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Free papers #6

Chronic Ankle Instability and biomechanics

Chair: TBA

#32 - Prediction of Opioid Use Among Emergency Departments Across the United States for an Ankle Sprain Visit: An Analysis of the National Hospital Ambulatory Medical Care Survey

Presenting Author: Kyle Kosik

Authors & Affiliations: Kyle Kosik(1), Mathew Hoch(1), Alejandro Villasante Tezanos(1),Phillip Gribble(1)
(1)   University of Kentucky, Lexington, Kentucky, USA

Background: Ankle injury is the second most common musculoskeletal injury treated among Emergency Departments in the United States. Practice guidelines recommend an ankle sprain should be managed with RICE and home-based exercises. However, 1 out of 5 adults discharged with an ankle sprain filled a 3-day supply of opioids in 2015. This is concerning given that ankle sprains often occur among the adolescent population; an age group that has been increasingly exposed to opioids and at risk of future misuse. Recognizing factors that predict an ankle sprain patient to receive an opioid can help direct resources aimed at reducing their use.

Objective(s): To identify predictors of receiving an opioid from an Emergency Department in the United States for an ankle sprain.

Design & Methods: This was a secondary analysis of retrospective data collected using the National Hospital Ambulatory Medical Care Survey from 2010-2015. Visits with an isolated diagnosis of an ankle sprain were selected. Next, ankle sprain visits with an opioid listed within the first 5 medications were identified. Outcome variables included visit demographics (age, sex & race), pain (0-10), region (Northeast, South, Midwest & West), visit details (wait time & length of visit) and healthcare provider seen (physician, resident, nurse practioner & physician assistant). A binary logistic regression (p<0.100) using backwards elimination with initial consideration for variables with group differences (p<0.150).

Results: An estimated 5,264,675 ankle sprain visits occurred between 2010-2015 in Emergency Departments across the United States. Among those visits identified, approximately 40.82% were given an opioid. The explanatory variables included into the logistic model were age (p<0.001), sex (p=0.121), pain (p=0.030) and region (p<0.001). Results from the logistic regression revealed a significant odds ratio for age (OR: 0.965 [95% CI: 0.949 to 0.981], p < 0.001) and the Northeast (OR: 2.831 [95% CI: 1.402 to 5.719], p = 0.0080).

Conclusions: The odds of receiving an opioid increased when ankle sprain patients were younger, or the visit occurred in the Northeast region of the United States. These results provide targeted areas to reduce opioid exposure efforts by introducing other effective therapeutic interventions for mitigating acute pain following ankle sprain.


#33 - Disinhibition of spinal reflexes during landing tasks are characteristic of CAI, acute LAS-copers, and higher peak forces at ground contact

Presenting Author: Cassandra Thompson

Authors & Affiliations: Cassandra Thompson(1), Peter Clothier(1), Siobhan Schabrun(2)
(1)   School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith NSW 2751 
(2)    Neuroscience Research Australia, 186 Barker St, Randwick, NSW 2034, Australia

Background: Instability during landing is purported to result from the inappropriate integration of sensory feedback. However, research has yet to directly how the central nervous system regulates spinal reflex excitability during a dynamic landing task in those with CAI. Further, it is unclear if differences in spinal reflex excitability under static postures translate to altered spinal reflex excitability during dynamic tasks. Thus, a relationship between altered spinal reflex excitability, instability and force control during landing has yet to be well-established.

Objective(s): The aim of the current study was to determine if CAI participants present with whole-limb differences in spinal excitability during a horizontal jump-landing task using thoracolumbral stimulation. A secondary aim was to determine a relationship between differences in spinal reflex excitability and stability.

Design & Methods: Ten individuals with CAI, ten acute LAS-copers and ten healthy age, limb and gender-matched controls participated in this cross-sectional laboratory study. All participants met IAC inclusion criteria. Multi-segmental muscle responses (MMRs) were examined in soleus, tibialis anterior, peroneus longus, vastus medialis, vastus lateralis, rectus femoris and gluteus medius. MMRs were elicited at two time points following ground contact of a horizontal-jump landing task: the short-latency spinal reflex response (~45 ms post ground contact) and long-latency transcortical reflex response (~120 ms post ground contact).

