Pes Planus (flat foot)
The science of walking comfort
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Pes planus consists of a number of physical features that includes excessive eversion of the subtalar joint during weightbearing with plantarflexion of the talus, plantarflexion of the calcaneus in relation to the tibia, a dorsiflexed and abducted navicular and valgus posture of the heel. The lateral border of the foot is short compared with the medial border, which creates midfoot sag and a lowering of the medial longitudinal arch.
In many cases a flat-footed person may not present with any specific complaint. Other pes planus patients may present with common foot complaints including plantar fasciitis, achilles tendonitis, tired, aching feet as well as other complaints such as aching legs and knee pain
A true flat foot is very rare with an esitmated prevalence of only 1.8% of the adult population. This condition is referred to as rigid pes planus, whereby the foot is completely flat even during non-weight bearing.
On the other hand, flexible (or functional) pes planus is a biomechanical problem experienced by a surprisingly high percentage of the population. In this case the arch will appear normal when the patient is sitting (i.e. not bearing weight), however with the patient standing upright you will be unable to place an index finger under the arch. The entire bottom of the bare foot is in contact with the floor or ground surface during standing, walking, and other weight bearing activities.
Flexible pes planus is caused by joint laxity and severe excess subtalar joint pronation, which leads to excessive calcaneal eversion during the contact phase of gait.
Rigid pes planus, on the other hand, is a pathologic condition and often occurs in conjunction with an underlying disease. It can be divided into congenital and acquired forms. Causes of rigid pes planus include structural abnormalities (e.g. vertical talus and tarsal coalition), collagen disorders (e.g. Marfan syndrome), musculoskeletal abnormalities, trauma (e.g., interarticular fractures or tendon lacerations), spastic conditions (e.g. arthritis of talocalcaneal joint as seen in juvenile rheumatoid arthritis), or neuromuscular conditions (e.g. cerebral palsy or meningomyelocele).
Pediatric pes planus is a normal condition in infancy. The arch develops gradually during childhood. Thus, pes planus is normal in infants, common in children, and often present in adults. Its prevalence decreases with age. Commonly, by the age of 5-6 years old, children should have developed a visible arch.
Flexible pes planus can be treated successfully with orthotic therapy. Footlogics orthotics control excessive pronation and grreatly reduce excessive calcaneal eversion during the contact phase of gait, thus preventing secondary unlocking of the midtarsal joints during midstance phase. Footlogics Kids orthotics are beneficial for flat-footed children from the age of around 5-6 years old.