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  • The foot exhibits both longitudinal (medial and lateral) and transverse arches.
  • These arches are maintained by: the shape of the foot bones, the activity of muscles and a wide variety of ligaments.
  • A flat foot (pes planus) is a foot with a large plantar contact area and a small or absent longitudinal arch in contrast to pes cavus (high arched foot).
  • Though flexible flatfeet are present in nearly all infants and many children the exact incidence is unknown.
  • It is present in 20-25% of adults and runs in families.

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Footprint demonstrating the differences between normal, flat and high arched foot.

  • Though the cause is unknown it is associated with generalized ligamentous laxity and runs in families.
  • The diagnosis is clinical.
  • The medial arch reappears on tiptoeing or on passive dorsiflexion of the great toe (Jacks test).
  • The Achilles tendon may be tight but subtalar joint motion should not be limited.
  • Subtalar motion should be full.

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Image source

Legend: Beightons assessment for ligamentous laxity

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Flexible flat feet. On tip toeing, the heel moves into varus and the medial arch reconstituted. Bottom left picture shows Jacks test.

  • Plain radiographs are not required to make a diagnosis however they may be useful in quantifying the deformity
  • Several radiological parameters have been used to assess foot deformities.

On the lateral view:

  • The lateral distal tibial angle (LDTA=89°, range 86-92°). Abnormal value indicates distal tibia deformity which may contribute to the flat feet deformity.
  • The calcaneal pitch (17°, range 11-23°). The smaller the calcaneal pitch, the more plantarflexed the hindfoot.
  • The lateral tibiocalcaneal angle (69°, range 44-86°). The larger the tibiocalcaneal angle, the more plantarflexed the hindfoot.
  • The lateral talocalcaneal angle (49°, range 36-61°). The greater the talocalcaneal angle, the more valgus and abducted the hindfoot.
  • Lateral Meary’s angle (lateral talo-1st metatarsal angel) which is normally 5° (range 1-9°). The greater the lateral talo–first metatarsal angle, the more planus is the midfoot.

On the AP view

  • The anterior distal tibial angle (ADTA= 80°, range 78-82°).
  • The AP talocalcaneal angle of  Kite ( 21°, range 14-28°)
  • The AP  talo-first MT angle (10°, range -3-28°)

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Lateral foot plain radiograph showing useful measurements to assess foot deformity. These are useful in assessing pes cavus and other deformities. (See also hallux valgus).

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Lateral foot plain radiograph showing useful measurements to assess foot deformity. These are useful in assessing pes cavus and other deformities.

  • Treatment for a flexible flatfoot deformity is not required and the parents should be reassured.
  • ?Orthotic and operative treatment controversial.
  • Orthoses (medial arch supports) have been shown not to promote the development of the longitudinal arch and should not be routinely prescribed (1).
  • They may however relieve pain if present.
  • Calf stretching exercises may be helpful if the Achilles tendon/gastrocnemius is tight.

Surgery

  • Surgery is reserved for the older child with intractable symptoms unresponsive to nonsurgical options.
  • A joint sparing operation-osteotomy such as a lateral column lengthening procedure with or without release of the gastrocnemius/Achilles tendon is the procedure of choice.
  • Triple C osteotomies ( Medial calcaneal slide, Cuboid opening wedge and medial Cuneiform dorsal opening wedge.
  • Arthroeresis of the subtalar joint (using an implant) is an option but is not without complication and the parents should be consented appropriately.

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Clinical photograph and plain x-ray of a teenager with severe flat feet undergoing triple C osteotomy.

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Fluoroscopy pictures of triple C osteotomies. Notice the medial calcaneal slide, Cuboid opening wedge and medical cuneiform dorsal opening wedge.

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Arthrodesis for bilateral flat feet.

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References

  • 1. Gould N, Moreland M, Alvarez R, Trevino S, Fenwick J. Development of the child's arch. Foot Ankle. 1989 Apr;9(5):241-5.