Not all children learn to walk at the same age and some are not very good at it when they do. Some children walk with an ungainly gait, as do some adults, and some learn to walk by using one leg as a prop at the front while the other pushes forwards from behind. This and other ‘trick’ gaits look bizarre but should correct spontaneously, although pathological and normal gaits can look very similar.

Before reassuring a patient that a child’s gait is normal, always think of developmental dysplasia of the hip (DDH), particularly if the child is aged between 12 and 18 months (p. 354). If there are any of the following features, assume that the child has a dislocated hip until radiographs prove otherwise:

The consequences of missing DDH are very serious and radiographic examination of the pelvis is always justified if there is the slightest doubt about the stability of the hips in a child.

The most common cause is abnormal rotation at the hip due to excessive anteversion of the neck of the femur relative to its shaft. This allows a greater range of internal rotation than external (Fig. 21.3). Abnormalities of rotation are much more obvious with the leg straight than with the hip and knee flexed.

In an adult, the ranges of internal and external rotation of the hip are roughly the same but in a child there may be 90° of internal rotation and only 30° of external rotation. Such a child will walk with the foot in the middle of the range of motion, i.e. in 30° of internal rotation, and will be able to squat with the legs turned outwards. It is not unusual for one of the parents to recall doing the same thing when young, which makes reassurance easy.

Metatarsus adductus also causes an in-toe gait and is dealt with under foot deformities below.

The commonest forefoot deformity is metatarsus adductus or hooked forefoot, which is usually noticed at about the age of 6 months when children begin to pull themselves upright. The deformity occurs at the midtarsal joint (Fig. 21.6a) and the hindfoot is completely normal. This can be confirmed by covering the forefoot while examining the hindfoot. When this is done, the foot looks entirely normal (Fig. 21.6b).

The cause is not known but an attractive suggestion is that the forefoot is pushed inwards by the child while sleeping face down with their bottom in the air, a position only stable if the feet are pointing towards each other. It is certainly true that the condition begins to correct when the child is too ‘bottom-heavy’ to sleep in this position, usually at the age of about 18 months.

The most common type of club foot, congenital talipes equinovarus (CTEV), is a deformity of the whole foot, which is pulled downwards (equinus) and inwards (varus) (Fig. 21.7).

The condition has been recognized for centuries but remains an enigma. The demi-god Vulcan, who injured his foot when cast from heaven, is depicted with a club foot. The poet Byron also had a club foot.

As far as we know, the condition is caused by failure of growth in the posteromedial muscles of the calf, particularly tibialis posterior, the toe flexors, gastrocnemius and soleus. The muscles are entirely normal in all other respects but are simply too small for the patient. The bones of the forefoot, and sometimes the tibia and fibula, may be shorter than those of the opposite side. The condition is more common if a relative is affected or there is any other genetic abnormality.

Because the muscles on the medial side of the foot and calf are too short, the foot is pulled downwards and inwards with the ankle in flexion. As growth proceeds, the talonavicular joint is distorted, the navicular is pulled off the talus medially and a bony deformity quickly develops as the soft bones of childhood mould themselves to surrounding tissues.