Biomedical Engineering Reference
In-Depth Information
Table 5.1
Information on the carpometacarpal ratio used in this study in comparison with the
literature
Literature [
4
]
Current study
Simulation
Healthy:
CR = 0.54 ± 0.03
Healthy:
CR =
Translation of metacarpals
10.1 mm proximally to simulate
severe RA model
32
:
45
0
:
55
¼
0
:
55
Severe RA:
CR = 0.40
Severe RA:
CR
¼
22
:
35
0
:
55
¼
0
:
38
between bones. In real clinical environment, the adjacent anatomical of the joint
makes these gaps 'removed' by physiologically connecting the related bones.
5.1.2 Simulation of Loss of Carpal Height
The reduction of gaps has resulted in loss of carpal height. Carpometacarpal ratio
(CR)—the ratio between the distance from the distal radius to the base of the third
metacarpal with the length of the third metacarpal [
4
]—was utilised to simulate
this condition. Further details were mentioned in Table
5.1
and the simulated loss
of carpal height was shown in Fig.
5.2
.
5.1.3 Simulation of Dislocation of the Carpus in the Ulnar
Direction
Dislocation of the carpus in the ulnar direction occurs due to loss of tension of the
radiotriquetral ligament, irrespective of the status of the ulnar head [
2
]. The entire
carpus excluding the scaphoid was involved in the simulation. Figure
5.3
a depicts
the dislocated carpus towards ulnar. The simulation was done by rotating 10 of
carpus towards ulnar with the center of the radius used as the center of rotation
(COR). Figure
5.3
b shows the simulated loss of tension (in circular) of the
radiotriquetral ligament where only one link remained mimicking weakened
ligaments.
5.1.4 Simulation of Dislocation of the Proximal Carpal Row
in the Palmar and Ulnar Directions
Dislocation of the proximal carpal row in the palmar occurred physiologically as
during ulnar deviation (either due to physiological movements or as a results of
disease),
the
scaphoid,
lunate,
and
triquetrum
rotate
palmarly
[
16
].
In
the
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