The biomechanical effects of 3D printed and traditionally made foot orthoses in individuals with unilateral plantar fasciopathy and flat feet

Background Foot orthoses (FOs) are used to manage foot pathologies such as plantar fasciopathy. 3D printed custom-made FOs are increasingly being manufactured. Although these 3D-printed FOs look like traditionally heat-molded FOs, there are few studies comparing FOs made using these two different manufacturing processes. Research question How effective are 3D-printed FOs (3D-Print) compared to traditionally-made (Traditional) or no FOs (Control), in changing biomechanical parameters of flat-footed individuals with unilateral plantar fasciopathy? Methods Thirteen participants with unilateral plantar fasciopathy walked with shoes under three conditions: Control, 3D-print, and Traditional. 2×3 repeated measures analysis of variance (ANOVAs) with Bonferroni post-hoc tests were used to compare discrete kinematic and kinetic variables between limbs and conditions. Waveform analyses were also conducted using statistical parametric mapping (SPM). Results There was a significant condition main effect for arch height drop (p=0.01; ηp2=0.54). There was 0.87 mm (95% CI [-1.84, -0.20]) less arch height drop in 3D-print compared to Traditional. The SPM analyses revealed condition main effects on ankle moment (p<0.001) and ankle power (p<0.001). There were significant differences between control condition and both 3D-print and Traditional conditions. For ankle moment and power, there were no differences between 3D-print and Traditional conditions. Significance 3D-printed FOs are more effective in reducing arch height drop, whist both FOs lowered ankle plantarflexion moment and power compared to no FOs. The results support the use of 3D-printed FOs as being equally effective as traditionally-made FOs in changing lower limb biomechanics for a population of flat-footed individuals with unilateral plantar fasciopathy.