Effects of foot orthoses on lower extremity joint kinematics and kinetics in runners with asymptomatic flatfeet: A systematic review and meta-analysis

Background: Foot orthoses (FO) are commonly prescribed by clinicians to manage foot and ankle conditions and improve biomechanical function. Research question: Are there any potential kinematic and kinetic effects of FO on individuals with asymptomatic flatfeet during running? Methods: The database search from inception to September 2024, including PubMed, Scopus, Web of Science, Embase, ProQuest, Cochrane, and CINAHL, identified 12 studies including 18 different orthotic interventions. These included FO with either arch-support-only or arch-support with medial-side posts. The methodological quality and risk of bias were assessed using ROBINS-I index. Primary outcome measures were joint angles and moments of midfoot/arch, ankle, and knee. Results: Our meta-analysis revealed non-significant changes with the arch-support-only FO. However, random effects analysis indicated that arch-support FO with rearfoot and forefoot medial posts significantly decreased standardized mean difference (SMD) in peak ankle eversion angles (SMD=-0.41, 95 %CI[-0.78 to −0.04]), peak ankle invertor moments (SMD=-0.51, 95 %CI[-0.97 to −0.05]), and Achilles tendon loading rates (SMD=-0.94, 95 %CI[-1.78 to −0.09]) during running. Significance: The findings of this meta-analysis suggest that arch-support FO with strategically placed medial posts may enhance stability and alleviate internal loading on the foot-ankle complex during running in individuals with asymptomatic flatfeet. Specifically, FO with medial posts at both the rearfoot and forefoot reduced peak ankle eversion angle, although this is based on only six studies. FO with such features may also decrease loading on the invertor muscles and Achilles tendon during running in individuals with asymptomatic flatfeet. Further research is needed to confirm these findings in larger populations.