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Free papers #3

Chronic Ankle Instability- imaging, mechanisms and care

Chair: Igor Tak

#13 - Ultrasound measures of intrinsic foot muscle size an motor activation following lateral ankle sprain and chronic ankle instability 

Presenting Author: John Fraser

Authors & Affiliations: John Fraser(1,2),Jay Hertel(1)
(1)   Department of Kinesiology, University of Virginia, USA
(2)    Warfighter Performance Department, Naval Health Research Center, San Diego, CA, USA

Background: The foot is a dynamic complex that allows for rapid changes in shape and rigidity during ground accommodation, force attenuation, and return of force during propulsion. The ability of the intrinsic foot muscles (IFM), which include the abductor hallucis (AbdH), flexor digitorum brevis (FDB), quadratus plantae (QP), and flexor hallucis brevis (FHB), to contract and resist force are essential during these functions. Peripheral and central neuromotor deficits are common following lateral ankle sprains (LAS) and in chronic ankle instability (CAI) that may affect IFM size and function.

Objective(s): To assess the effects of ankle injury status on IFM size at rest and during contraction in recreationally-active young adults with LAS, Copers, CAI, and healthy controls, while factoring the influences of sex, BMI, and foot phenotype.

Design & Methods: Foot Posture Index (FPI), Foot Mobility Magnitude (FMM), and ultrasonographic cross-sectional area of the AbdH, FDB, QP, and FHB were assessed at rest, unresisted, and with resistance in 22 healthy (13 females, mean age: 19.6±0.9, BMI: 22.5±3.2, FPI: 4.2±3.9, FMM: 2.5±1.8), 17 LAS (9 females, mean age: 21.8±4.1, BMI: 24.1±3.7, FPI: 2.5±3.4, FMM: 2.7±1.7), 21 Copers (13 females, mean age: 20.8±2.9, BMI: 23.7±2.9, FPI: 3.6±4., FMM: 1.8±1.3), and 20 CAI (15 females, mean age: 20.9±4.7, BMI: 25.1±4.5, FPI: 4.4±3.6., FMM: 2.3±1.1) participants. Contraction measures were normalized to resting IFM size.

Results: A linear regression analysis assessing group, sex, BMI, FPI, and FMM on IFM size at rest and during contraction found sex (p<.001), BMI (p=.01), FPI (p=.05), and the FMM*FPI interaction (p=.008) predicted 19% of the variance (p=.002) in resting AbdH measures. Sex (p<.001) and BMI (p=.02) also explained 24% of resting FDB measures (p<.001). Having a recent LAS (p=.03) and FMM (p=.02) predicted 11% of unresisted QP contraction measures (p=.04), with sex (p<.001) explaining 13% of resting QP measures (p=.02). Both sex (p=.01) and FMM (p=.03) predicted 16% of resting FDB measures (p=.01). There were no other statistically significant findings.

Conclusions: IFM resting ultrasound measures were primarily determined by sex, BMI, and foot phenotype. Injury status was not a significant or substantial factor in IFM size or activation, which limits the clinical utility of these ultrasonographic assessments in young adults with LAS and CAI.


#14 - Fibular position in chronic ankle instability radiographically measured in weight-bearing

Presenting Author: Ishanka Weerasekara

Authors & Affiliations: Ishanka Weerasekara(1), Peter Osmotherly(1), Suzanne Snodgrass(1), John Tessier(1), Darren A. Rivett(1)
(1)   School of Health Sciences, Faculty of Health and Medicine, The University of Newcastle, Callaghan, Australia

Background: Bony incongruence related to fibular position has been observed following ankle sprains in non weight-bearing radiographs. However, the use of differing radiographic measurement methods has resulted in inconsistent findings. A discrimination score for an abnormally positioned fibula in relation to the tibia to differentiate individuals with and without ankle instability has not been described to date. Furthermore, reliability measures of fibular position from weight-bearing radiographs have not been reported.

Objective(s): To compare weight-bearing radiographic measures of normalised fibular position in individuals with chronic ankle instability (CAI) with those from healthy individuals. In addition, to assess reliability, specificity and sensitivity of weight-bearing radiographic measures of normalised fibular position for identifying altered fibular positon in CAI.

Design & Methods: A lateral X-ray was taken of the affected ankle of 33 adults ≥ 18 years with CAI, and the matched ankle in 33 healthy controls in weight-bearing. Fibular position was considered as the distance between the anterior edges of the distal fibula and tibia. Fibular position was normalised to the maximum tibial width (within the distal-epiphysis) and compared between groups using t-tests. 
Reliability measures were calculated using intra-class correlation co-efficients. Sensitivity, specificity and a recommended threshold for the normalised fibular position that best differentiates individuals with CAI from those with healthy ankles was determined using a receiver operating characteristic curve.

