Chronic Ankle Instability Subjects Research Articles

A new patient-reported outcome measure for the evaluation of ankle instability: description of the development process and validation protocol

BackgroundAcute ankle sprains represent one of the most common traumatic injuries to the musculoskeletal system. Many individuals with these injuries experience unresolved symptoms such as instability and recurrent sprains, leading to chronic ankle instability (CAI), which affects their ability to maintain an active lifestyle. While rehabilitation programs focusing on sensorimotor, neuromuscular, strength and balance training are primary treatments, some patients require surgery when rehabilitation fails. A critical analysis of the patient-reported outcome tools (PROs) used to assess CAI surgical outcomes raises some concerns about their measurement properties in CAI patients, which may ultimately affect the quality of evidence supporting current surgical practice. The aim of this research is to develop and validate a new PRO for the assessment of ankle instability and CAI treatment outcomes, following recent methodological guidelines, with the implicit aim of contributing to the generation of scientifically meaningful evidence for clinical practice in patients with ankle instability.MethodsFollowing the COnsensus-based Standards for the selection of Health Measurement Instruments (COSMIN), an Ankle Instability Treatment Index (AITI) will be developed and validated. The process begins with qualitative research based on face‒to‒face interviews with CAI individuals to explore the subjective experience of living with ankle instability. The data from the interviews will be coded following an inductive approach and used to develop the AITI content. The preliminary version of the scale will be refined through an additional round of face‒to‒face interviews with a new set of CAI subjects to define the AITI content coverage, relevance and clarity. Once content validity has been examined, the AITI will be subjected to quantitative analysis of different measurement properties: construct validity, reliability and responsiveness.DiscussionThe development of AITI aims to address the limitations of existing instruments for evaluating surgical outcomes in patients with CAI. By incorporating patient input and adhering to contemporary standards for validity and reliability, this tool seeks to provide a reliable and meaningful assessment of treatment effects.Trial registrationNot applicable.

GaitNet+ARL: A Deep Learning Algorithm for Interpretable Gait Analysis of Chronic Ankle Instability.

Chronic ankle instability (CAI) is a major public health concern and adversely affects people's mobility and quality of life. Traditional assessment methods are subjective and qualitative by means of clinician observation and patient self-reporting, which may lead to inaccurate assessment and reduce the effectiveness of treatment in clinical practice. Gait analysis becomes a commonly used approach for monitoring human motion behaviors, which can be applied to specific diagnosis and assessment of CAI. However, it is still challenging to recognize the pathological gait pattern for CAI subjects. In this paper, we propose an integrated deep learning framework to solve the CAI recognition problem using kinematic data. Specifically, inspired by the biomechanics of human body system, we create a simple graph neural network (GNN), termed GaitNet, that operates on a spatial domain and exploits interactions among 3-D joint coordinates. We also develop an attention reinforcement learning (ARL) model that determines attention weights of frames on a temporal domain, which is combined with GaitNet for prediction. The effectiveness of our method is validated on the kinematic NEU-CAI dataset which is collected in our institution using a stereophotogrammetric system. According to extensive experiments, we demonstrate that the selected key phases (i.e., sequences of frames with high attentions) significantly increase the predictability of the proposed biomechanics-based GNN model to differentiate between CAI cohort and control cohort. Moreover, we show a significant prediction accuracy improvement (20%-25%) by our approach compared to state-of-the-art machine learning and deep learning methods.

Unexpected inversion perturbation during a single-leg landing in patients with chronic ankle instability

ABSTRACT It remains unclear how unexpected perturbations during single-leg landings affect lower extremity kinematics and muscle activations in patients with chronic ankle instability (CAI). The purpose of this study was to identify the differences in lower extremity movement patterns among CAI subjects, copers, and healthy controls. Sixty-six people including 22 CAI subjects, 22 copers, and 22 healthy controls volunteered to participate in the study. Lower extremity joint kinematics and EMG activations from 200-ms pre to 200-ms post the initial contact during unexpected tilted landings were measured. Functional data analysis was used to evaluate between-group differences for outcome measures. Relative to copers and healthy controls, CAI subjects showed more inversion from 40-ms to 200-ms after initial contact. Relative to healthy controls, CAI subjects and copers showed more dorsiflexion. Relative to healthy controls, CAI subjects and copers showed more muscle activation in tibialis anterior and peroneus longus, respectively. In conclusion, CAI subjects demonstrated greater inversion angles and muscle activation before initial contact compared to LAS copers and healthy controls. This suggests that CAI subjects and copers prepare for their landing with protective movements, but the prepared movements shown by CAI subjects may be insufficient to reduce risk of recurrent injury.

