Experimental set-up. (a) A cadaveric lower limb is equipped with rigidly attached bone-pins, at the medial side of the femur (F) and tibia (T) segments. Each bone-pin is equipped with retro reflective marker clusters (that are used to create optical marker-based coordinate systems OF and OT) and inertial sensors (orange boxes) with sensor coordinate systems SF and ST. (b) Three-dimensional surface bone models are reconstructed for the femur and tibia bone and osseous anatomical landmarks are identified within Mimics. Anatomical reference coordinate systems AF and AT are defined on the base of virtual anatomical landmarks. Anatomical landmarks are furthermore rotated into a common intermediate coordinate system (pink) within the CT-scan coordinate system M, to rotate the landmarks into the optical motion capture reference frame G. The full explanation of all abbreviations of the annotated anatomical landmarks can be found in Table 1. (c) Inertial sensor are rigidly attached on the femur and tibia-attached bone-pins via zip ties. The alignment rotations qOFSF and qOTST define the rotation from coordinate frame S to coordinate frame O for the femur and tibia-attached inertial sensors. As a result, all coordinate systems can be tracked with respect to the optical motion capture reference coordinate system G, after the necessary coordinate system transformations. (d) Illustration of the measurement set-up with the different coordinate frames.
展开▼
