Physiological flatfoot is by far the most common of all types: It is typically seen in children of walking age. The feet otherwise appear normal except for a nonvisualization of the medial planter arch. The Jack’s windup test and standing on tip toes restore the arches (see above).

The hypermobile flatfoot (flexible flatfoot) is a more severe entity than a physiological flatfoot. It is characterized by absent arches and normal or excessive subtalar motion on clinical testing. The whole foot appears hyperpronated. In some cases, the hyperpronation is so extreme that the lateral border of the foot loses contact with the ground and does not take part in weight bearing. The talus may protrude medially. The heel is seen to have a prominent valgus. In severe cases, tendo Achilles contracture will be present. The Jack’s test may or may not restore the medial arch. Usually, standing on tiptoes restores the arch or improves it (see Fig. 16.2a, b). Tests for general hyperlaxity may be positive. Shoes of the child will show uneven inside wear.

X-ray of the feet lateral standing and AP views standing show increased talocalcaneal angles with increased obliquity of the talus (see Fig. 16.3a, b).

It is most important to differentiate a physiological hypermobile flatfoot from a pathological or a rigid flatfoot. The treatment of a rigid flatfoot at birth needs orthopedic intervention in the first month of life. At this early stage in life, orthopedic intervention consists of serial casting followed by minimally invasive surgery or a limited surgery. Good long-term results are obtainable by these newer techniques with maintenance of good foot form, mobility, and function. When detected at a later stage, extensive surgery is required.

By contrast, the initial treatment of tarsal coalition is always conservative. Initial treatment starts with a foot orthosis to reduce inversion and eversion stress on the hindfoot and thereby relieves pain. Children who do not respond to orthotic management may respond to a 6-week immobilization in a cast, followed by orthotic support. Often, the relief is long lasting with the child requiring no further treatment. Children who complain of repeated episodes of pain may be candidates for surgery. Small limited areas of coalition are treated by excision of coalition and interposition of the muscle or fascia or tendon graft so as not to allow the fusion to reform. This approach has a success rate of 80–90 % [8]. Failure of treatment is considered if the pain returns. Children who fail resection surgery or who are symptomatic with large coalitions and large heel valgus may be treated by fusion surgery.

Mobile flatfeet are physiological at 3–7 years of age. They represent a variant of normal feet and need no special treatment. Their natural history is one of gradual improvement over the first eight years of life. Orthotic soles and specialized footwear do not improve the natural history of this condition [9]. Shoe wear may actually be detrimental for the development of good arches [10]. Therefore, the advice for these children is to maximize barefoot walking – especially in sand and grass. Tiptoe walking as exercise is also recommended. These activities improve the muscle tone and strength in the feet and calf – thereby improving the development of plantar arches.

One must bear in mind that hypermobile flatfoot is a spectrum disorder. The children who fail to improve over a period of observation, who have pronated feet with tight heel cords and medial border weight bearing, are diagnosed as hypermobile flatfoot. The more severe forms may require early childhood interventions with casting, followed by orthotics combined with foot muscle exercises. Surgery, if required, is carried out after 9 years of age and consists of osteotomy to lengthen the calcaneum, combined with soft tissue procedures [11].

What is your diagnosis and plan of treatment?

This child has a severe genu valgum. This may be due to a focal familial epiphyseal dysplasia. It is obvious that this cannot be managed by observation or splintage. This case needs an urgent orthopedic referral (see Fig. 16.6c, d).

The legs in a newborn are usually bowed. They show 10–15° of varus angulation. This condition is named physiological genu varum. The deformity is fairly evident from the gap that appears between the knees as the legs are held out straight (hence the name “bowlegs”). The varus tends to get even worse as the infant begins to stand. Tibial intorsion, an inward twisting of the tibia, is associated with genu varum, and it tends to make the deformity look worse. Parents usually seek medical advice for bowleg at 1–2 years of age. On clinical examination, the child shows a medial bowing of the legs that is bilateral and symmetrical. When measured, the angle between the thigh (femur) and the leg (tibia) measures at least 10° at the knee [12]. If a radiograph is taken, the growth plates around the knee are always normal (see Fig. 16.5a, b).

The natural history of physiological genu varum is one of the gradual age-dependent resolutions: Heath and Staheli (1993) [13] analyzed the deformities of the knees in young children. They measured the intercondylar distance at the knee to assess genu varum and intermalleolar distance at the ankle to assess genu valgum. They found the genu varum to be maximum at 6–12 months of age, and this recovered by 18–24 months. After this time, they found the knee to angulate into valgus creating the maximum genu valgum at 4 years of age. The knee angles finally settled to an average adult value of 6° by 8–11 years [12]. Published data from India reflects a similar trend [14].

In some children, the knee deformity may not follow the expected pattern of age-related change and eventual resolution. Progressive genu varum is seen in physes that are pathological. Examples are Blount’s disease, hereditary multiple exostoses, multiple epiphyseal dysplasia, rickets from various causes, and following infections and trauma.

Rarely, genu varum results from an abrupt varus at metaphyseo-diaphyseal junction without any physeal involvement. This condition is labeled as focal fibrocartilaginous dysplasia. The cause is unknown, and it improves spontaneously in a majority of cases.

Progressive genu valgum is also seen similarly in various conditions where the physes are pathological (see Table 16.2). Large degrees of genu valgum are associated with obesity, even though the physes may appear normal.

In our clinic, the assessment of a child with knee deformity consists of a careful history taking, a general physical examination, and a local examination. The local examination includes measurement of the standing intercondylar distance in genu varum and standing intermalleolar distance in genu valgum. This is done by standing up the child on a hard surface with the parent supporting the trunk for balance. In genu varum, the legs are gently brought together till the ankles touch. A measurement is taken of the distance between the medial femoral condyles for intercondylar distance. Similarly, in genu valgum deformity, the knees are gently but firmly brought together. The distance between medial malleoli is then measured carefully and documented as intermalleolar distance. Where rickets is suspected, a serum measurement of vitamin D level, alkaline phosphatase, calcium, and phosphate levels is done. A radiograph of both knees AP view is carried out as well.