Outcomes of a Stepcut Lengthening Calcaneal Osteotomy (SLCO) Compared to Evans Calcaneal Osteotomy for Stage IIb Adult-Acquired Flatfoot Deformity

Abstract

Category: Hindfoot Introduction/Purpose: Lateral column lengthening is a powerful procedure utilized to correct the associated abduction deformity in stage II flatfoot deformity; however, prior studies have shown complications of nonunion, graft collapse, and lateral column overload with the Evans osteotomy. The Stepcut Lengthening Calcaneal Osteotomy (SLCO) is a z-lengthening calcaneal osteotomy that can correct midfoot abduction while providing inherent stability by creating a large surface area for bony healing. The goal of our study was to compare outcomes in patients undergoing a SLCO versus an Evans osteotomy. It is our hypothesis that patients following a SLCO would have a decreased incidence of nonunion and lateral overload of the foot, and similar improvement in clinical outcome scores. Methods: All consecutive patients from 2006 to 2013 undergoing stage IIB flatfoot reconstruction from our institution’s Foot & Ankle Registry were identified and included. There were 65 Evans & 79 Stepcut patients with a minimum of two year followup. All patients undergoing flatfoot reconstruction were included regardless of associated procedures which were not significantly different between the groups (Table 1). Deformity correction was assessed using preoperative and postoperative weightbearing radiographs. Healing of the osteotomy was assessed by computed tomography (CT). Clinical outcomes were assessed by the Foot and Ankle Outcomes Score (FAOS) survey which has been validated for flatfoot. Rate of return to the OR was also assessed. Differences in continuous variables between groups were assessed with independent samples t-tests, or Mann-Whitney U tests when non-normally distributed. Differences in categorical variables between groups were assessed with chi-squared and Fisher’s exact tests. An alpha level of 0.05 was deemed statistically significant. Results: The Evans group had a 0.9 mm larger graft size (p < 0.001) than the SLCO Group (Table 2). The SLCO group had greater improvement in talonavicular coverage angle (p < 0.001) and talonavicular incongruency angle (p = 0.023) than the Evans group. The Evans group returned more often for additional surgeries (p = 0.030). While there was improvement in mean FAOS scores in both groups for all subscales, only the mean FAOS score for sports activities (p = 0.012) was statistically better in the SLCO group. Rate of nonunion was not statistically significant (p = 0.086) between groups. There was no occurrence of loss of correction or lack of healing of the main (horizontal) arm of the osteotomy site in the SLCO group. Conclusion: Patients who underwent the SLCO for stage IIb adult-acquired flatfoot deformity demonstrated excellent healing, good correction of deformity, utilized a smaller graft size for correction, and less frequently needed to have a second operation on the involved foot. Additionally when compared to the Evans osteotomy, the SLCO group had comparable improvements in FAOS scores; thus making the SLCO a reasonable alternative for lateral column lengthening