Postoperative fibrosis after surgical treatment of the porcine spinal cord: a comparison of dural substitutes

Abstract

Postoperative adhesion- and fibrosis-induced spinal cord tethering is not uncommon and may be associated with delayed clinical sequelae. Multiple dural substitutes have been used in surgery without a full appreciation of the grafts' adverse effects. The authors conducted a comparative animal experimental study to evaluate the degree of chronic inflammatory reactions, adhesions, and fibrosis caused by the use of four dural substitutes--Surgicel, Durasis, DuraGen, and Preclude. Twenty-six pigs weighing 30 to 40 kg underwent a two-level lumbar laminectomy (a midline durotomy, implantation of a 2-cm dural substitute in the subarachnoid space, and watertight dural closure). After 8 weeks the animals were killed, and two independent neuropathologists blinded to the dural substitute group evaluated several sites along the implants, providing descriptions and quantitative scoring of fibrosis, chronic inflammatory reactions, foreign-body reactions, and spinal cord changes. Kruskal-Wallis one-way analysis of variance for ranks corrected for multiple comparisons was used to examine differences among the materials. The DuraGen dural substitute produced the least amount of inflammation in the subarachnoid space and Preclude generated the most (p < 0.001). Surgicel and DuraGen were completely resorbed on histological sections, but both produced some inflammation, which diminished gradually from the dural implant center. Histological evaluation of the nonresorbed grafts demonstrated that Durasis caused the least degree of inflammatory cell infiltration (p < 0.001). The Preclude dural substitute consistently demonstrated encapsulation and arachnoidal reaction. There was no evidence of implant-related adverse effects on the underlying pia mater and white matter regardless of the substitute type.