Recalibration and validation of the Cumberland Ankle Instability Tool cutoff score for individuals with chronic ankle instability

OBJECTIVE

To independently recalibrate and revalidate the Cumberland Ankle Instability Tool (CAIT) cutoff score for discriminating individuals with and without chronic ankle instability (CAI). There are concerns the original cutoff score (≤27) may be suboptimal for use in the CAI population.

DESIGN

Case control.

SETTING

Research laboratory.

PARTICIPANTS

Two independent datasets were used (total N=200). Dataset 1 included 61 individuals with a history of ≥1 ankle sprain and ≥2 episodes of giving way in the last year (CAI group) and 57 participants with no history of ankle sprain or instability in their lifetime (uninjured group). Dataset 2 included 27 uninjured participants, 29 participants with CAI, and 26 individuals with a history of a single ankle sprain and no subsequent instability (copers).

INTERVENTIONS

All participants completed the CAIT during a single session. In dataset 1, a receiver operating characteristic (ROC) curve was calculated using the CAIT score and group membership as test variables. The ideal cutoff score was identified using the Youden index. The recalibrated cutoff score was validated in dataset 2 using the ROC analysis and clinimetric characteristics.

MAIN OUTCOME MEASURES

CAIT cutoff score and clinimetrics.

RESULTS

In dataset 1, the optimal cutoff score was ≤25, which is lower than previously reported. In dataset 2, the recalibrated cutoff score demonstrated a sensitivity of 96.6%, specificity of 86.8%, positive likelihood ratio of 7.318, and negative likelihood ratio of .039. There were 7 false positives and 1 false negative.

CONCLUSIONS

The recalibrated CAIT score demonstrated very good clinimetric properties; all properties improved compared with the original cutoff score. Clinicians using the CAIT should use the recalibrated cutoff score to maximize test characteristics. Caution should be taken with copers, who had a high rate of false positives.

Postural-stability tests that identify individuals with chronic ankle instability

CONTEXT

Chronic ankle instability (CAI) is characterized by repeated ankle sprains, which have been linked to postural instability. Therefore, it is important for clinicians to identify individuals with CAI who can benefit from rehabilitation.

OBJECTIVE

To assess the likelihood that CAI participants will exhibit impaired postural stability and that healthy control participants will exhibit better test performance values.

DESIGN

Case-control study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

People with CAI (n = 17, age = 23 ± 4 years, height = 168 ± 9 cm, weight = 68 ± 12 kg) who reported ankle "giving-way" sensations and healthy volunteers (n = 17, age = 23 ± 3 years, height = 168 ± 8 cm, weight = 66 ± 12 kg).

INTERVENTION(S)

Participants performed 7 balance tests: Balance Error Scoring System (BESS), time in balance, foot lift, single-legged stance on a force plate, Star Excursion Balance Test, side hop, and figure-of-8 hop.

MAIN OUTCOME MEASURE(S)

Balance was quantified with errors (score) for the BESS, length of time balancing (seconds) for time-in-balance test, frequency of foot lifts (score) for foot-lift test, velocity (cm/s) for all center-of-pressure velocity measures, excursion (cm) for center-of-pressure excursion measures, area (cm2) for 95% confidence ellipse center-of-pressure area and center-of-pressure rectangular area, time (seconds) for anterior-posterior and medial-lateral time-to-boundary (TTB) measures, distance reached (cm) for Star Excursion Balance Test, and time (seconds) to complete side-hop and figure-of-8 hop tests. We calculated area-under-the-curve values and cutoff scores and used the odds ratio to determine if those with and without CAI could be distinguished using cutoff scores.

RESULTS

We found significant area-under-the-curve values for 4 static noninstrumented measures, 3 force-plate measures, and 3 functional measures. Significant cutoff scores were noted for the time-in-balance test (≤25.89 seconds), foot-lift test (≥5), single-legged stance on the firm surface (≥3 errors) and total (≥14 errors) on the BESS, center-of-pressure resultant velocity (≥1.56 cm/s), standard deviations for medial-lateral (≤1.56 seconds) time-to-boundary and anterior-posterior (≤3.78 seconds) time-to-boundary test, posteromedial direction on the Star Excursion Balance Test (≤0.91), side-hop test (≥12.88 seconds), and figure-of-8 hop test (≥17.36 seconds).