Results: Individuals with CAI had a normalised fibular position that was significantly more anterior compared to healthy controls (mean difference (MD)=3.01%, 95% CI=0.19-5.83, p=0.04). Reliability was excellent for measuring normalised fibular position (intra-rater, ICC2, 1 0.99, 95% CI 0.98-1.00; inter-rater 0.98, 95% CI 0.96-.99). The threshold normalised fibular position was 27%, and a score >27% indicates an increased likelihood of being an individual with CAI. Sensitivity and specificity were reported as 69.7% and 54.5% respectively, for this threshold of normalised fibular position.

Conclusions: Individuals with CAI had a more anteriorly positioned fibula in relation to the tibia in weight-bearing as compared to matched healthy controls. Weight-bearing radiographic measurements of fibular position have excellent reliability. Low specificity and sensitivity for normalised fibular position suggest it has little ability to predict the presence of CAI.


#15 - Gluteus medius dysfunction throughout walking gait in chronic ankle instability patients compared to copers

Presenting Author: Alexandra DeJong

Authors & Affiliations: Alexandra DeJong(1), Rachel Koldenhoven(1), Jay Hertel(1)
(1)   University of Virginia, Department of Kinesiology, Exercise and Sport Injury Lab

Background: Chronic ankle instability (CAI) patients often present with altered gait mechanics compared to ankle sprain copers. There is increasing evidence to suggest proximal alterations contribute to the lasting impairments uniquely associated with CAI, however less is known about the influence of gluteal muscle function during gait. Ultrasound imaging (USI) allows for a visual analysis of dynamic muscle activity, and overcomes limitations of cross-talk associated with electromyography. Previous USI investigations have identified gluteus medius (GMED) deficits in CAI patients when compared to healthy individuals; it would be important to note if these differences persist in individuals with disparate ankle sprain outcomes.

Objective(s): To investigate unilateral gluteus maximus (GMAX) and GMED functional activity throughout treadmill walking at three speeds (preferred, 120% preferred, and 1.35 meters per second) in individuals with CAI compared to ankle sprain copers.

Design & Methods: 14 females (21±3yrs) with CAI (IdFAI=11) and 14 copers (IdFAI=21) walked at preferred, 120% preferred, and standardized speeds in randomized order. Ground reaction forces and 10-second USI GMAX and GMED clips were simultaneously recorded. USI clips were reduced using ground reaction forces to extract 55 measurement frames (11 frames over 5 cycles). Normalized gluteal thickness measures were used to determine functional activity ratios (FARs). 2x3 ANOVAs were run to assess group and speed effects on GMAX and GMED FARs throughout walking using statistical parametric mapping (SPM). Post-hoc SPM t-tests and Cohen’s d effect sizes were assessed for significant findings (p≤.05).

Results: There was a significant main effect for GMED thickness differences throughout the entire gait cycle (p<.001); post-hoc t-tests revealed that CAI patients had significantly less GMED FARs when compared to coper counterparts (Mean Differences: 0.10-0.18; Cohen’s D: 1.00-3.17). GMED FAR’s remained below resting thickness measures (FARs<1), while copers demonstrated increased activity throughout the majority of gait (FARs: 0.97-1.11). GMED alterations were independent of gait speed as there was no significant main effect for speed, nor an interaction between group and speed. Additionally, there were no significant group or speed main effects, nor a group by speed interaction for GMAX FARs.

Conclusions: GMED dysfunction throughout gait may influence lasting movement impairments associated with CAI, as ankle sprain copers did not present with similar deficits (FAR’s>1). These findings offer novel insights into proximal muscle dysfunction throughout fundamental movement, and suggest a potential avenue for neuromuscular education to improve CAI patient outcomes.


#16 Efficacy of stability-based training with visualisation in people with chronic ankle instability

Presenting Author: Lauren Forsyth

Authors & Affiliations: Lauren Forsyth(1), Jason Bonacci(2), Craig Childs(3)
(1)   Faculty of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
(2)   School of Exercise and Nutrition Science, Deakin University, Geelong, Australia
(3)   Faculty of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom

Background: Chronic ankle instability (CAI) is associated with recurrent ankle sprains, mechanical laxity and/or perceived instability. Stability-based rehabilitative training has been found to prevent further injury, however poor programme compliance can hinder the programme’s effectiveness. Virtual reality (VR) systems have been shown to provide a stimulating and motivational environment that may be more conducive to rehabilitation adherence. An emerging technique, visualisation, is the connection of biomechanical analysis and VR. Visualisation produces real-time feedback, by accurately monitoring movement and progress, using VR to create a diverse, challenging, and controllable environment, representative of real-world situations.

