109. An investigational study of a dual-layer, chorion-free amnion patch as a protective barrier following lumbar laminectomy in a sheep model

BACKGROUND CONTEXT A decompressive laminectomy is the most common surgery performed to relieve symptoms of lumbar spinal stenosis. While this surgery has been shown to be successful in relieving patient symptoms, partially removing the lamina exposes the dura to elements and potential damage, from the surrounding environment. While a number of different biomaterials have been investigated for use as a protective barrier in spine surgery, the inherent properties of the human amniotic membrane (HAM) may make it favorable to protect neural elements and anterior vessels from the surrounding environment. The effect of a dual-layer HAM patch used as a physical barrier following a laminectomy in an animal model has yet to be investigated. PURPOSE The objective of this study was to evaluate the effect of a dual-layer, chorion-free amnion patch (DLAM) processed from HAM as a protective barrier following lumbar laminectomy in a sheep model. STUDY DESIGN/SETTING Prospective animal study. PATIENT SAMPLE Twelve skeletally mature female crossbred Suffolk sheep randomly divided into two equal postoperative periods (4 and 10 weeks). OUTCOME MEASURES A multiplex immunoassay was performed to quantify the inherent cytokines present in the amnion after processing. Additionally, at each time point extent of epidural fibrosis and neurohistopathological responses at the laminectomy sites was assessed based on epidural fibrosis-dura tenacity scores and decalcified histology, respectively. METHODS Each sheep underwent a laminectomy at L3 and L5, and one of the surgical sites randomly received the DLAM treatment. At each post-surgical time point, the extent of epidural fibrosis and neurohistopathological responses at the laminectomy sites was assessed based on epidural fibrosis-dura tenacity scores and decalcified histology, respectively. RESULTS Immunoassay results showed that inflammatory mediators and immunomodulatory cytokines were present in the amnion after processing, but no pro-angiogenic cytokines were detected. At 10 weeks, tissue tenacity was significantly less in the DLAM treatment group when compared to the operative control (1.2 ± 0.4 vs 2.8 ± 0.4, p CONCLUSIONS This study found that DLAM reduced fibroblast infiltration and tissue tenacity following lumbar laminectomy in a sheep animal model. These findings support the potential use of DLAM in clinical practice as a protective barrier for neural elements and anterior vessels. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.