Segmental foot and ankle kinematic differences between rectus, planus, and cavus foot types

Area of Science:

• Biomechanics
• Orthopedics
• Human Locomotion

Background:

• Variability in healthy adult foot structure is attributed to distinct foot types: rectus, planus (low arch), and cavus (high arch).
• Previous studies on foot type biomechanics show inconsistent kinematic differences due to methodological variations.

Purpose of the Study:

• To evaluate segmental foot kinematics differences among rectus, planus, and cavus foot types using a radiographically-indexed model.
• To identify distinct dynamic foot function characteristics across different foot types during the gait cycle.

Main Methods:

• Utilized the radiographically-indexed Milwaukee Foot Model for precise segmental foot kinematics evaluation.
• Compared foot types based on true bony alignment, focusing on peak coronal hindfoot position during stance.
• Employed locally weighted regression smoothing with alpha-adjusted serial t-test analysis (LAAST) for comprehensive gait cycle comparison.

Main Results:

• Significant differences in peak hindfoot coronal position were found among Planus (-1.6° ± 5.1°), Rectus (6.7° ± 3.5°), and Cavus (13.6° ± 4.6°) groups.
• Kinematic differences between Rectus and Planus, and Cavus and Planus groups were evident throughout the gait cycle.
• The Planus group exhibited premature peak velocity towards varus and early transition to valgus, suggesting a deficient windlass mechanism.

Conclusions:

• Distinct foot types (rectus, planus, cavus) demonstrate significantly different hindfoot kinematics during gait.
• The findings highlight unique dynamic foot function characteristics associated with each foot type.
• This kinematic assessment provides a foundation for understanding functional implications of foot morphology.