The impact of whole-body vibration training and proprioceptive neuromuscular facilitation on biomechanical characteristics of lower extremity during cutting movement in individuals with functional ankle instability: A parallel-group study

BACKGROUND

We compared the effects of whole-body vibration training and proprioceptive neuromuscular facilitation on the biomechanical characteristics of the lower limbs in functional ankle instability patients during cutting movement to ascertain the superior rehabilitation method.

METHODS

Twenty-two male College students with unilateral functional ankle instability volunteered for this study and were randomly divided into whole-body vibration training group and proprioceptive neuromuscular facilitation group. Kinematics data and ground reaction forces were collected using infrared motion capture system and 3-D force plates synchronously during cutting. Repeated measures two-way ANOVA was performed to analyze the data.

FINDINGS

Both training methods reduced the maximum hip abduction angle (p = 0.010, effect size: proprioceptive neuromuscular facilitation = 0.69; whole-body vibration training = 0.20), maximum knee flexion angle (p = 0.008, effect size: proprioceptive neuromuscular facilitation = 0.39, whole-body vibration training = 1.26) and angular velocity (p = 0.014, effect size: proprioceptive neuromuscular facilitation = 0.62, whole-body vibration training = 0.55), maximum ankle inversion angular velocity (p = 0.020, effect size: proprioceptive neuromuscular facilitation = 0.52, whole-body vibration training = 0.81), and knee flexion angle at the time of maximum vertical ground reaction forces (p = 0.018, effect size: proprioceptive neuromuscular facilitation = 0.27, whole-body vibration training = 0.76), and increased the maximum ankle dorsiflexion moment (p = 0.049, effect size: proprioceptive neuromuscular facilitation = -0.52, whole-body vibration training = -0.22). Whole-body vibration training reduced the maximum ground reaction forces value in the mediolateral directions (p = 0.010, effect size = 0.82) during cutting movement.

INTERPRETATION

These findings suggested that the two types of training might increase neuromuscular conduction function around the ankle. After these two types of training, functional ankle instability patients showed a similar risk of injury to the lateral ankle ligaments during cutting.

Randomized controlled trial study of intelligent rehabilitation training system for functional ankle instability

To investigate the intervention effect of an intelligent rehabilitation training system on patients with functional ankle instability (FAI) and to advance the research to optimise the effect of FAI rehabilitation training. Thirty-four FAI patients who participated in this trial in Guilin City from April 2023 to June 2023 were recruited as research subjects, and all subjects were randomly divided into the control group (n = 17) and the observation group (n = 17). Both groups received the conventional rehabilitation training intervention for 6 weeks, and the observation group received the additional training using the intelligent rehabilitation training system training invented by our team. Visual analogue scale (VAS), ankle active mobility, ankle muscle strength and Y-balance test (YBT) were assessed before and after treatment. Two-way repeated measures ANOVA shows that the interaction effect between time and group of VAS scores was significant (F = 35.644, P < 0.05). The interaction effect between time and group of plantar flexion mobility was significant (F = 23.948, P < 0.05), the interaction effect between time and group of dorsiflexion mobility was significant (F = 6.570, P < 0.05), the interaction effect between time and group of inversion mobility was significant (F = 8.360, P < 0.05), the interaction effect between time and group of eversion mobility was significant (F = 10.113, P < 0.05). The interaction effect between time and group of inversion muscle strength was significant (F = 18.107, P < 0.05). The interaction effect between time and group of YBT scores was significant (F = 33.324, P < 0.05). The Intelligent Rehabilitation Training System can effectively reduce pain in FAI patients, improve joint range of motion, increase inversion strength, and improve dynamic balance of the affected limb.

Evaluation of dynamic postural control during single-leg landing tasks using initial impact force, landing leg stiffness and time to stabilisation

Time to stabilisation (TTS) provides limited information to evaluate the dynamic postural control for individuals with functional ankle instability in single-leg landing task. More information is needed to understand TTS and evaluate the dynamic postural control better. The purpose is to develop a method estimating TTS, initial impact force (IIF) and landing leg stiffness (LLS) through fitting ground reaction force (GRF) decay in single leg landing with exponential vibration decay function (EVDF), and investigate effects of landing directions and GRF components on these parameters. Thirty-nine healthy participants were recruited. EVDF was used to fit GRF decays in different single-leg landings. TTS, IIF, and LLS were compared across landing directions and GRF components. The mean regression determinants of fitting GRF decays with EVDF were greater than 0.50. TTS was sensitive to GRF components (P = 0.041 females, P = 0.028 males). IIF was sensitive to GRF components (P = 0.001) for both genders. LLS was sensitive to GRF components (P = 0.023) for males. This method showed a moderate to strong feasibility for reporting GRF decay during landing, and provided movement characteristic information for better understanding of dynamic postural control together with TTS during landing.

Effects of biofeedback on biomechanical factors associated with chronic ankle instability: a systematic review with meta-analysis

BACKGROUND

Biofeedback may alter the biomechanics of lower extremities in patients with chronic ankle instability (CAI). We aimed to systematically review the literature on the effect of gait-training and biofeedback on biomechanical parameters in individuals with CAI and conduct a meta-analysis.

METHODS

We searched four databases including PubMed, Web of Science, Scopus and Embase from their inception through 30th June 2022. The Downs and Black appraisal scale was applied to assess quality of included studies. Two reviewers screened studies to identify those reporting the effect of biofeedback on biomechanical factors associated with CAI. Outcomes of interest were kinetics and kinematics. Two authors separately extracted data from included studies. Data of interest were study design, number of sessions, intervention, tools, outcomes, number, sex, age, height, and body mass of participants.

RESULTS

Thirteen studies with a total of 226 participants were included. Biofeedback was capable of shifting center of pressure (COP) and lateral plantar pressure medially and reducing foot inversion, adduction, propulsive vertical ground reaction force (vGRF), ankle joint contact force, peak pressure and pressure time integral in the lateral mid-foot and forefoot. Auditory biofeedback had agreater impact on modifying plantar pressure in individuals with CAI. The meta-analyses revealed that visual biofeedback reduces peak pressure in lateral mid-foot and pressure time integral at lateral and medial heel and pressure increases under the hallux.

