Innovative approaches to designing and manufacturing a prosthetic thumb.

CASE DESCRIPTION Conventional methods for producing custom prosthetic fingers are time-consuming, can be uncomfortable for the patient, and require a skilled prosthetist. The subject was a 40-year-old male with congenital absence of the thumb and related metacarpal bone on the right non-dominant hand, anomaly of the lengths of individual upper limb segments, and contracture of the elbow joint. This hand presentation made it impossible for him to perform thumb opposition, which is a very important function for common daily activities. OBJECTIVE The goal was to design an individual passive thumb prosthesis using free open-source software, 3D scanning technology, and additive manufacturing methods (i.e., fused filament fabrication). STUDY DESIGN Case report. TREATMENT Artificial thumb prostheses with two types of bases and fastening interfaces were designed and manufactured. One combination was chosen as the best alternative. OUTCOMES The shape, positioning, firmness, and fastening of the prosthesis were compliant enough for the patient to be able to hold objects with his healthy fingers and artificial thumb. This innovative approach to fabrication of a custom thumb prosthesis provided considerable advantages in terms of custom sizing, manufacturing time, rapid production, iteration, comfort, and costs when compared to conventional methods of manufacturing a hand prosthesis. CONCLUSION The methodology of designing and manufacturing a prosthetic thumb using 3D scanning and additive manufacturing technologies have been demonstrated to be adequate from a practical point of view. These technologies show potential for use in the practice of prosthetics.