Development and Manufacturing of an Individual Wrist Implant

The wrist joint is of high functional importance and is one of the most complex joint systems of the human body due to the bony and ligamentous structures that interact in a very small space. Main reasons for disabling pain of the wrist are in the first instance rheumatoid arthritis and in the second instance posttraumatic and primary osteoarthritis. For the patient the loss of wrist functionality is associated with a reduced quality of life and possibly the loss of the ability to work. This can cause considerable socioeconomic costs. In contrast to total hip and knee replacement, the replacement of the wrist joint is not an established procedure, due to the short lifetimes of the implants and the low long-term survival rates. Functional aspects about the kinematics of the wrist joint and the patient-specific morphology are usually not considered in the current implant design. The arthrodesis of the wrist joint is the current “gold standard” to treat progressive arthritis.

The goal of this cooperation project together with the Department of Orthopaedic Surgery of the University Hospital, RWTH Aachen University and the Institute of Imaging and Computer Vision of the RWTH Aachen University is to make a contribution to the enhancement of wrist implants by a functional and morphological analysis of the wrist, an integration of suitable medical imaging methods and the use of additive manufacturing technologies. The passive kinematics of the wrist joint will be reconstructed by CT and MRT imaging of human specimens in order to analyze the bony interaction as well as the individual morphology of the wrist bones. The results will be used to develop a functional and morphological adapted patient-specific wrist implant that will be manufactured by 3D printing. In a first step the implant will be made of plastics and in a second step the manufacturing by selective laser melting will be tested. The implant prototypes will be implanted into the human specimens and their function will be evaluated.