Master of Science
A consensus, detailed understanding of carpal kinematics remains elusive. 4-dimensional CT (4DCT) is a validated modality capable of accurately studying in-vivokinematic motion. The objective of this work is to quantify normal, in-vivo kinematic motion of the carpus through a flexion-extension arc of motion using 4DCT. Ten healthy, un-injured volunteers underwent a 4DCT scanning protocol through a complete arc of flexion-extension motion. Kinematic changes in motion were quantified using helical axis motion data for each carpal bone. Helical axes were compared between bones and statistical analysis performed using repeated-measures ANOVA to identify difference in kinematic motion between bones (p<0.05). The carpus can be divided into four main kinematic blocks: the distal carpal block, the proximal carpal block and individual scaphoid and trapezial blocks. This work supports an additional segmentation of the trapezium from the distal carpal row, which suggests some modulation between the scaphoid and distal carpal row.
Summary for Lay Audience
Two of the most impactful health interventions of the 20th centuries have been joint replacement surgery of both the hip and the knee. A crucial element of the success of these surgeries stems from thorough understanding of the normal way the joint moves, also known as its normal kinematics. The wrist is comprised of the most complex series of joints in the body, and is heavily relied upon for day-to-day human functions and activities. Although several theories regarding carpal kinematics exists, a consensus understanding remains elusive. Our understanding draws largely from biomechanical cadaver analysis, or static non-invasive imaging modalities. Without truly the understanding the native motion and interactions of a joint, we do not have precise targets to tailor interventions to; nor can we truly recreate normal function in the setting of pathology or injury.
We use 4-dimensional Computerized Tomography (4DCT) technology, to define normal, in-vivo kinematics of the carpus. 4DCT presents the opportunity to study in-vivo, real-time motion and kinematics in a non-invasive manner. This, all whilst preserving muscle tone and soft tissue stabilizers present during functional range of motion of a patient’s wrist. Four-dimensional CT allows the inclusion of time, and can analyze changes in 3-dimensional orientation over time or throughout a movement or activity. The accuracy of this method of measurement is high and unparalleled by older modalities. Additionally, it provides a lower-cost model of study than cadaveric samples, and lower risk profile to participants than implantable trackers; making it an ideal modality.
This work contributes data needed to thoroughly understand the way in which the wrist and carpus move. By understanding the complex kinematics of the wrist, we can set our sights on optimizing implants and surgical interventions aimed to restore peak function in patients burdened with injury and pathology.
Mistry, Manisha R., "4DCT analysis of in-vivo carpal kinematics during FEM" (2021). Electronic Thesis and Dissertation Repository. 8227.
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