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Tarsal coalition can present as a problem in pediatric, adolescent, and adult patients, and refers to the condition that exists when fusion of two or more bones of the hindfoot or, less commonly, the midfoot, results in absent or restricted movement between these bones. The coalition may be a cartilaginous (synchondrosis), fibrous (syndesmosis), or bony (synostosis) union between the adjoining involved bones. This abnormal union may be congenital or acquired. The congenital form may go unrecognized until a twist or sprain of the ankle or foot leads to diagnosis. However, the condition may continue unrecognized as a cause for chronic pain or discomfort in the hindfoot, often leading to incorrect diagnosis and inappropriate treatment.
Although evolution and refinement of plain radiology and computed tomography (CT) have contributed greatly to a better understanding of this condition. some aspects of its treatment remain controversial. This article discusses the diagnosis, evaluation, and treatment of this relatively uncommon condition.
HISTORICAL PERSPECTIVE
Tarsal coalition was first described by Buffon1 in 1769. In 1829, Cruveilhier2 first described a calcaneonavicular coalition. Zuckerkandl3 first described a talocalcaneal coalition in 1877, and Anderson4 first described talonavicular coalitions in 1879. A year later, in 1880, HoIl5 first suggested a relationship between tarsal coalition and the so-called peroneal spastic flatfoot.
Calcaneonavicular coalition was the first type to be imaged on an oblique radiograph, as described by Slomann6 in 1921. This preceded the description of its clinical presentation and treatment by Badgeley7 in 1927. Korvin8 is credited with describing the axial view radiograph in 1934, which was used to image the posterior and middle facets of the talocalcaneal joint. It was Harris and Beath9 though, who are credited with popularizing this view in 1948. They also were responsible for linking coalitions to the painful, rigid flatfoot and for clearly demonstrating on radiographs middle or posterior facet coalition of the subtalar joint. Conway and Cowell10 described coalition of the anterior facet of the talocalcaneal joint in 1969 and recommended tomography to corrfirm its presence. More recently, CT and magnetic resonance imaging (MRI) have refined further the ability to delineate the size and exact location of a coalition.11-17
ETIOLOGY
Two theories have been proposed for the etiology of tarsal coalition. The first, and currently favored theory by Leboucq18...