What is nonosseous calcaneonavicular coalition?

Cartilage connection. Coalitions are connections between two bones. These connections can either be osseous or nonosseous. Nonosseous coalitions are two bones that are connected to each other generally via cartilage instead of two fused bones (osseous coalition). A nonosseous calcaneonavicular coalition means that these two bones are not fused together but are connected likely via cartilage.