Medical Student (MS2) Mercer University School of Medicine
Introduction: Instrumentation-related postoperative back pain is a potentially debilitating complication of lumbar fusion. To delineate who will be the most appropriate patient to undergo removal of instrumentation (ROI), a reliable diagnostic indicator is needed. Diagnostic injections around the instrumentation can provide valuable feedback on source pain though there is minimal existing literature investigating a correlation between pain relief from diagnostic injections of lumbar instrumentation and pain relief from lumbar ROI.
Methods: A retrospective review was completed examining patients with 1- 3+ levels of lumbar spine fusions with symptomatic lower back pain who underwent ROI following diagnostic novel injection of instrumentation. Review of pre- and post-ROI Visual Analog Scale (VAS) and pain journals following novel lumbar injections in the pre-ROI period were examined. Analysis of the relationships between pre-ROI, post-injection pain relief and post-ROI relief were assessed. Pearson’s correlations were utilized to evaluate relationship between pain level after injection and pain level after ROI.
Results: 197 patients who underwent lumbar ROI at for 1, 2, or 3+ levels were included in the study. Dependent t test showed that for all levels of ROI VAS pre-op is significantly higher than VAS post-op (p < 0.001). VAS pre-op is significantly higher than best VAS score immediately after injection for all three groups (p < 0.001). VAS post-injection is significantly lower than VAS post-op for all three groups (p < 0.001). The relationship between pain level after injection and pain level after ROI had a very strong correlation with a pearson’s correlation of 0.849 (p < 0.001).
Conclusion : Our results indicate that a peripedicle screw injection serves as a reliable diagnostic indicator for pedicle screw related pain. The pain relief from this injection correlates directly to the degree of pain relief seen with ROI. The amount of pain relief seen is greater when more levels are involved. Therefore, the authors propose that peripedicle screw injections are a reliable diagnostic indicator of pedicle screw related pain.
