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Araki R.1, Sadler J.1, Kunze J.1, Moore A.1, Mcdonell C.1, Huntsinger M.1, Peterson C.1, Yoshida R.1, Kachingwe A.1
1California State University, Northridge, Doctorate of Physical Therapy, Northridge, United States
Background: Lateral ankle sprains accounting for 25% of all musculoskeletal injuries, are the single most prevalent sports-related injury, and have a 70% recurrence rate.1-3 Ankle sprains are typically treated with immobilization, leading to significant proprioceptive deficits.1 Ankle sprains often result in chronic ankle instability due to ligamentous laxity, proprioceptive deficits, and/or functional ankle instability (FAI)-the subject´s perception that the ankle is unstable, weaker, more painful, or less functional following injury.3
Purpose: The purpose of this study was to investigate the effects of applying variable vibrations via an external vibration- inducing device to an immobilized ankle joint after sustaining an acute ankle sprain. Vibrations are theorized to improve FAI by preventing the loss of proprioceptive input from the joint via activation of muscle spindles and mechanoreceptors typically impaired during immobilization.4 We hypothesized that applying variable frequency and amplitude vibrations with a vibration AFO would produce significant improvements in outcome measures evaluating post-immobilization kinesthesia (Joint Position Sense (JPS)), proprioceptive input (Sensory Organization Test (SOT)), ankle function (Motor Control Test (MCT)), Unilateral Stance (US), STAR Excursion Balance Test (SEBT), Foot & Ankle Disability Index (FADI)) as compared to standard immobilization without vibration.
Methods: Ten subjects presenting to a university student health center with a Grade II-III lateral ankle sprain were randomly allocated into 2 groups. Control subjects were immobilized with a standard ankle foot orthosis (AFO). Experimental subjects were immobilized with a specially designed vibration AFO. Motors were placed at 5 tendons surrounding the ankle to create illusory movement5 and controlled by a circuit board set to perform vibrations at 50-100 hertz for a cumulative time of 45 minutes per day. Participants were evaluated after 7 days of immobilization by testers blinded to group assignment.
Results: Within-subject statistically significant differences were found for MCT amplitude scaling with backward translation (p = 0.038) and for SEBT in the posteromedial direction (p = 0.038). Between-subject differences were found for SOT condition 1 (p = 0.019) and FADI (p = 0.010). Statistical significance
(p 0.05) was not detected for the other outcome measures, although they trended in support of vibration for reduced proprioceptive loss.
Conclusion(s): Applying variable vibrations via an external vibration-inducing device to an immobilized ankle joint following an acute lateral ankle sprain showed limited support for preventing proprioceptive loss.
Implications: There is some evidence suggesting that individuals receiving vibration during immobilization post ankle sprain have less proprioceptive loss. This may result in returning to previous level of function more quickly and fewer recurring ankle sprains compared to standard immobilization. This pilot study provides a foundation for more research to be conducted investigating the effects on proprioception when utilizing a variable vibration brace after an acute ankle sprain.
Funding acknowledgements: California State University Northridge Research and Graduate Studies; California State University Associated Students
Topic: Musculoskeletal: lower limb
Ethics approval: California State University Northridge Committee for the Protection of Human Subjects - Institutional Review Board
All authors, affiliations and abstracts have been published as submitted.