CONCLUSION

Biofeedback can alter pressure, vGRF, and foot inversion associated with CAI. Auditory biofeedback had greater impact on modifying plantar pressure in individuals with CAI. Further studies are required to assess the prolonged effect and clinical consequences of biofeedback or a combination of feedback on CAI in different age groups. Moreover, developing a low-cost and user-friendly device that can be evaluated in high quality RCTs is important prior to implementing the intervention in the clinical setting to reduce symptoms of CAI.

Relationship between ankle pain, range of motion, strength and balance in individuals with functional ankle instability: a cross-sectional study

BACKGROUND

About 15-60% of individuals with ankle sprains may develop functional ankle instability (FAI), which is characterised by ankle pain, decreased muscle strength, limited range of motion, and impaired balance, causing a decline in social activity and quality of life. However, the relationship between those characters is still unclear. This study aimed to investigate whether a relationship existed between ankle pain, active range of motion (AROM), strength and balance and if ankle pain, AROM and strength can predict balance in individuals with FAI.

METHODS

Seventy-seven subjects (46 males; 31 females) with unilateral FAI participated in this study. Ankle pain was measured by the visual analogue scale (VAS), ankle AROM was measured using a universal goniometer, ankle strength was measured using a handheld dynamometer, the static balance was measured by the Time in Balance Test (TBT) and the dynamic balance was measured by the modified Star Excursion Balance Test (mSEBT). Pearson product-moment correlations were used to determine the correlations between ankle pain, AROM, strength and balance. Multiple linear regressions were used to investigate if ankle pain, AROM and strength can predict balance in individuals with FAI.

RESULTS

VAS and AROM-plantarflexion predicted 25.6% of the TBT (f2 = 0.344, P < 0.001). AROM-dorsiflexion predicted 24.6% of the mSEBT-anterior reach (f2 = 0.326, P < 0.001). VAS, AROM-plantarflexion and strength-plantarflexion predicted 33.5% of the mSEBT-posteromedial reach (f2 = 0.504, P < 0.001). AROM-plantarflexion and strength-plantarflexion predicted 28.2% of the mSEBT-posterolateral reach (f2 = 0.393, P < 0.001).

CONCLUSION

This study shows that ankle plantarflexion strength, AROM of dorsiflexion and plantarflexion and pain are predictors of balance in individuals with FAI. These factors could be considered in the rehabilitation of FAI.

TRIAL REGISTRATION

Trial registration number: ChiCTR2200063532.

The immediate effect of synergistic muscles kinesio taping on function and balance of volleyball players with functional ankle instability: A randomized controlled trial

OBJECTIVES

To determine the immediate effect of synergistic muscles Kinesio taping (KT) on the function and balance of volleyball players with functional ankle instability (FAI).

DESIGN

Parallel, superiority randomized controlled trial.

METHODS

Twenty-six semi-professional volleyball players with FAI were randomly assigned to either the intervention or control group. All participants received KT of fibularis longus, gastrocnemius, and gluteus maximus muscles for one session. The intervention group received KT with 35 % tension, while the control group received KT without tension. The function was assessed using the side hop and single hop distance tests. Dynamic balance was assessed with the Y Balance test. The outcomes were measured at baseline, 20 min after KT, and 24 h after KT. Statistical analyses were performed using Mixed-model repeated measures analysis of variance (ANOVA) and one-way ANOVA.

RESULTS

The interactions of time*group for the outcomes of function using the single hop test and stability in the anterior direction of the Y Balance test were significant (p < 0.05). Within-group comparisons showed after KT, both groups experienced significant improvements in all outcomes compared to the baseline. Results of between-group comparisons revealed that the application of KT with tension compared to no tension significantly improved function and balance in the anterior of the Y Balance test.

CONCLUSIONS

Kinesio taping can be an effective treatment option to improve function and balance in FAI. Additionally, Kinesio taping with tension compared to KT without tension had superiority.

Effects of textured insoles and elastic braces on dynamic stability in patients with functional ankle instability

BACKGROUND

Functional ankle instability (FAI) is a common condition that affects individuals who have experienced previous ankle sprains. Textured insoles and elastic ankle braces have been previously used as interventions to improve stability in FAI patients. However, the optimal combination of these interventions has not been fully explored. The objective of this study was to investigate the effects of different types of textured insoles and elastic ankle braces on the dynamic stability of individuals diagnosed with FAI.

METHODS

The study involved 18 FAI patients who performed single-leg landing tasks with and without wearing an eight-band elastic ankle brace while wearing textured insoles with protrusion heights of 0 mm, 1 mm, and 2 mm. The dynamic posture stability index (DPSI) and its components in the anterior-posterior (APSI), mediolateral (MLSI) and vertical (VSI) directions were calculated from the ground reaction force collected from the Kistler force plate during the first three seconds of the landing tasks.

RESULTS

A significant interaction was found between textured insole type and ankle brace for DPSI (P = 0.026), APSI (P = 0.001), and VSI (P = 0.021). However, no significant interaction was observed for MLSI (P = 0.555). With elastic ankle braces, textured insoles with 1-mm protrusions significantly enhanced anterior-posterior, mediolateral, vertical, and overall stability compared to textured insoles with no and 2 mm protrusions (P < 0.05). Without elastic ankle braces, textured insoles with 1-mm protrusions significantly improved the anterior-posterior (P = 0.012) and overall stability (P = 0.014) of FAI patients compared to smooth insoles.

CONCLUSIONS

The combination of textured insoles with 1-mm protrusion heights and an elastic ankle brace could enhance the dynamic stability of individuals with FAI, potentially mitigating the risk of ankle sprains.

Functional effects of arthroscopic modified Broström procedure on lateral ankle instability: A pilot study

BACKGROUND

This study aims to assess the mechanical and functional effects of the arthroscopic modified Broström procedure (AMBP) on patients with lateral ankle instability.

METHODS

Eight patients with unilateral ankle instability treated with AMBP and eight healthy subjects were recruited. Healthy subjects, preoperative and one-year postoperative patients were assessed using outcome scales and the Star Excursion Balance Test (SEBT) for dynamic postural control. One-dimensional statistical parametric mapping was performed to compare ankle angle and muscle activation curve during stair descent.

RESULTS

The patients with lateral ankle instability showed good clinical outcomes and increased posterior lateral reach during the SEBT after the AMBP (p = 0.046). The medial gastrocnemius activation after initial contact was reduced (p = 0.049), and the peroneal longus activation after initial contact was promoted (p = 0.014).

CONCLUSION

The AMBP has functional effects of promoting dynamic postural control and peroneal longus activation within one year of follow-up, which can benefit patients with functional ankle instability. However, the medial gastrocnemius activation was unexpectedly reduced post operation.

