A three-dimensional study of calcaneonavicular tarsal coalitions.

The authors studied 37 presumed calcaneonavicular tarsal coalitions from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History. The anatomy of the coalitions and the associated subtalar and transverse tarsal joints was quite variable. The coalitions in 8 specimens completely spared the anterior facet of the calcaneus and in 7 specimens it was partially replaced by the navicular portion of the coalition, whereas in 22 specimens the anterior calcaneal facet was completely replaced by the navicular portion of the coalition. The authors suggest that the pathoanatomy of calcaneonavicular coalitions is not uniform and may involve the subtalar and transverse tarsal joints. This may have clinical relevance and contribute to the unsatisfactory results in feet undergoing coalition resection and soft tissue interposition.