SLR - January 2018 - Brian Schenavar

A Radiologic Classification of Talocalcaneal Coalitions Based on 3D Reconstruction

References: Rozansky A, Varley E, Moor M, Wenger DR, Mubarak SJ, A Radiologic Classification of Talocalcaneal Coalitions Based on 3D Reconstruction. J Child Orthop (2010) 4:129–135.

Scientific Literature Review

Reviewed By: Brian Schenavar, DPM
Residency Program: Wheaton Franciscan Healthcare, St. Joseph Hospital, Milwaukee, WI

Podiatric Relevance: Talocalcaneal coalitions are relatively easy to detect based on clinical signs; however, locating the exact location of the coalition is difficult with plain film radiographs. While 2D CT imaging is common in preoperative planning, this article proposes a classification system that incorporates 3D CT imaging. The goals of the study were to identify the precise location, nature and position of talocalcaneal coalitions. This may help surgeons plan a more appropriate cleavage plane compared to imaging from 2D CTs only.

Methods: This is a retrospective review of talocalcaneal coalitions based on clinical and radiographic findings. All coalitions were confirmed with CT. The patient population was taken from September 2005 to April 2009 with a total of 54 feet. 3D CT reconstructions were analyzed on all 54 feet. The institutions tarsal coalition protocol was followed. The classification was determined by using the coronal CT images first, then the 3D reconstruction.

Results: Of the 35 patients (54 feet), 14 were male and 21 females. The average age was 13.5 years, and 63 percent were bilateral. Twenty-two feet were noted to have Type I with an average age of 13.4 years. Nine patients had Type II, and eight patients had Type III with average ages of 14.8 and 13.9 years, respectively. Six patients were noted to have Type IV with the average age of 15.79 years. Finally, nine were noted to have Type V with average age of 10.7 years.
 
Type I – Linear coalition: Noted to be the easiest to resect. 3D imaging allows the correct plane of resection to be visualized.  
Type II – Linear coalition with posterior hook: The posterior hook is difficult to identify on 2D CT scans. The 3D imaging helps identify the hook and helps prevent too much sustentaclum tali from being resected.
Type III – Shingled coalition: This coalition occurs with a hypoplastic sustentaculum tali. The plan of cleavage is not accurately identified on 2D imaging. The authors reported, due to the excessive overhang of the talus, this positions the plane of resection far more inferior than demonstrated on 2D imaging.
Type IV – Complete osseous coalitions: These coalitions can be the most difficult to resect. Complete osseous coalition size needs to be taken into consideration during management. Poor outcomes have been demonstrated with resection osseous coalitions > 50 percent.  
Type V – Posterior coalitions: These are commonly missed on plain film XR and 2D CT imaging. They are a small posterior coalition that is located directly beneath the posterior tibial artery and nerve. Though small, they can play a significant role in limiting STJ motion, but they can be easily visualized with 3D CT.

Conclusion: 3D imaging allows for preoperative planning that reveals the precise plane and orientation of coalitions that prevents aggressive over resection. The limitations include both the retrospective nature of the study along with small sample size. Further clinical studies would be useful to validate the use of this classification scheme to aid in surgical treatment.

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