The pathology of bunions

Abstract

What is a bunion? Rather than being a medical scientific term it is a lay word relating to the changes seen in association with a valgus deformity of the first metatarso-phalangeal joint of the foot so frequently seen in both the adolescent and the adult. When teaching students, I have always defined a bunion as 'a chronically inflamed adventitious bursa situated on the medial side of the head of the first metatarsal and often associated with a hallux valgus deformity'. However, many orthopaedic textbook authors and teachers define a bunion as the whole complex of changes that occur in association with the valgus deformity of the great toe including the thickened cornified skin with or without ulceration, the underlying bursitis, and the increased prominence of the first metatarsal head resulting from varus deformity of the metatarsal and subluxation of the first metatarsophalangeal joint. The derivation of the word is uncertain. Most dictionaries believe it arises from the Latin word 'bunio' or the Greek word 'bounion' meaning 'a turnip'. If one superimposes a turnip onto a diagram of the deformed forefoot it demonstrates the pathology very well (Fig. 1). On the other hand, the shorter Oxford Dictionary states that it is connected with the old English word 'bunny', meaning a swelling caused by a blow. Whatever the meaning of the word, there is no doubt that the adventitious bursa situated in the soft tissues between the skin and the medial capsular structures and lying over the medial prominence of the first metatarsal head is an important source of the pain associated with the condition.