This paper presents – using the examples “knee orthosis” and “patellar stabilizing braces” – a method which delivers an insight into the “patient -orthopedic aid” system using an open low-field MRI, adapted MRI-sequences, MR compatible measurement techniques and self-build software. The basic principle is a consistent three-dimensional image acquisition and reconstruction of bony structures.
Created in Matlab, our software is able to segment, reconstruct and registrate objects, to determine the principle axes, and to calculate translational and rotational components (a. e. movements and tilts of the patella proportional to the femur) as well as joint axes using the helical axes method.
A previously acquired structured light 3D-scan of the orthopedic aid and the application of 3D-MRI-markers during the MRI scan allow a mapping of the orthopedic device on the scanned anatomy, thus a. e. giving the possibility of comparing joint axes with those of the orthopedic device.