CONCLUSIONS

Clinicians can use any of the 10 significant measures with their associated cutoff scores to identify those who could benefit from rehabilitation that reestablishes postural stability.

Clinical examination results in individuals with functional ankle instability and ankle-sprain copers

CONTEXT

Why some individuals with ankle sprains develop functional ankle instability and others do not (ie, copers) is unknown. Current understanding of the clinical profile of copers is limited.

OBJECTIVE

To contrast individuals with functional ankle instability (FAI), copers, and uninjured individuals on both self-reported variables and clinical examination findings.

DESIGN

Cross-sectional study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants consisted of 23 individuals with a history of 1 or more ankle sprains and at least 2 episodes of giving way in the past year (FAI: Cumberland Ankle Instability Tool [CAIT] score = 20.52 ± 2.94, episodes of giving way = 5.8 ± 8.4 per month), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers: CAIT score = 27.74 ± 1.69), and 23 individuals with no history of ankle sprain and no instability (uninjured: CAIT score = 28.78 ± 1.78).

INTERVENTION(S)

Self-reported disability was recorded using the CAIT and Foot and Ankle Ability Measure for Activities of Daily Living and for Sports. On clinical examination, ligamentous laxity and tenderness, range of motion (ROM), and pain at end ROM were recorded.

MAIN OUTCOME MEASURE(S)

Questionnaire scores for the CAIT, Foot and Ankle Ability Measure for Activities of Daily Living and for Sports, ankle inversion and anterior drawer laxity scores, pain with palpation of the lateral ligaments, ankle ROM, and pain at end ROM.

RESULTS

Individuals with FAI had greater self-reported disability for all measures (P < .05). On clinical examination, individuals with FAI were more likely to have greater talar tilt laxity, pain with inversion, and limited sagittal-plane ROM than copers (P < .05).

CONCLUSIONS

Differences in both self-reported disability and clinical examination variables distinguished individuals with FAI from copers at least 1 year after injury. Whether the deficits could be detected immediately postinjury to prospectively identify potential copers is unknown.

Customized noise-stimulation intensity for bipedal stability and unipedal balance deficits associated with functional ankle instability

CONTEXT

Stochastic resonance stimulation (SRS) administered at an optimal intensity could maximize the effects of treatment on balance.

OBJECTIVE

To determine if a customized optimal SRS intensity is better than a traditional SRS protocol (applying the same percentage sensory threshold intensity for all participants) for improving double- and single-legged balance in participants with or without functional ankle instability (FAI).

DESIGN

Case-control study with an embedded crossover design.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twelve healthy participants (6 men, 6 women; age = 22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg) and 12 participants (6 men, 6 women; age = 23 ± 3 years, height = 174 ± 8 cm, mass = 69 ± 10 kg) with FAI.

INTERVENTION(S)

The SRS optimal intensity level was determined by finding the intensity from 4 experimental intensities at the percentage sensory threshold (25% [SRS₂₅], 50% [SRS₅₀], 75% [SRS₇₅], 90% [SRS₉₀]) that produced the greatest improvement in resultant center-of-pressure velocity (R-COPV) over a control condition (SRS₀) during double-legged balance. We examined double- and single-legged balance tests, comparing optimal SRS (SRS(opt1)) and SRS₀ using a battery of center-of-pressure measures in the frontal and sagittal planes.

MAIN OUTCOME MEASURE(S)

Anterior-posterior (A-P) and medial-lateral (M-L) center-of-pressure velocity (COPV) and center-of-pressure excursion (COPE), R-COPV, and 95th percentile center-of-pressure area ellipse (COPA-95).

