Injuries to the distal tibiofibular joint are often associated with ankle fractures, sports-related injuries, or instability, whereas proximal tibiofibular joint injuries are more commonly present with lateral- or posterolateral-compartment lesions of the knee. These conditions may be related to the relative motion between the tibia and fibula;​ however, precise movement patterns have yet to be fully elucidated. This study analyzes the relative motion of the tibia and fibula in 16 healthy adults (32 bones;​ 8 males and 8 females) throughout a normal gait cycle. CT scan data were initially acquired to construct 3D models of the tibia and fibula. X-ray images were taken at seven points during the gait cycle for 3D-2D and 3D-3D model registration, facilitating the calculation of relative degrees of freedom (DOF) movements between these bones. Our results demonstrate that from the heel strike to the single-legged stance phase, the fibula transitions from plantarflexion to dorsiflexion, reaching up to 0.41°. It shifts from inversion to eversion, increasing to 0.06°, while internal rotation decreases to 0.5°. From the single-legged stance to the toe-off phase, changes in plantarflexion/dorsiflexion are minimal, eversion decreases to 0.02°, and internal rotation increases to 0.63°. The proximal fibula exhibits anterior-posterior, medial-lateral, and inferior-superior movements, with similar patterns observed in the distal fibula. During a standard gait cycle, internal/external rotational movements, along with anterior-posterior and medial-lateral shifts, are predominant.