Nonunion Rate of Evans Osteotomy Without Fixation Pediatric Flatfoot

Abstract

Category: Hindfoot; Other Introduction/Purpose: The Evans osteotomy is a calcaneal lateral column lengthening procedure commonly used to correct flatfoot deformities. Currently, there is no consensus on whether fixation is needed when performing this osteotomy. Also, large sized grafts have been found to lead to degeneration of the calcaneocuboid joint. The aim of this study was to determine the nonunion rate of an unfixed Evans osteotomy with use of an allograft wedge performed in patients undergoing flexible flatfoot reconstruction and if addition of a medial calcaneal slide osteotomy will help limit graft size. Methods: We retrospectively reviewed 39 pediatric patients with idiopathic symptomatic flatfoot deformity who underwent 46 unfixed Evans osteotomies with allogenic bone graft for flatfoot reconstruction between March 2013 and September 2017, with a mean follow-up of 49 (range 9.9- 243.9) weeks. Hospital record, preoperative, follow-up radiographs and complications were reviewed. Results: Of the 46 feet, 42(91.3%) underwent an associated medial displacement calcaneal osteotomy. Mean graft wedge size was 7.2mm(SD 1.6). Mean time to union was 10.3weeks (range, 6.7-13.9)(Table 1). There were no nonunions. There was significant improvement in all radiographic parameters at final follow-up (Table 2). Postoperative calcaneocuboid subluxation occurred in 70% of feet, with no correlation with wedge size(r=0.01,p=0.53). Magnitude of calcaneocuboid subluxation was small and only significant at 6-months (p=0.02), with regression to no significance by 1-year(p=0.3). Mean change in calcaneocuboid subluxation at final follow-up was 1.07mm(SD 2.18), with postoperative subluxation diminishing over time(Table 3). No correlation was observed between wedge size and change in lateral column length (r=0.01,p=0.45). One patient had persistent sinus tarsi pain requiring arthroscopic debridement of fibrosis and graft prominence. Conclusion: An unfixed Evans osteotomy for symptomatic pediatric flatfoot deformity resulted in a significant improvement in the radiographic alignment and achieved 100% union rate with minimal calcaneocuboid subluxation at final follow-up. Performing adjunctive procedures allowed the Evans procedure to be routinely limited to less than 10 mm of lengthening. Mean graft size in our cohort was smaller than that reported by other studies. While calcaneocuboid subluxation was detectable in 70% of feet, it was small in magnitude and diminished with longer postoperative follow-up.