The prevalence of chronic ankle instability in basketball athletes: a cross-sectional study

Background

Ankle sprain is the most common injury in basketball. Chronic ankle instability develops from an acute ankle sprain may cause negative effects on quality of life, ankle functionality or on increasing risk for recurrent ankle sprains and post-traumatic osteoarthritis. To facilitate a preventative strategy of chronic ankle instability (CAI) in the basketball population, gathering epidemiological data is essential. However, the epidemiological data of CAI in basketball is limited. Therefore, this study aims to investigate the prevalence of CAI in basketball athletes and to determine whether gender, competitive level, and basketball playing position influence this prevalence.

Methods

In a cross-sectional study, in total 391 Taiwanese basketball athletes from universities and sports clubs participated. Besides non-standardized questions about demographics and their history of ankle sprains, participants further filled out the standard Cumberland Ankle Instability Tool applied to determine the presence of ankle instability. Questionnaires from 255 collegiate and 133 semi-professional basketball athletes (male = 243, female = 145, 22.3 ± 3.8 years, 23.3 ± 2.2 kg/m²) were analyzed. Differences in prevalence between gender, competitive level and playing position were determined using the Chi-square test.

Results

In the surveyed cohort, 26% had unilateral CAI while 50% of them had bilateral CAI. Women had a higher prevalence than men in the whole surveyed cohort (X²(1) = 0.515, p = 0.003). This gender disparity also showed from sub-analyses, that the collegiate female athletes had a higher prevalence than collegiate men athletes (X²(1) = 0.203, p = 0.001). Prevalence showed no difference between competitive levels (p > 0.05) and among playing positions (p > 0.05).

Conclusions

CAI is highly prevalent in the basketball population. Gender affects the prevalence of CAI. Regardless of the competitive level and playing position the prevalence of CAI is similar. The characteristic of basketball contributes to the high prevalence. Prevention of CAI should be a focus in basketball. When applying the CAI prevention measures, gender should be taken into consideration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-022-00418-0.

Effects of Tai Chi on the neuromuscular function of the patients with functional ankle instability: a study protocol for a randomized controlled trial

Background

Ankle instability limits physical activities and undermines a person’s quality of life. Tai Chi’s health benefits have been reported in different population groups. However, the effects of Tai Chi on neuromuscular function among young adults with functional ankle instability (FAI) remain unclear. Therefore, we aim to investigate the effect of Tai Chi on young adults with FAI.

Methods

This study will be conducted as a randomized controlled trial with blinded assessors. A total of 104 young adults with FAI will be recruited and randomly assigned to intervention and control groups. The participants in the simplified Tai Chi exercise program (STCEP) group will receive a 12-week Tai Chi training. The participants in the control group will receive a low-intensity exercise program and health education for 12 weeks. The primary and secondary outcomes will be assessed at baseline, 4th, 8th, and 12th weeks. Primary outcome measures will include the Cumberland Ankle Instability Tool (CAIT) score, kinematics/kinetics data, electromyography during single-leg landing tasks, and the modified Star Excursion Balance Test (mSEBT). Secondary outcome measures will include the total time of Dynamic Leap and Balance Test (DLBT), ankle muscle strength, and ankle proprioception.

Discussion

This study will investigate the effects of Tai Chi exercise on the neuromuscular function of patients with FAI, as indicated by ankle joint biomechanics, ankle proprioception, balance, ankle muscle strength, and ankle muscle activation. Results will demonstrate that Tai Chi can be an effective exercise for young adults with FAI.

Trial registration

Chinese Clinical Trial Registry ChiCTR2100044089. Registered on 10 March 2021

Comparison of the effects of Wii and conventional training on functional abilities and neurocognitive function in basketball-players with functional ankle instability: Matched randomized clinical trial

OBJECTIVE

To compare the effects of Wii and conventional training on functional abilities and neurocognitive function in basketball-players with Functional Ankle Instability (FAI).

DESIGN

Single-blind matched randomized clinical trial study.

SETTING

Outpatients setting.

PARTICIPANTS

Fifty-four basketball-players were randomly assigned to the Wii and control group.

INTERVENTIONS

All athletes in the Wii group (n = 27) performed Wii Fit Plus games; and in the control group (n = 27), they performed conventional training three days a week for 12 sessions.

MAIN OUTCOME MEASURES

To assess functional performance and neurocognitive function, we used hop tests (8-hop, side hop, and single hop) and Deary-Liewald Reaction Time Task (DLRT), respectively. DLRT measured simple and choice reaction time and error rate. Measures were taken at baseline, four weeks, and eight weeks after baseline.

RESULTS

In all 54 athletes completed the study. The results showed no significant differences for all hop tests in between-group comparison but the neurocognitive function showed significant improvements in the Wii group compared to the control group (P < 0.05). Mean (SD) for 8-hop and side hop tests for the involved limb, and simple and choice reaction time four weeks after baseline in the control group were 10.15 (1.02), 12.36 (1.31), and 339.10 (41.57), 530.52 (53.36), respectively and in the Wii group, were 10.46 (1.23), 12.40 (1.31), and 295.25 (13.16), 431.19 (33.46), respectively.

CONCLUSION

Based on our results, both training protocols were equal to positively affect functional abilities. Besides, Wii training improved neurocognitive function and can be applied in FAI rehabilitation protocols.

The epidemiology of chronic ankle instability with perceived ankle instability- a systematic review

Background

Chronic ankle instability, developing from ankle sprain, is one of the most common sports injuries. Besides it being an ankle issue, chronic ankle instability can also cause additional injuries. Investigating the epidemiology of chronic ankle instability is an essential step to develop an adequate injury prevention strategy. However, the epidemiology of chronic ankle instability remains unknown. Therefore, the purpose of this study was to investigate the epidemiology of chronic ankle instability through valid and reliable self-reported tools in active populations.

Methods

An electronic search was performed on PubMed and Web of Science in July 2020. The inclusion criteria for articles were peer-reviewed, published between 2006 and 2020, using one of the valid and reliable tools to evaluate ankle instability, determining chronic ankle instability based on the criteria of the International Ankle Consortium, and including the outcome of epidemiology of chronic ankle instability. The risk of bias of the included studies was evaluated with an adapted tool for the sports injury review method.