Objective(s): The aim of this study was to determine the feasibility of incorporating visualisation into stability training for people with chronic ankle instability. Specifically, the effect of visualisation on performance of the Star Excursion Balance Test (SEBT), as well as participant’s enjoyment of the experience

Design & Methods: Individuals with CAI were randomly allocated to the 4-week stability-based training programme with visualisation (VIS), or without (NO-VIS). Balance exercises were based on standard practice, with adaptations for visualisation. Participants completed the SEBT and Cumberland Ankle Instability Tool (CAIT) prior to, and after training. Participants recorded enjoyment of training using the Physical Activity Enjoyment Scale (PACES-8). The Strathclyde Cluster Model and pointer calibration were applied to all participants. Movement was tracked using Vicon Tracker (Vicon, Oxford, UK), with testing controlled and recorded using D-Flow (Motek Medical, Amsterdam, The Netherlands). Effect size (d) was calculated and interpreted using Hopkin’s recommendations.

Results: Of 17 participants (Vis=10,No-Vis=7), there were 2 drop outs (Vis=1,No-Vis=1). No adverse events were reported and participant drop-out was due to injury unrelated to the study. There were no between-group differences in population demographics and pre-training CAIT scores (p⩾0.2). Following training there was a non-significant but small effect (d=0.6,p=0.3) favouring the NO-VIS group for an increase in CAIT score. There was a non-significant but moderate effect (d=1,p=0.20) favouring the VIS group for an increase in average reach distance on the SEBT. There was a non-significant but large effect (d=1.4,p=0.16) for higher enjoyment of training in the VIS group.

Conclusions: Results of this study support the feasibility and safety of stability training with visualisation in those with CAI. Observations of a more enjoyable experience, alongside improved postural control suggest visualisation may enhance stability-based training. Implications of this will be discussed, along with the practicalities and logistics of running such programmes.

#17 - Altered spinal-level sensorimotor control related to pain and perceived instability in people with chronic ankle instability

Presenting Author: Cassandra Thompson

Authors & Affiliations: Cassandra Thompson(1), Claire Hiller(2), Siobhan Schabrun(3)
(1)   Department of Sport and Exercise, Western Sydney University AU
(2)    Department of Physiotherapy, Sydney University AU
(3)    Research Fellow, Neurological Research Australia (NeuRA)

Background: Individuals with CAI are unable to modulate presynaptic inhibition, and have greater recurrent inhibition, of soleus spinal reflex excitability when compared to healthy controls. However, comparisons of presynaptic and recurrent inhibition in CAI have yet to include a LAS-coper population. Thus, it is unknown whether impaired regulation of the spinal reflex pathway through presynaptic and recurrent inhibition, is characteristic of injury history (common to CAI and LAS-copers), or symptomatic of chronic ankle instability (CAI alone).

Objective(s): To compare soleus spinal reflex excitability, presynaptic inhibition and recurrent inhibition between CAI, acute Lateral Ankle Sprain coper (LAS-coper) and healthy populations. The relationship between spinal reflex excitability and pain and perceived instability in people with CAI was also examined.

Design & Methods: Twelve individuals with CAI, twelve ‘copers’ and twelve healthy age, limb and gender-matched controls participated in this cross-sectional laboratory study. All participants met IAC inclusion criteria. Soleus H-reflex recruitment curves, presynaptic excitability and recurrent inhibition of the spinal-reflex pathway were examined during static double- and single-leg stance. Reporting of pain and perceived instability were used to perform a regression analysis on measures of soleus spinal excitability in people with CAI, LAS-coper and healthy controls.

Results: Soleus spinal reflex excitability was greater during single-leg stance in CAI compared to healthy and coper individuals. Presynaptic inhibition was three-times less in CAI participants compared to both healthy controls and copers. There were no differences between healthy and coper participants in spinal-level measures of sensorimotor control. Reports of pain explained 15-16% of the variance in soleus spinal reflex excitability and presynaptic inhibition during single and double-leg stance, while perceived instability explained 20% of the variance in spinal reflex during single-leg stance only.

Conclusions: CAI participants presented with an inability to supress soleus spinal reflexes during tasks with increased postural threat; likely due to disinhibition of presynaptic mechanisms. Pain and perceived instability may exacerbate changes in spinal-level sensorimotor control in CAI.


#18 - Gait Biomechanics at Three Walking Speeds in Individuals with Chronic Ankle Instability and Ankle Sprain Copers

Presenting Author:Rachel Koldenhoven

Authors & Affiliations:Rachel Koldenhoven(1), Mark Abel(2), Susan Saliba(1), Joseph Hart(1), Jay Hertel(1)
(1)    University of Virginia, Department of Kinesiology, Charlottesville, VA 22904
(2)    University of Virginia, Department of Orthopaedic Surgery, Charlottesville, VA 22904

Background: Individuals with CAI have demonstrated a more inverted foot position during walking when compared to a healthy control group. Copers are individuals who have had an ankle sprain but learn to cope and return to pre-injury levels of function and may be a better comparison group than healthy controls because they have had the same initial injury. Differences in gait biomechanics during different walking speeds between copers and individuals with CAI have not been established.

