Detecting Ankle Instability With an Instrumented Ankle Arthrometer: An Experimental Study

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 > .05). Afferent traffic increased with increased force and torque in test trials (P < .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 < .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.

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

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-021-02750-6 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Helge Eberbach ◽

Dominic Gehring ◽

Thomas Lange ◽

Spartak Ovsepyan ◽

Albert Gollhofer ◽

...

Keyword(s):

Contact Area ◽

Ankle Instability ◽

Axial Loading ◽

Mechanical Effect ◽

Neutral Position ◽

Mechanical Instability ◽

Joint Congruency ◽

Ankle Arthrometer ◽

Ankle Brace ◽

Stabilizing Effect

Abstract 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).

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

Exercise Science ◽

10.15857/ksep.2021.30.1.43 ◽

2021 ◽

Vol 30 (1) ◽

pp. 43-51

Author(s):

Hongsuk Lee ◽

Hyunsoo Kim ◽

Ty Hopkins ◽

S. Jun Son

Keyword(s):

Ankle Instability ◽

Pearson Correlation ◽

Frontal Plane ◽

Static Stability ◽

Chronic Ankle Instability ◽

Control Group ◽

Control Groups ◽

Ankle Arthrometer ◽

Ankle Function ◽

And Control

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.

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

Journal of Athletic Training ◽

10.4085/1062-6050-51.5.05 ◽

2016 ◽

Vol 51 (4) ◽

pp. 336-343 ◽

Cited By ~ 13

Author(s):

Samantha Bowker ◽

Masafumi Terada ◽

Abbey C. Thomas ◽

Brian G. Pietrosimone ◽

Claire E. Hiller ◽

...

Keyword(s):

Ankle Instability ◽

Chronic Ankle Instability ◽

Spinal Reflex ◽

Hoffmann Reflex ◽

Neural Excitability ◽

Reflex Excitability ◽

Total Displacement ◽

Ankle Arthrometer ◽

Healthy Control ◽

And Control

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:

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Effects of the Subtalar Sling Ankle Taping Technique on Combined Talocrural-Subtalar Joint Motions

Foot & Ankle International ◽

10.1177/107110070502600310 ◽

2005 ◽

Vol 26 (3) ◽

pp. 239-246 ◽

Cited By ~ 16

Author(s):

Gary B. Wilkerson ◽

John E. Kovaleski ◽

Mark Meyer ◽

Christopher Stawiz

Keyword(s):

Repeated Measures ◽

Ankle Instability ◽

Frontal Plane ◽

Critical Factor ◽

Normal Subjects ◽

Ligament Injury ◽

Exercise Session ◽

Ankle Motion ◽

Ankle Arthrometer ◽

Joint Motions

Background: The findings of research on the effectiveness of ankle taping for protection against ligament injury have been inconsistent, and the topic remains controversial. The precise orientation of the force vectors created by tension within the various tape strip components of an ankle taping procedure may be a critical factor influencing the degree of motion restraint that is provided. We hypothesized that the addition of the subtalar sling component to the widely recognized standard (Gibney) ankle taping procedure would enhance restraint of ankle motion. This was a controlled laboratory study, with fully repeated measures (subjects served as their own controls). Methods: An ankle arthrometer was used to quantify anteroposterior (AP) translation and frontal plane inversion-eversion (I-E) tilt of the talocrural-subtalar joints under untaped and taped conditions in normal subjects. A 15-minute exercise session was conducted to loosen the tape before measurement of its effect on motion restraint. Results: The ankle taping procedure that incorporated the subtalar sling provided significantly greater restriction of postexercise AP translation (p < 0.001, η2 = 0.63) and postexercise I-E tilt (p < 0.001, η2 = 0.66). Conclusions: The subtalar sling ankle taping procedure provides greater restriction of motions associated with ankle instability than the more widely used Gibney procedure.

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Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013955x ◽

1995 ◽

Vol 53 ◽

pp. 636-637

Author(s):

Norio Baba ◽

Norihiko Ichise ◽

Syunya Watanabe

Keyword(s):

Experimental Study ◽

Spherical Aberration ◽

Incident Beam ◽

Optical Parameters ◽

Beam Tilting ◽

Illumination Method ◽

Restoration Method ◽

Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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