Does the Presence of Asymptomatic Flatfoot Impact the Clinical and Radiographic Outcomes of the Minimally Invasive Chevron and Akin Bunionectomy?

Abstract

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Pes planus is believed to play a role in hallux valgus (HV) development and recurrence. While symptomatic flatfoot can be treated with a dedicated reconstruction at the time of HV correction, addressing the asymptomatic flatfoot remains unclear. Theoretically, stabilizing the medical column while correcting HV could decrease the likelihood of flatfoot progression, however these procedures are invasive, technically difficult, and require prolonged recovery. Minimally invasive techniques are becoming increasingly popular due to immediate weight bearing, less pain, and quicker recovery; however, their role for treating HV with asymptomatic flatfoot is unknown. Therefore, we aimed to investigate whether the outcomes of the minimally invasive chevron and Akin bunionectomy (MISB) are influenced by the presence of asymptomatic flatfoot. Methods: This retrospective cohort study included 62 patients treated by 2 fellowship-trained surgeons who have been performing MIS bunionectomy for at least 3 years. Patients were included if they were over 18 years old, underwent a MISB procedure to correct a hallux valgus deformity, had minimum 1-year postoperative PROMIS scores, and preoperative and minimum 6-months postoperative radiographs. Patients were excluded if they had any prior procedures on the ipsilateral forefoot. Twenty-five asymptomatic patients (mean age: 55 years) met the radiographic criteria for flatfoot (Meary’s angle > 4 degrees, calcaneal pitch (CP) 7 degrees) while 37 had a normal arch (mean age: 56.4 years). Clinical outcomes were evaluated using validated PROMIS measures. Radiographic outcomes including hallux valgus angle (HVA), intermetatarsal angle (IMA), Meary’s angle, CP, and TNCA were measured and compared preoperatively and minimum 6 months postoperatively. Results: The average clinical follow-up was 16.7 months in the control group and 15.9 months in the flatfoot group (p=0.6) while the average radiographic follow-up was 8.5 months for the control and 9.7 months for the flatfoot group (p=0.2). Both groups demonstrated similar preoperative and postoperative PROMIS scores with significant improvements in physical function, pain interference, and pain intensity (Table 1). Preoperative and postoperative HVA and IMA were similar between groups, however patients in the flatfoot group had a significantly higher Meary’s angle, TNCA, and lower CP preoperatively and postoperatively. Both groups showed significant improvements in HVA, IMA, and TNCA (Table 2). The flatfoot group demonstrated a 1.4-degree improvement in Meary’s angle while the control group had a 1.5-degree worsening in Meary’s angle. Conclusion: Our study indicates that the minimally invasive chevron and Akin bunionectomy improves patient-reported outcomes and provides significant correction of the hallux valgus deformity without adversely impacting flatfoot parameters. Additionally, although the MISB procedure was not able to normalize the flatfoot parameters, this did not seem to affect patient-reported outcomes 1-2 years after surgery. Therefore, the MIS bunionectomy may be an effective option for hallux valgus correction in patients with mild, asymptomatic flatfoot, however longer-term radiographic follow-up is required to determine if outcomes are influenced by further progression of the flatfoot.