Effect of Hallux Valgus Correction Osteotomies on Flatfoot Deformity
Authors: Urrutia Tomas , Massri-Pugin Jafet , Matamoros Gabriel , Filippi Jorge , Briceno Jorge 
Published: December 2024

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: Flatfoot deformity is frequent in patients with hallux valgus deformity (HVD). Prior studies have shown that distal correction of HVD such as first metatarsophalangeal (MTP) fusion is capable of improving some radiologic parameters of flatfoot deformity, reinforcing the theory that the recovery of the tension of the distal medial arch is fundamental for stabilizing the first tarsometatarsal joint, preventing the arch collapse and the failure of HV correction. However, to our knowledge, it is unknown whether the first metatarsal osteotomies can generate a similar phenomenon. The purpose of this study was to evaluate if the first metatarsal osteotomies for HVD can improve the radiologic parameters of flatfoot deformity. Methods: A retrospective review of consecutive patients treated with open surgery for HVD between 2018 and 2021 at a single institution was performed. Inclusion criteria were moderate hallux valgus angle (HVA) >20º, open first metatarsal osteotomy (i.e chevron and scarf osteotomies), concomitant flatfoot deformity (Meary angle>4º), pre-and postoperative weightbearing foot radiographs, and at least 3 months of follow-up. Exclusion criteria were HVD treated with any type of first ray fusion, first MTP or TMT arthritis, prior surgery, or complications (malunion, infections). The following variables were collected by two fellowship trained-foot and ankle orthopaedic surgeons: Meary angle (MA), calcaneal pitch (CP), medial cuneiform height (MCH), talonavicular coverage angle (TNCA), anteroposterior talo-first metatarsal angle (TFMA), hallux valgus angle (HVA), and 1-2 intermetatarsal angle (IMA). The Wilcoxon signed-rank test was used to compare the variables pre and post-surgery. P value< 0.05 was considered significant. Results: A total of 225 patients were initially evaluated, of which 23 patients fulfilled the eligibility criteria. The mean age was 40.9 (+-19.1) years and all patients were female. A significant decrease was observed in the HVA and IMA (p< 0.001). The median and interquartile ranges of pre-and postoperative variables were: MA, 8.2º (6.8-12.7) to 5.7º (4.3-11.2); CP, 16.7º (13.4-20.2) to 17.5º (14.1-19.8); MCH, 27.7mm (25.9-32.5) to 29.9mm (26.4-34.2); TNCA, 19.7º (13.8-25.5) to 17.2º (13.8-22.7), and TFMA, 7.3º (6.2-9.9) to 12.3º (6.3-15.1). A significant change after first metatarsal osteotomy was observed in the MA (p=0.04), CP (p=0.03), TNCA (p=0.03), and TFMA (p=0.01), but not in the MCH. Conclusion: This study demonstrated that HVD correction through first metatarsal osteotomy is capable of significantly improving the radiological parameters commonly altered in flatfoot deformity. These findings, concordant with prior studies on first MTP fusion, reinforce the important role that soft tissue tension plays in foot alignment. However, the clinical importance and its applicability in the treatment of patients with symptomatic flat feet must be determined by future work.