Exogenous Collagen Crosslinking of the Intervertebral Disc Restores Joint Stability After Lumbar Posterior Decompression Surgery

Study Design. In vitro evaluation of a chemical, injectable intervention for discectomy induced destabilization. Objective. To investigate the ability of two collagen crosslinking agents to restore mechanical properties to lumbar joints destabilized by surgical decompression procedures. Summary of Background Data. Posterior decompression surgery is a common procedure indicated for tissue pathology that interferes with surrounding neural structures. Previous in vitro, analytical, and clinical studies have shown that removal of load-supporting tissue can compromise joint stability mandating some form of postsurgical stabilization. Currently, no nonsurgical treatments are capable of restoring stability and preventing subsequent degeneration. Exogenous crosslinking of intact discs has shown a fourfold increase in joint stability. Methods. Fifteen bovine lumbar intervertebral joints were randomly separated into methylglyoxal or genipin treatment groups. Flexion-extension flexibility was quantified in three conditions: intact, postdecompression surgery, and after crosslinking reagent injections. Instability was quantified by calculating neutral zone (NZ), percentage of hysteresis, range of motion, and percentage of strain energy. Results. Simulated surgical decompression increased NZ 111% (P = 0.009), 28% (P = 0.004), range of motion 57% (P = 0.003), and decreased strain energy 37% (P = 0.004). For those discs undergoing methylglyoxal treatment NZ was subsequently reduced 68% (P = 0.012), hysteresis 28% (P = 0.018), range of motion 29% (P = 0.012), and strain energy was increased 71% (P = 0.018). For discs subjected to genipin treatment, NZ was reduced 52% (P = 0.018), hysteresis 23% (P = 0.012), range of motion 44% (P = 0.017), and strain energy was increased 66% (P = 0.012). Mean NZ was lower than intact mean after both methylglyoxal and genipin treatments, 10% and 17% less, respectively, but these differences were not significant. Mean values for all other parameters posttreatment were within 6% of the corresponding intact mean values. Conclusion. Injections of crosslinking reagents into lumbar intervertebral discs after simulated decompression surgery restored joint stability according to all parameters. Similar results were found for genipin and methylglyoxal reagents. Implementing exogenous collagen crosslinking as an adjunct to current surgical decompression procedures may be beneficial in preventing or delaying subsequent spinal instability and degeneration.