Effects of Serum Level of Osteoprotegerin on Postlaminectomy Epidural Fibrosis

Abstract

Aim: Epidural fibrosis (EF) is a part of the normal physiological tissue response to laminctomy and it may be an important cause of failed back surgery syndrome (FBSS). In spinal surgery, the recurrent of postoperative back and/or leg pain after an initial pain-free period often is related to the formation of fibrosis tissue around the nerve root. There is currently no effective medical or surgical therapy for EF. Osteoprotegerin (OPG) is a soluble member of the tumor necrosis factor receptor family; it may also play a role in postoperative EF. The objective of this study was to evaluate the relationship between serum OPG level and the existence of postlaminectomy EF. Methods: Sixty rabbits were used and divided randomly in 2 groups; group A, which covered 20 rabbits as a control group and group B with 40 rabbits. Bilateral laminectomy at the L4 and L5 lumbar levels was performed under an approved surgical protocol. Serum sample was obtained after 8 weeks in all the rabbits and then group B rabbits were killed in accordance with the guidelines for euthanasia. The spine segment from L3 to L6 was removed en bloc. The amount of scar tissue at the laminectomy defect was scored on an ordinal score from 0 to 3. According to the amount of scar tissue, the rabbits of group B were divided in to 2 groups: B1 with low fibrosis (grade 0, 1) and B2 with high fibrosis (grade 2, 3). The serum OPG level of groups A, B1, and B2 were determined using an enzyme-linked immunosorbent assay method. The 1-way analysis of variance was used to assess significant difference between values in various groups of study. Results: We did not observe any significant difference of OPG levels in these 3 groups. Conclusions: This study showed there is not any relation between OPG level and existence of postlaminectomy EF after 8 weeks.