Biomechanical Properties and Behaviours of the Wrist Joint - Computational Biomechanics of the Wrist Joint - page 19

2.4.2.3 Past Finite Element Studies
The FE method has been widely used to study various human joints such as the hip
and knee [ 30 - 39 ], and has been accepted by medical researchers as one of the
important assistive tools in surgical planning [ 31 , 32 , 40 - 44 ]. Previous studies
have shown its superior in varieties of analyses: pathomechanics, load transfer
behaviour, contact analysis and also in investigation to assess viability of joints
replacements including arthroplasty and arthrodesis. Although this method has
been used for simulation of various human joints, the number of literatures related
to the wrist was fairly limited with mostly reported on the model development
[ 25 , 44 - 48 ]. In the hip joint, only two bones were involved compared with
15 bones in the wrist joint, thus resulted in much more complicated analyses need
to be done. Contact analysis of this multi-articulation joint proves to be especially
tricky. In addition, the huge number of ligaments associated with the wrist joint
make the analyses become much more challenging. For instance, wrong properties
and locations of insertions resulted in unphysiological alterations of kinematics
and dynamic of the joint. Additionally, solution convergence has been addressed
as another main concern in finite element analysis of the wrist joint concerning the
stability of the constructed FE models. Accurate and precise bone geometrical
shape, articulations and the ligamentous structure are vital assuring successful
analysis [ 46 ].
Therefore, of these few studies, there were lot of assumptions and simplifica-
tions made. For instance, the computational investigation of the wrist was started
with two-dimensional FE analysis [ 49 ]. This study was performed to undertstand
the behaviour of the Kienbock's disease treated using ceramic lunate replacement
method. In this study, the complexity of the joint was simplified by grouping bones
into proximal, distal and forearm and excluding ligamentous constraint. It was
quantified that contact analysis for the actual wrist joint could not be performed
due to limited articulations. A more recent study on three-dimensional finite ele-
ment analyses have been carried investigating static carpal load transfer [ 50 ]. This
study sufficiently includes the whole wrist joint, consisted of separated 8 carpal
bones, the radius and ulna which emphasised more at the radiocarpal joint. Non-
physiological constraints were applied to achieve solution convergence. Similarly,
studies by Cheng et al. [ 51 ] and Troy et al. [ 52 ] which partially analysed the
behaviour of the wrist joint by having investigation on the distal radius fracture. To
the best of the authors knowledge, there were none of previous studies successfully
investigated the behaviour of the whole complete structure of the wrist joint
without performing non-physiological constraint as well as wide range of para-
metric studies.
Regarding three-dimensional finite element studies on the pathological condi-
tion of the wrist, only a few numbers of works were found. There was a study
performed to analyse the biomechanical effects of different position of Kirschner
wires to provide initial stability of scaphoid fractures [ 48 ]. This study modelled the
scaphoid whereas the adjacent bones were represented via articular cartilages with
the thickness of 1 mm, assumed to be constant for each articulation. Another study