Prevention of postlaminectomy membrane: experimental and clinical observations.

An animal experimental study was performed to investigate the prevention of scar formation after laminectomy by applying Gelfoam, a free-fat graft and steroids as interposing material between the dura and muscles. There were 52 adult guinea pigs equally divided into four groups. They were sacrificed 2 weeks, 4 weeks and 12 weeks respectively after surgery. In the control group, there was young fibrous tissue at 2 weeks, which became more mature at 4 weeks. At 12 weeks, it became mature with varying thickness and canal extension. In the steroid group, it showed the same picture as the control group. In the Gelfoam group, there was foreign body reaction with disintegration of Gelfoam at 2 to 4 weeks. At 12 weeks, however in the free-fat graft group, viable fat graft could be seen at the laminectomy site with little fibrous tissue overlying the dura. In the clinical part, from September 1981 to September 1984, one of the authors (PQC) performed 100 laminectomies on patients with various causes of low back pain. A piece of free subcutaneous fat was laid on dura before wound closure. At follow-up, there was no adverse effect pertaining to its application. Most patients had considerable pain relief after the surgery. From the above observation, we believe that a free-fat graft is a simple and effective way to prevent postlaminectomy membrane. Steroids and Gelfoam do not have such advantage.