A test battery for evaluation of muscle strength, balance and functional performance in subjects with chronic ankle instability: a cross-sectional study

BackgroundStudies investigating ankle condition in subjects with chronic ankle instability (CAI) using an on-the-field test battery are scarce. Understanding which tests that are most challenging for these subjects has the potential to set realistic goals in rehabilitation and return-to-sports criteria. Thus, the primary aim of this study was to investigate CAI subjects regarding strength, balance and functional performance with an easily used test battery that required minimal equipment.MethodsThis study was conducted with a cross-sectional design. A total of 20 CAI subjects, engaged in sports, and 15 healthy subjects serving as a control group, were tested for assessment of strength, balance and functional performance. A test battery was developed accordingly; isometric strength in inversion and eversion, the single leg stance test (SLS), single leg hop for distance (SLHD) and side hop test. The limb symmetry index was calculated to determine whether a side-to-side lower limb difference could be classified as normal or abnormal. The sensitivity of the test battery was also calculated.ResultsThe subjects were 20% weaker on the injured side compared with the non-injured side in eversion (p < 0.01) and 16% weaker in inversion (p < 0.01) (Table 2). For the SLS test, the mean score of the injured side was 8 points (67%) higher (more foot lifts) compared to the non-injured side (p < 0.01). The mean distance of the SLHD was 10 cm (9%) shorter for the injured side compare to the non-injured side (p = 0.03). The mean number of side hop was 11 repetitions (29%) fewer for the injured side compare to the non-injured side (p < 0.01). Six of the 20 subjects obtained abnormal LSI values in all five tests whereas none obtained normal values in all tests. The sensitivity of the test battery was 100%.ConclusionDeficits in muscle strength, balance and functional performance appear to be present in CAI subjects with the largest impairments in balance and side hop performance, which stresses the need for return to sport criteria for this group of subjects.Trial registrationRegistered retrospectively on 24/01/2023. NCT05732168.

Effect of varied dorsiflexion range of motion on landing biomechanics in chronic ankle instability.

Limited dorsiflexion range of motion (DFROM) is a risk factor for lateral ankle sprain. However, varied DFROM exists within the chronic ankle instability (CAI) population, and how the variability may influence altered movement patterns during landing is unclear. The purpose of this study was to identify different movement strategies during maximal jump landing/cutting among CAI patients classified by varied DFROM. One hundred CAI subjects were classified into 3 subgroups based on their DFROM, measured by the weight-bearing lunge test: a Hypo- (≤40°), Normal- (40-50°), and Hyper-DFROM group (≥50°). Participants completed five trials of maximal jump landing/cutting. Lower extremity joint angles and EMG activation of seven muscles were collected from initial contact to toe-off. Functional analyses of variance were used to evaluate between-group differences for these outcome variables. Hypo-DFROM group (14M, 10F) displayed the reduced ankle dorsiflexion and inversion angles with increased hip flexion angle as a compensatory kinematic chain movement strategy. In addition, motion restrictions of the ankle are associated with altered muscle activation in both distal and proximal muscles during landing/cutting. Normal-DFROM (25M, 30F) and Hyper-DFROM (11M, 10F) groups also have different movement strategies including greater inversion angle and less EMG activation, which could contribute to further ankle injuries. Our data suggest that limited DFROM negatively affects the ankle joint during demanding movement within the CAI population. These movement patterns in CAI patients with pathomechanical deficits could contribute to further ankle sprains.

