Congenital abnormalities

Congenital abnormalities in the foot can be divided into minor and major abnormalities. Minor congenital abnormali­ties include many conditions which are inherited. These abnormalities rarely cause significant problems. They largely constitute toe abnormalities such as syndactyly or curly toes; these variations are not uncommon and rarely need any treatment. Congenital hallux varus is not common but can require surgery if severe or progressive. Hallux valgus is surprisingly rare considering its incidence in the adult population. Major abnormalities include genetic disorders, major chromosomal malformations, and failure of formation or differentiation. In addition, there are several conditions which, although present in the newborn child, do not fit into these headings. They can be described as either structural or postural deformities.

Of the major deformities clubfoot or talipes equinovarus is the commonest (Fig. 31.1). It has a familial incidence (one in 1000 live births reduces to one in 35 live births if one sibling is affected) and it has a varied incidence with different ethnic groups (Maoris having the highest incidence). Although this suggests a genetic propensity it seems likely there is a multifactorial mode of inheritance. The exact mechanism of the production of the deformity is unknown; it seems likely that a number of different conditions produces the same deformity. This should be taken into account when planning treatment.

Treatment

Treatment of talipes equinovarus needs to commence within 24 hours of birth. Various techniques for strapping or taping the foot or the use of plaster of Paris or special splints have been advocated. What is common to all of these techniques is the need for early treatment and the careful attention to detail. This form of treatment should go on for at least 3 months and, no matter what, should be followed by a period of stretching undertaken by the parents and a suitable therapist. At this stage care should be taken to avoid stretching the midfoot into a rocker bottom foot position in an attempt to correct tight posterior structures. If early treatment is instigated then between 30 and 40 per cent of feet will correct sufficiently not to require surgery.

The remainder of the feet will require surgical correction. Although there is a great deal of controversy about the exact timing of surgery, the extent of surgery and the expected functional result, most authors would advocate that it is undertaken during the first year of life. The aim of surgery is to achieve the best functional result. By ensuring that the foot can be placed in plantigrade (or flat to the floor) position this is likely to be associated with the most satisfactory result. This will require an adequate posterior release to allow the foot to dorsiflex actively at the ankle. The subtalar and midtarsal joints need to be released to allow the primary rotational deformity to be reduced. In many cases this will involve both medial and lateral releases. Continued therapy and splintage should then back up the surgery, having achieved adequate correction, during the first years of life. In particular, the weakness of the peroneal tendons seen in many cases will not improve until at least 18 months of age. Children with this condition should be monitored throughout the period of growth. The genetic propensity for the deformity is likely to continue to be expressed throughout the growing period.

Other major congenital deformities need treatment on their merits with the aim of achieving the best functional result for the child.