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a breaking down of the arches of the foot, either longitudinal, transverse, or both; the resulting deformity is flat (longitudinal) or splay (transverse) foot, or both.
flat footA common (20–30% of the population) complaint, which affects many age groups. True flat feet (as defined by orthopaedists) are uncommon. Often, a parent will perceive flattening of the foot when a child first ambulates; laxity of the ligaments may result in collapse of the foot with valgus on the hind-foot, and eversion or pronation of the forefoot. Avalgus deformity of > 10% requires therapy; often a shoe will suffice as therapy. Flat foot grades are based on disability, ranging from mere strain or tenderness to osseous rigidity. The peroneal spastic flat feet variant is commonly due to abnormal coalescence between 2 or more tarsal bones, often at the calcaneocuboid, calcaneonavicular, and talocalcaneal bars.
Flat foot, acquired types
Ligamentous—Due to tendino-ligamentous trauma
Muscular—Due to poor control or incoordination (from e.g., poliomyelitis or cerebral palsy).
Osseous—Due to trauma or degeneration.
Postural—Due to internal tibial torsion as occurs in obesity, muscle fatigue, faulty footwear and/or strenuous work on feet, and arthritis.