Bunionette Foot Hyperbook

Description: Pathological anatomy
The bunionette deformity is a prominence of the fifth metatarsal head, usually with medial deviation of the fifth toe. It is associated with
* wide fifth metatarsal head (Fallat and Bucholz 1980, Leach and Igou 1975) – Coughlin found this in 8/30 in his surgical series, but Nestor, in a large radiological series, did not find any significant difference in metatarsal head width between patients and controls
* lateral bowing of the 5 th metatarsal shaft (Fallat and Bucholz 1980) – however, Nestor et al (1990) did not find any increased lateral bowing in patients compared with controls; they considred this a normal variation which was made more symptomatic by increased 4 th-5 th MT angle
* an increased angle between the 4 th and 5 th metatarsal shafts - Fallat and Bucholz found a normal angle of 6.2deg, although some studies have used a value of 8deg as the upper limit of normal. Coughlin (1991) found an average angle of 10.6deg in surgically treated patients and Nestor (1990) an average of 10.8deg in 91 feet with bunionette compared with 9.1deg in 91 matched controls
* an increased incidence of hallux valgus – Nestor et al (1990) found a 23% prevalence of hallux valgus in patients with bunionette compared to 9% in controls, although there was probably some selection of controls implying that the difference with normal feet may be even higher