Guide the patient to stand (or sit). Ask the patient to relax the arch of the foot or stand on one foot while the arch is relaxed. If given permission, place your thumb on the medial aspect of the navicular bone. If the patient had excessive pronation, the tuberosity of the navicular bone will be prominent distal to the head of the talus, which will bulge medially and be displaced downward.
With the prominence of the navicular bone and the medial bulge and downward displacement of the talus, the muscles on the medial foot, the tibialis posterior, flexor digitorum longus, and flexor hallucis longus will be stretched and can be painful as they attempt to maintain the position of the sustentaculum tali, which is the bony structure supporting the talus.