title: Characterizing fluoroscopy based kinematic accuracy as a function of pulse width and velocity.
abstract: Fluoroscopic imaging has become increasingly popular to investigate total knee arthroplasty kinematics non-invasively - 3D implant models are aligned with 2D image projections, and optimized via an edge-contour alignment technique. Previous studies have quantified the accuracy of this approach, however they do not always adequately address the impact of image collection parameters. A particularly sensitive parameter is the pulse width, or exposure time per frame. At longer pulse widths, more motion is captured in a single frame; this can lead to image blur and subsequent degradation to image edge quality. Therefore, the comparative accuracy of relative joint kinematics as a function of pulse width and joint velocity needs to be defined. A limits of agreement approach was taken to define the mean differences between optoelectric kinematic measures (gold standard) and fluoroscopic methods at various pulse widths (1, 8 and 16ms) and knee velocities (50, 100 and 225°/s). The mean absolute differences between the optoelectric and fluoroscopic methods for 1ms pulse width were less than 1.5° and 0.9mm. Comparable rotational differences (1.3°) were observed for the 8ms pulse width but had larger translational differences (1.4mm). The 16ms pulse width yielded the greatest mean differences (2.0° and 1.6mm), which increased with knee flexion velocity. The importance of pulse width and velocity should not be overlooked for future studies - this parameter has proven to be a sensitive metric in the quantification of joint motion via fluoroscopy and must be identified and reported in future studies.
authors: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA; Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN, USA.
authors: Arin M
authors: AM
authors: Ellingson
authors: Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA; Biomedical Engineering and Physiology Graduate Program, Mayo Graduate School, Rochester, MN, USA.
authors: Joseph D
authors: JD
authors: Mozingo
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Dixon J
authors: DJ
authors: Magnuson
authors: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
authors: Mark W
authors: MW
authors: Pagnano
authors: Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA; Biomedical Engineering and Physiology Graduate Program, Mayo Graduate School, Rochester, MN, USA. Electronic address: zhao.kristin@mayo.edu.
authors: Kristin D
authors: KD
authors: Zhao
mesh_terms: D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D005471:Fluoroscopy; D006339:Heart Rate; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000502:physiology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male
keywords: Accuracy; Agreement; Arthroplasty; Fluoroscopy; Joint kinematics; Knee; Knee replacement; Pulse width