In vivo three-dimensional determination of kinematics for subjects with a normal knee or a unicompartmental or total knee replacement.
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Anterior Cruciate Ligament↗
Biomedical subjects
R Komistek
Publications and source records attributed to R Komistek.
A novel approach to knee kinematics.
We describe our experience with in vivo dynamic fluoroscopy that uses simple 2-plane video fluoroscopy of subjects performing maneuvers such as deep knee-bends, gait, and stair climbing after total knee arthroplasty (TKA). Kinematic analysis has evolved from 2-dimensional vector calculations to automated 3-dimensional computer-assisted design matching techniques that are accurate to 0.75-mm translation and 0.75 degrees rotation and that allow simultaneous determination of medial and lateral condyle contact positions. TKAs that retain the posterior cruciate ligament (PCL) have consistently shown posterior contact in extension and anterior translation with flexion with a large variability among subjects. PCL-stabilized implants and mobile bearings with high conformity have posterior femoral rollback more consistent with normal knees--which is a function of prosthetic geometry. Condylar liftoff and screw-home rotation are typical kinematic features of all TKAs.
Arthroplasty, Replacement, Knee↗
An interactive system for kinematic analysis of artificial joint implants.
The objective of this project was to develop and test a software system for the kinematic analysis of total joint arthroplasty (TJA) implants. Using a supervised iterative optimization algorithm (simulated annealing), the system iteratively adjusts the pose of an implant model to maximize correlation between the model's pose and the pose of an actual implant in a x-ray image. A graphical user interface (GUI) was developed that provides visualization of the model-fitting process, and permits human guidance for error correction. The resulting system was evaluated to determine its accuracy and repeatability. On synthetic images, the mean translational and rotational errors were found to be 0.005 mm and 0.0015 degrees, respectively. On in vitro images, the repeatability was found to be 0.15 mm of translation and 0.17 degrees of rotation. The outcome is a working joint-measurement software system and quantitative data to support comparison with other methods.
Arthroplasty, Replacement, Knee↗
"In vivo" pose estimation of artificial knee implants using computer vision.
This paper describes an algorithm to estimate the position and orientation (pose) of artificial knee implants from fluoroscopy images using computer vision. The resulting information is used to determine contact position from " in vivo" bone motion in implanted knees. This determination can be used to support the development of improved prosthetic knee implants. Current generation implants have a limited life span due to premature wear of the polyethylene material at the joint surface. To get "in vivo" motion, fluoroscopy videos were taken of implant patients performing deep knee bends. Our algorithm determines the full 6 degree of freedom translation and rotation of knee components. This is necessary for artificial knees which have shown significant rotation out of the sagittal plane, in particular internal/external rotations. By creating a library of images at known orientation and performing a matching technique, the 3-D pose of the femoral and tibial components are determined. By transforming the coordinate systems into one common system contact positions can be determined. The entire process, when used at certain knee angles, will give a representation of the positions in contact during normal knee motion.
Algorithms↗