ABSTRACT
Objective To quantitatively study the pressure of residual lateral displacement in distal radius AO C3.1 fracture after manual reduction corrected by dynamic airbag pad using finite element analysis and to verify its effectiveness for correcting the residual displacement of fractures. Methods Imageware 13.0, Mimics 15.0 and ANSYS Workbench were used to simulate 1 cm residual lateral displacement after manual reduction of distal radius fracture corrected by dynamic airbag pad. Then the correlation between the distance of residual lateral displacement and the adjustment of dynamic airbag pad pressure were quantitatively analyzed. Results In the case of constant load restrained by airbag ribbon, during the process of pressure adjustment by splint pad, the stress was mainly distributed in the fracture end where the airbag pad was located. About 2.4 kPa pressure was needed to correct 1 mm displacement on radial side, while about 1.3 kPa pressure was needed to correct 1 mm displacement on dorsal side. The dynamic airbag pad was depressurized after the restoration of residual shift. At this time, displacement could be effectively prevented due to the constant load of airbag ribbon and the frictional load at the fracture end. Conclusions In the case of constant load constrained by airbag ribbon, intelligent airbag splint can effectively correct the residual lateral displacement after the manual reduction of the distal radius AO C3.1 fracture and prevent it from being displaced by adjusting pressure of the dynamic airbag pad.
ABSTRACT
This study examined the correlation between osteoporosis and the degeneration of intervertebral discs. Sprague-Dawley rats were maintained up to 22 or 28 months. The femoral bone, tibial bone and lumbar vertebra were histologically studied and the expression of collagen type II and X in intervertebral discs was immunohistochemiscally determined. Several indices for the degeneration of intervertebral discs and osteoporosis and the correlation among them were then analyzed. Close correlations were found among the indices for the degeneration of intervertebral discs, including the relative area of the vascular bud, the ratio of the uncalcified and the calcified layers, the expression of collagen type II and X. The correlation with collagen type X was negative. There existed positive correlations among the indices for osteoporosis, including the thickness ratio of cortical bone, the relative area of bone trabecula, the density of femoral and vertebral body bones, and the maximum stress and strain on bone. Analysis on the relationship of osteoporosis and the disease on disc showed that the indices of osteoporosis were negatively correlated with the indices of the degeneration of intervertebral discs but the expression of collagen type X was positively correlated, with the density of vertebral body bones having the strongest dependence on collagen type X. The maximum stress and strain bore no correlation with the degeneration of intervertebral discs. These results suggest that osteoporosis was negatively correlated with the degeneration of intervertebral discs.