Limited Dorsiflexion Range Of Motion Alters Joint Kinematics During Walking In Chronic Ankle Instability Patients

Limited dorsiflexion range of motion (DFROM) may be one of risk factors for lateral ankle sprains. Further, chronic ankle instability (CAI) patients consistently showed reduced DFROM during functional movements. Although DFROM seems to vary between CAI patients, it is unclear whether varied DFROM changes lower-limb joint kinematics during walking. PURPOSE: To examine the effects of varied DFROM on lower-limb kinematics during walking within the CAI population. METHODS: 100 CAI subjects were classified into 3 subgroups based on DFROM, measured by the weight-bearing lunge test: a Hypo (14 M, 10F; ≤ 40°; 35 ± 2.5°, 23 ± 2 yr, 176 ± 13 cm, 80 ± 13 kg), Normal (25 M, 32F; 40-50°; 46 ± 2.6°, 21 ± 2 yr, 174 ± 7 cm, 72 ± 14 kg), or Hyper DFROM group (11 M, 8F; ≥ 50°; 54 ± 3°, 22 ± 2 yr, 175 ± 11 cm, 74 ± 14 kg). Subjects performed 5 walking trials at a preferred speed while 3D joint kinematic data were collected using high-speed video (250 Hz) and a force plate (1000 Hz). Functional linear models were used to detect between-group differences. If 95% confidence intervals did not cross zero, differences were significant. RESULTS: Figure 1 shows that the Hypo-DFROM group showed increased ankle inversion and hip flexion and decreased hip abduction angles relative to the Normal-DFROM group. In addition, Hypo-DFROM group showed the lowest plantarflexion angle but greatest ankle inversion angle after heel contact among three groups. The Hyper-DFROM group showed the greatest plantar flexion and lowest inversion angles before and/or after heel contact. CONCLUSIONS:During gait, Hypo-DFROM group show increased ankle inversion angle relative to the Normal- and Hyper-DFROM groups, which may increase the risk for lateral ankle sprains. However, decreased plantarflexion and hip flexion angles in the Hypo-DFROM group may be compensatory patterns in effort to avoid further injuries. Future studies are needed to determine whether these kinematic compensations would reduce further injuries in the Hypo-DFROM group.

Dorsiflexion Range Of Motion Deficits Alter Joint Muscle Activation Patterns During Walking In Chronic Ankle Instability

Decreased dorsiflexion range of motion (DFROM) has been identified as a risk factor for ankle sprains. Patients with chronic ankle instability (CAI) demonstrate reduced DFROM during functional tasks. However, variation in DFROM exists within a CAI population. It remains unclear whether varied DFROM affects muscle activation during walking. PURPOSE: To examine the effects of varied DFROM on tibialis anterior (TA), peroneus brevis (PB), peroneus longus (PL), and gluteus maximus (Gmax) activation during walking within the CAI population. METHODS: 100 CAI subjects were classified into 3 subgroups based on DFROM, measured by the weight-bearing lunge test: a Hypo (14 M, 10F; ≤ 39°; 35 ± 2.5°, 23 ± 2 yrs, 176 ± 13 cm, 80 ± 13 kg), Normal (25 M, 32F; 40-50°; 46 ± 2.6°, 21 ± 2 yrs, 174 ± 7 cm, 72 ± 14 kg), and Hyper DFROM group (11 M, 8F; ≥ 51°; 54 ± 3°, 22 ± 2 yrs, 175 ± 11 cm, 74 ± 14 kg). Subjects performed 5 walking trials at a preferred speed while muscle activation were collected using wireless surface electrodes (2000 Hz). Functional liner models were used to detect between-group differences. If 95% confidence intervals did not cross zero, differences were significant. RESULTS: Figure 1 shows Hypo DFROM group showed increased muscle activation of the TA and Gmax during early stance phase, as well as increased muscle activation of the PL and PB during the late stance phase compared to Normal and/or Hyper DFROM groups. CONCLUSION: While CAI patients with Normal and Hyper DFROM show similar muscle activation patterns during walking, CAI patients with Hypo DFROM appear to demonstrate increased muscle activation during walking. These muscle activation patterns may elicit perceived, protective neuromuscular control in an attempt to prevent injuries due to ankle instability. Differences in muscle activation may compensate for limited arthrokinematics at the ankle joint. However, prospective studies are needed to determine whether these patterns would reduce injury risk and performance deficits.

