Clubfeet and tarsal coalition.

Tarsal coalition was noted in 18 cases of rigid equinovarus deformity. Sixteen cases were encountered at surgery and two at morbid dissection. There were 14 patients in the series; six had associated pathologic conditions that might have caused their clubfeet to be deemed "teratologic," whereas eight did not and were considered to have congenital clubfeet. Four patients in the series had bilateral coalitions. Preoperative radiographs demonstrated the coalition in only one case. A presurgical magnetic resonance image (MRI) clearly showed the coalition in another case. Nonoperative treatment was unsuccessful. Two patients with tibial dysplasia had ankle disarticulations. The remaining 16 feet required extensive soft-tissue releases, internal fixation, and coalition excision. The vast majority of cases showed cartilaginous subtalar coalition at the medial facet. The patients were followed for an average of 6 years, and two recurrences were noted. Remaining feet were painless and plantargrade, but were rather stiff. This anomaly may be more common than previously described. It is usually not suspected preoperatively and may likewise be difficult to recognize at surgery. A preoperative MRI scan may also be helpful.