Influence Of Parathyroid Hormone On Rat Spinal Fusion

Objectives Through the establishment of rat spinal fusion model, to assess the effects of Intermittent injection of Parathyroid Hormone, on posterolateral lumbar fusions in rats model. Analyzing the PTH effect of autologous bone graft, the mechanism of spinal fusion for PTH(1-34) provide theoretical basis for clinical application in spine surgery.Methods Sixty 3-months-old healthy female Sprague Dawley(SD) rats were divided into three groups after a week adaptive feeding, 20 animals each: control group(Sham+V group), spinal fusion group(PLF+V group), PTH treatment group(PLF+PTH group), All rats of PLF+V and PLF+PTH groups accepted a spinal fusion operation(grafting autologous bone at the intertransverse process of bilateral L4–L5+ fixing steel wire to the spinous processes of L4-L5). After operation PLF+PTH group were beginning subcutaneous injection of PTH(1-34) 30μg / kg 5 days a week, Meanwhile,sham+V and PLF+V group received subcutaneous injection of the same dose of saline. After administration of 8 weeks, X-ray radiograph was taken on the whole spine of all rats, and then the fusion segments were scored. All animals were sacrificed after radiography, and the L4–5 spinal segments were removed to assess using dual energy absorptiometry measurements, Micro-CT detection of fusion segments L4-5, palpation techniques fusion rate, Hematoxylin/Eosin(HE) for histological stained and made histological examination.Results 1 Bone mineral density test showed that there was no difference between PLF+V group and PLF+V group. Bone density of PLF+ PTH group was higher than that of Sham+V group(P < 0.05). 2 The score of PLF+V group was 2.5 + 0.9, the score of PLF+PTH group was 3.9 + 0.9, and the score of PLF+PTH was higher than that of PLF+V group by X-ray score, and the difference was statistically significant(P < 0.05). 3 Palpation technique results showed that all the PLF surgical rat flexion extension, lateral bending and rotation were not active, that had fused. 4 Results of micro-CT scanning evaluation:, Sham + V group L4-5 transverse gap is clearly visible, and no integration of bone tissue. PLF + V group of rat spinal fusion L4-5 transverse shows a small amount of bone tissue. PLF + PTH group L4-5 between the transverse process larger amounts of visible bone fusion. 5 Results of histological examination: the fusion part of the histological observation, PLF + V group showed a large number of fibroblasts, but notabsorbed visible bone fragments, showing a small amount of osteoblasts and a small amount of new bone formation in the presence of a large number of regional integration collagen fiber tissue, trabecular disorganized, incomplete recanalization canal. PLF + PTH group found little unabsorbed implanted bone fragments, shows a large number of osteoblasts and new bone formation, and a small amount of collagen tissue, bone trabeculae rules canal complete recanalization. Results of histological scores: PLF + V group was 3.6 ± 1.0 points, PLF + PTH group was 5.5 ± 1.0 points, PLF + PTH group scored higher than the PLF + V group, the difference was statistically significant(P<0.05)Conclusions Posterolateral fusion in SD rat model of lumbar, subcutaneous PTH(1-34) 30μg/kg five days a week, can effectively promote bone formation and fusion segments improve fusion rates.