Comparison of Maximum Isometric Strength, Proprioceptive, Dynamic Balance, and Maximum Angle by Applying the Fascial Distortion Model to Chronic Ankle Instability Subjects

Comparison of Maximum Isometric Strength, Proprioceptive, Dynamic Balance, and Maximum Angle by Applying the Fascial Distortion Model to Chronic Ankle Instability Subjects

Effects of Dry Needling on Neuromuscular Control of Ankle Stabilizer Muscles and Center of Pressure Displacement in Basketball Players with Chronic Ankle Instability: A Single-Blinded Randomized Controlled Trial.

This study aimed to compare the effects of dry needling (DN) versus placebo DN applied to the peroneus longus (PL) and tibialis anterior (TA) on neuromuscular control and static postural control in basketball players with chronic ankle instability (CAI). A single-blinded randomized controlled trial was conducted. Thirty-two male and female basketball players with CAI were randomly assigned to receive either DN (n = 16) or placebo DN (n = 16). Pre-activation amplitudes of PL and TA were assessed with surface electromyography (EMG) during a dynamic landing test. Center of pressure (CoP) displacement and sway variability in anterior-posterior (AP) and medio-lateral (ML) directions were measured with a force platform during a single leg balance test (SLBT). Measures were obtained prior to a single DN intervention, immediately after, at 48 h, and 1 month after. The DN group displayed a significant increase in PL and TA pre-activation values, which were maintained 1 month later. Significant reductions in the ML and AP displacements and sway variability of CoP were found for the DN group. These results showed improvements in feedback/feed-forward strategies following DN, including enhanced neuromuscular control and static postural control, with the potential to become a convenient and accessible preventive treatment in CAI subjects.

The interrater reliability of dynamic leap and balance test in healthy and chronic ankle instability.

The primary aim of this study was to assess the interrater reliability of the Dynamic Leap and Balance Test (DLBT) in chronic ankle instability (CAI) and healthy groups. The secondary aim was to assess the differences in errors and time taken to complete the DLBT between the two groups for both raters and to identify cutoff scores to distinguish between patients with CAI and healthy controls. This was a controlled laboratory reliability analysis study. Fourteen healthy college-aged subjects (9 women 5 men; weight=62.10±8.03; height=168.35±6.0) and sixteen with a history of CAI (9 women, 7 men; weight=68.01±10.74; height=172.08±11.37) participated. Interrater reliability was determined by independent raters for both total time taken to complete the task and errors made. The most optimal score to discriminate between two groups was determined by receiver operator curve analysis. Total time taken and errors made were also documented for group differences as secondary analysis. A strong agreement was found between the two raters for time and errors with intraclass correlation coefficient >0.80. Significantly (P<.05) higher number of errors were made and greater time taken by the CAI subjects when compared with healthy for both raters. The most optimal score to discriminate between CAI and healthy control was 43.28s and 4 errors. Excellent interrater reliability substantiates that it can be used confidently by different clinicians for testing dynamic balance. CAI group took more time and made more errors to complete the DLBT.

Attentional Demands of Postural Control in Chronic Ankle Instability, Copers and Healthy Controls: A Controlled Cross-sectional Study

