Cubonavicular Coalition

Clinical History

Pain on the dorso-lateral aspect of the mid-foot worse on exercising. On examination subtalar joint movements were reduced and painful.

Imaging Findings

Pain on the dorso-lateral aspect of the right mid-foot for 2 years and pain brought on by exercise. No history of trauma. On examination movement of the right subtalar joint was reduced and painful. Plain radiographs with antero-posterior and oblique weight-bearing views suggested a bone bar of the cubonavicular joint. Computed tomography (CT) of the tarsus was performed. Scan acquisition was direct coronal with the patient supine, the hips and knees flexed and the feet together flat on the scanner table. There was no gantry angulation and slices were taken at 2mm intervals. Axial and 3-D reconstruction were performed. This confirmed a large cubonavicular coalition mainly on the plantar aspect. This was explored surgically through a dorsal approach and a cubonavicular coalition resected.

Discussion

Tarsal coalition is abnormal bony, cartilaginous or fibrous fusion between two or more tarsal bones. Calcaneonavicular and talocalcaneal are the most common forms. Cubonavicular coalition is a rare form thought to occur in less than 1% of all coalitions (Palladino et al 1991). Most coalitions can be diagnosed by plain radiography and CT. Studies have shown magnetic resonance imaging (MRI) to have the same diagnostic accuracy as CT (Emery et al 1998). MRI may be useful in showing cartilaginous or fibrous unions in cases where the clinical suspicion of a tarsal coalition is high but both radiographs and CT are negative. Other modalities such as scintigraphy may be helpful. In this case a CT reconstruction was used to aid in surgical planning.

Differential Diagnosis List

Final Diagnosis

Cubonavicular coalition

URL:	https://eurorad.org/case/829
DOI:	10.1594/EURORAD/CASE.829
ISSN:	1563-4086