Objectives: To compare foot and ankle function, patient satisfac­tion, and insole durability between 3D-printed customized insoles and conventional custom-made insoles for the treatment of flat feet.

Study design: A randomized controlled trial.

Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Subjects: Sixty Thais with bilateral flat feet.

Methods: Participants were randomized into either the 3D-printed insole group (study) or the conventional insole group (control). The effectiveness of both types of insoles was compared using the visual analog scale foot and ankle (VAS-FA) score to evaluate foot and ankle function, navicular height, and participant insole use to evaluate insole durability. Patient feedback was used to evaluate patient satisfaction.

Results: Patient characteristics and baseline VAS-FA score were comparable between groups. The median change (range) in VAS-FA score from baseline to the third month score was 1.5 (-6.3, 68.0; p = 0.002) in the study group and 4.0 (-6.5, 35.0; p < 0.001) in the control group. Mean and standard deviation change in the deformation of insoles in the third month were as follows: right side in the study group: 0.2 (0.3) cm (p = 0.010) and in the controls: 0.2(0.3) cm (p < 0.001); left side among study group 0.1 (0.2) cm (p = 0.005) and in the controls: 0.3 (0.4) cm (p = 0.001). In addition, the study group overall satisfaction score was significantly higher than the control group: 3.8 (0.4) vs. 3.3 (0.6), respectively (p < 0.001).

Conclusions: The VAS-FA scores significantly improved at three months in both groups. There was no statistically significant difference between the groups. Deformation of insoles was found in both groups with no significant difference between the groups. Measured durability and patient-reported satisfaction were both statistically significantly higher in the study group than in the control group.