Biomechanical Properties and Behaviours of the Wrist Joint - Computational Biomechanics of the Wrist Joint - page 14

of the film and the difficulties in accessing those articulations. As an alternative,
pressure transducer was used by Short et al. [ 1 ] to analyse pressures in the
ulnocarpal and radiocarpal joints. Despite easier accessibility, considerably high
percentage of error, 11 % was found.
It was also revealed that the compressive forces to the radius were mainly
transferred through the scaphoid and lunate. Another cadaveric study has reported
that the radius was the greatest load bearer, which was subjected with 82 % of loads
at the neutral position and 63-87 % of loads during radial-ulnar deviation and
pronosupination, respectively [ 2 ]. In conjunction with the load transfer to the radius
in the neutral position, 60 % of the load was transferred via the scaphoid [ 3 ].
Additionally, the radioscaphoid articulation was also found to have wider contact
area, contributes approximately 50 % larger as compared to the radiolunate artic-
ulation [ 4 ].
There was also a study performed to investigate load transfer at the midcarpal
and radiocarpal joints [ 3 ]. It was found that the stress at the midcarpal joint was
well-distributed, 20 % through the hamotriquetral articulation, 29 % through the
capitolunate articulation, 28 % through the scaphocapitate articulation and the
remaining 23 % through the scaphotrapeziumtrapezoid articulation. It was also
found that 20-40 % of the available articulations were occupied during physio-
logical loading condition [ 3 ].
2.2 Biomechanical Consideration of the Cartilage Structure
Despite extensive experimental studies on the interactions between cartilage and
its underlying support [ 5 ], the relative importance of subchondral injuries and their
likely effects on load transfer of both articular cartilage and bone remains not well
quantified. Due to difficulties in controlled experimental studies of such injuries in
the subchondral region and their detection by joint images, computational simu-
lation has been recognized as a feasible tool to simulate perturbed conditions and
to determine their effects on the mechanical environments of the joint. The success
of such attempts, however, depends on the accuracy of the computational model
used. In earlier computational investigations of articular cartilage, biphasic fibril-
reinforced composite models were introduced [ 6 ] and validated. It consists of non-
fibrillar solid matrix and collagen fibrils, and their properties and mechanical
functionality have also been simulated [ 7 , 8 ]. Such composite models have
extensively employed in recent knee model studies [ 9 , 10 ]. Alternatively, collagen
fibrils have been implicitly taken into consideration in constitutive models of the
solid matrix [ 11 ].