Contribution of Medial Cuneiform Osteotomy to Correction of Longitudinal Arch Collapse in Stage IIb Adult-Acquired Flatfoot Deformity.

UNLABELLED: Background Residual forefoot supination after correcting the hindfoot in stage IIb adult-acquired flatfoot deformity can be addressed with a dorsal opening wedge medial cuneiform (Cotton) osteotomy. The amount of correction is generally judged clinically, and there currently are no preoperative guides that can predict the size of graft needed. The aim of this study was to evaluate the correlation between patient and operative factors and the correction achieved with the Cotton osteotomy.

METHODS

Seventy-nine feet in 74 patients undergoing Cotton osteotomy as part of flatfoot reconstruction were reviewed retrospectively. Preoperative and minimum 40-week postoperative lateral foot weightbearing radiographs were compared to assess correction of longitudinal arch collapse as measured by 13 radiographic parameters, with particular emphasis on the cuneiform articular angle (CAA). Additional demographic and intraoperative variables analyzed for association with radiographic change included age, gender, body mass index, amounts and graft types of Cotton osteotomy and lateral column lengthening, and amount of medializing calcaneal osteotomy. A multivariate linear regression model was developed for each variable found to be significant in univariate analysis.

RESULTS

The Cotton osteotomy graft size was significantly associated with changes in the CAA ( P < .001), calcaneal pitch ( P = .03), lateral talonavicular Cobb angle ( P = .03), and lateral naviculomedial cuneiform Cobb angle ( P = .03). The Cotton graft size was the only factor found to significantly predict a change in the CAA in the final linear regression model ( P < .001, R2 = 0.27), with each millimeter of Cotton corresponding to a 2.1-degree decrease of the CAA.

CONCLUSION

Correction of longitudinal arch collapse, as measured by the CAA, was primarily influenced by the size of the graft used for the Cotton osteotomy in a linear fashion. The preoperative CAA may help surgeons titrate the proper amount of graft placed intraoperatively.

LEVEL OF EVIDENCE: Level IV, Retrospective Case Series.