Efficacy of a semirigid ankle brace in reducing mechanical ankle instability evaluated by 3D stress-MRI

Background Novel imaging technologies like 3D stress-MRI of the ankle allow a quantification of the mechanical instability contributing to chronic ankle instability. In the present study, we have tested the efficacy of a semirigid ankle brace on joint congruency in a plantarflexion/supination position with and without load. Methods In this controlled observational study of n = 25 patients suffering from mechanical ankle instability, a custom-built ankle arthrometer implementing a novel 3D-stress MRI technique was used to evaluate the stabilizing effect of an ankle brace. Three parameters of joint congruency (i.e., 3D cartilage contact area fibulotalar, tibiotalar horizontal and tibiotalar vertical) were measured. The loss of cartilage contact area from neutral position to a position combined of 40° of plantarflexion and 30° of supination without and with axial load of 200 N was calculated. A semirigid ankle brace was applied in plantarflexion/supination to evaluate its effect on joint congruence. Furthermore, the perceived stability of the brace during a hopping task was analyzed using visual analogue scale (VAS). Results The application of a semirigid brace led to an increase in cartilage contact area (CCA) when the foot was placed in plantarflexion and supination. This effect was visible for all three compartments of the upper ankle joint (P < 0.001; η2 = 0.54). The effect of axial loading did not result in significant differences. The subjective stability provided by the brace (VAS 7.6/10) did not correlate to the magnitude of the improvement of the overall joint congruency. Conclusions The stabilizing effect of the semirigid ankle brace can be verified using 3D stress-MRI. Providing better joint congruency with an ankle brace may reduce peak loads at certain areas of the talus, which possibly cause osteochondral or degenerative lesions. However, the perceived stability provided by the brace does not seem to reflect into the mechanical effect of the brace. Trial registration The study protocol was prospectively registered at the German Clinical Trials Register (#DRKS00016356).

Analysis of Ankle Laxity, Self-reported Function, and Perceived Instability in Chronic Ankle Instability, Coper, and Control Groups

PURPOSE:This study aimed to identify differences in ankle laxity in chronic ankle instability (CAI), coper, and control groups, and a correlation between ankle laxity, self-reported function, and perceived instability.METHODS: Sixty-six participants (22 CAI patients, 22 copers, and 22 controls) selected by recommendations of the International Ankle Consortium volunteered for this study. Foot and Ankle Ability Measure Activities of Daily Living (FAAM-ADL), FAAM-Sports, and Ankle Instability Instrument (AII) were used to assess participants’ self-reported function and perceived instability. The FAAMADL and FAAM-Sports are reported as a percentage. Higher scores indicate better function. The AII is reported as “yes” responses while more “yes” responses indicate higher instability. Three trials of anterior/posterior (A/P) displacement and inversion/eversion (I/E) displacement were assessed by an instrumented ankle arthrometer. Greater displacement indicates higher laxity. The ankle positioned in sagittal- and frontal-plane neutral while A/P and I/E displacement were assessed with 125 N and 4 N-m, respectively. The means of three trials were used for data analysis. One-way ANOVA and Tukey post-hoc comparisons (α=0.05) were performed to identify differences in ankle laxity between groups. Pearson correlation analysis was performed to identify a relationship between ankle laxity, self-reported function, and perceived instability.RESULTS: CAI patients show greater A/P displacement compared to control group (p<.03), and greater I/E displacement compared to coper and control groups (p<.03). Several positive and negative correlations were found between ankle laxity, self-reported function, and perceived instability (p<.00).CONCLUSIONS: As self-reported function and perceived instability are correlated with greater laxity (I/E displacement), improving static stability (ankle laxity) may play an important role in improving perceived ankle function and instability in CAI.

Use of an Instrumented Ankle Arthrometer and External Strain Gauge to Assess Ankle Dorsiflexion Motion and Plantarflexor Stiffness

Background Ankle dorsiflexion motion and plantarflexor stiffness measurement offer clinical insight into the assessment and treatment of musculoskeletal and neurologic disorders. We aimed to determine reliability and concurrent validity of an ankle arthrometer in quantifying dorsiflexion motion and plantarflexor stiffness. Methods Ten healthy individuals were assessed for dorsiflexion motion and plantarflexor stiffness using an ankle arthrometer with a 6 degree-of-freedom kinematic linkage system and external strain gauge to apply dorsiflexion torque. Two investigators each performed five loads to the ankle at different combinations of loads (10 or 20 Nm), rates (2.5 or 5 Nm/sec), and knee angles (10° or 20°). Anteroposterior displacement and inversion-eversion rotation were also assessed with arthrometry, and functional dorsiflexion motion was assessed with the weightbearing lunge (WBL) test. Results Good-to-excellent intrarater reliability was observed for peak dorsiflexion (intraclass correlation coefficient [ICC][2,k] = 0.949–0.988) and plantarflexor stiffness (ICC[2,k] = 0.761–0.984). Interrater reliability was good to excellent for peak dorsiflexion (ICC[2,1] = 0.766–0.910) and poor to excellent for plantarflexor stiffness (ICC[2,1] = 0.275–0.914). Reliability was best for 20-Nm loads at 5 Nm/sec. Strong correlations were observed between peak dorsiflexion and anteroposterior displacement (r = 0.666; P = 0.035) and WBL distance (r = -0.681; P = 0.036). Conclusions Using an ankle arthrometer to assess peak dorsiflexion and plantarflexor stiffness seems reliable when performed to greater torques with faster speeds; and offers consistency with functional measures. Use of this readily available tool may benefit clinicians attempting to quantify equinus and dorsiflexion deficits in pathological populations.

