Software Development of Kinematics Analysis and Simulation for Taylor Spatial Frame External Fixator

• Main Author: Akbar Ermansyah, Yoga
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40646
• Institution: Institut Teknologi Bandung

Bone fractures due to accidents are very common occurrences and could cause permanent disability if not treated properly. Generally, treatment involves internal- or external-fixation devices. Hence, bone-fixation devices are important medical equipments, and play major roles in the treatment of fractures. An external fixation devices may be used to keep fractured bones stabilized and in alignment. The device could be adjusted externally to ensure the bones remain in an optimal position during the healing process. This device is commonly used when the skin over the fracture has been damaged. Various types of external fixators have been developed and utilized. Recently, alternative designs based on Stewart Platform, the Taylor Spatial Frame (TSF), have been developed with objective to correct complex fractures or bone pathologies. The Taylor Spatial Frame consists of 2 rings connected by 6 struts using universal joints, and has 6 degrees of freedom (DOF). TSF works by moving the ring - which is mounted on the bone – in order to fix the position of the fracture. Ring is mounted onto the bone by wires or half pins. Moving the ring would move the position of the bone position accordingly, from initial to final position in stages. The position of ring is controlled by changing the length of each strut. In this research, a software to perform inverse kinematics analysis on the ring movement to obtain the intermediate as well as the final desired positions is developed. The orthopedic surgeons input necessary data and the initial and final position of the bone during treatment. The inputs are dimensional deformation of the bone, dimensions of the ring, and mounting dimensions of the ring on the bone. Dimensions of bone deformities are usually obtained from radiographic data, such as CT scanning image, in lateral view, AP view, and axial view. In addition to kinematic analyses, the software is capable of displaying the simulation of bone shape deformation and simulating changes in bone position on each stage of ring motion. The software is developed to provide guidance for orthopedic surgeons when repairing bone fractures using the Taylor Spatial Frame. To evaluate the developed inverse kinematics equations, the output length of the strut at the beginning and end configuration is compared to the motion of an Autodesk Inventor model. In the 4 cases analyzed, one has relatively large errors, where discrepancies of up to 2 mm are found in 4 of the struts. While three other cases have errors in the order of about 1 mm in 2 to 3 struts. Based on these findings, in general the developed software could serve as the basis for utilization with Taylor Spatial Frame in treating bone fractures and bone pathologies.