PLANTAR PRESSURE EVALUATION OF FLATFOOT AMONG YOUNG FEMALES: SPECIFICITY AND SENSITIVITY ANALYSIS

E. BinMulayh¹, F. Khan¹, M.F. Chevidikunnan¹

¹King Abdulaziz University, Physical Therapy, Jeddah, Saudi Arabia

Background: Flatfoot is one of the most common foot disorders, which occurs more frequently among females than males in young adults. Various biomechanical methods have been proposed to assess the foot's structural alignment, such as plantar pressure platforms, demonstrating highly reliable results. Nevertheless, using X-ray radiography to estimate foot arches' characteristics is the most reliable method. Although studies correlating radiographs with plantar pressure for general foot alignment have been conducted, no previous studies addressed flatfoot diagnosis using plantar pressure distribution based on features of truly positive flatfeet diagnosed by X-ray.

Purpose: The current study aims to identify the plantar pressure characteristics of X-ray-positive flatfoot and assess the sensitivity and specificity of such plantar pressure measures in diagnosing flatfoot.

Methods: Forty healthy females aged 20.38 ± 1.1 were included in the study participants. A sample of 32 flatfeet was analyzed, including 16 X-ray positive flatfeet based on Arch Angle and Calcaneus Pitch. The study included Sixteen normal feet for comparison purposes. Plantar pressure measures of each foot included surface area, force, and pressure for the great toe, first metatarsal head, medial foot, and medial heel, in addition to the static and dynamic arch index (AI). A 3D surface plot was created to visualize averaged plantar pressure differences among normal feet, flatfeet, and X-ray positive flatfeet. In addition, the receiver operating characteristic (ROC) curve was plotted to find the sensitivity, specificity, and area under the curve (AUC) for the significant variables in plantar pressure differences and arch angle.

Results: There were significant differences between normal feet and X-ray positive flatfeet in static AI (p-value: 0.003, 95% CI: -0.21 to -0.04), dynamic AI (p-value: 0.003, 95% CI: -0.13 to -0.02), and the surface area of medial foot (p-value: 0.01, 95% CI: -26.58 to -3.62). Based on the ROC curve and AUC, the cut-off value for the static AI was 0.203 with 81% sensitivity and 63% specificity (AUC: 0.7,p-value: 0.03, 95% CI: 0.53 to 0.86). For the medial foot surface area, the cut-off value was 19.45 with 81% sensitivity and 67% specificity (AUC: 0.7,p-value: 0.04, 95% CI: 0.52 to 0.85).

Conclusions: The findings demonstrated significant differences between normal feet and x-ray positive flatfeet in the medial foot surface area and AI, suggesting that these plantar pressure measures can be utilized as indicators to diagnose flatfeet. Additionally, our sensitivity and specificity analysis based on the arch angle measured by X-ray resulted in significant values for the AUC, suggesting that plantar pressure values of static arch index higher than 0.203 and medial foot surface area higher than 19.45 cm² can be indicative of X-ray positive flatfoot.

Implications: The current analysis provides valuable insights into assessing flatfeet by providing plantar pressure characteristics to distinguish truly positive flatfeet as measured by X-ray radiography. Moreover, our findings support plantar pressure analysis in flatfoot assessment by identifying potential diagnostic variables and their cut-off values.

Funding acknowledgements: The authors did not receive any funding

Keywords:
Flatfoot
Plantar Pressure
Arch Index

Topics:
Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: King Abdulaziz University

Committee: CEGMR Bioethics Committee

Ethics number: 05-CEGMR-Bioeth-2019