Results

After removing duplicated studies, 593 articles were screened for eligibility. Twenty full-texts were screened and finally nine studies were included, assessing 3804 participants in total. The participants were between 15 and 32 years old and represented soldiers, students, athletes and active individuals with a history of ankle sprain. The prevalence of chronic ankle instability was 25%, ranging between 7 and 53%. The prevalence of chronic ankle instability within participants with a history of ankle sprains was 46%, ranging between 9 and 76%. Five included studies identified chronic ankle instability based on the standard criteria, and four studies applied adapted exclusion criteria to conduct the study. Five out of nine included studies showed a low risk of bias.

Conclusions

The prevalence of chronic ankle instability shows a wide range. This could be due to the different exclusion criteria, age, sports discipline, or other factors among the included studies. For future studies, standardized criteria to investigate the epidemiology of chronic ankle instability are required. The epidemiology of CAI should be prospective. Factors affecting the prevalence of chronic ankle instability should be investigated and clearly described.

The effects of Kinesiology Tape on static postural control in individuals with functional ankle instability

OBJECTIVE

To investigate if applying Kinesiology Tape (KT) on the unstable ankle may improve static postural control in individuals with Functional ankle instability.

DESIGN

A repeated measured study. Participants performed a series of static quiet bipedal and unipedal stances on a force platform. Measurements were taken at three different times: baseline or no tape, immediately and 24 h after the taping application with the tape remaining on the ankle.

SETTING

A university's psychomotor laboratory.

PARTICIPANTS

Twenty young adults with Functional ankle instability aged from 18 to 30 years old.

OUTCOME MEASURES

Postural control was assessed by four measures derived from the centre of pressure data: Area of 95% Confidence ellipse, standard deviation of displacements, mean velocity and mean power frequency. The analysis of variance (ANOVA) was performed to determine any significant improvement in postural control over time due to KT.

RESULTS

Only minor changes in mean velocity and MPF in unipedal stances were observed immediately after KT application. However, the overall results indicated statistically insignificant improvements in postural control neither immediately after KT application nor after 24 h.

CONCLUSION

Results suggest that the use of KT did not affect bipedal and unipedal stances of individuals with functional ankle instability.

The "Ankle Instability Instrument": Cross-cultural adaptation and validation in French

BACKGROUND

Functional ankle instability affects 20-40% of individuals who have already suffered from a sprain. Such dysfunctions are difficult to diagnose. Therefore, the information provided by self-administered questionnaires is essential. Thus, the Ankle Instability Instrument (AII) was developed and initially validated in English. Our goal is to create a French version of the instrument, named AII-F, by scrupulously respecting the cultural adaptation phases and to make sure the new instrument has good psychometric properties.

METHODS

International recommendations have been rigorously followed for the cultural adaptation and the French-translation phase. Six steps are recommended: I) two initial translations from English to French; II) synthesis of the two versions; III) back-translations from French to English; IV) comparisons between the back-translations and the original questionnaire by the expert committee; V) pretest; and VI) approval of the final French version of the AII. In order to validate this French-translation, 91 subjects suffering from ankle instability matched to 91 healthy subjects were asked to complete the AII-F. The Short Form Health Survey (SF-36) was used as a comparative questionnaire as well as the French Cumberland Ankle Instability Tool (CAIT-F). The psychometric properties of the questionnaire were evaluated by determining the test-retest reliability after a 10-14-day interval, the internal consistency, construct validity, and the floor/ceiling effects.

RESULTS

The French-translation did not pose a problem and could be validated by the expert committee. The AII-F showed a very good test-retest reliability for the total score, with an Intra Class Coefficient of 0.983. The internal coherence is high with an alpha coefficient of Cronbach of 0.861. The association of the AII-F with the CAIT-F was high, for the summary of the physical component of the SF-36, meaning a great convergent validity. The other subscales of the SF-36 (mental health) were weakly correlated with the AII-F, reflecting good divergent validity. An optimal cut-off score was obtained to dissociate pathological patients from healthy subjects: when the subject responded to "yes" 5 times or more, he is considered, with a very high degree of confidence, to be pathological.

CONCLUSION

The AII-F is reliable and valid for evaluating and measuring functional ankle instability.

Ultrasound Analysis of Lateral Ankle Ligaments in Functional Ankle Instability

The anterior talofibular ligament and the calcaneofibular ligament were sonographically investigated in 16 patients with functional ankle instability (FAI) and 16 controls under neutral and standardized stress conditions of 15 kp with a TELOS device. Clinical investigation revealed a significantly higher rate of a positive anterior drawer and talar tilt (p <0.001, respectively), significantly increased supination (p = 0.047) of the right ankle joint and increased plantarflexion (p = 0.009) of the left ankle joint in the FAI group compared with controls. Significantly higher rates of inhomogeneity and hypo-echogenicity were sonographically observed in both ligaments in the FAI group (p < 0.05, respectively). The anterior talofibular ligament was significantly longer under stress conditions, and the calcaneofibular ligament was significantly longer under both neutral and stress conditions in the FAI group (p < 0.05, respectively). Peritendinous edema of the peroneal tendons was found in 22% of the FAI group and 6% of controls.

Validity and reliability of smartphone use in assessing balance in patients with chronic ankle instability and healthy volunteers: A cross-sectional study

BACKGROUND

Chronic ankle instability (CAI) is associated with defective posture control and balance; thus, a proper assessment of these impairments is necessary for effective clinical decision-making. There is a need for portable, valid, and reliable methods to facilitate the easy collection of real-world data, such as mobile phones.

RESEARCH QUESTION

Is the smartphone "MyAnkle" application valid and reliable in assessing balance in patients with CAI and healthy volunteers?

METHODS

This was a cross-sectional study. Sixty-five participants completed two assessment sessions, including 31 patients (n = 41 ankles with CAI and 21 asymptomatic ankles) and 34 healthy volunteers (n = 68 ankles). In each session, dynamic single-leg stance balance was measured simultaneously using the "MyAnkle" application and the Biodex balance system (BBS) version 3. Testing was conducted at three levels of BBS difficulty-4 (D4, hard, loose platform), 6 (D6, moderate), and 8 (D8, easy, stiffer platform)-and repeated with opened and closed eyes. Both limbs were tested in a random order by two independent blinded assessors.

