Nucleoplasty with NuCore Injectable Nucleus Replacement for Herniated Lumbar Disc: A Multicenter Study with a Minimum Five-Year Follow-up

Study Design: Multicenter pooled analysis of prospective singlearm clinical trials. Objective: To assess the results of NuCore® Injectable Nucleus in long term. Summary of Background Data: Randomized controlled trials have shown discectomy to be effective in relieving pain due to first-time lumbar disk herniation. However, loss of intervertebral disk height and reherniation is not uncommon. NuCore® material is a synthetic polymer, implanted via injection into the nuclear void at discectomy. A previous mono-center study on 15 patients reported promising 2-year results. Methods: Thirty patients (age 18-60 years) at 4 centers were eligible. All patients underwent standard lumbar microdiscectomy followed by the injection of NuCore® Injectable Nucleus material. Outcomes included leg and back pain (Visual Analogue Scale), function (Oswestry Disability Index), quality-of-life assessed (SF- 36) and disc height (plain radiographs). An independent reviewer analyzed MRIs taken at different time points. Results: Twenty-five patients completed the five-year followup with an average follow-up period of 77 months. Overall four patients were revised due to reherniation of the nucleus, 2 of them within one week after index operation, two of them after >3 years postoperative. Clinical long-term improved in all categories: VAS leg pain decreased from 6.4(SD ± 2.4) pre- op to 1.1 (± 1.5) at latest follow-up. VAS back pain decreased from 4.2 (± 2.9) to 1.8 (± 2.0) and ODI from 42 (± 17) to 10 (± 8). Disc height loss was 15.9% at latest follow-up compared to pre-op. On MRI analysis no relevant reactions of the endplate nor new or worsening of pre-existing Modic changes were seen. Conclusion: Long-term data of patients undergoing nucleus augmentation with NuCore® Injectable Nucleus following lumbar microdiscectomy is favorable and comparable with the literature on outcomes after lumbar microdiscectomy. However, potential advantages such as a slow-down in the degenerative cascade of the disc have to be verified in randomized studies.