Tarsal navicular relations in club foot: is there a role for magnetic resonance imaging?

OBJECTIVE

To correlate radiographic and MR appearances with surgical findings to determine the accuracy of these modalities in demonstrating tarsal navicular (TN) relations in order to select the appropriate surgical intervention.

DESIGN AND PATIENTS

Fourteen consecutive patients with 19 club feet had anteroposterior and lateral radiographs and magnetic resonance (MR) imaging performed. Blinded retrospective interpretation of these studies was correlated with surgical findings. Movement artifact was responsible for initial non-diagnostic MR scans in 3 out of 19 feet.

RESULTS

Plain radiographs and MR imaging had sensitivities of 79% and 84% respectively for TN subluxation, while both modalities had 100% positive predictive value for TN subluxation. Each modality produced indeterminate results in cases where subluxation was present at surgery, but in combination there were no false negatives.

CONCLUSION

Radiography confidently predicted the TN alignment in the majority of cases. MR demonstrated TN relationships in all cases where radiography was indeterminate. It is proposed that MR has a potential role to demonstrate TN relationships when radiography is indeterminate or when there is disparity between the clinical and radiographic assessment.