An injectable nucleus replacement as an adjunct to microdiscectomy: 2 year follow-up in a pilot clinical study.

Literature indicates that loss of disc tissue from herniation and/or surgery can accelerate degeneration of the disc. The associated loss of disc height may correspond with recurrent back and/or leg pain. A novel hydrogel has been developed to replace lost nucleus pulposus and potentially restore normal disc biomechanics following herniation and surgery. A single-center, non-randomized, prospective feasibility study was undertaken to investigate the use of NuCore Injectable Nucleus hydrogel (Spine Wave, Inc., Shelton, CT, USA) as a replacement for nuclear tissue lost to herniation and microdiscectomy. Fourteen patients were enrolled at the authors' hospital as the initial site in a worldwide multicenter pilot study. Subjects who were entered into the study suffered from radicular pain due to single-level herniated nucleus pulposus and were non-respondent to conservative therapy. Following a standard microdiscectomy procedure, the hydrogel material was injected into the nuclear void to replace what tissue had been lost to the herniation and surgery. Leg and back pain, function and disability scores were monitored pre- and post-operatively through 2 years. Neurologic and physical evaluations, blood and serum analyses, and radiographic evaluations of disc height and implant stability were also performed. Results showed significant improvement for leg and back pain, as well as function scores. No complications or device related adverse events were observed. MR controls confirmed stable position of the implants with no reherniations. Radiographic measurements indicated better maintenance of disc height compared to literature data on microdiscectomy alone. The NuCore material appears to protect the disc from early collapse following microdiscectomy; and therefore, may have the potential to slow the degenerative cascade of the spinal segment over time.