BackgroundIt has been shown that cognitive loading affects postural control in different populations. However, there is limited and conflicting information about dual task challenges on postural control in chronic ankle instability (CAI). Research QuestionDoes cognitive task performance change standing postural control in individuals with CAI, copers and healthy subjects? MethodsA descriptive, analytic, and controlled cross-sectional study was conducted on 75 individuals. They were assigned into three matched groups, including CAI, copers, and healthy controls. Postural control variables were collected during single leg standing on a force plate with and without vision and cognition. Parameters of center of pressure (COP), including mean COP area, range, sway index and velocity, were measured. Additionally, cognitive task performance by auditory stroop was assessed by calculating the reaction time and error ratio. Mixed model ANOVAs were used to determine the effects of group and testing conditions. ResultsThe CAI group demonstrated greater COP sway parameters compared to other groups under all testing conditions. The main significant effect of vision was observed for all COP parameters with greater COP sway during eyes closed compared to eyes open (P < 0.05). The main effect of a cognitive task was significant with reduced COP sway while performing the secondary cognitive compared to a single task in all three groups (P < 0.05). The cognitive task results revealed significantly longer reaction times in the CAI group compared to copers and healthy individuals (p < 0.05). SignificanceConsidering postural control deficits in CAI, especially in eye-closed condition and effects of cognitive loading, may guide us to improve postural control in those with CAI with neurocognitive training. Furthermore, no difference between coper and healthy groups may imply a successful compensatory postural control mechanism in copers.

Electromyographic Activity of Hip Musculature During Functional Exercises in Participants With and Without Chronic Ankle Instability

ObjectiveThe main objective of the present study was to investigate the electromyographic (EMG) activity of gluteus medius (Gmed) and gluteus maximus (Gmax) muscles during functional exercises in subjects with chronic ankle instability (CAI) vs healthy controls. MethodsSeventeen subjects (age, 24.4 ± 2.03 years) with CAI and 17 healthy controls (age, 24.6 ± 2.57 years) were recruited for the present study. For all participants, after testing maximum voluntary isometric contraction of the Gmed and Gmax muscle, EMG activity of these muscles was recorded during functional exercises, such as the Y Balance Test and the single-leg squat with and without Swiss ball. ResultsEMG activity of Gmed and Gmax was found to be significantly (P < .05) reduced during all functional exercises in subjects with CAI when compared with healthy controls. No significant differences (P > .05) were observed in the EMG activity of both muscles across different functional exercises. ConclusionOur findings indicate that EMG activity of hip muscles is significantly reduced in CAI subjects, which might give an indication regarding the inclusion of hip muscle strengthening (Gmax and Gmed) in the rehabilitation of CAI. Moreover, Gmed and Gmax muscle activity did not vary during the different functional exercises within each group, which might indicate that activation pattern of these muscles are not sensitive to the type of functional task.

Dynamic Leap and Balance Test: Ability to Discriminate Balance Deficits in Individuals With Chronic Ankle Instability.

The Dynamic Leap Balance Test (DLBT) is a new dynamic balance task that requires serial changes in base of support with alternating limb support and recovery of dynamic stability, as compared with the Y modification of the Star Excursion Balance Test (Y-SEBT), which assesses dynamic stability over an unchanging base of support. To assess the dynamic balance performance in 2 different types of dynamic balance tasks, the DLBT and the SEBT, in subjects with unilateral chronic ankle instability (CAI) when compared with matched controls. The authors hypothesized that the DLBT score would significantly differ between the CAI involved and uninvolved limbs (contralateral and healthy matched) and demonstrate a modest (r = .50) association with the SEBT scores. Case-control. Controlled laboratory. A total of 36 physically active adults, 18 with history of unilateral CAI and 18 without history of ankle injury, were enrolled in the study. CAI subjects were identified using the Identification of Functional Ankle Instability questionnaire. The DLBT and the SEBT were performed in a randomized order on a randomly selected limb in CAI and healthy subjects. Time taken to complete the DLBT and the reach distances performed on the SEBT were compared between the CAI and the healthy subjects. There were no statistically significant differences (P < .05) in SEBT reach distances between groups. The DLBT time was greater (P < .01) for unstable ankles compared with the stable ankle. The authors found no correlation (P > .05) between DLBT time and any of the SEBT reach distances suggesting that the DLBT provides unique information in the assessment of patients with CAI. The DLBT challenges the ability to maintain postural control in CAI subjects differently than the SEBT. There is a need of more dynamic balance assessment tools that are functional and clinically relevant.

Effects of chronic ankle instability on cutaneous reflex modulation during walking.