Results: CAI individuals demonstrated greater spinal excitability of the ankle, knee and hip stabilisers during landing at both short- and long-latency responses. Copers similarly demonstrated higher spinal excitability of muscles surrounding the ankle and knee however, these changes were not significant. Differences in regulation of spinal excitability (MMRs) during landing explained up to 31% of the variance in reactive force control. Specifically, higher spinal excitability was associated with greater peak landing forces in mediolateral and vertical directions.

Conclusions: Up-regulating spinal reflex excitability may be an adaptive response to increase peripheral information regarding changes in ankle position. However, our data suggest that facilitated spinal excitability during landing contributes to higher peak forces and rate of force development experienced during the early stabilisation period. Unfortunately, higher peak forces at this time may also predispose individuals to further injury.


#34 - Differences in knee biomechanics during landing in chronic ankle instability, copers and healthy controls: Implications for ACL injury risk

Presenting Author: Chelsea Starbuck

Authors & Affiliations: Chelsea Starbuck(1,2), Chris Nester(1), Richard Jones(1,2)
(1)   University of Salford 
(2)    Manchester Institute of Health and Performance

Background: Lateral ankle sprains (LAS) are common in sport and associated with movements that require rapid decelerations such as landing. Up to 70% of individuals later develop chronic ankle instability (CAI). Those that do not develop CAI and appear to successfully cope following a LAS are classified as copers. There is some evidence to suggest chronically unstable ankles are associated with greater ACL loading (Terada et al., 2014). These individuals often present with reduced knee flexion and greater knee valgus and ankle eversion. However, it is unclear whether copers present with similar ACL injury risks as CAI individuals.

Objective(s): Despite a plausible link suggesting individuals with a history of LAS are likely to incur an ACL injury there is limited evidence exploring this relationship. Therefore, this study aims to compare knee and ankle biomechanical variables associated with ACL injury risk between CAI, copers and healthy controls. 

Design & Methods: Twenty-one physically active individuals participated in this study and were matched-grouped based on previous recommendations into CAI (age 23.5±3.2y, height 1.72±0.9m, mass 71.7±10.4kg), copers (age 24.4±4.4y, height 1.73 ± 1.0m, mass 71.7±10.4kg) and controls (age 24.4±4.4y, height 1.74±0.8m, mass 74.8±12.2kg). Knee and ankle kinematic data were collected during three single-leg landing (30cm height) trials. Values at initial contact and peak values were calculated. One-way ANOVA were conducted to compare differences between groups. Partial Omega squared effect sizes (ES) were also calculated, with values of 0.01, 0.06 and 0.09 indicating small, medium and large effect sizes.

Results: No significant differences were observed between groups. However, moderate to large ES (0.06-0.10) were observed. CAI (51.1±6.0º) and copers (47.6±15.5º) demonstrated reduced peak knee flexion compared to the control (57.6±4.4º) group. In addition, CAI had a more knee valgus position (-5.0±4.6º) when landing compared to both controls (-2.2±4.5º) and copers (-2.6±4.1º). Individuals with CAI landed with an inverted position (0.8±6.8º) compared to the controls (-0.72±6.5º). Whilst, copers were everted at initial contact (-2.3±5.6º) and demonstrated a greater peak eversion (-13.3±6.1º) compared to the control group (-8.9±6.5º).

Conclusions: Moderate to large ES presented provide preliminary evidence to suggest that a history of LAS could potentially increase ACL injury risk. CAI and copers demonstrated different mechanisms associated with increased ACL injury risk. Epidemiological studies are needed to explore this relationship between ankle sprain history and ACL injury risk.


#35 - White Matter Micostructue and Self-Reported Disability and Function in Individuals With and Without Chronic Ankle Instability

Presenting Author: Phillip Gribble

Authors & Affiliations: Phillip Gribble(1), Kyle Kosik(1), Nathan Johnson(1), Masafumi Terada(2)
(1)   University of Kentucky, Lexington, Kentucky, USA
(2)    Ritsumeikan University, Shiga, Japan

Background: Growing evidence suggests that central nervous system (CNS) adaptations are present in individuals with chronic ankle instability (CAI). Quantification of white matter (WM) microstructure via diffusion tensor imaging (DTI) MRI may help to capture the presence or result of such adaptations. DTI provides a novel approach to quantify the quality of critical microstructure in the brain, which could contribute to a better understanding of the potential source of neuromuscular alterations reported in CAI populations. Further, both WM-perceptual (self-reported function and disability) relationships may help to explain functional deficits in individuals with CAI.

