Abstract
BackgroundQuantifying detailed 3-dimensional (3D) kinematics of the foot in contact with the ground during locomotion is crucial for understanding the biomechanical functions of the complex musculoskeletal structure of the foot. Biplanar X-ray fluoroscopic systems and model-based registration techniques have recently been employed to capture and visualise 3D foot bone movements in vivo, but such techniques have generally been performed manually. In the present study, we developed an automatic model-registration method with biplanar fluoroscopy for accurate measurement of 3D movements of the skeletal foot.MethodsThree-dimensional surface models of foot bones were generated prior to motion measurement based on computed tomography. The bone models generated were then registered to biplanar fluoroscopic images in a frame-by-frame manner using an optimisation technique, to maximise similarity measures between occluding contours of the bone surface models with edge-enhanced fluoroscopic images, while avoiding mutual penetration of bones. A template-matching method was also introduced to estimate the amount of bone translation and rotation prior to automatic registration.ResultsWe analysed 3D skeletal movements of a cadaver foot mobilized by a robotic gait simulator. The 3D kinematics of the calcaneus, talus, navicular and cuboid in the stance phase of the gait were successfully reconstructed and quantified using the proposed model-registration method. The accuracy of bone registration was evaluated as 0.27 ± 0.19 mm and 0.24 ± 0.19° (mean ± standard deviation) in translation and rotation, respectively, under static conditions, and 0.36 ± 0.19 mm and 0.42 ± 0.30° in translation and rotation, respectively, under dynamic conditions.ConclusionsThe measurement was confirmed to be sufficiently accurate for actual analysis of foot kinematics. The proposed method may serve as an effective tool for understanding the biomechanical function of the human foot during locomotion.
Highlights
Quantifying detailed 3-dimensional (3D) kinematics of the foot in contact with the ground during locomotion is crucial for understanding the biomechanical functions of the complex musculoskeletal structure of the foot
Quantifying the detailed 3-dimensional (3D) kinematics of the foot in contact with the ground during human bipedal locomotion is crucial for improving our understanding of the biomechanical functions of the complex foot musculoskeletal
In the present study, we developed an automatic modelregistration method with biplanar fluoroscopy for accurate measurement of 3D foot skeletal movements, and demonstrated that 3D kinematics of the calcaneus, talus, navicular and cuboid in the stance phase of gait were successfully reconstructed using the proposed method
Summary
Quantifying detailed 3-dimensional (3D) kinematics of the foot in contact with the ground during locomotion is crucial for understanding the biomechanical functions of the complex musculoskeletal structure of the foot. Quantifying the detailed 3-dimensional (3D) kinematics of the foot in contact with the ground during human bipedal locomotion is crucial for improving our understanding of the biomechanical functions of the complex foot musculoskeletal. Dynamic kinematic measurements of the human knee [9], shoulder [10] and spine [11] have been conducted using X-ray fluoroscopy to capture precise joint kinematics in vivo. Such techniques have been applied to the analysis of animal locomotion, bringing substantial benefits to uncovering morphofunctional relationships between animal anatomy and locomotion [12, 13]. Yamaguchi et al [14] and Fukano et al [15] have employed single-plane fluoroscopy and Wan et al [16], de Asla et al [17], and Kozanek et al [18] have used biplanar fluoroscopy to successfully reconstruct 3D kinematics of the ankle and subtalar joints in vivo
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