Chronic ankle instability (CAI) is characterized by persistent giving way at the ankle following an acute lateral ankle sprain and is associated with an early onset of osteoarthritis. Researchers have reported that the cutaneous afferent pathway from certain leg muscles is modified in people with CAI while in a seated position. However, we do not know if these reflex modulations persist during functional activities. The purpose of this study was to further explore sensorimotor function in patients with CAI by analyzing cutaneous reflex modulation during gait. CAI (n = 11) and uninjured control (n = 11) subjects walked on a treadmill at 4km/h and received non-noxious sural nerve stimulations at eight different time points during the gait cycle. Net electromyographic responses from four lower leg muscles were quantified 80-120ms after stimulation for each phase of the gait cycle and compared between groups. We found that cutaneous reflex responses between groups were largely similar from the late stance to late swing phases, but uninjured control subjects, and not CAI subjects, experienced significant suppression in the medial gastrocnemius and lateral gastrocnemius muscles during the early stance phase of the gait cycle. Our results indicate that people with CAI lack a protective unloading response in the triceps surae following high-intensity sural nerve stimulation during the early stance phase of the gait cycle. Evaluating cutaneous reflex modulations may help to identify neural alterations in the reflex pathways that contribute to functional deficits in those with CAI.

Evaluation for the Effect of Smartphone Based Training on Chronic Ankle Instability Subjects

Evaluation for the Effect of Smartphone Based Training on Chronic Ankle Instability Subjects

Effect of ankle taping on postural control measures during grasp and release task in patients with chronic ankle instability.

The aim of this study was to examine the effect of Mulligan ankle taping on center of pressure (COP) parameters during performance of a functional upper limb task in patients with chronic ankle instability (CAI). A clinical controlled trial study designed between 4ankle conditions: untaped and taped, CAI and healthy subjects. Fifteen subjects with CAI and 15healthy controls were asked to grasp an object at their waist level and release it above shoulder level in an oblique pattern during performance of single-leg stance balance test. All the subjects performed 3trials of single-leg stance with eyes opened before and after Mulligan taping on a force plate during performance of functional upper limb task. The mean displacement (mdCOP), range of COP excursion (rangeCOP) and average speed of COP (velCOP) in anteroposterior (AP) and mediolateral (ML) directions were analysed for differences between groups. mdCOP and rangeCOP in AP direction were significantly increased (P= 0.04 and 0.03, respectively) in the CAI group. Mulligan taping significantly reduced velCOP in AP and ML directions (P= 0.02). In CAI patients Mulligan ankle taping can improve postural control by decreasing velCOP, therefore Mulligan taping can have immediate positive effects on postural parameters and maintenance of dynamic postural control.

Effects of one session of manual therapy or squat exercise on ankle function in subjects with chronic ankle instability

Introduction: Our systematic review has shown that manual therapy is effective in improving ankle range of motion in subjects with Chronic Ankle Instability (CAI). However, it has not been determined whether self-administered active exercise has a similar effect. In addition, it is not known whether manual therapy or exercise can improve ankle proprioception in CAI subjects.

Foot and ankle kinematics in chronic ankle instability subjects using a midfoot strike pattern when running, including influence of taping

BackgroundInvestigate differences in multi-segment foot kinematics between controls and participants with chronic ankle instability during running with a midfoot striking pattern and to evaluate the effect of Low-Dye and High-Dye taping. MethodsThree-dimensional multi-segment foot kinematics of 12 controls and 15 participants with chronic ankle instability were collected while running barefoot, and in both taping conditions. Ranges of motion occurring at each joint, each sub phase of stance, were compared between groups and between taping conditions (0-dimensional inference). Kinematic data were also compared using one-dimensional statistical parametric mapping. FindingsThe symptomatic group demonstrated while barefoot running a significantly decreased rearfoot dorsiflexion range of motion during the peak impact phase as well as a less dorsiflexed position from 6 to 12% of the running cycle. During the absorption and generation phase, the symptomatic group also showed a significantly increased rearfoot dorsiflexion and adduction motion as well as an increased midfoot inversion motion. In the peak impact phase of both taping conditions, a decreased midfoot inversion motion was found. The High-Dye taping resulted in a decreased rearfoot plantarflexion motion whereas the Low-Dye caused a decreased midfoot inversion motion. InterpretationPersons with chronic ankle instability seem to have altered rearfoot and midfoot kinematics while running with a midfoot striking index. High-Dye taping seems to have better therapeutic features than Low-Dye taping.

