Develop remote orthotic fabrication workflow using 3D modeling and 3D printing technology for carpometacarpal osteoarthritis.

Abstract

Background: Carpometacarpal (CMC) osteoarthritis often requires orthotic intervention to reduce pain and improve function. Traditional orthosis fabrication typically demands in-person clinical visits, which can be a barrier to care.

Purpose: To develop and validate a fully remote workflow for fabricating custom orthoses using mobile 3D scanning, web-based assessment, and 3D printing technologies for patients with CMC osteoarthritis.

Study design: Pilot validation study.

Methods: A five-step workflow was created: (1) a web-based application ("Hand Scan") for assessing pain, sensory function, and range of motion; (2) mobile 3D hand scanning using smartphone cameras, with scans processed in Agisoft Metashape; (3) digital joint repositioning using finite element analysis software; (4) orthosis design using parametric modeling; and (5) fabrication using 3D printing with Orfit's low-temperature polycaprolactone filament. Five patients with CMC osteoarthritis were recruited. The application's usability was tested via cognitive interviews. Mobile scanning accuracy was validated against high-precision photogrammetry, and surface deviations of the 3D-printed orthoses were compared with traditional thermoplastic models.

Results: The Hand Scan app demonstrated strong content validity. Mobile scans showed a mean absolute deviation of 0.93 mm (SD = 0.61 mm). Joint repositioning yielded a mean deviation of 0.87 mm. The 3D-printed orthoses demonstrated a better fit than thermoplastic models, with a mean surface deviation of 0.95 mm compared to 1.96 mm. The maximum deviation was 3.17 mm for 3D-printed and 5.81 mm for traditional orthoses.

Conclusions: This remote orthotic fabrication workflow is accurate, feasible, and clinically applicable. It supports personalized orthosis design while reducing the need for in-person visits. The workflow has strong potential for telehealth and remote hand therapy services.