The arch index: a useful measure from footprints

Area of Science:

• Biomechanics
• Podiatry
• Orthopedics

Background:

• Traditional methods for foot type classification lack objectivity.
• Accurate foot type assessment is crucial for biomechanical analysis and clinical applications.

Purpose of the Study:

• To present a reliable planimetric method for objective foot type classification.
• To introduce the 'arch index' as a quantifiable measure of foot arch height.

Main Methods:

• A planimetric method was developed using the ratio of the middle third footprint area to the total footprint area.
• The 'arch index' was measured during 50% body weight standing.
• Reliability was assessed for within-day and between-day measurements.

Main Results:

• The proposed 'arch index' demonstrated high reliability (0.96 within-day, 0.94 between-day).
• Static footprint analysis using the arch index allows for objective classification of feet.
• Data from 107 subjects support the classification criteria for high, normal, and flat arches.

Conclusions:

• The 'arch index' provides a reliable and objective method for classifying foot types from footprints.
• This method offers a valuable tool for comparative biomechanical studies and clinical assessments.
• Suggested criteria enable consistent categorization of foot arches based on measured data.