###### Abstract  
Foot orthotics are recommended for the treatment of hallux valgus. The effects of customized foot orthoses (FOs) designed with both medial longitudinal and transverse arch supports are poorly understood, however. This study aimed to investigate the immediate effect of customized FOs on the plantar pressure and contact area in patients with symptomatic hallux valgus. We recruited 18 patients with a mean hallux valgus angle of 27.3 \(\pm\) 11.1\({}^{\circ}\). Plantar pressure while walking with FOs or flat insoles (FIs) was monitored with a wireless in-shoe plantar pressure-sensing system. Peak pressure (PP), peak force (PF), pressure-time integral (PTI), force-time integral (FTI), and contact area with FOs and FIs were compared. The PF, PTI, and FTI of the midfoot were significantly higher (\(p\) < 0.05), and the PP and PTI of the rearfoot were significantly lower (\(p\) < 0.05) with the FOs than the FIs. The FOs significantly increased the contact area of the midfoot and rearfoot (\(p\) < 0.05) and reduced the contact area of the forefoot (\(p\) < 0.05). These results suggest that customized FOs redistribute plantar pressure and the contact area of the midfoot and rearfoot, improving the functional support of the midfoot for patients with hallux valgus. h 2022 26 July 2022 26 July 28 July 2022 27 May 2022 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 July 26 26 July 26 26 July 26 26 July 26 26 July 26 26 July 26 26 26 July 26 26 26 26 26 26 2  
calcaneus to the metatarasals and lateral area of the midfoot to redistribute plantar pressure and thereby reduce foot pain [10]. The plantar pressure distribution in the metatararsal area can be used to evaluate the effects of hallux valgus intervention [4]. For patients with hallux valgus, wearing medial arch support insoles can reduce peak pressure and peak force under the hallux, metatararsal I, and metatarasals III to V and increase medial midfoot pressure, force, and contact area [5], thereby improving the propulsion effect of the hallux during walking [11]. Nevertheless, another study observed that customized insoles could not decrease the medial pressure on the first metatararsal head in patients with hallux valgus [12]. A study of foot medial longitudinal and transverse architecture and forefoot gait kinematics has revealed that foot architecture is supple until midstance and subsequently creates a rigid lever arm with restored arches to support propulsion [13]. During loading response, the lateral forefoot rapidly exerts and abducts, whereas the medial forefoot exerts and adducts gradually throughout the entire stance phase. Throughout the midstance phase, no kinematic changes occur in the forefoot. In the terminal stance phase, the lateral forefoot inverts and adducts, whereas the medial forefoot exerts and abducts to restore the transverse arch [13]. Hallux valgus may affect this mechanism as well as the arch structure. The greater the hallux valgus angle (HVA) is, the wider the metatararsal area is, which may affect the widening of the transverse arch and decrease or block the ability to absorb impact and thereby cause forefoot pain [14; 15]. A study also reported differences in the transverse arch structure during the quiet standing of feet with and feet without hallux valgus. In addition, the height of the transverse arch and HVA are positively correlated [16]. Therefore, improving insole design through transverse arch support may benefit patients with hallux valgus. The material used to construct insoles influences their effectiveness. Softer material can more effectively absorb the impact of walking, whereas harder material provides faster ground reaction force feedback and greater support [17]. Previous insole studies have mainly described the production principles and materials of the insoles used in the experimental groups but not of those in the control groups [5; 9; 18].