RESULTS

The two devices showed significant poor-to-moderate correlations when eyes were closed (p < 0.05). For discriminant validity, the application did not distinguish the two study groups in all tested conditions (p > 0.05), whereas the BBS weakly to moderately distinguished the dominant limbs in the two groups at all difficulty levels with eyes-open and at D8 with eyes-closed regardless to limb dominance. For reliability, a significantly poor to moderate inter-session reliability was noted for the two devices.

SIGNIFICANCE

"MyAnkle" application is valid in assessing balance in patients with CAI when the eyes are closed. However, similarly to BBS, its one-week test-retest reliability may be insufficient for accurate follow-up of balance changes and need to be interpreted with caution. Future studies need to establish its inter-tester reliability and its usefulness in telerehabilitation.

Gluteus medius dysfunction in females with chronic ankle instability is consistent at different walking speeds

BACKGROUND

Patients with chronic ankle instability often present with altered gait mechanics compared to ankle sprain copers. There is increasing evidence to suggest proximal neuromuscular alterations contribute to the injury etiology, however little is known about how these changes manifest during gait. The purpose of this study was to investigate ipsilateral gluteus maximus and medius functional activity ratios throughout treadmill walking at three speeds (preferred, 120% preferred, and 1.35 m per second) in chronic ankle instability patients compared to copers.

METHODS

28 females (14 chronic ankle instability, 14 copers) walked at the three gait speeds in randomized order. Ground reaction forces and 10-s gluteal ultrasound clips were simultaneously recorded. Clips were reduced using ground reaction forces to extract 55 measurement frames. Normalized gluteal thickness measures were used to determine functional activity ratios. 2 × 3 analyses of variance were run to assess group and speed effects on gluteal outcomes throughout walking using statistical parametric mapping. Post-hoc t-tests, mean differences, and Cohen's d effect sizes were assessed for significant findings (P ≤ .05).

FINDINGS

The chronic ankle instability group had significantly decreased gluteus medius activity throughout the entire gait cycle when compared to the coper group, independent of gait speed (P < .001, mean differences: 0.10-0.18; d: 1.00-3.17). There were no significant group or speed main effects, nor an interaction for gluteus maximus activity.

INTERPRETATION

Gluteal dysfunction throughout walking was identified in chronic ankle instability. The coper group remained within healthy reference muscle activity ranges, suggesting that proximal muscle activation alterations are associated chronic ankle impairments.

Improvements in strength and functional performance after Kinesio taping in semi-professional male soccer players with and without functional ankle instability

OBJECTIVE

The objectives of this study were to compare the immediate effects of two methods of Kinesio taping on muscle strength, functional performance, and balance in athletes with and without functional ankle instability (FAI).

METHODS

The present study investigated the effects of distal taping (muscle application over peroneus longus) and proximal- distal taping (muscle application over gluteus medius and peroneus longus) on the strength of evertor and hip abductor muscles, side hop test, figure of 8 hop test, and star excursion balance test in semi-professional male soccer players with and without FAI (n=15 in each group). A Multifactorial repeated measure ANOVA was used for comparison.

RESULTS

There were significant differences for factor effect in all outcome measures (P<0.05), except for the figure of 8 hop test. No significant differences for group effects and group by factor interaction effects (P>0.05) was observed except for the side hop test.

CONCLUSION

Kinesio taping had immediate effects on improving strength, performance and balance. However, there were no differences on the method of application. Clinicians can consider the application Kinesio taping during the rehabilitation process of athletes with FAI, to improve balance and strength. The long-term impacts of taping on the functional, balance and strength measures should be investigated in future studies.

In vivo kinematics of functional ankle instability patients during the stance phase of walking

BACKGROUND

Previous studies showed functional ankle instability (FAI) patients have morphological ligamentous abnormality, despite having no apparent joint laxity.

RESEARCH QUESTION

Whether tibiotalar and subtalar joints hypermobility exists in FAI patients during stance phase of walking, remains controversial.

METHODS

Ten unilateral FAI patients, ten unilateral lateral ankle sprain (LAS) copers and ten healthy controls were included. A dual fluoroscopy imaging system was utilized to capture the fluoroscopic images of tibiotalar and subtalar joint during the stance phase of walking. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint excursions about six degrees of freedom were compared among the three groups. The correlations between range of motion and Cumberland Ankle Instability Tool (CAIT) scores were assessed utilizing the Spearman's correlation coefficient (r).

RESULTS

During the stance phase, the FAI patients and LAS copers showed larger tibiotalar anterior/posterior translation than the healthy controls (FAI patients, p = .013; LAS copers, p = .002). The FAI patients also showed significantly larger lateral/medial translation (p = .035) and inversion/eversion rotation (p = .003) of subtalar joints than healthy controls. By contrast, the subtalar joints of the LAS copers were not different from those of the healthy controls in the lateral/medial translation (p = .459) and inversion/eversion rotation (p = .091). CAIT scores were negatively correlated with range of motion.

SIGNIFICANCE

During the stance phase of walking, FAI patients showed significantly larger hypermobility of subtalar joints than healthy controls, contrary to the LAS copers. These findings justify the utilization of dual fluoroscopy imaging system to detect joint hypermobility in FAI patients. Treatment for FAI patients may require stabilization of the subtalar joint.

Gluteus medius activity during gait is altered in individuals with chronic ankle instability: An ultrasound imaging study

BACKGROUND

Altered gait mechanics are frequently reported in individuals with chronic ankle instability (CAI), and increasing information suggests proximal muscle adaptations occur in this population. Ultrasound imaging (USI) offers a visual means to evaluate muscle activity during movement, and overcomes limitations of electromyography (EMG) to detect hip muscle activity.

RESEARCH QUESTION

A descriptive laboratory study was conducted to determine if gluteus maximus (GMAX) and medius (GMED) muscle activity differed throughout gait in patients with CAI compared to healthy counterparts.

METHODS

Twenty young adults with CAI (21.6 ± 2.4 years, 10 males) and 20 healthy participants (21.2 ± 2.8 years, 10 males) walked on a treadmill at 1.35 m/s while researchers obtained 10-second clips of bilateral USI of the GMAX and GMED. USI clips were reduced to 55 frames consisting of 11 points over five full gait cycles. Muscle thickness values during walking were normalized to quiet bipedal standing USI images to obtain functional activity ratios (FARs). FARs with 90% confidence intervals (CI) were plotted as 10% interludes from 0 to 100% of the gait cycle to compare groups and limbs. Mean differences and Cohen's d effect sizes were used to assess the extent of differences. The CAI group had decreased GMED activity bilaterally from 0 to 40% of walking gait compared to healthy counterparts with large effect sizes (d≥0.60). CAI group FARs were below quiet stance levels (FARs<1.0) throughout the entire gait cycle. There were no differences noted between groups or limbs for GMAX measures.

