and 30% of MVIC) through a feedback mechanism during an active test. These findings suggested that deficits in sensorimotor control predisposed patients with CAI to injury positions because they had difficulty integrating the peripheral information and correcting their movements in relation to visual information.

The effects of stroboscopic balance training on cortical activities in athletes with chronic ankle instability

OBJECTIVES

To investigate the effect of a 6-week stroboscopic balance training program on cortical activities in athletes with chronic ankle instability.

DESIGN

Randomized controlled trial.

SETTING

Single-center.

PARTICIPANTS

Thirty-nine participants were assigned to the strobe group (SG, n = 13), non-strobe group (NSG, n = 13), and control group (CG, n = 13).

MAIN OUTCOME MEASURES

Cortical activity and balance velocity were evaluated while the athletes were on the HUBER balance device. Electroencephalographic measurements of cortical activity were made at the transition from bipedal stance to single-leg stance.

RESULTS

The SG showed significant increases in Cz theta and alpha values and COP-v (center of pressure velocity) between pretest and posttest (p < 0.001, p = 0.003, p < 0.001). Posttest Cz theta was significantly higher in the SG compared to the CG (p = 0.009) and posttest Cz alpha was significantly higher in the SG compared to the NSG (p = 0.039) and CG (p = 0.001). Posttest COP-v was significantly higher in the SG than in the CG (p = 0.031) and NSG (p = 0.03).

CONCLUSIONS

Stroboscopic training may be clinically beneficial to improve balance parameters in athletes with CAI, and may have utility in sport-specific activity phases of rehabilitation to reduce visual input and increase motor control.