FUNCTIONAL ANKLE INSTABILITY AND A REACTIVE STRATEGY TO AVOID AN ANKLE SPRAIN
AUTOR(ES)
Marcio José dos Santos
FONTE
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia
DATA DE PUBLICAÇÃO
21/08/2006
RESUMO
(...)Functional ankle instability (FAI) is commonly defined as a condition in which individuals have recurrent sprain and/or a feeling of their ankle \"giving way (Freeman, 1965).\" The causes of this pathology are generally attributed to ankle muscular weakness, impaired proprioception, balance control, and neuromuscular reaction time or joint laxity, or a combination of them (Hintermann, Boss, &Schafer, 2002; Pontaga, 2004; Refshauge, Kilbreath, &Raymond, 2003; Tropp &Odenrick, 1988; Vaes, Van Gheluwe, &Duquet, 2001). However, few studies have focused on the protection mechanism of an ankle sprain injury, suggesting that only peroneal muscle reaction or pre-activation of muscles surrounding the ankle may protect the ankle against sprain injuries (Ashton-Miller, Ottaviani, Hutchinson, &Wojtys, 1996; Konradsen, Voigt, &Hojsgaard, 1997). Since ankle sprain depends on the downward load applied to a supinated foot (Tropp, 2002), our premise is that unloading the body weight from the ankle preceding its overstretching may protect the ankle from sprain injuries. To promptly perform such a strategy, individuals might use a modified type of classical flexion reflex, i.e., unloading reactions. Therefore, in this study, we conducted three experiments involving unloading reactions. Therefore, in this study, I tested a new mechanism for protecting the ankle from a sprain injury and evaluated the protection mechanism\ s patterns in subjects with functional ankle instability (FAI). I then analyze the interrelationship between potential disruptions in this mechanism and other possible deficits attributed to the FAI. In the first experiment, we tested the possibility that the individuals use an unloading reaction to protect their ankles from an ankle sprain. We provoked unloading reactions in standing normal individuals with the ankle at neutral and supinated positions using electrical stimulation on the lateral part of the ankle. Then, we compared the ground reaction forces and the lower limb kinematics between both conditions. In the second, experiment we included subjects with FAI. Past studies have shown that individuals with FAI may present with ankle mechanoreceptors disruptions (Freeman, 1965) and synovial chronic inflammation (Hintermann et al., 2002). These conditions may modify the afferents inputs at the ankle joint altering the unloading reactions. Therefore, similarly to the first experiment, in the second, we evaluated the patterns of unloading reactions in standing individuals with FAI and compared them to the control group. Finally, in the third experiment we evaluated the interrelationship of potential disruptions in unloading reactions and other causes of FAI. If we observe disruptions of unloading reactions in individuals with FAI, we may be adding or associating another factor to the FAI causes. In this case, we also evaluated the other potential causes of FAI among the injured subjects, and related them with potential disruptions of unloading reactions. Chapters 2, 3, and 4 present details of these experiments.(...)
ASSUNTO(S)
instabilidade crônica de tornozelo reflexo de retirada functional ankle instability ankle sprain fisioterapia e terapia ocupacional
