Introduction
The Postural system offers multiple inputs : vestibular, visual, proprioceptive and plantar. Several studies have demonstrated the postural effect resulting from the vibratory stimulation of the plantar surface [2, 3]. In clinical practice, orthotic devices are used to complement postural treatment. Podiatric induces variation of pressure through raised on the orthopaedic sole. In our study, we have selected the plantar stimulation used to orthotic devices.
Objective
The aim of our work was the analysis of the variations of the CoP in the horizontal plan after anterior plantar stimulations of the plantar rest.
Materials and methods
Subject : 15 healthy individuals were selected without irritative torn buch of plantar rest using the posturo-dynamic test into hard and foam ground or disturbances in plantar support [4, 5, 7]. They were divided in 2 groups according to their visual dependence (VD) and visual independence (VI) calculated on the quotient into area sway eyes closed and eyes open [1].
Recording : the variations of CoP (x, y, surface, length) were recorded by a stabilometric platform. The CoP was performed at 40Hz during 52 seconds on stabilometric 40/16 plateform of MEDICAPTEUR France, fusyo Software 1.3.
Stimulations : 3 plantar orthotic devices are selected : Anterio External (AE), Anterio Internal (AI) and the Retro Capital Bar (BRC). The thickness of these devices is 3mm with 60 Sch, 250 Kg/mm_ of hardness of PODISER Belgium was positioned symmetrical under foot (fig.1).
Procedure : Recordings were made in an analysis apparatus like a round booth in front of the subject to eliminate all visual landmarks [6]. The individual was positioned in a 30º foot placement including lateral notches for anatomical location and stimuli positioning. The recordings (52 sec at 40Hz) were performed with the following protocol : Eyes closed (EC), eyes opened (EO) and finally the orthotic devices were made randomly. Eyes opened without stimulations was the control condition. An ANOVA and Newman-Keuls test were performed.
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| Fig. 2 - Y variation of CoP. N: Control condition; AE: Antero-External; AI: Antero-internal; BRC: Retrocapital bar. | ||||
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| Figure 3 Variations of the CoP : the surface area and length with orthotic devices N : control condition; AE : Anterio External; AI : Anterio Internal; BRC : Retro Capital Bar. |
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Results :
All the devices contribute to posteriorly displace the CoP. This amplitude varies according to the position of the devices: AI and BRC have higher posterior displacements than AE (fig.2).
The stimulation devices have the following effect on the surface area covered by the CoP : AE decreases the surface area in comparaison to AI and BRC (p<0,01). The surface area (p<0,05) and the length of the displacement of the CoP (p<0,05) are more important for the vision dependant group, according to the applied quotient (fig.3).
Discussion
These results are superimposable to those obtained while vibrating. The devices move the CoP posteriorly and modify the surface area. Surface area and length change according to the classification of the individual. The position of the stimulation device has impact on the displacement of the CoP. The clinical observations are reinforced by this study.
Bibliography :
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