Change in Shoe Size and Forefoot Morphological Parameters After Scarf + P1 Osteotomy for Hallux Valgus: a Prospective Study Using Surface 3D Scanning

Overview

Background and Rationale: Surgical correction of Hallux Valgus via Scarf and P1 osteotomy aims to realign the first ray, modifying overall forefoot morphology. While radiological correction is well established, a discrepancy often exists between objective foot measurements and patient-perceived postoperative shoe fitting. Weight-bearing 3D surface scanning provides a non-irradiating, precise method to evaluate volumetric and dimensional changes without the biases of traditional foot-measuring gauges. Objective and Hypothesis: The primary objective is to measure changes in shoe size (in French/Paris points) using weight-bearing 3D surface scanning between baseline and 6 months postoperatively. The study hypothesis is that Scarf + P1 osteotomy induces a shoe size reduction of at least 0.5 Paris points at 6 months, correlated with forefoot width reduction, M1 shortening, and angular correction (HVA and M1-M2 angles). Study Design: Prospective, single-center, non-comparative interventional study with minimal risks and constraints (RIPH 2) involving 100 participants.

Study Procedures and Follow-up Schedule: Preoperative Assessment: Clinical evaluation, standing plain radiographs (HVA and M1-M2 angles), baseline self-reported shoe size, foot-measuring device measurement, and weight-bearing 3D surface scan. Surgical Intervention: Hallux valgus correction via Scarf osteotomy of the first metatarsal combined with P1 phalanx osteotomy. Postoperative Follow-up Visits: 6-Week Visit: Routine clinical evaluation, 3D surface scan, foot-measuring device measurement, and self-reported shoe size assessment. 6-Month Visit: Final follow-up visit including standing radiographs, 3D surface scan, foot-measuring device measurement, self-reported shoe size assessment, and recording of surgical/mechanical complications.