RESUMO
The common mechanism for lateral ankle sprain is inversion, plantar flexion, or the combination of both, if untreated successfully can lead to chronic ankle instability. It seems that the foot position, while touching the ground, has an effective role to cause ankle sprain. Thus it is possible to prevent ankle sprain through limiting foot position. Therefore the aim of this research is to study the effect of plantar flexion and eversion on mediolateral ground reaction force while landing in individuals who suffering from functional ankle instability. In this case-control research study 32 subjects [17 subjects with unilateral functional ankle instability [FAI] and 15 control subjects], aged from 18 to 35 years, were tested. All subjects in instability group were selected by the orthopedic physician, then the anterior drawer and talar tilt tests were performed for diagnosis of functional ankle instability and other physical examinations. Control group were matched with instability group by age, weight, height, gender and body mass index. The subjects standing with single leg on a 40 cm high platform in 25 cm front of a force-plate while the test leg relaxed and non-weight bearing. The subject landed on the test leg on the center of the force-plate. The subjects landed according to four types of position: A: neutral position of ankle and lateral foot wedge, B: neutral position of ankle, C: positive heel and lateral foot wedge and D: positive heel. Among control group, medial ground reaction force increased in the "C" position relative to "B" position [p=0.007] and "C" position relative to "D" position [p=0.018]. In FAI group, lateral ground reaction force increased in "C" position relative to "B" position [p=0.001] and "C" position relative to "A" position [p=0.002]. Also in FAI group medial ground reaction force decreased in "D" position relative to "A" position [p=0.014]. According to the findings, applying lateral foot wedge, while the ankle is in plantar flexion, increases the mediolateral ground reaction forces. Based on the results, position of plantar flexion is more possibly effective than inversion in ankle sprain. According to the study, the lateral foot wedge in ankle plantar flexion position may be more effective than in neutral one to change mediolateral ground reaction forces.
RESUMO
BACKGROUND: Alpha-hydroxy acids such as glycolic acid (GA) and lactic acid (LA), are used in cosmetic patches. The important fact in cosmetic patches is its suitable adhesion and peel properties. AIM: The objective of this study was to prepare LA- and GA-containing cosmetic patches and evaluate in-vitro/in-vivo correlation of adhesion properties. METHODS: Pressure-sensitive adhesives with different concentrations of GA and LA were cast on a polyethylene terephthalate film. The patches were evaluated for peel adhesive strength. On the basis of in vitro adhesion properties the patches were selected for wear performance tests and skin irritation potential. RESULTS: The adhesion properties (adhesion to steel plate and skin) and cohesive strength tests indicated the substantial influence of GA and LA concentrations. Based on in vitro adhesion studies the patches containing 3% (w/w) GA were selected for in vivo studies. In vivo studies show that a formulation containing 3% GA displays good adhesion on the skin, but it leaves little residues on the skin. Skin Irritation studies on healthy human volunteers showed negligible erythema at the site of application after 48 h. CONCLUSION: The noninvasive patch test model was found useful for detecting irritant skin reactions to the cosmetic patch containing GA. Our results demonstrated a strong correlation between the adhesion to steel plate and adhesion to skin. But a weak correlation between the degree of adhesive residue on the skin in in vitro and in vivo tests was observed for the formulation containing 3% (w/w) GA.