Calculation of Staheli's Planter Arch Index, Chippaux-Smirak Index, Clarke’s Angle Prevalence and Predictors of Flat Foot: a Cross Sectional Study

Abstract

Human foot is the region most affected by anatomical variations, which presents a highest level of variability and the medial longitudinal arch along with various index that provides a quantitative measurement of the plantar arch. A non-interventional descriptive cross sectional study was conducted among 300 preclinical undergraduate students Staheli's planter arch index, Chippaux-Smirak index, Clarke’s angle and truncated foot length was calculated using Foot Impression gaining kit with Ink Pad. For inferential analysis, unpaired student t-test was applied and regression equations was derived along with ROC curve. Staheli's, Chippaux-Smirak planter index, Clarke’s angle on right side foot was found to be 60.98±23.24, 36.09±13.94, 32.74±7.8 and 63.85±24.63, 36.64±14.62, 36.45±8.51 on left foot respectively. Significant difference was present in between BMI, navicular height and truncated foot length (p< 0.05). A bivariate logistic regression model was created, which revealed BMI, mid foot length, truncated foot length a strong predictors (regression coefficient, R=0.94, 0.78, 0.81, p<0.01), which were independently associated with flat foot to be detected by CSI and SPI. Receiver Operating Curve (ROC) revealed SPI (AUC=0.942, SEE-0.018, p<0.01) was seen to be highly sensitive and specific. Most of student have medium to high medial longitudinal arch. To find whether the foot is flat or not, plantar arch index can be performed and categorize into unilateral flat foot and bilateral flat foot. Staheli’s planter index was sensitive for identification of flat foot.