Factors affecting bone union after distal shortening oblique osteotomy of the lesser metatarsals

Objectives: There have been few reports on factors affecting bone union after metatarsal osteotomies. The purpose of this study was to clarify the factors affecting bone union after distal shortening oblique osteotomy of the lesser metatarsals.Methods: Patients who underwent distal shortening oblique osteotomy of the lesser metatarsals were retrospectively investigated. Failure to achieve bone union at 6 months after surgery was defined as delayed union. Background characteristics and radiographic measurements were compared between patients with and those without delayed union, and factors affecting bone union were assessed using multivariate analysis.Results: Among 204 toes in 58 patients evaluated in this study, delayed union occurred in 28%. In multivariate analysis, corticosteroid use (odds ratio (OR), 3.68; 95% confidence interval (CI), 1.65-8.16; p< .01), larger preoperative overlap between the metatarsal and the proximal phalanx (OR, 1.11 (per 1 mm increase); 95% CI, 1.02-1.21; p= .02), and larger gap at the osteotomy site (OR, 3.02 (per 1 mm increase); 95% CI, 1.76-5.16; p< .01) were identified as independent risk factors of delayed union.Conclusion: The identified risk factors of delayed union after distal shortening metatarsal osteotomies were corticosteroid use, preoperative overlap between the metatarsal and the proximal phalanx, and a gap at the osteotomy site.