Biomechanical evaluation of 3D-printed joint-type orthosis for hallux valgus

Orthoses play an important role in the conservative treatment of hallux valgus (HV) with different therapeutic effects. In this study, a new HV orthosis was developed using three-dimensional (3D) printing technology. In addition, its kinematic effect was evaluated using motion analysis.

Seventeen participants with an HV angle of >20° were included in the study. The first metatarsophalangeal abduction angle before and after the orthosis was measured statically. Subsequently, dynamic first metatarsophalangeal abduction, dorsiflexion angle and ground reaction force with and without the orthosis were recorded and calculated during walking using a Vicon motion analysis system and force plates. The patients' comfort scales were determined after the motion analysis.

The angular corrections of the orthosis in the first metatarsophalangeal abduction were 14.6° and 6.3° under static and dynamic conditions, respectively. Reduced hallux dorsiflexion was observed with the orthosis in the early stance phase. However, no significant changes in ground reaction forces were observed.

The results of our study confirm the potential of the 3D-printed HV orthosis in the static and dynamic correction of deformities while ensuring patient comfort with minimal impact on hallux kinematics, suggesting the potential of our design for long-term use.