Efficacy of 5-fluorouracil in inhibition of unintended bone formation in spinal surgery: a histological evaluation on a rat model of spontaneous spinal fusion.

Objective: The aim of this study was to investigate the influence of the antiproliferative agent 5-Fluorouracil (5FU) over inhibition of spinal bone formation in an experimental rat model.

Methods: The study included 30 6-month-old Sprague-Dawley rats divided into 3 groups. Aggressive periosteal denuding was performed by scalpel to induce punctuate bleeding in the posterior elements of the L4-L5 vertebrae in the spontaneous fusion model. Spinous processes were fixated by wires and no graft substitute was applied. Adcon-L was applied in Group 1, single-touch technique 5FU in Group 2. Group 3 was the control group. Rats were sacrificed at 4 weeks and specimens acquired for histological examination.

Results: 5FU substantially inhibited fibroblast and inflammatory cell densities as well as bone formation compared to the control group. 5FU was considerably superior to Adcon-L with regard to inhibition of bone formation and inflammatory cells (p=0.0001).

Conclusion: 5FU can inhibit fusion, fibrosis and unwanted scar tissue in spinal surgery. We believe that after further studies on its local delivery dose, it can be used in humans for inhibition of unintended fusion.