Viable Disc Tissue Allograft Supplementation; One- and Two-level Treatment of Degenerated Intervertebral Discs in Patients with Chronic Discogenic Low Back Pain: One Year Results of the VAST Randomized Controlled Trial.

Background: A viable disc tissue allograft has been developed to supplement tissue loss associated with degenerative lumbar disc disease and the development of chronic discogenic lower back pain. Objectives: Viable disc allograft was injected into painful degenerated discs to evaluate safety and determine whether it can improve pain and function. Study Design: Patients received an active treatment of allograft or saline, or continued with nonsurgical management (NSM). Prior to entering the study, patients had back pain for a minimum of 6 months before treatment that was recalcitrant to nonoperative treatment modalities. Standardized outcome measures were used to evaluate the patient’s condition before and after treatment. Primary endpoints included improvement in Oswestry Disability Index (ODI) and Visual Analog Scale of Pain Intensity (VASPI). Conventional radiographs and magnetic resonance imaging scans were used to assess disc space height and spinal alignment, and to determine the degree of disc degeneration. Patients were followed for one year after enrollment. The NSM group could cross over to the allograft group after 3 months. Setting: This multicenter trial was completed in outpatient surgical centers and office injection suites. A total of 218 patients with chronic low back pain secondary to single-level or 2-level degenerative disc disease were enrolled. Inclusion criteria included pretreatment VASPI >= 40 mm, ODI score >= 40 and symptoms present longer than 6 months. Patients were blinded and randomized to receive intradiscal injections of either viable disc allograft or saline. Patients randomized to the NSM group continued existing treatment. Patients were assessed at 6 and 12 months. Adverse events (AEs) were continually assessed. Methods: The VAST trial is a prospective, multicenter, blind, randomized clinical trial (RCT) for patients with single-level or 2-level degenerative lumbar disc disease. Results: At 12 months, clinically meaningful improvements in mean VASPI and ODI scores were achieved in the investigational allograft and saline groups. A responder analysis demonstrated a clinically meaningful reduction in ODI of >= 15 points at 12 months that was statistically significant; 76.5% of patients randomized to allograft were responders (P = 0.03) compared to 56.7% in the saline group. A responder group characterized by a ? 20 point reduction in pain at 12 months achieved a statistically significant reduction in pain compared to the saline group (P = 0.022). In the allograft group, 11 safety adverse events occurred in 141 patients (3.5%) and there were no persistently symptomatic AEs. Limitations: Limitations of this study include a comparison to saline that has been shown to be more representative of an active comparator as opposed to a placebo. In addition, 36 patients were lost to follow-up; this loss resulted in the saline and NSM/crossover groups being smaller than the predetermined group size to have an appropriately powered analysis. Conclusions: This large, prospective blinded RCT demonstrated safety and efficacy results indicating that viable disc tissue allograft may be a beneficial nonsurgical treatment for patients who have chronically painful lumbar degenerative discs. Further studies would be optimal to confirm efficacy Key words: Viable disc tissue allograft, discogenic back pain, allograft supplementation, degenerative disc disease, low back pain, intervertebral disc, intradiscal injection