Spinal duraplasty materials and hydrostasis: a biomechanical study

Abstract

Object Dural tears are a frequent complication of spinal surgery and contribute to significant morbidity. Occasionally, dural tears cannot be closed primarily and dural patch grafts must be utilized. No data exist on the comparative immediate hydrostatic strength of various patch materials used alone or with a biological adhesive in a spinal dural tear model. Thus, the authors conducted this study to determine the comparative effectiveness of various patch materials used with and without biological adhesive. Methods Twenty-four thoracic spines from calves were prepared with laminectomies and spinal cord evacuation, leaving the dura intact. Foley catheters were inflated on either side of a planned dural defect, and baseline hydrostasis was measured using a fluid column at 30, 60, and 90 cm of H2O. A standard dural defect (1 × 2 cm) was created, and 8 patches of each material (human fascia lata, Duragen, and Preclude) were sutured in place using 5-0 Prolene hemo-seal running sutures. Hydrostasis was again tested at the same pressures. Finally, a hydrogel sealant (Duraseal) was placed over the defect and hydrostasis was again tested. Results were analyzed with repeated measures ANOVA. Results The leakage rate increased significantly at each pressure tested for all conditions. There was no difference in leakage among the 3 patch materials at any of the pressures or for either condition (with or without sealant). All patch materials allowed significantly greater leakage than the intact condition at all pressures. The use of sealant reduced leakage significantly at the 30 and 60 mm Hg pressures to levels similar to the intact condition. At 90 mm Hg, leakage of the sealed construct was greater than at the intact condition but significantly less than without the use of sealant. Conclusions All 3 dural patch materials were of similar hydrostatic strength and allowed greater leakage than at the intact condition. The use of sealant reduced the amount of leakage at all pressures compared with patching alone but allowed more leakage than the intact state at a high hydrostatic pressure (90 mm Hg).