SIGNIFICANCE

Proximal stabilizing musculature was altered bilaterally in CAI individuals compared to healthy counterparts, which may contribute to movement dysfunction. Previous studies using EMG have not detected this extent of bilateral gluteal muscle alterations in CAI groups during gait, however our findings suggest USI was able to detect significant proximal alterations during walking in this population.

Effects of visual feedback balance training on the balance and ankle instability in adult men with functional ankle instability

[Purpose] This study examined the effects of visual feedback balance training on the balance and ankle instability in adult men with functional ankle instability. [Subjects and Methods] Twenty eight adults with functional ankle instability, divided randomly into an experimental group, which performed visual feedback balance training for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Bio rescue was used for balance ability. It measured limit of stability at one minute. For ankle instability was measured using Cumberland ankle instability tool (CAIT). This measure was performed before and after the experiments in each group. [Results] The experimental group had significant increase in the Limit of Stability and CAIT score. The control group had significant increase in CAIT score. While the Limit of Stability increased without significance. [Conclusion] In conclusion, visual feedback balance training can be recommended as a treatment method for patients with functional ankle instability.

Effects of spiral taping on proprioception in subjects with unilateral functional ankle instability

[Purpose] The Purpose of this study was to investigate the effects of spiral taping on proprioception in functional ankle instability. [Subjects and Methods] Thirty-five participants in this study had discomfort in only one ankle and Cumberland ankle instability score of ≤23. ST was applied to the unstable ankle, and proprioception was measured baseline and 30 min later. Proprioception was measured using the active joint angle reproduction test. [Results] Plantar flexions of 10° (ES, 0.303) and 20° (ES, 1.369) and inversion 20° (ES, 0.998) showed a significant improvement. [Conclusion] Spiral taping improved on proprioception. Therefore, spiral taping may be an effective method for functional ankle instability.

Effects of Achilles tendon vibration, surface and visual conditions on lower leg electromyography in young adults with and without recurrent ankle sprains

Functional ankle instability is associated with decreased ankle muscle function. Compliant surfaces and eyes-closed training are commonly used for rehabilitation and prevention of ankle sprains. Brief Achilles tendon vibration is commonly used in the study of postural control. To test the level of activation of tibialis anterior (TIB) and fibularis longus (FIB), bilateral Achilles tendon vibration was applied for the middle 20 s in a series of 60-s trials, when 10 healthy young adults and 10 adults with history of repeated ankle sprains were standing bipedal: on floor, on memory foam, or on a Both Sides Up (BOSU) ball, with eyes open, and on floor and foam with eyes closed. Differences in Integrated surface electromyography (IEMG) of TIB and FIB were significant for both groups pre, during, and post vibration (Friedman Tests, p < 0.001 for all). In both groups, the highest IEMG for TIB was obtained during vibration when standing on foam with eyes closed, whereas the highest IEMG for FIB was obtained during vibration when standing on the BOSU. Bipedal stance on BOSU and brief Achilles tendon vibration may be a useful intervention when a session's goal is to facilitate lower leg muscles activation. Future research should explore training effects as well as the effect of FIB tendon vibration.

Effects of balance training by knee joint motions on muscle activity in adult men with functional ankle instability

[Purpose] This study examined the effects of balance training by applying knee joint movements on muscle activity in male adults with functional ankle instability. [Subjects and Methods] 28 adults with functional ankle instability, divided randomly into an experimental group, which performed balance training by applying knee joint movements for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Electromyographic values of the tibialis anterior, peroneus longus, peroneus brevis, and the lateral gastrocnemius muscles were obtained to compare and analyze muscle activity before and after the experiments in each group. [Results] The experimental group had significant increases in muscle activity in the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles, while muscle activity in the peroneus brevis increased without significance. The control group had significant increases in muscle activity in the tibialis anterior and peroneus longus, while muscle activity in the peroneus brevis and lateral gastrocnemius muscles increased without significance. [Conclusion] In conclusion, balance training by applying knee joint movements can be recommended as a treatment method for patients with functional ankle instability.

Effects of balance training by knee joint motions on muscle activity in adult men with functional ankle instability

[Purpose] This study examined the effects of balance training by applying knee joint movements on muscle activity in male adults with functional ankle instability. [Subjects and Methods] 28 adults with functional ankle instability, divided randomly into an experimental group, which performed balance training by applying knee joint movements for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Electromyographic values of the tibialis anterior, peroneus longus, peroneus brevis, and the lateral gastrocnemius muscles were obtained to compare and analyze muscle activity before and after the experiments in each group. [Results] The experimental group had significant increases in muscle activity in the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles, while muscle activity in the peroneus brevis increased without significance. The control group had significant increases in muscle activity in the tibialis anterior and peroneus longus, while muscle activity in the peroneus brevis and lateral gastrocnemius muscles increased without significance. [Conclusion] In conclusion, balance training by applying knee joint movements can be recommended as a treatment method for patients with functional ankle instability.

Effects of Nintendo Wii Fit Plus training on ankle strength with functional ankle instability

[Purpose] The objective of this study was to examine the effects of a training program using the Nintendo Wii Fit Plus on the ankle muscle strengths of subjects with functional ankle instability. [Subjects and Methods] This study was conducted using subjects in their 20s who had functional ankle instability. They were randomized to a strengthening training group and a balance training group with 10 subjects in each, and they performed an exercise using Nintendo Wii Fit Plus for 20 minutes. In addition, every participant completed preparation and finishing exercises for 5 minutes, respectively. [Results] The muscle strengths after conducting plantar flexion and dorsiflexion significantly increased at the angular velocities of 60° and 120° in the strengthening training group. Furthermore, the muscle strengths after conducting plantar flexion, dorsiflexion, eversion, and inversion significantly increased at the angular velocities of 60° and 120° in the balance training group. [Conclusion] The balance training group using Nintendo Wii Fit Plus showed better results than the strengthening training group. Consequently, it is recommended to add the balance training program of the Nintendo Wii Fit Plus to conventional exercise programs to improve ankle muscle strength in functional ankle instability at a low cost.

