Forty RCTs and two QRCTs were found by a Cochrane review [Abstract] 1. There were four trials comparing surgical treatment of lumbar disc prolapse with some form of natural history, conservative treatment, or placebo. Nine of the trials were of different forms or techniques of surgical discectomy. Seventeen of the trials were of some form of chemonucleolysis. Two trials compared automated percutaneous discectomy (APD) with chymopapain and two compared it with microdiscectomy. There were two included trials of laser discectomy. Eight trials considered the effect of different types of inter-position membrane on the formation of intra-spinal scarring following discectomy. Surgical discectomy produced better clinical outcomes than chemonucleolysis with chymopapain, and chemonucleolysis produced better clinical outcomes than placebo. In nine trials comparing different forms or techniques of surgical discectomy, use of the microscope lengthened the operative procedure, but did not appear to make any significant difference to peri-operative bleeding or other complications, length of in-patient stay, or the formation of scar tissue. Three trials failed to show a significant reduction in scar formation or improved outcomes by inserting an inter-position membrane to cover the spinal dura after discectomy, although a lesser number of painful episodes one year after surgery was recorded in a fourth trial.
Comment: The quality of evidence is downgraded by inadequate intention-to-treat adherence, by inconsistency of results and heterogeneity in interventions and outcomes
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