The Effects of Open versus Closed Kinetic Chain Exercises on Ankle Joint Function in Athletes with Chronic Ankle Instability

Objective: Lateral ankle sprains are common sport injuries that often result in structural and functional alterations leading to chronic ankle instability (CAI). Insufficiencies in proprioception, neuromuscular control, and strength are suggested as contributing factors to CAI. Open Kinetic Chain (OKC) and Closed Kinetic Chain (CKC) exercises often constitute the core of ankle specific training before progression to advanced training. Though commonly used in the management of CAI, there is no consensus regarding their efficacy on physical therapy outcomes. The purpose of this study was to compare the effect of OKC and CKC exercises on dynamic postural control, self-reported function, and subjective sense of instability in subjects with CAI. Methods: Subjects with unilateral CAI were randomly assigned into three groups: OKC (n=5), CKC (n=6), and control (n=6). Outcome measures included star excursion balance test (SEBT) reach distance, center of pressure (COP) sway velocity, sway area, and path length; and Foot and Ankle Ability Measure-Sport Subscale. Intervention groups completed 6 weeks of exercises. Also, subjects completed a global rating of change (GROC) form at week 6 post-intervention. Results: Following intervention, both OKC and CKC groups had significant improvements in the outcome measures, indicating an improvement in dynamic postural control and subjective function; however, CKC had greater improvements than OKC. The control group did not show improvements. GROC revealed a significant difference in median score for CKC group when compared to OKC and control groups (p=0.04 and p=0.03, respectively). Conclusion: The 6-week of OKC and CKC exercise programs improved parameters of postural control and subjective function in CAI subjects. CKC exercises, however, were more effective than OKC exercises. Hence, exercise programs should become more functional and task oriented. Further research is needed in a larger cohort of subjects to determine effects of both training programs on ankle joint injury risk factors.

Individuals with Chronic Ankle Instability Exhibit Altered Ground Reaction Force Patterns during Walking

Lateral ankle sprains frequently occur and often lead to chronic ankle instability (CAI). CAI has been shown to alter neuromuscular function and walking mechanics which impact ground reaction force (GRF). PURPOSE: To examine patterns of ground reaction forces across the stance phase of gait in those with and without CAI. METHODS: 100 CAI patients (M=49, F=51; 22±2 yrs, 174±10 cm, 71±14 kg, 82±9% FAAM ADL, 62±13% FAAM Sports, 4.5±2.6 ankle sprains) and 100 controls (M=56, F=44; 22±3 yrs, 172±13 cm, 72±18 kg, 100% FAAM ADL & Sports, no previous sprains) performed five walking trials. Three dimensional GRFs (anterior-posterior, medial-lateral, and vertical) were measured during the stance phase of gait (0-25%: initial stance, 25-50%: loading response, 50-75%: midstance, and 75-100%: terminal stance). Functional linear models were used to compare difference in GRFs between the groups during walking (α=.05). If functions and associated 95% confidence intervals did not cross zero, group differences existed. RESULTS: Figure 1. CAI subjects demonstrated greater vertical GRF during 0-10% and 67-95% of stance. Patients with CAI also increased posterior and anterior GRFs during 10-20% and 70-95% of stance respectively. Lateral GRF was greater in CAI subjects during 65-75% of stance compared to controls. CONCLUSION: CAI subjects may compensate for ankle instability with a more rigid walking strategy by increasing anterior-posteior, lateral and vertical GRFs during the stance phase of gait. The greater GRF of the CAI group indicates altered gait mechanics which could increase loads on lower extremity joints and potentially increase re-injury risk.Figure