RESULTS

Data were organized into bins that represented optimal (SRS(opt1)), second (SRS(opt2)), third (SRS(opt3)), and fourth (SRS(opt4)) improvement over SRS₀. The SRS(opt1) enhanced R-COPV (P ≤ .05) over SRS₀ and other SRS conditions (SRS₀ = 0.94 ± 0.32 cm/s, SRS(opt1) = 0.80 ± 0.19 cm/s, SRS(opt2) = 0.88 ± 0.24 cm/s, SRS(opt3) = 0.94 ± 0.25 cm/s, SRS(opt4) = 1.00 ± 0.28 cm/s). However, SRS did not improve R-COPV over SRS₀ when data were categorized by sensory threshold. Furthermore, SRS(opt1) improved double-legged balance over SRS₀ from 11% to 25% in all participants for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) also improved single-legged balance over SRS₀ from 10% to 17% in participants with FAI for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) did not improve single-legged balance in participants with stable ankles.

CONCLUSIONS

The SRS(opt1) improved double-legged balance and transfers to enhancing single-legged balance deficits associated with FAI.

Functional ankle instability and health-related quality of life

CONTEXT

To our knowledge, no authors have assessed health-related quality of life (HR-QOL) in participants with functional ankle instability (FAI). Furthermore, the relationships between measures of ankle functional limitation and HR-QOL are unknown.

OBJECTIVE

To use the Short Form-36v2 Health Survey (SF-36) to compare HR-QOL in participants with or without FAI and to determine whether HR-QOL was related to functional limitation.

DESIGN

Cross-sectional study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixty-eight participants with FAI (defined as at least 1 lateral ankle sprain and 1 episode of giveway per month) or without FAI were recruited (FAI group: n = 34, age = 25 ± 5 years, height = 1.71 ± 0.08 m, mass = 74.39 ± 12.78 kg, Cumberland Ankle Instability Tool score = 19.3 ± 4; uninjured [UI] group: n = 34, age = 23 ± 4 years, height = 1.69 ± 0.08 m, mass = 67.94 ± 11.27 kg, Cumberland Ankle Instability Tool score = 29.4 ± 1).

MAIN OUTCOME MEASURE(S)

All participants completed the SF-36 as a measure of HR-QOL and the Foot and Ankle Ability Measure (FAAM) and the FAAM Sport version (FAAMS) as assessments of functional limitation. To compare the FAI and UI groups, we calculated multiple analyses of variance followed by univariate tests. Additionally, we correlated the SF-36 summary component scale and domain scales with the FAAM and FAAMS scores.

RESULTS

Participants with FAI had lower scores on the SF-36 physical component summary (FAI = 54.4 ± 5.1, UI = 57.8 ± 3.7, P = .005), physical function domain scale (FAI = 54.5 ± 3.8, UI = 56.6 ± 1.2, P = .004), and bodily pain domain scale (FAI = 52.0 ± 6.7, UI = 58.5 ± 5.3, P < .005). Similarly, participants with FAI had lower scores on the FAAM (FAI = 93.7 ± 8.4, UI = 99.5 ± 1.4, P < .005) and FAAMS (FAI = 84.5 ± 8.4, UI = 99.8 ± 0.72, P < .005) than did the UI group. The FAAM score was correlated with the physical component summary scale (r = 0.42, P = .001) and the physical function domain scale (r = 0.61, P < .005). The FAAMS score was correlated with the physical function domain scale (r = 0.47, P < .005) and the vitality domain scale (r = 0.36, P = .002).

CONCLUSIONS

Compared with UI participants, those with FAI had less HR-QOL and more functional limitations. Furthermore, positive correlations were found between HR-QOL and functional limitation measures. This suggests that ankle impairment may reduce overall HR-QOL.

