Is discectomy effective for treating low back pain in patients with lumbar disc herniation and Modic changes? A systematic review and meta-analysis of cohort studies

Previous low-quality evidence has suggested preoperative Modic changes (MC) showed a trend toward less improvement in low back pain in patients with lumbar disc herniation (LDH) undergoing discectomy. However, a recent meta-analysis concluded that the presence of preoperative MC did not significantly impact clinical outcomes following lumbar discectomy.To compare low back pain and functional outcomes of patients after discectomy for LDH with preoperative MC.Systematic review and meta-analysis of cohort studies.This comprehensive systematic review and meta-analysis used English-language articles identified through searches using Pubmed, Web of Science, Embase, and Cochrane library until August 2022. The included studies identified publications that concentrated on the patients suffering from LDH with different preoperative MCs treated by discectomy. The Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI) were the two main metrics to evaluate outcomes.A series of 2,299 LDH patients with a definitive type of MC were included in four retrospective and five prospective studies. Overall, there is moderate to high quality evidence suggesting no significant difference between normal and MC groups for pain outcomes as well as normal and Modic type 2 groups in terms of pain or functional outcomes at one or two-year follow up. There are less functional outcomes in LDH patients with preoperative MC compared with no MC at 2-year follow up and showed no significant difference at 1-year follow-up. However, above all results may due to heterogeneity. Subgroup analysis revealed that only Modic type 1 showed statistically lower functional scores (mean difference in ODI scores range from 0 to 100) compared with Modic type 2 or compared with no MC at 2-year follow-up and showed no significant difference at 1-year follow-up (MC1 vs. MC0, p=.24, MD= -2.70; 95% CI, -7.15 to 1.76 for 1-year;p<.00001, MD= -7.92; 95% CI, -11.19 to -4.66 for 2 years. MC1 vs. MC2, p=.58, MD= -1.29; 95% CI, -5.83 to 3.25 for 1-year;p<.0001, MD= -6.77; 95% CI, -9.94 to -3.61 for 2 years).These data suggest LDH patients with or without preoperative MCs show a similar improvement of low back pain at 1 and 2-year follow-up and functional scores after discectomy at one-year follow-up. LDH patients with preoperative Modic type 1 are associated with worse functional status after discectomy at 2-year follow-up. However, high-quality randomized controlled trials and prospective cohort studies which focus on analyzing the risk and confounding factors are lacking.