Background Three dimensional (3D) Prototyping allows the creation of individual 3D objects with almost any material. It is a rapid emerging technology, easy to use and quickly accessible.
Objectives In this experimental study we tested the feasibility to generate exact models of joints of patients suffering from rheumatoid arthritis and healthy controls.
Methods Using a high resolution CT (Xtreme CT, Scanco) we can generate images of metacarpal heads with a resolution as exact as 81 microns voxel size. Two dimensional images were transformed into 3D images, which were visualized by the DICOM viewer Osirix (Open Source software for MacBook). In the following step 3D images were transformed in a printable format called STL (Standard triangulation language), a common file format for 3D printers. Using a ZPrinter (3D Systems/Zcorp), core material (cement-like pouder) was spread in thin layers over the building platform. After each layer, binder is jetted from print heads over the core layer, which causes the core to solidify.
Results We generated two 3D prints of a metacarpal head, one from a patient (age 67, male) with long standing Rheumatoid Arthritis (RA) and one from a healthy individual of the same age and sex without clinical signs of arthritis. Notably, this approach allowed creating a high quality and exact 3D model of the metacarpal head (Fig. 1A). The printed model reached a resolution as low as 100 micrometers. Cortical bone breaks resembling bone erosions as well as cortical proliferation can be exactly localized and measured. Particularly this technique also allows an enlargement of 3:1 to visualize the trabecular network of the periarticular bone which is massively reduced in the RA patient (Fig. 1B).
Conclusions Herein we show that it is technically possible to print 3D models of arthritic joints and exactly localize and measure bone erosions and loss of trabecular bone network in patients with inflammatory arthritis. To our knowledge this is the first 3D printing approach in the context of clinical rheumatology. We demonstrate that the production of models reflecting exact copies of the joint surface in brilliant quality is feasible. These findings open multiple new possibilities in rheumatology and management of arthritis such as improved patient education, validation of imaging modalities, monitoring of damage as well as improved site-directed injection
Disclosure of Interest None declared
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