Balance assessments for predicting functional ankle instability and stable ankles

A number of instrumented and non-instrumented measures are used to detect balance deficits associated with functional ankle instability (FAI). Determining outcome measures that detect balance deficits associated with FAI might assist clinicians in identifying impairments that may otherwise go undetected with less responsive balance measures. Thus, our objective was to determine the balance measure that best predicted ankle group membership (FAI or stable ankle). Participants included 17 subjects without a history of ankle sprains (168±9 cm, 66±14 kg, 24±5 yr) and 17 subjects with FAI (172±9 cm, 71±11 kg, 22±3 yr). Balance trials were performed without vision and subjects stood on a single leg as motionless as possible for 20s. Balance was quantified with center-of-pressure measures (velocity, area) and error score. Measures were positively correlated with each other (r range: 0.60-0.76). The multifactorial model with all three measures best predicted group membership (F((3,30))=7.20, P=0.001; R(2)=0.42; percent classified correctly=77%), and was followed by the multifactorial model with resultant center-of-pressure velocity and error score (F((2,31))=8.73, P=0.001; R(2)=0.36; percent classified correctly=74%). The resultant center-of-pressure velocity (F((1,32))=13.46, P=0.001; R(2)=0.30; percent classified correctly=74%; unique variance=12.7%) and error score (F((1,32))=12.51, P=0.001; R(2)=0.28; percent classified correctly=71%; unique variance=12.0%) predicted group membership; however, 95th percentile center-of-pressure area ellipse did not (F((1,32))=4.16, P=0.05; R(2)=0.12; percent classified correctly=65%; unique variance=5.8%). A multifactorial single leg balance assessment is best for predicting group membership. COPV is the best single predictor of group membership, but clinicians may use error score to identify deficits associated with FAI if force plates are not available.

Concentric evertor strength differences and functional ankle instability: a meta-analysis

OBJECTIVE

To determine whether concentric evertor muscle weakness was associated with functional ankle instability (FAI).

DATA SOURCES

We conducted an electronic search through November 2007, limited to English, and using PubMed, Pre-CINAHL, CINAHL, and SPORTDiscus. A forward search was conducted using the Science Citation Index on studies from the electronic search. Finally, we conducted a hand search of all selected studies and contacted the respective authors to identify additional studies. We included peer-reviewed manuscripts, dissertations, and theses.

STUDY SELECTION

We evaluated the titles and abstracts of studies identified by the electronic searches. Studies were selected by consensus and reviewed only if they included participants with FAI or chronic ankle instability and strength outcomes. Studies were included in the analysis if means and SDs (or other relevant statistical information, such as P values or t values and group n's) were reported for FAI and stable groups (or ankles).

DATA EXTRACTION

Data were extracted by the authors independently, cross-checked for accuracy, and limited to outcomes of concentric eversion strength. We rated each study for quality. Outcomes were coded as either fast or slow velocity (ie, equal to or greater than 110 degrees /s or less than 110 degrees /s, respectively).

DATA SYNTHESIS

Data included the means, SDs, and group sample sizes (or other appropriate statistical information) for the FAI and uninjured groups (or ankles). The standard difference in the means (SDM) for each outcome was calculated using the pooled SD. We tested individual and overall SDMs using the Z statistic and comparisons between fast and slow velocities using the Q statistic. Our analysis revealed that ankles with FAI were weaker than stable ankles (SDM = 0.224, Z = 4.0, P < .001, 95% confidence interval = 0.115, 0.333). We found no difference between the fast- and slow-velocity SDMs (SDM(Fast) = 0.189, SDM(Slow) = 0.244, Q = 29.9, df = 24, P = .187). Because of the small SDM, this method of measuring ankle strength in the clinical setting may need to be reevaluated.

Thigh muscle activity, knee motion, and impact force during side-step pivoting in agility-trained female basketball players

CONTEXT

Improving neuromuscular control of hamstrings muscles might have implications for decreasing anterior cruciate ligament injuries in females.

OBJECTIVE

To examine the effects of a 6-week agility training program on quadriceps and hamstrings muscle activation, knee flexion angles, and peak vertical ground reaction force.

DESIGN

Prospective, randomized clinical research trial.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty female intramural basketball players with no history of knee injury (age = 21.07 +/- 2.82 years, height = 171.27 +/- 4.66 cm, mass = 66.36 +/- 7.41 kg).

INTERVENTION(S)

Participants were assigned to an agility training group or a control group that did not participate in agility training. Participants in the agility training group trained 4 times per week for 6 weeks.

