The association between pain scores and disc height change following discectomy surgery in lumbar disc herniation patients: a systematic review and meta-analysis

To evaluate the impact of discectomy on disc height (DH) in lumbar disc herniation (LDH) patients following discectomy surgery and address the association of DH change with pain score change. We searched three online databases for randomized controlled trials (RCTs) and observational studies. In LDH patients, eligible for discectomy surgery, the changes in pre- and post-operative back and/or leg pain score and DH and/or disc height index (DHI) were considered as primary outcomes. Standardize mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The GRADE approach was used to summarize the strength of evidence. Two RCTs and sixteen observational studies were included in the analysis of 893 LDH patients undergoing discectomy surgery. The mean overall follow-up was 211 weeks. There was a statistically significant reduction in DH (14.4% reduction: SMD =  −0.74 (95% CI =  −0.86 to −0.61)) and DHI (11.5% reduction: SMD =  −0.81 (95% CI =  −0.97 to −0.65)) following discectomy surgery. There was a significant relationship between the reduction in DH and decrease in back pain score (r = 0.68, (95% CI = 0.07–1.30), p = 0.034) after discectomy surgery. No significant relationship between DHI change and decrease in clinical pain scores (back and leg pain) could be established. Discectomy surgery produces significant and quantifiable reductions in DH and DHI. Additionally, the reduction in DH is responsible for the decrease in back pain scores post discectomy, but further studies will improve understanding and aid preoperative counselling.