Cortical Thickness of the Second Metatarsal After Correction of Hallux Valgus

Abstract

Background: Hallux valgus is a functional deformity of the first ray. When incorrectly aligned, the first ray is less effective as a support structure, and the stresses then theoretically transfer to the second metatarsal which could lead to increased cortical density. The aim of this study was to evaluate if surgical correction of hallux valgus lead to changes in the cortical density of the second metatarsal. Materials and Methods: This was a retrospective study involving 13 patients who had surgery for isolated hallux valgus. The average postoperative followup was 16 (range, 11 to 24) months. We analyzed pre- and postoperative radiographs of the feet. We assessed the variations in the medial and lateral cortical thickness, the medullary thickness and the shaft thickness (ST) of the second and fourth metatarsals. Results: A significant reduction of the medial cortical bone thickness of the second metatarsal (MT2) ( p < 0.001) and a significant medullary increase of MT2 ( p < 0.001) were observed postoperatively. However, no significant difference in the lateral cortical thickness or shaft thickness of the metatarsal was found. A significant reduction of the MCT/ST ratio ( p < 0.001) was also observed. Regarding the fourth metatarsal, which was used as a control, no significant change was observed. Conclusion: The isolated cortical variations of the second metatarsal suggests that isolated hallux valgus correction led to a redistribution of the stresses on to the first ray. Level of Evidence: IV, Retrospective Case Series