MAIN OUTCOME MEASURE(S)

We used surface electromyography to assess muscle activation for the rectus femoris, vastus medialis oblique, medial hamstrings, and lateral hamstrings for 50 milliseconds before initial ground contact and while the foot was in contact with the ground during a side-step pivot maneuver. Knee flexion angles (at initial ground contact, maximum knee flexion, knee flexion displacement) and peak vertical ground reaction force also were assessed during this maneuver.

RESULTS

Participants in the training group increased medial hamstrings activation during ground contact after the 6-week agility training program. Both groups decreased their vastus medialis oblique muscle activation during ground contact. Knee flexion angles and peak vertical ground reaction force did not change for either group.

CONCLUSIONS

Agility training improved medial hamstrings activity in female intramural basketball players during a side-step pivot maneuver. Agility training that improves hamstrings activity might have implications for reducing anterior cruciate ligament sprain injury associated with side-step pivots.

Interest in health information exchange in ambulatory care: a statewide survey

OBJECTIVE

Assess the interest in and preferences of ambulatory practitioners in HIE.

BACKGROUND

Health information exchange (HIE) may improve the quality and efficiency of care. Identifying the value proposition for smaller ambulatory practices may help those practices engage in HIE.

METHODS

Survey of primary care and specialist practitioners in the State of Colorado.

RESULTS

Clinical data were commonly (always [2%], often [29%] or sometimes [49%]) missing during clinic visits. Of 12 data types proposed as available through HIE, ten were considered "extremely useful" by most practitioners. "Clinical notes/consultation reports," "diagnosis or problem lists," and "hospital discharge summaries" were considered the three most useful data types. Interest in EKG reports, diagnosis/problem lists, childhood immunizations, and discharge summaries differed among ambulatory practitioner groups (primary care, obstetrics-gynecology, and internal medicine subspecialties).

CONCLUSION

Practitioners express strong interest in most of the data types, but opinions differed by specialties on what types were most important. All providers felt that a system that provided all data types would be useful. These results support the potential benefit of HIE in ambulatory practices.

Ankle instability is associated with balance impairments: a meta-analysis

PURPOSE

Our primary purpose was to determine whether balance impairments were associated with functional ankle instability (FAI).

METHODS

Our literature search consisted of four parts: 1) an electronic search of PubMed, CINAHL, pre-CINAHL, and SPORTDiscus; 2) a forward search of articles selected from the electronic search using the Science Citation Index; 3) a hand search of the previously selected articles; and 4) a direct contact with corresponding authors of the previously selected articles. We initially identified 145 articles and narrowed these to 23 for inclusion in the meta-analysis. Identified outcomes were categorized by measurement units and balance task type (i.e., dynamic or static). Each study was coded based on whether inclusion or exclusion criteria were identified. Our statistical analysis included fixed, random, or mixed effect analyses based on the presence of within study heterogeneity and whether categories were being compared.

RESULTS

FAI was associated with poorer balance (standard difference of the mean [SDM] = 0.455, 95% confidence interval = 0.334-0.577, Z = 7.34, P < 0.001), but no difference existed between dynamic and static measure categories (Q = 3.44, P = 0.063). However, there was a significant difference between the dynamic measures (Q = 6.22, P = 0.013) with both time to stabilization and the Star Excursion Balance Test producing significant SDM and between static measures (Q = 13.00, P = 0.012) with the linear, time, velocity, and other measurement categories (but not area) producing significant SDM. Examination of individual outcomes revealed that time in balance and foot lifts produced very large SDM (3.3 and 4.8, respectively).

CONCLUSION

FAI is associated with impaired balance. Due to the relatively large effect sizes and simplicity of use of time in balance and foot lifts, we recommend that further research should establish their clinical validity and clinical cutoff scores.

Balance measures for discriminating between functionally unstable and stable ankles

PURPOSE

To identify force plate measures that discriminate between ankles with functional instability and stable ankles and to determine the most accurate force plate measure for enabling this distinction.