Evaluating Postural Control and Ankle Laxity Between Taping and High-Top Cleats in High School Football Players

Context: Lateral ankle sprains are the most common injuries in high school sports. While ankle taping is a preferred method of external prophylactic support, its restrictive properties decline during exercise. The Under Armour® Highlight cleat is marketed on the premise that it provides added support without the need for additional ankle taping. Objective: To determine if differences in ankle joint laxity and postural control exist between football players wearing the Under Armour® Highlight cleat (Under Armour Inc, Baltimore, MD) as compared to a low/mid-top cleat with ankle tape. Design: Crossover trial. Setting: Athletic training room and football practice field sideline. Patients: 32 interscholastic football players (15.8 ± 1.0 y; 178.9 ± 7.4 cm; 87.1 ± 21.4 kg). Interventions: Ankle laxity was assessed using an instrumented ankle arthrometer (Blue Bay Research Inc, Milton, FL), while postural control testing was performed on the Tekscan MobileMat™ Balanced Error Scoring System (BESS; South Boston, MA). The 2 treatments included Under Armour® Highlight cleats and a low/mid-top cleat with ankle tape applied to the nondominant ankle only. Measurements were taken before and immediately after practice. Main Outcome Measures: The independent variable was treatment (Highlight vs low/mid-top cleat with ankle tape). Dependent variables included ankle arthrometry measures of anterior displacement (mm), inversion/eversion rotation (deg), and the modified BESS error scores. A linear mixed-effects model was used for analysis. Results: The low/mid-top cleat with tape condition had significantly higher inversion range-of-motion (ROM) and inversion/eversion rotation postexercise when compared to the Highlight cleat (P < 0.05). Conclusions: The results of this study provide some evidence that the Under Armour® Highlight cleat restricts ankle ROM following a training session better than the taped low/mid-top cleat. Further study is warranted to determine if this high-top style of football cleat can reduce the incidence of ankle sprains and how it might compare to spat taping.

Neural Excitability and Joint Laxity in Chronic Ankle Instability, Coper, and Control Groups

Neuromuscular and mechanical deficiencies are commonly studied in participants with chronic ankle instability (CAI). Few investigators have attempted to comprehensively consider sensorimotor and mechanical differences among people with CAI, copers who did not present with prolonged dysfunctions after an initial ankle sprain, and a healthy control group.Context: To determine if differences exist in spinal reflex excitability and ankle laxity among participants with CAI, copers, and healthy controls.Objective: Case-control study.Design: Research laboratory.Setting: Thirty-seven participants with CAI, 30 participants categorized as copers, and 26 healthy control participants.Patients or Other Participants: We assessed spinal reflex excitability of the soleus using the Hoffmann reflex protocol. Participants' ankle laxity was measured with an instrumented ankle arthrometer. The maximum Hoffmann reflex : maximal muscle response ratio was calculated. Ankle laxity was measured as the total displacement in the anterior-posterior directions (mm) and total rotation in the inversion and eversion directions (°).Main Outcome Measure(s): Spinal reflex excitability was diminished in participants with CAI compared with copers and control participants (P = .01). No differences were observed among any of the groups for ankle laxity.Results: Changes in the spinal reflex excitability of the soleus that likely affect ankle stability were seen only in the CAI group, yet no mechanical differences were noted across the groups. These findings support the importance of finding effective ways to increase spinal reflex excitability for the purpose of treating neural excitability dysfunction in patients with CAI.Conclusion:

