I Lotfinia - Associate Professor of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
E KHalagi - Resident of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
M Mesgari - Research Assistant, Tabriz University of Medical Sciences, Tabriz, Iran
R Estakhri - Assistant Professor of pathology, Tabriz University of Medical Sciences, Tabriz, Iran

Background & Aims: Epidural fibrosis (EF) is part of natural physiological tissue response to laminctomy and it may be an important cause of failed back surgery syndrome (FBSS). There is still no effective medical or surgical therapy for EF. Osteoprotegerin (OPG) is a soluble member of the tumor necrosis factor receptor family that might play a role in postoperative EF. The objective of this study was to evaluate the relationship between serum OPG level and EF after laminectomy. Methods: Sixty rabbits were employed and divided randomly into two groups. Group A contained ۲۰ rabbits as controls and group B contained ۴۰ rabbits that underwent bilateral laminecyomy at L۴ and L۵ lumbar levels under an approved surgical protocol. Serum sample was obtained after ۸ weeks from all rabbits and then the animals in group B were killed in accordance with the guidelines for euthanasia. The spine segment from L۳ to L۶ was removed en bloc. The amount of scar tissue at the laminectomy defect was scored on an ordinal score from ۰ to ۳ with a scoring system similar to that of He et al. According to the amount of scar the rabbits in group B, were divided into two groups: B۱ with low fibrosis (grade ۰, ۱) and B۲ with high fibrosis (grade ۲, ۳). The serum OPG level of groups A, B۱ and B۲ were determined using ELISA method. The one way ANOVA was used to assess significant difference among groups. Results: Serum OPG level ranged from ۰-۴ Pmol/l with a median of ۱.۵ Pmol/l in group A, ۰-۶ Pmol/l with a median of ۲.۴۲ Pmol/l in group B۱ and ۰-۶ Pmol/l with a median of ۲.۱۵ Pmol/l in group B۲. There was not any significant difference in OPG levels among these ۳ groups. Conclusion: This study showed no relation between OPG level and existence of postlaminectomy EF after ۸ weeks

Osteoprotegerin, fibrosis, Epidural space, Laminectomy