The wrist can be considered a two degrees‐of‐freedom joint with all movements reflecting the combination of flexion‐extension and radial‐ulnar deviation. Wrist motions are accomplished by the kinematic reduction of the forty‐two degrees‐of‐freedom of the individual carpal bones. While previous studies have demonstrated the minimal motion of the scaphoid and lunate as the wrist moves along the dart‐thrower's path or small relative motion between hamate‐capitate‐trapezoid, an understanding of the kinematics of the complete carpus across all wrist motions remains lacking. To address this, we assembled an open‐source database of in‐vivo carpal motions and developed mathematical models of the carpal kinematics as a function of wrist motion. Quadratic surfaces were trained for each of the 42‐carpal bone degrees‐of‐freedom and the goodness of fits were evaluated. Using the models, paths of wrist motion that generated minimal carpal rotations or translations were determined. Model predictions were best for flexion‐extension, radial‐ulnar deviation, and volar‐dorsal translations for all carpal bones with R2 of more than 0.8, while the estimates were least effective for supination‐pronation with R2 of less than 0.6. The wrist path of motion's analysis indicated that the distal row of carpal bones moves rigidly together (< 3º motion), along the anatomical axis of wrist motion, while the bones in the proximal row undergo minimal motion when the wrist moves in a path oblique to the main axes. The open‐source dataset along with its graphical user interface and mathematical models should facilitate clinical visualization and enable new studies of carpal kinematics and function.
|Predicting carpal bone kinematics using an expanded digital database of wrist carpal bone anatomy and kinematics, Journal of Orthopaedic Research. (2019) View|
|A digital database of wrist bone anatomy and carpal kinematics. Moore DC, Crisco JJ, Trafton TG, Leventhal EL., J Biomech. 2007;40(11):2537-42. Epub 2007 Feb 5., PMID: 17276439 (2007) View|
The skeletal wrist consists of eight small, intricately shaped carpal bones. The motion of these bones is complex, occurs in three dimensions, and remains incompletely defined. Our previous efforts have been focused on determining the in vivo three-dimensional (3-D) kinematics of the normal and abnormal carpus. In so doing we have developed an extensive database of carpal bone anatomy and kinematics from a large number of healthy subjects. The purpose of this paper is to describe that database and to make it available to other researchers. CT volume images of both wrists from 30 healthy volunteers (15 males and 15 females) were acquired in multiple wrist positions throughout the normal range of wrist motion. The outer cortical surfaces of the carpal bones, radius and ulna, and proximal metacarpals were segmented and the 3-D motion of each bone was calculated for each wrist position. The database was constructed to include high-resolution surface models, measures of bone volume and shape, and the 3-D kinematics of each segmented bone. The database does not include soft tissues of the wrist. While there are numerous digital anatomical databases, this one is unique in that it includes a large number of subjects and it contains in vivo kinematic data as well as the bony anatomy.