Correlates of functional ankle instability in children and adolescents with Charcot-Marie-Tooth disease

BACKGROUND

Functional ankle instability (FAI) is commonly reported by children and adolescents with Charcot-Marie-Tooth disease (CMT), however,, the specific variables associated with FAI remain unknown. An improved understanding of these variables may suggest interventions to improve ankle stability and possibly prevent the long-term complications associated with ankle instability in this population. The aim of this study was to therefore investigate the relationship between FAI and other functional, structural, anthropometric and demographic characteristics in a cross sectional sample of children and adolescents with CMT.

METHODS

Thirty children and adolescents with CMT aged 7-18 years were recruited from the Peripheral Neuropathy Clinics of a large tertiary paediatric hospital. Measures of FAI were obtained using the Cumberland Ankle Instability Tool (CAIT). Demographic and anthropometric data was also collected. Other variables collected included foot structure (Foot Posture Index), ankle range of motion (weight bearing lunge) and functional parameters (balance, timed motor function and falls). Descriptive statistics were calculated to characterise the participants. Pearson's correlation coefficients were calculated to investigate the correlates of right and left FAI and demographic (age), anthropometric (height, weight, BMI), foot/ankle (foot structure and ankle flexibility) and functional parameters (balance task, timed motor function and falls frequency). Point biserial correlation was employed to correlate gender with right and left FAI.

RESULTS

All but one study participant (n = 29) reported moderate to severe bilateral FAI with females reporting significantly greater ankle instability than males. FAI was significantly associated with cavus foot structure (r = .69, P < .001), female gender (r = -.47, P < .001) and impaired balance (r = .50, P < .001).

CONCLUSIONS

This study confirms FAI is common in children and adolescents with CMT. An examination of the correlates of FAI suggests interventions, which target balance, and normalise foot structure should be explored to evaluate whether they might help to improve ankle stability in this population.

Reliability of the Identification of Functional Ankle Instability (IdFAI) Scale Across Different Age Groups in Adults

Background:

Functional ankle instability (FAI) is the tendency of the foot to ‘give way’. Identification of Functional Ankle Instability questionnaire (IdFAI) is a newly developed questionnaire to detect whether individuals meet the minimum criteria necessary for inclusion in an FAI population. However, the reliability of the questionnaire was studied only in a restricted age group.

Aim:

The purpose of this investigation was to examine the reliability of IdFAI across different age groups in adults.

Materials and Methods:

One hundred and twenty participants in the age group of 20-60 years consisting of 30 individuals in each age group were asked to complete the IdFAI on two occasions. Test-retest reliability was evaluated by intraclass correlation coefficient (ICC_2,1).

Results:

The study revealed that IdFAI has excellent test-retest reliability when studied across different age groups. The ICC_2,1 in the age groups 20-30 years, 30-40 years, 40-50 years and 50-60 years was 0.978, 0.975, 0.961 and 0.922, respectively with Cronbach's alpha >0.9 in all the age groups.

Conclusion:

The IdFAI can accurately predict if an individual meets the minimum criterion for FAI across different age groups in adults. Thus, the questionnaire can be applied over different age groups in clinical and research set-ups.

No correlation between joint position sense and force sense for measuring ankle proprioception in subjects with healthy and functional ankle instability

BACKGROUND

In general, ankle proprioception is most often evaluated by assessing joint position sense and force sense. However, in contrast to observational studies of joint position sense and force sense, no studies have examined the correlations between joint position sense and force sense. Therefore, the objective of this study was to investigate the correlations between joint position sense and force sense in subjects with healthy and functional ankle instability.

METHODS

Of the sixty nine subjects enrolled in the cross-sectional laboratory study, 35 had functional ankle instability and 34 were healthy subjects. Angle reproduction and force matching methods were used to quantify joint position sense and force sense of the ankle proprioception. These methods were also measured by using a flexible twin axis electrogoniometer and linear force, respectively. Three trials were performed at each angle and force. And then, absolute errors were calculated.

FINDINGS

Significant differences between the functional ankle instability and healthy group were found for absolute errors of plantar flexion, dorsiflexion, inversion, and eversion (P<0.05). No significant correlations between the joint position sense and force sense were found in subjects with both healthy, except for absolute errors of the eversion (r=0.652, P<0.05, r(2)=0.425), and functional ankle instability group (P>0.05).

INTERPRETATION

These findings suggest that it could be explained for deficits of ankle proprioception when angle reproduction and force matching tests to quantify joint position sense and force sense were applied and presented at the same time, not individually.

Functional ankle instability as a risk factor for osteoarthritis: using T2-mapping to analyze early cartilage degeneration in the ankle joint of young athletes

OBJECTIVE

The aim of this study was to investigate, using T2-mapping, the impact of functional instability in the ankle joint on the development of early cartilage damage.

METHODS

Ethical approval for this study was provided. Thirty-six volunteers from the university sports program were divided into three groups according to their ankle status: functional ankle instability (FAI, initial ankle sprain with residual instability); ankle sprain Copers (initial sprain, without residual instability); and controls (without a history of ankle injuries). Quantitative T2-mapping magnetic resonance imaging (MRI) was performed at the beginning ('early-unloading') and at the end ('late-unloading') of the MR-examination, with a mean time span of 27 min. Zonal region-of-interest T2-mapping was performed on the talar and tibial cartilage in the deep and superficial layers. The inter-group comparisons of T2-values were analyzed using paired and unpaired t-tests. Statistical analysis of variance was performed.

RESULTS

T2-values showed significant to highly significant differences in 11 of 12 regions throughout the groups. In early-unloading, the FAI-group showed a significant increase in quantitative T2-values in the medial, talar regions (P = 0.008, P = 0.027), whereas the Coper-group showed this enhancement in the central-lateral regions (P = 0.05). Especially the comparison of early-loading to late-unloading values revealed significantly decreasing T2-values over time laterally and significantly increasing T2-values medially in the FAI-group, which were not present in the Coper- or control-group.

CONCLUSION

Functional instability causes unbalanced loading in the ankle joint, resulting in cartilage alterations as assessed by quantitative T2-mapping. This approach can visualize and localize early cartilage abnormalities, possibly enabling specific treatment options to prevent osteoarthritis in young athletes.

