Background and Objective <p>Dynamic flexion or extension orthoses for the proximal interphalangeal joint (PIP) are commonly employed in rehabilitation to enhance mobility after trauma. This study aims to compare the biomechanical performance of two commercial extension orthoses (sizes S and L) and a 3D-printed orthosis.</p> Methods <p>The tests were conducted with increasing loads ranging from 0 to 1500&#xa0;g. Angular displacements were measured using a specific experimental setup. The forces exerted were modeled using simplified assumptions about the geometry of the orthoses and their interaction with the finger.</p> Results <p>The results show that the 3D-printed orthosis, while offering advantages in customization, exhibited limited mechanical resistance, failing under a load of 700&#xa0;g. In contrast, the commercial orthoses demonstrated excellent fatigue resistance, with an average angular displacement difference of less than 0.1° between repeated series. The 3D-printed orthosis exhibited the highest slope in the stress–strain curve (13.9°N⁻¹ compared to 9.3 °N⁻¹ and 7 °N⁻¹ for commercial S size and L size respectively). These results indicate that, although of the same order of magnitude, this 3D-printed orthosis is more deformable.</p> Conclusions <p>In conclusion, commercial orthoses provide better mechanical reliability under the tested conditions, while the 3D-printed orthosis requires improvements. Integrating multi-material components and force sensors could improve durability and efficiency, opening promising perspectives for customized rehabilitation orthoses.</p> Graphical Abstract <p></p>