Muscle Spindle Traffic in Functionally Unstable Ankles During Ligamentous Stress

Context: Ankle sprains are common in athletes, with functional ankle instability (FAI) developing in approximately half of cases. The relationship between laxity and FAI has been inconclusive, suggesting that instability may be caused by insufficient sensorimotor function and dynamic restraint. Research has suggested that deafferentation of peripheral mechanoreceptors potentially causes FAI; however, direct evidence confirming peripheral sensory deficits has been elusive because previous investigators relied upon subjective proprioceptive tests. Objective: To develop a method for simultaneously recording peripheral sensory traffic, joint forces, and laxity and to quantify differences between healthy ankles and those with reported instability. Design: Case-control study. Setting: University laboratory. Patients or Other Participants: A total of 29 participants (age = 20.9 ± 2.2 years, height = 173.1 ± 8.9 cm, mass = 74.5 ± 12.7 kg) stratified as having healthy (HA, n = 19) or unstable ankles (UA, n = 10). Intervention(s): Sensory traffic from muscle spindle afferents in the peroneal nerve was recorded with microneurography while anterior (AP) and inversion (IE) stress was applied to ligamentous structures using an ankle arthrometer under test and sham conditions. Main Outcome Measure(s): Laxity (millimeters or degrees) and amplitude of sensory traffic (percentage) were determined at 0, 30, 60, 90, and 125 N of AP force and at 0, 1, 2, 3, and 4 Nm of IE torque. Two-factor repeated-measures analyses of variance were used to determine differences between groups and conditions. Results: No differences in laxity were observed between groups (P &gt; .05). Afferent traffic increased with increased force and torque in test trials (P &lt; .001). The UA group displayed decreased afferent activity at 30 N of AP force compared with the HA group (HA: 30.2% ± 9.9%, UA: 17.1% ± 16.1%, P &lt; .05). Conclusions: The amplitude of sensory traffic increased simultaneously with greater ankle motion and loading, providing evidence of the integrated role of capsuloligamentous and musculotendinous mechanoreceptors in maintaining joint sensation. Unstable ankles demonstrated diminished afferent traffic at low levels of force, suggesting the early detection of joint loading may be compromised.

Sex Differences, Hormone Fluctuations, Ankle Stability, and Dynamic Postural Control

Context: Hormonal fluctuation as a risk factor in anterior cruciate ligament injury has been investigated with conflicting results. However, the influence of hormone fluctuations on ankle laxity and function has not been thoroughly examined. Objective: To examine the potential hormone contributions to ankle laxity and dynamic postural control during the preovulatory and postovulatory phases of the menstrual cycle using an ankle arthrometer and the Star Excursion Balance Test in healthy women. The cohort group consisted of male control participants. Design: Cohort study. Setting: Research laboratory. Patients or Other Participants: Twenty healthy women (age = 23.8 ± 6.50 years, height = 163.88 ± 8.28 cm, mass = 63.08 ± 12.38 kg) and 20 healthy men (age = 23.90 ± 4.15 years, height = 177.07 ± 7.60 cm, mass = 80.57 ± 12.20 kg). Intervention(s): Ankle stability was assessed with anterior-posterior and inversion-eversion loading. Dynamic postural control was assessed with the posteromedial reaching distance of the Star Excursion Balance Test. Main Outcome Measure(s): Female participants used ovulation kits for 3 months to determine the time of ovulation; during their preovulatory and postovulatory phases, they were tested in the laboratory with an ankle arthrometer and the Star Excursion Balance Test. Male participants were tested on similar dates as controls. For each dependent variable, a time by side by sex repeated-measures analysis of variance was performed. Statistical significance was set a priori at P &lt; .05. Results: For anterior-posterior laxity, a side main effect was noted (F1,38 = 10.93, P = .002). For inversion-eversion laxity, a sex main effect was seen (F1,38 = 10.75, P = .002). For the posteromedial reaching task, a sex main effect was demonstrated (F1,38 = 8.72, P = .005). No influences of time on the dependent variables were evident. Conclusions: Although women presented with more ankle inversion-eversion laxity and less dynamic postural control, hormonal fluctuations during the menstrual cycle (preovulatory compared with postovulatory) did not affect ankle laxity or dynamic postural control, 2 factors that are associated with ankle instability.

Arthrometric Measurement of Ankle-Complex Motion: Normative Values

Context: Valid and reliable measurements of ankle-complex motion have been reported using the Hollis Ankle Arthrometer. No published normative data of ankle-complex motion obtained from ankle arthrometry are available for use as a reference for clinical decision making. Objective: To describe the distribution variables of ankle-complex motion in uninjured ankles and to establish normative reference values for use in research and to assist in clinical decision making. Design: Descriptive laboratory study. Setting: University research laboratory. Patients or Other Participants: Both ankles of 50 men and 50 women (age = 21.78 ± 2.0 years [range, 19–25 years]) were tested. Intervention(s): Each ankle underwent anteroposterior (AP) and inversion-eversion (I-E) loading using an ankle arthrometer. Main Outcome Measure(s): Recorded anterior, posterior, and total AP displacement (millimeters) at 125 N and inversion, eversion, and total I-E rotation (degrees) at 4 Nm. Results: Women had greater ankle-complex motion for all variables except for posterior displacement. Total AP displacement of the ankle complex was 18.79 ± 4.1 mm for women and 16.70 ± 4.8 mm for men (U = 3742.5, P &lt; .01). Total I-E rotation of the ankle complex was 42.10° ± 9.0° for women and 34.13° ± 10.1° for men (U = 2807, P &lt; .001). All variables were normally distributed except for anterior displacement, inversion rotation, eversion rotation, and total I-E rotation in the women's ankles and eversion rotation in the men's ankles; these variables were skewed positively. Conclusions: Our study increases the available database on ankle-complex motion, and it forms the basis of norm-referenced clinical comparisons and the basis on which quantitative definitions of ankle pathologic conditions can be developed.