Surgical Treatment of the Flexible, Progressive Collapsing Foot: Deformities, Definitions, and Decisions.

The complex adult acquired flatfoot deformity involves progressive collapse of the foot with attenuation of medial soft tissues such as the posterior tibialis tendon and spring ligament complex. Multiple deformities at different levels can coexist in the collapsed foot, including hindfoot valgus, midfoot abduction, forefoot varus, and valgus ankle instability. Definitions of flatfoot have evolved to encapsulate the peritalar basis of the deformity, with instability around the talus as the fulcrum. The goals of treatment are to minimize pain, dysfunction, and progressive deformity. Some treatment options directly address the pathologic areas, such as tendon transfer for posterior tibialis tendon dysfunction and spring ligament reconstruction. Others such as calcaneal osteotomies secondarily counteract the primary ligamentous dysfunction and realign the foot to neutralize deforming forces. Selective fusions of the hindfoot and medial column are also viable options to correct the deformity at the joint level when appropriate. The treatment selected depends on flexibility and locations of the deformity, and ultimately patient-specific factors.