METHODS

Twenty-two subjects (177 +/- 10 cm, 77 +/- 16 kg, 21 +/- 2 yr) without a history of ankle injury and 22 subjects (177 +/- 10 cm, 77 +/- 16 kg, 20 +/- 2 yr) with functional ankle instability (FAI) performed a single-leg static balance test and a single-leg jump-landing dynamic balance test. Static force plate measures analyzed in both anterior/posterior (A/P) and medial/lateral (M/L) directions included the following: ground reaction force (GRF) SD; center-of-pressure (COP) SD; mean, maximum, and total COP excursion; and mean and maximum COP velocity. COP area was also analyzed for static balance. A/P and M/L time to stabilization quantified dynamic balance. Greater values of force plate measures indicated impaired balance. A stepwise discriminant function analysis examined group differences, group classification, and accuracy of force plate measures for discriminating between ankle groups.

RESULTS

The FAI group had greater values than the stable ankle group for A/P GRF SD (P = 0.027), M/L GRF SD (P = 0.006), M/L COP SD (P = 0.046), A/P mean COP velocity (P = 0.015), M/L mean COP velocity (P = 0.016), A/P maximum COP velocity (P = 0.037), M/L mean COP excursion (P = 0.014), M/L total COP excursion (P = 0.016), A/P time to stabilization (P = 0.011), and M/L time to stabilization (P = 0.040). M/L GRF SD and A/P time to stabilization had the greatest accuracy scores of 0.73 and 0.72, respectively.

CONCLUSION

Although 10 measures identified group differences, M/L GRF SD and A/P time to stabilization were the most accurate in discriminating between ankle groups. These results provide evidence for choosing these GRF measures for evaluating static and dynamic balance deficits associated with FAI.

Assessment tools for identifying functional limitations associated with functional ankle instability

CONTEXT

Assessment tools should identify functional limitations associated with functional ankle instability (FAI) by discriminating unstable from stable ankles.

OBJECTIVE

To identify assessment tools that discriminated FAI from stable ankles and determine the most accurate assessment tool for discriminating between FAI and stable ankles.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen individuals with FAI and 15 healthy individuals; participants with unilateral FAI reported "giving-way" sensations and ankle sprains, whereas healthy participants did not.

INTERVENTION(S)

Participants answered 12 questions on the Ankle Joint Functional Assessment Tool (AJFAT). They also performed a single-leg jump landing, which required them to jump to half their maximum jump height, land on a single leg, and stabilize quickly on a force plate.

MAIN OUTCOME MEASURE(S)

Receiver operating characteristic curves determined cutoff scores for discriminating between ankle groups for AJFAT total score and resultant vector (RV) time to stabilization. Accuracy values for discriminating between groups were determined by calculating the area under the receiver operating characteristic curves.

RESULTS

The cutoff score for discriminating between FAI and stable ankles was > or =26 (sensitivity = 1, specificity = 1) and > or =1.58 seconds (sensitivity = 0.67, specificity = 0.73) for the AJFAT total score and RV time to stabilization, respectively. The area under the curve for the AJFAT was 1.0 (asymptotic significance <.05), whereas the RV time to stabilization had an area under the curve of 0.72 (asymptotic significance <.05).

CONCLUSIONS

The AJFAT was an excellent assessment tool for discriminating between ankle groups, whereas RV time to stabilization was a fair assessment tool. Although both assessments discriminated between ankle groups, the AJFAT more accurately discriminated between groups than the RV time to stabilization did. Future researchers should confirm these findings using a prospective research design.

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

Background

Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains.

Methods

This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea).

Results

Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s), M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s), M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0.11 cm), M/L COPmax (1.76 ± 0.25 cm vs. 1.98 ± 0.25 cm), and COParea (0.13 ± 0.03 cm² vs. 0.16 ± 0.04 cm²) than the pooled means of the CCT and control groups (P < 0.05).

Conclusion

Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI.

Noise-enhanced postural stability in subjects with functional ankle instability

OBJECTIVE

To examine the effects of stochastic resonance (SR) stimulation on the postural stability of subjects with functional ankle instability (FAI).

DESIGN

Experimental research design.

SETTING

Sports medicine research laboratory.

PARTICIPANTS

12 subjects with FAI who reported a history of recurrent ankle sprains and "giving way" sensations at the ankle.

