Effects of foot orthoses application during walking on lower limb joint angles and moments in adults with flat Feet: A systematic review with Meta-Analysis

• This study aimed to investigate the effects of foot orthoses application on lower limb mechanics in adults with flat-feet. • We observed greater effects of foot orthoses application on walking mechanics in the studies that used the foot posture index. • We recommend to uniformly use the foot posture index as a foot posture measure in future studies. This systematic review with meta -analysis aimed to investigate the effects of foot orthoses (FO) application on lower limb joint angles and moments in adults with flexible flat-feet during walking. The following five databases were systematically searched from inception until March 2024: Scopus, PubMed, EMBASE, PEDro, and Cochrane Central Register of Controlled Trials (CENTRAL). Between-group standardized mean differences (SMDs) with 95% confidence intervals were computed using a random-effects model. Study heterogeneity was assessed using the I 2 -index. Twenty-four studies were identified and meta -analyzed. Studies were then categorized according to the applied flat-feet assessment method: (1) foot posture index (FPI-6) or clinical observation; (2) foot print arch index or radiography; (3) arch height index (including navicular drop, the arch height index, navicular height normalized to foot length [NNHT]); (4) forefoot varus method; (5) rearfoot eversion or resting calcaneal stance position (RCSP). The meta -analysis showed significant effects of FO application during walking on peak rearfoot eversion (ten studies: moderate SMDs), peak ankle dorsiflexion (five studies: small SMDs), and eversion (seven studies: moderate SMDs). This meta -analysis indicated significant effects of FO application on peak ankle eversion moment (five studies: small SMDs) and peak knee adduction moment (six studies: small SMDs). We observed greater effects of FO application on walking mechanics in the studies that used the FPI-6 method for the assessment of foot posture. Since previous research showed particularly high test–retest reliability measures for the FPI-6 method, we recommend to uniformly use this type of foot posture measure in future studies.