Iliac crest autograft in rabbit dorsolateral spinal fusion

Abstract

The effectiveness of the iliac crest autograft in dorsolateral spinal fusion promotion of the lumbar vertebral body L5-L6 was evaluated in 33 New Zealand White rabbits, distributed in two groups, with nine animals in group 1 (G1), submitted the bilateral transverse processes decortification; and twenty-four in group 2 (G2), which received 2g of iliac crest autograft on decortificed bilateral transverse processes. Three rabbits of G1 and eight of G2 were killed at 5, 7 and 9 weeks after surgery and submitted to palpation, X-ray and light microscopic evaluations. The fusion site of animals of G2 was submitted to biomechanic tests accomplished for evaluation of force and rigidity. All animals of G1 presented normal mobility of the segment operated in all moments of evaluation and they didn't present fusion evidence in X-ray analysis. In the light microscopic evaluations periosteal discreet reaction was observed, without evidence of bony bridge formation. In G2, evaluation for palpation and x-rays evidenced bone fusion to the 5 weeks, intensifying along the weeks. At 5 weeks, in the light microscopic analysis, reabsorption of bone fragments was observed, presence of trabecular bone and chondroides hearts, besides the abundant irrigation to the 7 weeks and osteointegration in every grafted bed to the 9 weeks, with bone endochondral formation prevailing. Force and rigidity increase of the fusion bone mass along the time of evaluation was observed in the biomechanic test.. When a comparison of the treated vertebrae and no treated was accomplished, the union indexes were larger in all of the moments, in the treated group. A high percentage of vertebral fusion was gotten when iliac crest autograft was used in rabbits.