Sagittal plane height of the arch has been widely used to quantify foot structure.
Osseous and soft tissue variations make measurement difficult.
Poor reliability has been reported when assessing arch height
NWB & WB
• used to assess static posture of medial longitudinal arch
• this consists of a line drawn from the inferior aspect of the medial malleolus to the centre of the first metatarsal head
• a vertical line is then drawn from the navicular to the ground and then divided into equal thirds
• if foot is supinated or cavus the first line will pass through the upper third of the vertical line
• if the foot is pronated or flat the first line will pass through the middle third of the vertical line
Static foot angle (SFA):
• based on Fiess line
• angle formed between two lines – one from centre of medial malleolus to navicular tuberosity and from the navicular tuberosity to the centre of the medial aspect of the first metatarsal head
• several studies have shown the mean angle to be about 140 degrees and is predictive of dynamic function (McPoil, unpublished).
• angle has been shown to be lower in those with a history of medial tibial stress syndrome
Relative arch deformation (RAD)
• used as a measure of arch stiffness
• shown to be related to the coupling of foot and leg motion . Those with stiffer arches had a stronger connection
• highest point of soft tissue contour of medial arch is measured weightbearing (AH) and another measure when the patient is seated and foot is unloaded (AHU)
• RAD is defined as (AHU-AH)/AHU and then normalised to bodyweight