INTERVENTIONS

Subjects performed 20 s single-leg balance tests under SR stimulation at 0.05 mA and 0.01 mA and under control conditions. Testing order was randomised. Stimulators that delivered subsensory stimulation to ankle muscles and ligaments were worn. Subjects were blinded to the test conditions, as SR stimulation was subsensory and stimulators were turned off during the control condition.

MAIN OUTCOME MEASURES

Anterior/posterior and medial/lateral centre-of-pressure velocities (COPVs) were combined to form a resultant vector (COPV-R). The COPV-R differences between the optimal SR stimulation and control conditions were analysed. Optimal SR stimulation was defined as the SR stimulation input intensity level (0.05 mA or 0.01 mA) that produced the greatest percentage improvement in postural stability compared with the control condition. Slower velocities indicated enhanced postural stability.

RESULTS

The optimal input intensity was 0.05 mA for nine subjects and 0.01 mA for the other three. The optimal SR stimulation significantly (p<0.05) improved COPV-R compared with the control condition (6.60 (1.06) vs 7.20 (1.03) cm/s; mean (SD)).

CONCLUSION

SR stimulation may enhance signal detection of sensorimotor signals associated with postural stability. This result has clinical relevance as improvements in postural instability associated with FAI may decrease ankle sprain injury.

Functional balance training, with or without exercise sandals, for subjects with stable or unstable ankles

CONTEXT

Improving postural stability through balance training may prevent ankle sprains. Exercise Sandals may increase the demands placed on ankle muscles during rehabilitation, which could improve postural stability.

OBJECTIVE

To examine the effects of functional balance training, with and without the use of Exercise Sandals, on postural stability in subjects with stable or unstable ankles.

DESIGN

Prospective, nonrandomized clinical trial.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixteen subjects with functional ankle instability and 16 subjects with no history of ankle sprains.

INTERVENTION(S)

Subjects were assigned to an Exercise Sandal functional balance training group or a shoe functional balance training group. Subjects trained 3 times per week for 8 weeks and then performed a single-limb stance posttest.

MAIN OUTCOME MEASURE(S)

Subjects were required to remain as motionless as possible during a single-limb stance pretest. Anterior-posterior and medial-lateral center-of-pressure excursions were measured.

RESULTS

Exercise Sandal balance training improved anterior-posterior postural stability in both ankle groups ( P < .05). Both training interventions improved medial-lateral postural stability in stable and unstable ankles ( P < .05).

CONCLUSIONS

Postural stability improved after subjects performed functional balance training programs, both with and without Exercise Sandals. Training with Exercise Sandals might not be any more effective in improving postural stability than performing functional balance training without Exercise Sandals. However, Exercise Sandals did not impair postural stability and, consequently, might serve as an alternative therapy to improve postural stability.

Effect of coordination training with and without stochastic resonance stimulation on dynamic postural stability of subjects with functional ankle instability and subjects with stable ankles

OBJECTIVE

To examine the effects of coordination training with and without stochastic resonance (SR) stimulation on dynamic postural stability.

DESIGN

Experimental with repeated measures.

SETTING

Research Laboratory.

PARTICIPANTS

Thirty subjects with functional ankle instability (FAI) and 30 healthy subjects.

INTERVENTIONS

Subjects were assigned to a conventional coordination training group, SR stimulation coordination training group, or control group. Training groups performed coordination exercises for 6 weeks. Single leg jump-landing tests were performed before training began (pretest), and then once every 2 weeks. Jump-landing tests required subjects to land on a single leg on a force plate and stabilize quickly.

MAIN OUTCOME MEASURES

Anterior/posterior (A/P) and medial/lateral (M/L) time-to-stabilization (TTS).

RESULTS

The FAI group improved their A/P TTS over their pretest by 16% (test 2), 22% (test 3), and 22% (posttest). They also improved their M/L TTS over their pretest by 16% (test 3) and 22% (posttest). Control groups did not improve their TTS (P>0.05). SR stimulation did not statistically influence TTS (P>0.05). Effect sizes (ES), however, for our 3-way interaction analyses for A/P TTS (ES=0.40) and M/L TTS (ES=0.30) suggested that SR stimulation improved the FAI group's M/L TTS after 2 weeks of training, and improved their A/P TTS and M/L TTS to a greater degree after 4 weeks than coordination training alone.

