|Budget Amount *help
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1994 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1993 : ¥900,000 (Direct Cost : ¥900,000)
1.Morphological studies in experimental scoliosis in rabbits
The prupose of this study was to investigate experimentally the morphological changes of scoliosis. In 10 rabbits, under X-ray imaging two Kirshner wires were inserted into intervertebral discs at regular intervals, together with two parallel wires on the left side. In 9 of these 10 rabbits, right convex thoracolumbar or lumbar scoliosis was produced. In 3 rabbits, the K-wires were removed between 8 and 12 weeks after insertion and the scoliosis was found to be irreversible. However in the 4 rabbits, from which the wires were removed at less than 8 weeks after the operation, then the scoliosis was foud to be reversible. In the other 2 rabbits, although the upper K-wire was loose after the operation, a scoliotic deformity remained. In this experimental scoliosis model, degenerative changes were seen in the facet cartilage on the apical concave side histomorphologically.
2.External fixation in experimental scoliosis
The purpose of this experimental study was to investigate the effects of spinal external fixation in scoliosis. Two or four ribs on the right side of growing rabbits were partially resected. Between 4 and 6 weeks later, moderate right-convex thoracic scoliosis had developed.Then, in seven rabbits, a mini-Orthofix or fixano fixator was attached by Kischner wires to T9/10 and L1/2. The average Cobb angle was 27.1 degrees before external fixation, and was 13.6 degrees at initial correction just after attaching the fixator. In three of them, the fixators were removed at more than 8 weeks after the operation. Only slight progressive vertebral curvature was seen in these rabbits after removal of the fixator, with a relatively good effect of prophylaxis of progression compared to the controls. We propose that the effects of this spinal external fixation for scoliosis was due to correction of the axial rotation at the apical vertebra rather than to the traction force.