The dynamic rotation axis of ulnohumeral joint during active flexion-extension: an in vivo 4-dimensional computed tomography analysis

Abstract

Background As the collateral ligament reconstruction becomes more common to perform, the knowledge between the collateral ligament reconstruction and the elbow rotation axis is still ambiguous. The purpose of this study was to investigate the location of the intersections between the elbow rotation axis and medial and lateral aspect of the humerus. Methods Four-dimensional computed tomography (4D CT) scan was designed to obtain the images from 8 participants. The instantaneous rotation axis was created according to the trochlea notch of the ulna in the Rapidform XO software. Then the intersections between the instantaneous rotation axis and the medial and lateral aspect of the humerus were identified in the Geomagic Wrap software. Landmark coordinate systems of the distal humerus was created. Result The intersections in the medial aspect of the humerus were mostly located in the superior and posterior quadrant and showed the trend from anterior-superior to posterior-superior with the increment of the elbow flexion. The intersections in the lateral aspect of the humerus were mostly located in the middle half of the anterior quadrant and showed the trend from posterior-inferior to anterior-superior with the increment of the elbow flexion. Conclusion There’s no isometric point for medial collateral ligament (MCL) and lateral ulnar collateral ligament (LUCL) reconstruction. The isometric area for MCL reconstruction should be considered at the superior and posterior quadrant of the medial aspect of the humerus. The isometric area for LUCL reconstruction should be considered at the middle half of the anterior quadrant of the lateral aspect of the humerus. Trial registration This work was supported by the National Natural Science Foundation of China [No.81911540488] in 07/01/2019.

Improving the Feasibility of Mitigating Phase Errors in 4DCT caused by a Random Reference Breathing Pattern in the Quasar Phantom and the Role of Slice Thickness

“…Lung 4DCT scans frequently exhibit such artifacts, stemming from irregular breathing and suboptimal scan parameters. Factors contributing to these artifacts include variations in breathing pattern amplitudes and frequencies, instances of coughing, temporary breath-holding due to patient fatigue during extended repetitions, prolonged scan durations, and shifts in the baseline of the breathing pattern [18][19][20][21][22][23]. Consequently, addressing these issues requires adjustments in scan parameters, particularly concerning image acquisition times determined by the CT scanner based on the patient's breathing periods as provided by the Real-Time Position Management (RPM) system from Varian.…”

“…Phantom, an advanced tool crafted to replicate lung tissue and tumor motion accurately. The phantom simulated sinusoidal motion breathing patterns closely resembling real patient conditions, encompassing variations in both breathing period and tumor displacement [20]. The tracking of breathing patterns and tumor motions was executed using the Varian RPM system, which employs infrared camera technology to monitor a six-dot marker on the phantom's breathing platform.…”