Finite Element Analysis of the Wrist Joint Affected by Rheumatoid Arthritis - Computational Biomechanics of the Wrist Joint - page 42

Fig. 5.1 Modelling of the cartilage destruction

1. Cartilage destruction [ 1 - 3 ].
2. Loss of carpal height due to bone destruction [ 2 , 4 ].
3. Dislocation of the carpus in the ulnar direction [ 2 ].
4. Dislocation of the proximal carpal row in the palmar and ulnar direction [ 2 ].
5. Scapholunar dissociation (SLD) with scapholunate advanced collapse wrist
arthritis (SLAC) stage 2 [ 2 , 5 ].
6. Dislocation of the scaphoid in the palmar direction due to the radial insertion
of the Testut ligament synovialitis [ 2 ].
7. Hand scoliosis due to ruptured tendon. This mechanism ends in a changed axis
of the wrist to the ulna with a consecutive rotation of the metacarpal bones in
the radial direction [ 2 ].
8. Reduction of contact between the lunate and radius [ 2 ].
9. Bone erosion [ 2 , 3 , 6 - 8 ].
10. Osteoporotic bone [ 2 , 3 ]. This criterion was simulated by reducing the elastic
modulus of the bones; 33 % for the cortical bone and 66 % for the cancellous
bone [ 9 - 15 ].

All these ten characteristics were utilised as a whole to construct the model of
the rheumatic wrist. The succeeding sections explained steps performed to simu-
late each characteristic.

5.1.1 Simulation of Cartilage Destruction

The cartilage destruction was modelled by removing all the articular cartilages to
simulate worst-case scenario (Fig. 5.1 ). It was thus resulted in existence of gaps