Brent L. Arnold

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.

Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping.

The authors compared leg stiffness (KVERT), muscle activation, and joint movement patterns between 11 men and 10 women during hopping. Physically active and healthy men and women performed continuous 2-legged hopping at their preferred rate and at 3.0 Hz. Compared with men, women demonstrated decreased KVERT; however, after the authors normalized for body mass, gender differences in KVERT were eliminated. In comparison with men, women also demonstrated increased quadriceps and soleus activity, as well as greater quadriceps-to-hamstrings coactivation ratios. There were no significant gender differences for joint movement patterns (p >.05). The relationship between the observed gender differences in muscle recruitment and the increased risk of anterior cruciate ligament injury in women requires further study.

Activation of the VMO and VL during dynamic mini-squat exercises with and without isometric hip adduction

OBJECTIVE the purpose of this study was to compare vastus medialis obliquus (VMO) and vastus lateralis (VL) activity while performing a mini-squat with and without isometric hip adduction. DESIGN AND SETTING a repeated measures within subjects design was used. Subjects performed two sets of three repetitions of a traditional mini-squat and a mini-squat with concurrent hip adduction (squeeze). SUBJECTS 20 recreationally active subjects (10 men, 10 women age=28.10+/-5.91 years, height=170.94+/-11.03 cm, mass=72.32+/-16.66 kg) with no history of patellofemoral pain (PFP), quadriceps injury, or other knee injury participated in the study. MEASUREMENTS the EMG signal of the VMO and VL was recorded bilaterally during both exercises. EMG data were normalized to the maximal voluntary isometric contraction (MVIC) of the quadriceps produced during seated, isometric knee extension. RESULTS results of repeated measures ANOVAs revealed that the squeeze squat produced significantly greater VMO and VL activity than the traditional squat (p=0.02). For both the traditional and squeeze squats, intrasession reliability from the first to the second set was calculated using intraclass correlation coefficient (ICC) formula (3:1) bilaterally for both the VMO and the VL. All ICC values were greater than 0.9. CONCLUSION combining isometric hip adduction with a mini-squat exercise significantly increases the activity of the quadriceps. Performing mini-squats with isometric hip adduction will be beneficial to patellofemoral patients as they increase quadriceps activity, however, based on our data we cannot conclude that this exercise preferentially recruits the VMO. Further research is needed to determine the exact mechanism by which quadriceps function is altered.

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 ns) 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.

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.

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

BackgroundAnkle 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.MethodsThis 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).ResultsTreatment 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).ConclusionReduced 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.

Repeatability of the modified Oxford foot model during gait in healthy adults

BACKGROUND The Oxford foot model (OFM) is a multi-segment model for calculating hindfoot and forefoot motion. Limited information is available regarding the repeatability and error of this model in adults. Therefore the purpose of this study was to assess the intra-tester reliability of OFM hindfoot and forefoot gait kinematics in adults at initial contact (IC) and toe-off (TO). METHODS Seventeen healthy adults (age=25.1±4.8 years, height=1.75±0.10m, weight=74.0±12.4kg) were tested on a single visit, during which 1 examiner recorded 2 sessions. For each session, 10 walking trials were recorded using a 12-camera motion analysis system (Vicon, Oxford, UK). Markers were removed and re-applied between sessions. Dynamic hindfoot and forefoot angles were calculated both with and without referencing to neutral stance (assuming neutral stance angles are zero in all planes). Using the 10 trial average, intraclass correlation coefficients (ICC(2,k)) and standard errors of the measurement were calculated for each reference condition, anatomical plane, and joint (hindfoot, forefoot). RESULTS Referencing to neutral stance resulted in good reliability (ICC≥0.83) and small error (≤2.45°) for hindfoot and forefoot angle in all planes. Without referencing to neutral stance, sagittal and transverse plane reliability were also good (ICC≥0.90) and error small (≤3.14°); however, frontal plane reliability was poor (ICC≤0.77), with large error (≥4.86°). DISCUSSION Our results show that overall the OFM is reliable during adult gait. Reliability for adults is higher than previously reported in children. Referencing joint angles to neutral stance decreased error by up to 2° from previous reports.

Force sense deficits in functionally unstable ankles

The purpose of this study was to determine whether participants with functional ankle instability have deficits in force sense reproduction compared to uninjured participants. Twenty participants with no history of injury and 20 with functional ankle instability volunteered for this investigation. Participants in the instability group had a history of at least one ankle sprain and frequent episodes of giving way. Ankle force sense testing was performed at 10, 20, and 30% of eversion maximal voluntary isometric contraction. Ten trials were performed at each force. Absolute and variable errors were then calculated. We observed significant (p < 0.05) main effects for group for absolute and variable errors. Force sense absolute error was significantly greater in the functionally unstable ankles (3.7 ± 2.2 N) compared to uninjured ankles (2.8 ± 1.1 N). Variable error was also significantly greater in the functionally unstable ankles (3.2 ± 1.8 N) than the uninjured ankles (2.4 ± 0.8 N). Functional ankle instability is associated with deficits in an individuals ability to accurately reproduce a given force. This deficit may impair an individuals ability to set appropriate muscle force levels to provide stability to the joint.

Bracing and rehabilitation: What's new

Based on the recent evidence, ankle bracing and taping do appear to have positive effects on ankle support. For example, both bracing and taping restrict inversion range of motion, with tape and stirrup-style braces providing the best support. Although exercise reduces this restriction, the range remains consistent with levels considered to be within the normal range. Ankle supports also appear to improve the strength of the muscular response to perturbation, potentially providing a stronger muscular contraction. In contrast, ankle supports fail to improve the neuromuscular response time to unexpected perturbations. Thus, it appears that the stronger response may occur too slowly to protect the joint. This slowness of the neuromuscular response, however, may be offset by the supports ability to slow the inversion motion. The slowing of inversion appears to allow the neuromuscular system to respond at or before the point of ligament damage. Finally, ankle supports appear to improve balance only in individuals with previously injured ankles. This suggests that supports may have a selective effect in protecting injured but not uninjured individuals. Despite these positive effects, some cautions should be emphasized. First, most of the studies cited have been performed in the laboratory setting with joint velocities and loads much below what are encountered in the athletic and daily activities. Whether tape and braces can maintain their effectiveness under the more extreme conditions of functional activities remains unclear. Additionally, some evidence suggests that ankle supports may transfer loads to other joints putting them at risk for injury. Thus, further study is needed to determine the risk-to-benefit ratio of ankle supports. Finally, much of the research presented has been done only on uninjured ankles. Based on the current evidence, it seems possible that the effectiveness of ankle supports may differ depending on the population, and it seems clinically important to know whether we can expect the same results for injured and uninjured ankles. Proper and early rehabilitation is important in preventing residual ankle symptoms. Reports indicate that up to 73% of people who sustain a lateral ankle sprain have recurrent sprains, but it is unknown how many of these participants partake in rehabilitation. Proper immobilization and acute care of the injured ankle is imperative. An immobilization boot or strapping that can be removed during early non-weight bearing exercises seems to be most effective. Strength and balance training of the uninjured contralateral limb can be used to assist reaching full recovery in a shorter period of time. Functional exercises can also be performed earlier in the rehabilitation process by reducing the gravitational forces so patients can perform in a pain-free range and still receive the benefits of early activity. Evidence shows that daily ankle disk training assists in preventing ankle sprains, and is a relatively inexpensive and easy alternative to traditional rehabilitation protocols.

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.