External Fixation in Experimental Scoliosis

The purpose of this experimental study was to investigate the effects of spinal external fixation in scoliosis. Two of 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 these, 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.