Effects of variations in Dwyer calcaneal osteotomy determined by three-dimensional printed patient-specific modeling.

Dwyer (lateral calcaneal closing wedge) osteotomy is commonly used in surgical correction of heel varus deformity. The purpose of this study was to determine the effect of wedge size and angle of osteotomy on deformity correction using preoperative imaging analysis with three-dimensional (3D) printed modeling. Seven patients diagnosed with pes cavovarus deformity who underwent Dwyer calcaneal osteotomy were identified retrospectively. Preoperative computed tomogrphy scans were used to create 3D printed models of the foot. After18 variations of osteotomy and fixation performed for each foot, Harris heel and Saltzman images were obtained. The angle between the tibia-talus axis and calcaneal-tuber axis was measured and compared to pre-osteotomy state. Change in the calcaneal lengths was also analyzed. The average degree correction of deformity per mm of bone resected was 3.8 ± 0.2 degrees in the Harris Heel view and 2.7 ± 0.8 degrees in the Saltzman view. A significant increase in correction was obtained with 10 mm compared with 5 mm wide wedges (P < .001). The difference in correction was not statistically significant between 30 and 45 degree cuts or osteotomy distance from the posterior calcaneal tuberosity, but a 45 degree sagittal angle resulted in less calcaneal shortening compared to 30 degrees (P = .02). A clinically driven method using patient-specific 3D models for determining effects of calcaneal osteotomy variables in correcting hindfoot alignment was developed. In summary, the amount of wedge resected impacts hindfoot alignment more than location and sagittal angle of the cut. Calcaneal shortening depends on sagittal angle of the cut.