Individuals with chronic ankle instability exhibit decreased postural sway while kicking in a single-leg stance

Individuals with chronic ankle instability (CAI) usually experience deficits in balance control, which increase displacement in the body's center of pressure (COP) when they balance on a single leg. Little is known, however, about whether or not these individuals use the strategies of postural adjustment properly, especially during functional tasks that may predispose them to ankle sprain. The aim of this study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with and without CAI as they kick a ball while standing in a single-leg stance with their ankle in neutral and supinated positions. COP displacements were calculated and their magnitudes (range) analyzed during APA and CPA intervals and over the duration of the whole task, represented by the COP area of sway and mean velocity. The CAI group exhibited a significant decrease in CPA and area of sway over the whole task, relative to controls. These results suggest that the decreased balance sway could be caused by the need for further stabilization of the ankle in more unstable postures to prevent recurrent sprain. Our findings could help clinicians to better understand the strategies of postural adjustments in individuals with CAI, and may assist and motivate new investigations into balance control interventions in such individuals, as well as proactively address recurrent ankle sprain conditions.

Which Treatment is More Effective for Functional Ankle Instability: Strengthening or Combined Muscle Strengthening and Proprioceptive Exercises?

[Purpose] The purpose of this study was to implement combined muscle strengthening and proprioceptive exercises to examine the effects of combined exercises on functional ankle instability. [Subjects and Methods] Experiments were conducted with 30 adult males and females. The study subjects were randomly assigned to either a control group (Group A), a muscle strengthening exercise group (Group B), or a combined muscle strengthening and proprioceptive exercise group (Group C) consisting of 10 subjects each. In Group A, measurements were only conducted before and after the experiment without any intervention, whereas the exercise programs for Group B and Group C were implemented three days per week for four weeks. [Results] Muscle strength showed significant increases in Groups B and C compared with the control group during plantar flexion, dorsiflexion, inversion, and eversion. The Cumberland ankle instability tool showed significant increases in Group B and Group C compared with Group A and significant increases in Group C compared with Group B. [Conclusion] Applying combined muscle strengthening and proprioceptive exercises to those who have functional ankle instability is more effective than applying only muscle strengthening exercises.

Critical review of self-reported functional ankle instability measures: a follow up

OBJECTIVE

Determine which ankle instability questionnaire predicts subject's ankle instability status based on a minimum accepted criteria for FAI (MC_FAI).

DESIGN

Cross-sectional study.

SETTING

Large Midwestern University.

PARTICIPANTS

College aged subjects (n = 1127 19.6 ± 2.1 years) from a university population were recruited for this study. Any volunteer, regardless of ankle injury history was included in the study.

MAIN OUTCOME MEASURES

The independent variables were the score on three self-report ankle instability questionnaires: Ankle Instability Instrument, Cumberland Ankle Instability Tool, and Identification of Functional Ankle Instability. Subjects completed the questionnaires for their dominant limb during a single testing session. The dependent variable was created based on the previously established MC_FAI. This was established as at least one ankle sprain and at least one episode of giving way. Data were modeled using a chi-square and multinomial logistic regression. 95% confidence intervals were calculated for the resulting odds ratios.

RESULTS

A test of the full model with all three predictors against MC_FAI revealed that only the IdFAI (X² = 457.09, p = .001) had a significant relationship with the outcome variable. The IdFAI had an overall prediction rate of 87.8%.

CONCLUSIONS

This analysis illustrates that IdFAI is a good overall option for predicting ankle stability status by self-reported questionnaire.

Fibular taping does not influence ankle dorsiflexion range of motion or balance measures in individuals with chronic ankle instability

OBJECTIVES

To determine the effects of fibular taping on ankle dorsiflexion range of motion (ROM) and dynamic balance in individuals with chronic ankle instability (CAI).

DESIGN

Single-blind, randomized crossover.

METHODS

Twenty-three individuals (age=23.4 ± 2.5 years, height=171.6 ± 12.4 cm, mass=71.5±13.1 kg) with CAI were allocated to either a fibular taping intervention or sham taping intervention (tape applied without tension) over the course of two visits. Weight-bearing ankle dorsiflexion ROM and components of the Star Excursion Balance Test (SEBT) were measured before and after intervention.

RESULTS

There was not a significant change in ankle dorsiflexion ROM when comparing the taping interventions (F1,43=1.03, P=.32), but both interventions resulted in a small increase (F1,43=8.07, P=.007) in dorsiflexion ROM (pre=36.7° ± 6.9°, post=37.7° ± 6.2°). This increase in ROM did not exceed the established minimal detectable change for dorsiflexion ROM. Fibular taping with tension produced an increase (F1,41=5.84, P=.02) (pre=69.0 ± 9.1%, post=70.6±8.6%) in posterolateral reach distance when compared to taping without tension (pre=72.7 ± 11.0%, post=71.4 ± 9.6%), but this increase did not exceed the established minimal detectable change. There was not a significant change in dynamic balance between groups for the anterior (F1,41=2.33, P=.14) and posteromedial (F1,41=.41, P=.53) reach directions.

CONCLUSIONS

Although small changes in ankle dorsiflexion ROM and posterolateral reach distances were observed, these changes did not exceed established minimal detectable change values for these measures. These results suggest that the benefits of fibular taping are not related to an increase in ankle dorsiflexion ROM or dynamic balance.

Position-specific deficit of joint position sense in ankles with chronic functional instability

The present study was aimed to test a hypothesis that individuals with functional ankle instability (FAI) underestimate the joint angle at greater plantarflexion and inversion. Seventeen males with unilateral FAI and 17 controls (males without FAI) consented for participation in this IRB-approved, case-control study. Using a passive reproduction test, we assessed ankle joint position sense (JPS) for test positions between 30 and -10 degrees plantarflexion with an inclement of 10 degrees with or without 20° inversion at each plantarflexion angle. The constant error (CE) was defined as the value obtained by subtracting the true angle of a test position from the corresponding perceived angle. At plantarflexed and inverted test positions, the CE values were smaller in negative with greater in the FAI group than in the control group. That is, in the FAI group, the FAI group underestimated the true plantarflexion angle at combined 30° plantarflexion and 20° inversion. We conclude that the ankle with FAI underestimate the amount of plantarflexion, which increases the chance of reaching greater planterflexion and inversion than patients' intention at high risk situations of spraining such as landing. Key pointsJoint position sense (JPS) of the ankle with functional ankle instability was investigated utilizing a passive reproduction test.The FAI group demonstrated greater error of the joint position than the control group only when the ankle was positioned at combined inversion and plantarflexion.The FAI group underestimated plantarflexion angle when the ankle was placed at combined inversion and plantarflexion.