Navicular Drop
Definition
A clinical measurement of the difference in navicular tuberosity height between non-weight-bearing and weight-bearing positions. The navicular bone sits at the apex of the medial longitudinal arch. A drop greater than 10mm is considered excessive and indicates medial arch collapse under load.
Clinical Significance
Navicular drop quantifies the foot's pronation response to weight-bearing. Excessive drop indicates medial arch insufficiency, which internally rotates the tibia and femur, contributes to knee valgus, and changes hip mechanics. It is a reliable predictor of lower extremity injury risk in runners and athletes. The measurement distinguishes between a flexible (correctable) and rigid (structural) flat foot presentation.
How AKMI Assesses This
AKMI measures navicular height in seated (subtalar neutral) and standing (relaxed) positions. The difference is recorded in millimeters. Values are correlated with hip rotation data and knee alignment to determine whether the foot is a driver or a compensator in the kinetic chain.
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