Analysis of ROC Cut-off Value of Staheli Index of Footprint on Harris Mat for The Screening of Pes Cavus

Abstract

Background: Pes cavus (High-arch foot) was rarely found in outpatient department. There was usually diagnosed by history taking and physical examination and combined weight-bearing film. Anywise, diagnosis of pes cavus was still no gold standard and tool for screening. Recently, one study was published about Staheli index in Harris mat footprint for screening flatfoot in population. The aim of this study is finding Staheli index cut-off for screening, help diagnosis pes cavus and looking for correlation between clinical diagnosis, calcaneal pitch angle and lateral Meary's angle. Objective: To study correlation between sensitivity, specificity of weight-bearing film and Staheli index from Harris mat footprint by compared Calcaneal pitch angle, Lateral Meary's angle and Staheli index for diagnosis of cavus foot. Method: 143 participants were included in this study, examined by Foot - Ankle specialist and diagnosed. Afterward They were sent to X-ray department for shooting both feet weight-bearing film in AP, Lateral and oblique. Then, participants were printed their foot by digital footprint at equipment department. Calcaneal pitch angle and lateral Meary's angle were measured by Foot - ankle specialist and concealed. Staheli index was measured from footprint by research resident. The data were concealed from each other and calculated statistically. Result: Calcaneal pitch angle and lateral Meary's angle were very poor (r =- 0.793, p-value = .001) and not correlated with Staheli index (r = -0.096, p-value = .110) consecutively. The cut-off point of ROC curve for diagnosis pes cavus is at 0.5865 when sensitivity and sensitivity are suitable. (Sensitivity = 73.33%; 95%CI: 58.06, 85.40, Specificity = 50.22%; 95%CI: 43.59, 56.84). The accuracy is 53.99%. Conclusion: Calcaneal pitch angle and Lateral Meary's angle were poor correlated with staheli index. Clinical diagnosis was still highest reliable tools for diagnosis. The cut-off point of screening pes cavus is 0.5865 by Staheli index method with highest sensitivity (73.33%).