The metatarsal can be felt to flare slightly at its base where it meets the first metatarsocuneiform joint. From the joint, one should probe distally along the medial shaft of the first metatarsal bone. The head of the first metatarsal bone and the metatarsophalangeal joint are palpable at the ball of the foot.The first metatarsophalangeal joint is the site of the common pathologic condition, hallux abducto valgus, characterized by lateral deviation of the great toe (see Fig. 16-33E). The first metatarsal shaft may be medially angulated (metatarsus primus varus) as well. The hallux abductus angle, intermetatarsal angle, and forefoot angles are increased, and the first metatarsophalangeal joint is subluxed.