Objective(s): Identify differences in WM microstructure in motor tracts in individuals with and without CAI. Fractional anisotropy (FA), which measures directional diffusion of water, was used to quantify WM microstructure. Further, for CAI participants we examined associations between WM microstructure and self-reported ankle function and disability using patient reported outcomes (PROs).

Design & Methods: Seventeen volunteers with (n=9; age: 31.11±7.15 years) and without (n=7; age: 23.57±1.27 years) CAI underwent MRI scans and completed ankle-region specific PROs. From the MRI scans, DTI produced FA values ranging from 0-1, with values closer to 1 indicating greater WM microstructure. PROs included: Identification of Functional Ankle Instability (IdFAI), Ankle Instability Instrument (AII), Foot and Ankle Ability Measure, and Cumberland Ankle Instability Tool (CAIT). FA values and PROs were compared between groups using Independent T-tests and Cohen’s d effect sizes. Associations between FA and PROs in participants with CAI were analysed with Pearson Product Moment correlations.

Results: CAI participants had higher IdFAI (p<0.001), AII (p<0.001), and lower FAAM (p=0.017), FAAM-Sport (p=0.002) and CAIT (p<0.001) scores compared to Controls. Superior cellebelar peduncle FA values were higher in the CAI group (0.548±0.061) compared to the Controls (0.484±0.065) (p=0.066; d=1.06). No difference in corticospinal tract FA values (CAI=0.626±0.020; Controls=0.620±0.025) (p=0.630; d=0.13) was observed. Among the CAI participants, FA of the superior peduncle had moderate to strong correlations with IdFAI (r=0.634; p=0.067), AII (r=0.911;p=0.022), FAAM (r=-0.617;p=0.077), FAAM-Sport (r=-0.40;p=0.290), and CAIT (r=-0.504;p=0.167). While not statistically significant, weak to moderate non-signficant correlations for corticospinal FA and the PROs were observed (r=-0.383 to 0.435).

Conclusions: CAI participants demonstrated higher WM microstructure in an efferent/corrective pathway of the cerebellum, the superior cerebellar peduncles. Higher WM microstructure was associated with more self-reported ankle disability and lower self-reported ankle function. Findings suggest the potential presence of WM adaptations indicative of increased cerebellar output and decreased motor efficiency.


#36 - Brain Alterations in Patients with Chronic Ankle Instability A Functional MRI Study

Presenting Author: Yinghui Hua

Authors & Affiliations: Shengkun Li(1), Yinghui Hua(1)
(1)   Department of Sports Medicine, Huashan Hospital, Fudan University. Shanghai,China

Background: In recent years, there are a lot of evidences demonstrating the potential neuronal changes or mechanisms associated with recurrent anterior shoulder instability and knee instability using fMRI. However, the potential neuronal changes related to CAI by using fMRI have rarely been reported. Despite the obviously clinical manifestations of CAI, the potential neuronal mechanisms related to the subjective perception of CAI have not been explored.

Objective(s): To investigate whether there are brain alterations in subjects with chronic ankle Instability (CAI) and which brain regions are effected..

Design & Methods: This study includes 17 consecutive right leg-dominant patients with CAI and thirteen control subjects without CAI. Brain alteration was observed by the functional magnetic resonance imaging (fMRI) method. (3.0-T scanner). An event design of 2 event-related conditions was used for this fMRI task. The SPRAIN condition (SC) means that we play self-edited videos of sports sprain for the subjects under this condition, while in CONTROL condition (CC), matching sports videos without sprain are presented.

Results: The fMRI results showed that patients with CAI had brain alterations in several cortical areas. Data analysis showed a significant increase of dACC, insula, PreCG, IFG, STG and SMG in the CC – SC contrast of instability group (IG) and in the control group (CG) - IG contrast of SC.

Conclusions: Patients with CAI have alterations of the brain in several cortical areas, which suggest that CAI might be regarded as a multifactorial dysfunction rather than a simple musculoskeletal disease.


#37 - EMG activity of the foot evertor and investor muscles at different stance phases when performing medial and lateral incline walk

Presenting Author: Rok Bavdek

Authors & Affiliations: Rok Bavdek(1)
(1)   Faculty of Sport, University of Ljubljana; Secondary School of Technical Professions, Ljubljana; Slovenia

Background: Ankle joint function is controlled by the tibial muscles. EMG activity of the tibial muscles can be increased through different walking techniques and thus could be an appropriate way of exercise for people with different ankle injuries, the most common of which is ankle sprain. As ankle sprain can occur in lateral and medial directions, it is important that neuro-muscular activation of the foot evertor and invertor muscles is optimal. One way of effective strengthening of the foot evertor and invertor muscles could be walking on medial and lateral incline ramp with different variations of the foot position.

