Medial Longitudinal Arch Angle Presents Significant Differences Between Foot Types: A Biplane Fluoroscopy Study

Area of Science:

• Biomechanics
• Orthopedics
• Radiological Imaging

Background:

• The medial longitudinal arch (MLA) is crucial for foot function and plantar pressure dissipation.
• Previous MLA assessments used static radiography or marker-based motion analysis.
• A need exists for precise, dynamic MLA measurement across different foot types.

Purpose of the Study:

• To measure the contained medial longitudinal arch (MLA) angle using biplane fluoroscopy.
• To compare MLA angles between pes planus (low arch), normal, and pes cavus (high arch) foot types.
• To differentiate static versus dynamic MLA measurements during gait.

Main Methods:

• Utilized markerless fluoroscopic radiostereometric analysis (fRSA) with 3D foot bone models.
• Matched 3D models to 2D biplane radiographic images during midstance of gait.
• Recruited 15 participants (5 per foot type: pes planus, normal, pes cavus).

Main Results:

• Statistically significant differences in barefoot MLA angles were found between normal and pes cavus (p=0.036), and between pes cavus and pes planus (p=0.004) foot types.
• Dynamic walking measurements showed significant differences compared to static standing (p=0.014).
• The novel fRSA method successfully differentiated static and dynamic MLA kinematics.

Conclusions:

• Biplane fluoroscopy with fRSA provides a novel and accurate method for measuring contained MLA angles.
• Significant differences in MLA angles exist between various foot types and during dynamic vs. static conditions.
• Findings support clinical classification of foot types (pes cavus, pes planus) based on physical assessment.