A complaint of significant pain is a warning signal and is often associated with peroneal muscle spasm and a rigid flatfoot.

Flat foot (pes planus, pes planovalgus) in children is a common orthopaedic condition seen in office practice. It is defined as a low or absent arch and can have a variety of causes. These include: flexible flatfoot, often with a familial background; hyper-flexible flatfoot associated with conditions such as excessive ligamentous laxity, tight heelcords, neuromuscular diseases, and certain genetic conditions; and rigid flat foot caused by such things as tarsal bone coalitions, juvenile rheumatoid arthritis, infections of the foot, neoplasms, or a condition known as congenital vertical talus. A classification of flat foot is listed in Table A. This discussion will focus on the flexible flatfoot.

Flexible Flat Foot
Flexible flat feet are usually caused by laxity of ligaments in the foot. This may be idiopathic or familial in origin. The integrity of the longitudinal arch of the foot depends on the configuration of the mid-tarsal bones and the status of the ligamentous structures Muscles do not maintain this arch. EMG studies have demonstrated that there is no electrical activity in the intrinsic or extrinsic muscles of the foot or leg at rest. When weight is placed on the foot, the distal end of the os calcis moves laterally and upward and the head of the talus drops medially and downward. This produces substantial strain on the medial structures of the foot, which is not well resisted by lax ligaments. Thus, the arch descends and a flatfoot results. This can be demonstrated by radiographs of the foot in weight-bearing which show the increased angulation between the talus and the os calcis in both the AP and lateral planes (see Figures 3 & 4).

In conditions such as the Down, Marfan and Ehlers-Danlos syndromes, excessive ligamentous laxity is always present and therefore arches are absent during weight-bearing. In conditions with muscle abnormality such as cerebral palsy, polio, muscular dystrophies, and inflammatory conditions such as rheumatoid arthritis or infections, the arch is pulled into a flattened position by the muscle imbalance. In tarsal coalition, two of the tarsal bones (usually the talus and os calcis or navicular and os calcis) remain connected by a congenital bony or cartilaginous bar and are maintained in a divergent position producing a rigid flatfoot.

The child is usually brought to the office with a parental or grandparents complaint that the foot rolls out and/or that there is abnormal wear on the inner side of the shoe. There is no pain associated with this except in an older child or adolescent with severe flatfoot after excessive standing or walking. A complaint of significant pain is a warning signal and is often associated with peroneal muscle spasm and a rigid flatfoot. If this is the case, pathological conditions such as tarsal coalition, juvenile rheumatoid arthritis, neoplasm, infection or other problem must be ruled out. The history should include the duration of the flat foot, the possibility of a neurological or muscular disease, and a family history of flatfoot.

TABLE A

1. Flexible
   1. Idiopathic
   2. Familial
   3. Secondary to tight heel cord
   4. Ligamentous Hyperlaxity-Connective Tissue Disorders
       a. Marfan's Syndrome
       b. Down's Syndrome
       c. Ehlers-Danlos Syndrome
   5. Neuromuscular
       a. C.P.
       b. Polio
       c. Muscle disease
       d. Peripheral nerve injury
2. Rigid
   1. Tarsal Coalition
   2. Arthritis
       a. Inflammatory
       b. Traumatic
   3. Congenital convex pes valgus-vertical talus
   4. Infection
   5. Neoplasm

Physical examination begins with observation of the child standing on a flat surface, confirming the low or flattened arch of the foot (see Fig. 1). The amount of heel valgus (rolling out) and forefoot valgus should be noted, as well as whether the foot is flexible or rigid (see Fig. 2). The heelcord should be examined for tightness since a well recognized entity, hyper-mobile pes planovalgus with tight Tendo-Achillis may respond to treatment of the heelcord tightness and improvement in the foot. Generalized ligamentous laxity should be assessed by looking for five signs, including:

1. passive foot dorsiflexion in excess of 45 degrees
2. the ability to hyperextend the knees (recurvatum)
3. the ability to hyperextend the elbows
4. passive extension of the metacarpal phalangeal joints of the hands beyond 90 degrees
5. the ability to touch the thumb to the forearm with the wrist fully flexed. Assessment to rule out a neurologic or muscle disease including any type of spasticity or weakness also is indicated.

Unfortunately, it seems that most children who present with flat feet have been dressed up with brand new shoes for the visit to the doctor.

Conclude the physical examination by making an assessment of the child's shoes. Shoe wear patterns can give an excellent clue to the severity of the condition. Unfortunately, it seems that most children who present with flat feet have been dressed up with brand new shoes for the visit to the doctor.

A Historical Perspective
Treatment for flexible flatfoot requires some historical perspective. The majority of children on this planet, residing in warm climates and third world countries, often do not wear shoes and do not complain of foot problems. This carries over into adult life for most of them. A study of the Chinese population, with and without shoes, showed that shoe wear was associated with decreased flexibility and increased foot deformities.

There was an era in the United States when minor postural variations in feet were viewed as precursors to serious adult disability, deformity and pain and, therefore, the prescription and use of shoe modifications was extremely widespread. It is now recognized that the vast majority of mild to moderate flexible flatfeet do not require any treatment other than parental reassurance. Prescription shoes are expensive and prescription molded shoe orthotics are incredibly expensive. Both require frequent replacement in the growing child.

The severe flatfoot with absence of the longitudinal arch and a convex medial border of the foot with a prominent head of the talus and significant valgus of the heel probably does require treatment. Whereas the supportive device, whether it be a custom molded orthotic or a shoe modification such as a scaphoid pad and a one-eighth inch medial heel wedge, will support the foot, it will not produce any beneficial anatomical changes. The rationale for such treatment, therefore, is that it prolongs shoe wear (treating the shoe instead of the foot), it may prevent the severe flatfoot from becoming painful later in childhood or in adolescence, and although it will not correct the anatomical deformity of the foot, it may prevent it from becoming more severe.

Treatment Principles
What follows is a summary of treatment principles:

• BEWARE OF TREATING children under the age of three years because the area under the longitudinal arch is often filled with a fat pad that does not disappear until this age. The flat foot may really just be a fat foot.
• THERE IS EVIDENCE to show that no type of shoe support or orthosis will produce a lasting structural improvement in a flatfoot. On the other hand such devices, hypothetically, may prevent worsening of moderately severe or severe deformities.
• NO THERAPY IS INDICATED for a mild or moderate flexible flatfoot Exercise programs for foot or leg muscles (other than for a tight heelcord) have no therapeutic value.
  THE MODERATELY SEVERE flatfoot in the older child with discomfort can be treated with a scaphoid pad and one eighth inch medial heel wedge for relief of pain. This will not produce a structural change in the foot, but can be applied to virtually any shoe, even a sneaker. Check for a tight heelcord and if this is present, heelcord stretching exercises or serial casting will help diminish the symptoms.
• THE SEVERE FLEXIBLE flatfoot with heel valgus and no underlying neurologic or muscular disorder should be supported with a foot orthosis such as a UCBL. This is biomechanically more effective than shoe modifications and will restore the weight-bearing balance of the foot away from its abnormally medially shifted position. Such treatment should improve shoe wear, diminish the likelihood of discomfort and prevent worsening of the deformity.
• THE TREATMENT of rigid flat feet in almost all instances requires orthopaedic evaluation and management.