Are computed tomography scans necessary in the preoperative evaluation of calcaneonavicular tarsal coalitions?

Calcaneonavicular (CNC) and talocalcaneal coalitions (TCC) account for most tarsal coalitions. Plain radiographs are typically sufficient to diagnose CNC, while computed tomography (CT) scans are often required to diagnose TCC. The standard of care for all coalitions includes a CT to characterize the coalition and identify additional coalitions. Multiple ipsilateral coalitions are rare and literature on the topic is limited. While the role of routine CT in TCC is well-established, the benefits of routine CT in CNC are less clear. A retrospective review of medical records and plain radiographs of patients less than 20 years of age who underwent tarsal coalition resection at our institution from 2006 to 2021 was performed. Patients received preoperative foot XRs and CT scans. We evaluated demographics, surgical data, and whether the diagnosis was made with XR or CT. In multiple coexisting coalitions, special consideration was placed on whether CT modified treatment plans. The study population consisted of 76 patients. 55 (100%) of CNC were diagnosed on XR compared to 11 (52.4%) of TCC. CT was necessary to diagnose in 10 (47.6%) of the TCC patients. CT identified additional coalitions in two (2.6%) patients. The treatment plan was affected by CT findings in one (1.3%) patient. The rate of clinically significant multiple ipsilateral tarsal coalitions is extremely low in our patient population. The utility of CT scan remains important in diagnosing TCC that cannot be seen on XR but is suspected clinically. Patients with XR diagnosis and consistent clinical presentation of CNC are unlikely to benefit from routine CT. Modifying the standard of care would decrease cost, time, and radiation exposure. Level of evidence: Level IV.