Measuring Three-Dimensional Tibiofemoral Kinematics Using Dual-Slice Real-Time Magnetic Resonance Imaging.

PURPOSE The purpose of this study is to propose and evaluate a slice-to-volume registration (SVR) method integrating an advanced dual-slice real-time magnetic resonance image (MRI) and three-dimensional (3-D) MRI volume of the tibiofemoral joint for determining their 3-D kinematics. METHODS The real-time and 3-D MRI of the knee were collected from twelve healthy adults at five static flexion positions and during dynamic flexion/extension movement. The 3-D positions and orientations of the femur and tibia were obtained by registering their volumetric models constructed from the 3-D MRI to dual-slice real-time MRI using an optimization process. The proposed method was quantitatively evaluated for its performance in terms of the robustness and measurement accuracy, and compared to those of a single-slice SVR method. Its repeatability in measuring knee kinematics during flexion/extension movement was also determined. RESULTS In comparison to the single-slice SVR method, the dual-slice method was significantly superior, giving a successful registration rate > 95%, a bias less than 0.5 mm in translations and 0.6° in rotations and a precision less than 0.7 mm in translations and 0.9° in rotations for determining the 3-D tibiofemoral poses. For repeatability of the dual-slice SVR in measuring tibiofemoral kinematics during dynamic flexion-extension, the means of the time-averaged standard deviations were less than 0.9° for joint angles and 0.5 mm for joint translations. CONCLUSION A dual-slice SVR method in conjunction with real-time MRI has been developed and evaluated for its performance in measuring 3-D kinematics of the tibiofemoral joint in twelve young adults in terms of the accuracy, robustness and repeatability. The proposed MRI-based 3-D measurement method provides a non-invasive and ionizing radiation-free approach for 3-D kinematic measurement of the tibiofemoral joint, which will be helpful for future academic and clinical applications. This article is protected by copyright. All rights reserved.