Objective(s): The objective was to simultaneously analyze lower extremity walking gait kinematics, kinetics, and surface electromyography (sEMG) between individuals with CAI and copers at a preferred walking speed (PWS), 120% preferred walking speed (120PWS), and a standardized walking speed (SWS) of 1.34 m/s.

Design & Methods: Thirty-six young adult participants (16F, 2M coper; 16F, 2M CAI) walked on an instrumented treadmill at three walking speeds (PWS, 120WS, SWS). Three-dimensional kinematics and kinetics were analyzed at the ankle, knee, and hip. EMG root mean square amplitude was analyzed for fibularis longus, tibialis anterior, medial gastrocnemius, and gluteus medius muscles. Ten consecutive strides from each speed were analyzed using statistical parametric mapping (SPM). A 2x3 group by speed SPM-ANOVA and post-hoc SPM t-tests were used to compare differences between the coper and CAI groups.

Results: The CAI group had greater ankle inversion at IC (PWS: CAI=3.3+3.4º, Coper=-1.1+4.6º; 120PWS: CAI=3.6+3.7º, Coper =-1.4+4.1º; SWS: CAI=4.4+4.6, Coper=-2.2+5.0º) and during swing (Peak inversion: PWS: CAI=5.6+5.1º, Coper=0.4+4.3º; 120WS: CAI=5.6+5.4º, Coper=1.2+4.2º; SWS: CAI=6.8+5.9º, Coper=0.6+4.2º). Group differences lasted for more % of gait as speed increased (34% PWS, 61% 120WS, 90% SWS). The CAI group had greater peak hip adduction during swing (PWS: CAI=-5.1+5.7º, Coper=-0.6+3.4º; 120PWS: CAI=-5.1+4.5º, Coper=-1.0+3.3º; SWS: CAI=-5.2+4.2º, Coper=-1.6+3.1º). Peak internal ankle plantarflexion moment during mid-late stance was greater in CAI (120WS: CAI=-1.7+0.6 Nm/kg, Coper=-1.0+0.8 Nm/kg; SWS: CAI=-1.8+0.7 Nm/kg, Coper=-1.2+0.7 Nm/kg). There were no significant differences for sEMG outcomes.

Conclusions: Group differences in ankle inversion kinematics between the CAI and Coper groups got larger and lasted for more of the gait cycle as walking speed increased. We recommend that future studies evaluating gait biomechanics in CAI patients utilize a standardized walking speed of at least 1.34 m/s.


#19 - The Gut Microbiota Profile in Individuals with a History of Lateral Ankle Sprain

Presenting Author: Masafumi Terada

Authors & Affiliations: Masafumi Terada(1), Masataka Uchida(1), Tadashi Suga(1), Tadao Isaka(1)
(1)   Ritsumeikan University, Shiga, Japan

Background: Existing literature provides evidence of altered CNS function and increased psychological stress following lateral ankle sprain (LAS). It has become increasingly evident that the gut microbiota is interacted with central nervous system (CNS) and relates to reduced function and self-reported disability. Researchers have identified alterations in microbial diversity in the gastrointestinal tract in several pathologies, including Parkinson’s disease, psychological disorders, and osteoarthritis. However, associations between LAS and the gut microbiota profile have not been investigated. Determining if LAS is associated with the gut microbiota profile has the potential to create a paradigm shift for intervention strategies in patients with LAS.

Objective(s): Identify differences in the gastrointestinal microbiota profile in individuals with and without a history of LAS.

Design & Methods: Fifty male college student athletes (basketball, football, and track and field) with (n=32) and without (n=18) a previous history of LAS participated in this study. Faecal samples were collected in the morning after awakening, and faecal microbiota were characterized via bacteria 16S rRNA amplicon sequencing. Alpha diversity metrics (Chao1 index, ACE index, Shannon index, Simpson index, and Observed species) were calculated. Independent t-tests were used to compare differences in the gut microbial diversity and composition between participants with and without a history of LAS.

Results: The LAS history group had higher Chao1 index (2227.67±799.46) compared to the control group (2899.39±1432.48) (p=0.0038). There were significantly higher proportions of Bacteroides fragilis in athletes with a history of LAS (2.67%±4.26) compared with the controls (0.72%±1.51) (p=0.029). There were no significant results for other microbiota outcomes (p>0.05).

Conclusions: The gut microbiota of athletes with a previous history of LAS had less diverse compared to controls, indicating potential associations between LAS and the gut microbiota. Continued work is needed to improve the understanding of the underlying neuroimmunological mechanism of altered gut microbiota among individuals with a history of LAS.