Treatment of lumbar discitis using silicon nitride spinal spacers: A case series and literature review

INTRODUCTION: Septic infection of a lumbar intervertebral disc is a serious disorder which is often difficult to diagnose and appropriately treat because of the rarity of the disease, the varied presentation of symptoms, and the frequency of low-back pain within the overall population. Its etiology can be pyogenic, granulomatous, fungal, or parasitic; its incidence is rising due to increased patient susceptibility and improved diagnostic tools. Conservative treatments involve antibiotics, physical therapy, and/or immobilization. More aggressive management requires discectomy, debridement, and spinal fusion in combination with local and systemic antibiotic administration. PRESENTATION OF CASES: Presented here are two case studies of lumbar pyogenic discitis associated with Escherichia coli and Candida albicans infections. Both required single-level anterior discectomy followed by spinal fusion using an antimicrobial silicon nitride (Si(3)N(4)) spacer for stabilization without instrumentation. Localized antibiotics were used for only one of the patients. Follow-up CT and MRI scans showed that the infections had been resolved with no recurrence of symptoms. DISCUSSION: Si(3)N(4) is a relatively new spinal spacer material. It was utilized in these two cases because it reportedly provides a local environment which promotes rapid arthrodesis while resisting bacterial adhesion and biofilm formation. It is also highly compatible with X-ray, MRI, and CT imaging modalities. These properties were particularly attractive for these two cases given the patients’ histories, presentation of symptoms, and the decision to forego instrumentation. CONCLUSION: The use of Si(3)N(4) as an antimicrobial spacer may lead to improved outcomes for patients with pyogenic discitis of the lumbar spine.