Elongation of the dorsal carpal ligaments: a computational study of in vivo carpal kinematics.
OBJECTIVE
The dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments play an important role in scapholunate and lunotriquetral stability. The purpose of this study was to compute changes in ligament elongation as a function of wrist position for the DRC and the scaphoid and trapezoidal insertions of the DIC.


METHODS
We developed a computational model that incorporated a digital dataset of ligament origin and insertions, bone surface models, and in vivo 3-dimensional kinematics (n = 28 wrists), as well as an algorithm for computing ligament fiber path.


RESULTS
The differences between the maximum length and minimum length of the DRC, DIC scaphoid component, and DIC trapezoidal component over the entire range of motion were 5.1 ± 1.5 mm, 2.7 ± 1.5 mm, and 5.9 ± 2.5 mm, respectively. The DRC elongated as the wrist moved from ulnar extension to radial flexion, and the DIC elongated as the wrist moved from radial deviation to ulnar deviation.


CONCLUSIONS
The DRC and DIC lengthened in opposing directions during wrist ulnar and radial deviation. Despite complex carpal bone anatomy and kinematics, computed fiber elongations were found to vary linearly with wrist position. Errors between computed values and model predictions were less than 2.0 mm across all subjects and positions.


CONCLUSIONS
The relationships between ligament elongation and wrist position should further our understanding of ligament function, provide insight into the potential effects of dorsal wrist incisions on specific wrist ranges of motion, and serve as a basis for modeling of the wrist.
Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI 02903, USA.
Michael J
MJ
Rainbow
Joseph J
JJ
Crisco
Douglas C
DC
Moore
Robin N
RN
Kamal
David H
DH
Laidlaw
Edward
E
Akelman
Scott W
SW
Wolfe
D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D002348:Carpal Bones / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology; D050824:Carpal Joints / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D016014:Linear Models; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D021361:Scaphoid Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed; D014955:Wrist Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*