A Calcaneonavicular coalition is best evaluated by taking a 45 degree lateral oblique projection. A 1cm in width bar may be seen in bony coalitions, while fibrous or cartilaginous may show joint space narrowing with irregular edges. Lateral views may show elongated anterosuperior process of the calcaneus also known as the 'anteater sign'. Talocalcaneal coalitions are more difficult to diagnose on plain films. Harris Beath view, a 45 degree axial view o the calcaneus normally demonstrates the middle and posterior facets that are horizontal and parallel to one another.
Bone scans are an adjunct procedure for helping in the diagnosis.
CT Scans are considered the 'gold standard' for diagnosis. The articular classification system is based on the patient's age the articular involvement or relationship of the involved bones the amount of arthritic deformity present. Age is a factor in surgical treatment since patients with open growth plates have greater potential for remodeling and would respond better to resection arthroplasty. Extraarticular coalitions are between two or more tarsal bones that do not normally articulate with one another. Intra-articular coalitions occur within the joint space of two or more bones.