Template of instant centers of rotation developed for the knee joint (experimental study)

Relevance There are data in the literature describing the trajectory of displaced center of rotation of the knee joint. However, data on the exact location of instantaneous centers of rotation at various angles of the knee flexion are not available. Objective To identify the localization of instantaneous centers of rotation at various angles of the knee flexion and present the results in the form of a template. Material and methods The bench testing was performed using a specially developed device that provides fixation of the anatomic cadaver preparation of the lower extremity. The device made it possible to identify the zero instantaneous center of rotation using a radiographic positive marker. Control radiographs were performed to determine the "movement" of instantaneous centers of rotation at every 10° of flexion to reach an angle of 120°. The exact location of instantaneous centers of rotation at different knee flexion angles were obtained with a graphical editor and tibia internal rotation identified during the knee flexion. Results The identified instantaneous centers of rotation were applied to the contour of the distal femur to form the template and allow scaling. Conclusions The template developed could be useful for computer hexapod assisted orthopaedic surgery in the treatment of knee stiffness, for mechanotherapy and joint replacement.