'Paleontological Institute at The University of Kansas'
Abstract
Functional ankle instability (FAI) is a poorly defined entity but commonly used to describe patients who sustain multiple ankle injuries with slight or no external provocation and have a subjective feeling of ankle "giving way". There have been conflicting results reported in literature regarding the role of suggested etiological factors of FAI including deficit in joint proprioception, strength, and stiffness (laxity). Diagnosis of FAI has been mainly relied on a subjective reporting, so is the assessment of FAI treatments. In spite of controversies regarding FAI factors, balance training has been widely used in sports medicine clinics for patients with FAI. Most of past studies reported its effect for FAI, but strong evidence with definitive result is still missing. Furthermore, the mechanism that explains the effect of balance training on FAI is still unclear. Recently, it was suggested that altered threshold to the unloading reaction may be behind ankle giving way episodes in patients with ankle instability. Therefore, we wanted to duplicate this finding in individuals with FAI during sudden ankle inversion test and examine the effects of a four-week balance training program on unloading reactions in individuals with FAI. Twenty four recreationally active individuals with unilateral FAI were evaluated for unloading reactions on the involved and uninvolved limbs using a sudden ankle inversion test. In seven out of twenty-four subjects, we observed a drastic reaction (hyper-reactivity) in that they were unable to maintain upright standing position when a combination of dynamic ankle stretching and nociceptive stimuli was applied on their affected ankles. The subjects were then randomized to either a control or intervention group. Subjects in the intervention group were trained on the affected limb with static and dynamic components using a Biodex balance stability system for 4-weeks. The control group received no intervention. The results suggested that balance training may desensitize the hyper-reactivity to unloading reaction in FAI subjects, suggesting a possible mechanism for reducing the ankle "giving way" episodes. In addition, balance training was found to improve the subjective self-reported ankle instability and passive ankle joint position sense. No effect was observed on isometric and isokinetic peroneal muscle strength and ankle stiffness (laxity). In summary, this dissertation work provides evidence that balance training is effective in patients with FAI, however a further study with more sample size and additional outcome measures is required to better understand the mechanism of balance training in these individuals. The findings of this work have implications for research/rehabilitation of not only individuals with FAI but also in individuals with functional joint instability, such as functional knee instability which shares many common symptoms with FAI
