Is the history of a surgical discectomy related to the source of chronic low back pain?

Background: Recurrent or persistent low back pain (LBP) after surgical discectomy (SD) for intervertebral disc herniation has been well documented. The source of low back pain in these patients has not been examined. Objective: To compare the distribution of the source of chronic LBP between patients with and without a history of SD. Study Design: Retrospective chart review. Setting: Academic spine center. Patients: Charts from 358 consecutive patients were reviewed. Charts noting the absence/presence of SD in patients who subsequently underwent diagnostic injections to determine the source of chronic LBP were included resulting in 158 unique cases for analysis. Methods: Patients underwent either dual diagnostic facet joint blocks, intra-articular diagnostic sacroiliac joint injections, provocation lumbar discography, or anesthetic injection into putatively painful interspinous ligaments/opposing spinous processes/posterior fusion hardware. If the initial diagnostic procedure was negative, the next most likely structure in the diagnostic algorithm was interrogated. Subsequent diagnostic procedures were not performed after the source of chronic LBP was identified. Outcome: The source of chronic LBP was diagnosed as discogenic pain (DP), facet joint pain (FJP), sacroiliac joint pain (SIJP), or other sources of chronic LBP. Results: Based on a Fisher's exact test, there was marginal evidence the distribution of the source of chronic LBP differed for those with and without a history of SD (P = 0.080). Posthoc comparisons suggested that patients with a history of SD have a higher probability of DP compared to those without a history of SD (82% versus 41%; P = 0.011). Differences in the probability of FJP, SIJP, or other sources between the SD history groups were not significant. Limitations: Small sample size, restrospective design, and possible false-positive results. Conclusions: This is the first published investigation of the tissue source of chronic LBP after SD. It appears that DP is the most common reason for chronic LBP after SD. If more rigorous study confirms our findings, future biologic treatments may hold value in repairing symptomatic annular fissures after SD.