CONCLUSION

Coordination training can improve dynamic postural instabilities associated with FAI. SR stimulation might be an alternative therapy for FAI, as this stimulation might improve dynamic postural stability more quickly and to a greater extent than coordination training without SR stimulation.

Single-leg jump-landing stabilization times in subjects with functionally unstable ankles

CONTEXT

Factors contributing to functional ankle instability may cause individuals with the condition to land from a jump differently than those with stable ankles.

OBJECTIVE

To determine stabilization time differences during single-leg jump landings between stable and unstable ankle groups and to report the reliability and precision of time-to-stabilization measures.

DESIGN

A mixed design with 1 between factor (ankle group) and 1 within factor (direction) was used to analyze the comparison between our 10 subjects with functional ankle instability and 10 subjects with stable ankles. Time to stabilization (seconds) was the dependent measure. Reliability for time-to-stabilization measures of our 12 additional subjects with stable ankles were assessed using intraclass correlation coefficients (ICC 2,7). Standard errors of measurements were also calculated for time-to-stabilization measures.

SETTING

Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANT(S): Ten subjects with functional ankle instability who reported at least 2 sprains and "giving way'' sensations at their ankles constituted the functional ankle instability group. Ten subjects without a history of ankle sprain injury served as healthy subjects. Twelve additional healthy subjects participated in the reliability study.

INTERVENTION(S)

Subjects performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height and then land on a single leg on a force plate. After landing, they stabilized quickly and remained as motionless as possible in a single-leg stance for 20 s.

MAIN OUTCOME MEASURE(S)

Anterior-posterior and medial/ lateral vibration magnitude curve fit time-to-stabilization.

RESULTS

Time to stabilization was longer for the functional ankle instability group (1.98 +/- 0.81 s) than for the stable ankle group (1.45 +/- 0.30 s) (P < .05). Reliability (standard error of the measurement) values for anterior/posterior and medial/lateral time-to-stabilization were 0.79 (0.15 s) and 0.65 (0.26 s), respectively.

CONCLUSIONS

Time to stabilization was longer for subjects with functional ankle instability than subjects with stable ankles. The ankle instability may have impaired the subjects' ability to stabilize after a single-leg jump landing. Reliabilities and standard errors of the measurements of time-to-stabilization measures were moderate and low, respectively.

Examination of static and dynamic postural stability in individuals with functionally stable and unstable ankles

OBJECTIVE

To determine static and dynamic postural stability differences between functional ankle instability and stable ankle groups.

DESIGN

Subjects were required to balance on a single leg and remain motionless for 20 seconds. After completing 3 trials, they performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height. They landed on a single leg, stabilized quickly, and remained motionless for 20 seconds.

SETTING

Sports Medicine Research Laboratory.

PARTICIPANTS

Subjects with functional ankle instability (n = 14) who reported at least 2 sprains and "giving way" sensations at their ankle joint within the year prior to testing. Fourteen subjects with no history of ankle sprain injury were matched to subjects with functional ankle instability.

MAIN OUTCOME MEASURES

Anterior/posterior and medial/lateral mean sway quantified static postural stability during single-leg stance. Dynamic postural stability was quantified with anterior/posterior and medial/lateral time to stabilization during single-leg jump landing.

RESULTS

Mean sway was not significantly different between groups in the anterior/posterior (P = 0.28) and medial/lateral (P = 0.65) directions. The functional ankle instability group took significantly longer to stabilize in the anterior/posterior (3.27 +/- 0.72 seconds vs. 2.33 +/- 0.33 seconds; P < 0.001) and medial/lateral (2.48 +/- 0.50 seconds vs. 2.00 +/- 0.65 seconds; P = 0.04) directions.

CONCLUSIONS

Individuals with functional ankle instability took significantly longer to stabilize than individuals with stable ankles after a single-leg jump landing. Differences between groups were not detected with mean sway measured during single-leg stance.