Digital Planning for Foot and Ankle Deformity Correction: Evans Osteotomy

Preoperative planning is commonly performed for many foot and ankle procedures. The purpose of the present study was to prospectively determine the preoperative digital planning accuracy of predicting the calcaneal graft size used during the “Evans” calcaneal osteotomy. Preoperative digital deformity correction planning, using a standard planning method (TraumaCad® software), was performed on 10 feet scheduled to undergo an Evans procedure. Of the 10 patients, 6 were female and 4 were male, with an average age of 43 ± 22 years. Digital planning was used to predict the Evans graft size. The surgeon was unaware of the predicted graft size, which was then compared with the actual graft size inserted during the procedure. In addition, the pre- and postoperative radiographic angles were recorded and compared (anteroposterior view, talo–first metatarsal angle, calcaneocuboid abduction; lateral view, calcaneal inclination angle; and axial view, tibial–calcaneal angle). The average preoperative talo–first metatarsal angle, calcaneocuboid angle, calcaneal inclination angle, and tibial–calcaneal angle measured 21° ± 9.6°, 28.3° ± 9.0°, 13.8° ± 5.7°, and 15.3° ± 8.2°, respectively. The preoperative tibial–calcaneal position was 2.8 ± 1.2 mm. The radiographic weightbearing angles measured at an average follow-up of 7.4 (range 6 to 12) months improved to 6.3° ± 7.4° (p = .0015), 12.3° ± 6.1° (p < .001), 21.3° ± 7.7° (p = .0122), and 2.2° ± 3.6° (p = .0019) for the talo–first metatarsal, calcaneocuboid abduction, calcaneal inclination, and tibial–calcaneal angles, respectively. The final tibial–calcaneal position measured 1.4 ± 0.7 mm (p < .001). The preoperative Evans graft measurement (11.8 ± 2.6 mm) compared with the actual graft (12.2 ± 1.3 mm) placed was within 0.4 ± 1.8 mm (p = .51). Preoperative digital planning for Evans calcaneal osteotomy has been shown to be a valuable tool for predicting the surgical graft size for accurate pedal realignment.