Innovations in Regenerative Medicine:
Amniotic Membrane as an Adhesion Barrier
The recurrent radicular pain and physical impairment associated with FBSS is thought to be caused by postoperative epidural scarring. Post laminectomy intraspinal hemorrhage serves as a scaffold for the migration of fibroblasts from paraspinal muscles and the periosteum. Granulation tissue forms and subsequently deposits collagen fibers. The entire process then matures into a dense fibrotic scar known as the “postlaminectomy membrane”. Epidural scars can cause extradural compression or dural tethering, the primary reason for post-surgical lower back pain. Currently, there is not an effective treatment for this problem. Revision surgery may be performed to remove epidural scar adhesions in order to free up the tethered nerve roots; however, it is a time consuming endeavor with increased risk of complications and the adhesions will likely recur. The best case scenario to avoid this altogether is to develop a therapy that reduces the likelihood of epidural fibrosis and adhesions.
Enter amniotic membrane (AM) as an adhesion barrier, the inner layer of fetal membrane composed of a layer of epithelial cells connected to a basement membrane. AM has demonstrated the ability to reduce inflammation, promote bone growth and cartilage repair, and also exhibits anti-microbial properties. The tissue is immune privileged and speeds fibrogenesis and angiogenesis. AM has also demonstrated anti-scarring and anti-adhesive properties. In a 2009 study, performed to investigate the effects of AM on reducing epidural scar adhesion post laminectomy in a canine model, AM demonstrated through gross observation that scar amount and adhesion tenacity was significantly lower when compared to other potential barriers and non-treatment groups. Histology was performed which indicated a decrease in fibroblast infiltration thus a reduction in epidural fibrosis. The study concluded that AM was effective in reducing epidural fibrosis and scar adhesion post laminectomy.