TARSAL COALITION

The introduction of computed tomography has shown that fusion of one o r more tarsal bones is more common than was previously thought. In par ticular, talocalcaneal coalition can be missed on plain films but is s een clearly on computed tomography scans. Talocalcaneal and calcaneona vicular coalition are the most common types. Pain usually does not occ ur until the appearance of ossification during the teenage years. Pain , restricted motion, and deformity are the cardinal manifestations. Mo st patients have loss of inversion of the foot, spasm of the peroneal muscles, pes planus, and valgus deformity. Plain radiographs with at l east three or four projections should be obtained of both feet since t arsal coalition is bilateral in at least 50% of cases. Calcaneonavicul ar coalition can be identified on a 45 degrees oblique view. Talocalca neal coalition is difficult to see, although a number of indirect sign s on the lateral views and direct signs on the Harris-Beath view provi de valuable clues; computed tomography should be performed to confirm the diagnosis and to help plan the surgical procedure. Magnetic resona nce imaging does not Seem to offer any additional information.