Management of patients with unstable fracture or fracture-dislocation of thoraco-lumbar spine continues to be controversial. One area of disagreement involves spinal fusion with internal fixation for prevention of later spinal instability. Intemal fixation of the spine without fusion has been advocated in the treatment of the unstable thoraco-lumbar fracture or dislocation. During the period of January 1981 to March 1984, thirty-two patients underwent fixation by Harrington distraction rod without fusion for the treatment of thoraco-lumbar fractures. Eight cases among them had second operation for the removal of the Harrington rods in 13.4months after Harrington rod fixation and were followed up clinically and radiolagically for 1 year at the Department of Orthopaedic Surgery, St. Mary's Hospital, Catholic Medical College and Center. The rationales for this procedure were to minimize the number of permanently stabilized segments and to provide more spinal mobility. We have expected that spontaneous fusion of vertebral body occur by the prolonged immobilization with Hamngton distraction rods. After the Harrington rods, the average conection rate of kyphotic angle was 41.8% and average correction rate of height of collapsed vertebral body or displacement of vertebral body was 42.3% at one year follow up. Instrumentations in eight patient were removed at 13.4 months after the initial surgery and the patients were followed up for one year. At the time of removal of instrumentation, unilateral partial facetectomy was done for histologic examination of the facet joint which is above the lower Harrington hook in four patients. The average correction rate of kyphotic angle was 37.5% and the average correction rate of height of collapsed or displaced vertebral body was 40.6% at one year after the removal of H-rods. The range of spine motions were incresed gradually. But histologic findings of the immobilized facet joint revealed fibrillation, fissures, thinning of the normal cartilagenous surface, decreased cartilagenous cellularity, and vascular tidemark invasion which are characteristics of osteoarthritis. Through this study, we obtained following conclusions: 1. Immediate Harrington distraction rodding was effective for the anatomic reduction of the collapsed vertebral body. And it provided immediate spinal stability, and spontaneous fusion of vertebral body. 2. Prolonged immobilization of the spine by Harrington rods is believed to have deleterious effect on articular cartilage of the immobilized facet joint as the degenerative changes of the cartilage of the facet joint was consistently found in this study. And it was regarded as a predisposing factors in the development of symptomatic arthritis of the spine. 3. If a fractured and collapsed vertebral body can be reduced by Harrington distraction rods, a spontaneous fusion of vertebral body occur. Harrington rodding without fusion could be one of the useful surgeries for management of the fractures and fracture-dislocation of the spine.