Objective(s): The purpose of the study was to analyse the differences in EMG activity of evertor and invertor muscles during medial and lateral incline ramp walk at five different stance phases.

Design & Methods: The study included 30 subjects walking on a flat surface, walking at an inclination of 15˚ to foot eversion with an ankle inversion (INV) and walking at an inclination of 30˚ to foot inversion with an ankle eversion (EVE). We monitored the changes in the EMG values at m. TA, m. PL, m. SOL, m. GM and m. GL. The EMG signals was analysed at five different subphases of the stance phase (initial contact: 2 %, loading response: 20%, midstance: 50 %, terminal stance: 80%, and at 98% of stance phase). The EMG signals during walking were normalised to corresponding isometric MVC.

Results: The TA was the most active tibial muscle in INV at initial contact (39.8 ± 5.7 % MVC, p < 0.01), at terminal stance (45.5 ± 6.6 % MVC, p < 0.001) and at 98% of the stance phase (42.4 ± 5.5 % MVC, p < 0.001). The most active tibial muscle when walking in EVE was the PL at loading response (51.4 ± 6.2 % MVC; p < 0.001) and at midstance (54.4 ± 5.0 % MVC, p < 0.001).

Conclusions: The findings of this study showed that the TA, was the most active in INV. The muscle activity of the TA was high (quasi-isometric) during the entire stance phase. When performing EVE, we observed high muscle activity of the PL at loading response and at midstance, but not in the second half of the stance phase. To conclude, walking at a different inclination could be an appropriate exercise for the evertor and invertor muscles.


#38 - Electromyographic activity of the anterior tibial, fibular longus and gastrocnemius lateralis muscles during unipedal landing of healthy athletes: preliminary results

Presenting Author: Carolina Lins

Authors & Affiliations: Carolina Lins(1),Paloma Gonçalves Mendes(2),Adriano Alves Pereira(3),Pedro Henrique Alves Abreu(2), Matheus Rodrigues Campos(2),Lilian Ramiro Felício(2)
(1)   School of Medical Sciences of State University of Campinas - UNICAMP, Campinas/SP, Brazil.
(2)    School of Physical Education and Physical Therapy of Federal University of Uberlândia – UFU, Uberlândia/MG, Brazil.
(3)    School of Biomedical Engineereing of Federal University of Uberlândia – UFU, Uberlândia/MG, Brazil.

Introduction: Thelanding phase may cause a great number of ankle injuries, mainly lateral ankle sprain. The incidence of lower limb disorders is higher in sports which involve jump movements, such as volleyball and basketball. EMG parameters may help us to understand muscle interaction and the activation range during the landing phase of healthy athletes. It could clarify the muscle activation sequence in order to prevent ankle injuries and, therefore, enhance neuromuscular control in the sport population. 

Objective: to evaluate the sequence of EMG activity of ankle muscles during the unipedal landing phase of the single leg vertical jump test (SLVJ) in healthy athletes.

Methodology: 17 professional athletes from national volleyball and basketball teams were evaluated. Inclusion criteria were healthy athletes, aged 15 to 20, without lower limb injuries throughout their sports life. During the landing phase of the SLVJ test, the electrical activity of the muscles was recorded by using a surface EMG for measuring and comparing the range of EMG sign (integrated EMG activation) of the anterior tibial (AT), fibular longus (FL) and gastrocnemius lateralis (GL) muscles. The Shapiro-Wilk Test was used for testing normal distribution and the Wilcoxon Test was used for statistical analysis (p≤0.05).

Results: The activation level of AT was higher [1.14 (1.07; 1.58); p=0.002] when compared to FL [0.99 (0.75; 0.65); p= 0.0004] and GL [0.78 (0.65; 0.95); p=0.004] while the activation level of FL was higher when compared to GL (p=0.004).

Conclusion: The EMG activation level of ATwas higher when compared to FL and GL of healthy volleyball and basketball athletes in the landing phase of the SLVJ test. This is the first phase of a study that may evaluate and compare healthy athletes with athletes diagnosed with chronic ankle instability.