Do corticosteroids affect lumbar spinal fusion? A rabbit model using high-dose methylprednisolone.

The effect of corticosteroids on spinal fusion healing has not yet been determined. To evaluate the effect of corticosteroids on lumbar spinal fusion we designed a randomized, placebo-controlled animal study using high-dose methylprednisolone sodium succinate, which is widely used in patients with spinal cord injury who are undergoing spinal fusion. Two groups of 18 rabbits underwent a postero-lateral fusion at L5-L6 with autologous bone graft. After surgery, the animals were assigned to receive: (a) methylprednisolone sodium succinate 30 mg/kg over 15 min, followed by an intravenous infusion of 5.4 mg/kg/h for 23 h, or (b) normal saline in the same volume. Animals were killed 8 weeks after surgery; the presence of fusion was analyzed by use of two different methods: a manual palpation test and an antero-posterior radiograph. Both groups of animals were comparable in weight. Fusion was achieved in 5/18 rabbits (27.8%) in the methylprednisolone group and in 9/18 animals (50%) in the control group (p = 0.17). In a lumbar posterolateral fusion rabbit model, high-dose methylprednisolone sodium succinate reduced the success of lumbar fusion; however, our data did not reach statistical significance.