Original Article

Hybrid minimally invasive correction for flexible flatfeet in young adults: a prospective cohort study

¹ Department of Orthopedics, Kasr Al Aini Faculty of Medicine, Cairo University Hospitals, 11562 Cairo, Egypt
² James Paget University Hospital, A47 Lowestoft Road, Gorleston-on-Sea, Great Yarmouth, Norfolk, NR31 6LA, UK
³ Manchester University NHS Foundation Trust, Oxford Road, Manchester, M13 9WL, UK
⁴ 6th Of October Hospital For Health Insurance, 5 El Mosiqar Aly Ismail Street, 12588 Giza, Egypt
⁵ University Hospital of North Durham, North Rd, Durham DH1 5TW, UK

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 14 October 2025
Accepted: 22 December 2025

Abstract

Introduction: This study aims to assess the functional and radiological outcomes of combining minimally invasive medial displacing calcaneal osteotomy (MDCO) with subtalar arthroereisis (STA) for the treatment of symptomatic planovalgus feet in young adults. Methods: A single-centre, prospective cohort study was conducted between November 2015 and February 2022. The study included a total of 32 patients with flexible flatfoot who were treated with subtalar arthroereisis combined with medialising calcaneal osteotomy with at least three years of follow-up. Radiographic evaluation included talar coverage angle, AP talo-first metatarsal (T1MT), AP talo-calcaneal, lateral talo-first metatarsal, and calcaneal pitch angles. Function was assessed by the AOFAS score. Results: Angles and scores were compared preoperatively and at the third-year follow-up. The mean talo-navicular coverage angle TNCA reduced from 32.72° (±8.33) preoperatively to 8.84° (±5.70) at the last follow-up. The mean AP T1MT improved from 21.59° (±8.47) preoperatively to 7.78° (±4.03) at three years postoperatively. Meary’s angle decreased from 20.84° (±7.14) preoperatively to 4.78° (±3.20) following the correction. The mean preoperative AOFAS score was 62.69 (±9.26), and significantly improved to 94.19 (±3.80) at the last follow-up. Four feet experienced sinus tarsi pain (12.5%), and three patients (9.3%) needed removal of the arthroereisis implant. Conclusions: The combination of MDCO and STA holds significant promise for treating flexible flatfeet in adolescents and young adults, particularly in cases of moderate to severe deformity. This combination demonstrates a synergistic interaction, with the STA implant providing internal bracing to support MDCO and reducing stresses over the medial arch by preventing hyper-pronation. Simultaneously, the MDCO reinforces the reconstruction, achieving the necessary increased correction in moderate to severe flatfoot cases, while also reducing stresses over the STA implant.