A comparison of male and female foot structure : is the female foot predisposed to hallux abductovalgus?
Hallux abductovalgus (HAV) is common foot deformity that is known to predominate in women and is often assumed to be linked to the use of inappropriate footwear. The predominance of the deformity in females has been demonstrated through many surveys across different populations. The highest prevalence of the deformity reported found 44 per cent of women affect whilst the highest prevalence in men reported a prevalence of 22 per cent. Although the condition is seen less frequently in children and barefoot populations, the female foot is still affected twice as often as the male foot in such groups, weakening the theoretical association between the deformity and footwear. A review of 100 radiographs of male and female feet found an association between the functional angle of the metatarsal head and HAV deformity and found that the female metatarsal head is more rounded than the male metatarsal head. There was no difference in the degree of metatarsus adductus (MA) deformity between males and females but in females, when the MA angle was greater than normal (24') an abnormal HAV angle was always seen. A good association was seen between the proximal articular set angle and the HAV angle that was similar for males and females. A three dimensional study of 100 bone-sets was undertaken using a technique not previously applied to this field of study. The bones of the medial column (talus, navicular, medial cuneiform and 1st metatarsal) were included. Several differences between in the shape of male and female foot bones were found including the more rounded metatarsal head shape in females. When the differences were considered together it was suggested that the medial column in the female foot would be more adducted that in the male foot and the resultant adducted position of the 1st metatarsal would predispose the female foot to HAV deformity. A study of 226 children was undertaken to investigate if a relationship between hypermobility and HAV deformity existed. A new assessment tool for measuring lower limb joint hypermobility was developed initially. No association between HAV deformity and lower limb hypermobility was found in healthy children, but a significant association was identified in children diagnosed with joint hypermobility. In a study of foot pressure measurements in 61 children, significant differences in the amount of pressure placed through the hallux, the speed of loading of the 1st metatarsal head and the position of the centre of force through the foot were found between males and females. Associations with the pressure measurements and increasing joint flexibility were only seen for extreme levels of hypermobility. No association between HAV and plantar pressure was found.