Incidence of Spontaneous Resorption of Lumbar Disc Herniation: A Meta-analysis.

STUDY DESIGN: A meta-analysis. OBJECTIVE: This study aimed to analyze the incidence of spontaneous resorption of lumbar disk herniation (LDH) after conservative treatment. SUMMARY OF BACKGROUND DATA: The resorption of intervertebral disks has been more frequently reported, but there is a lack of reference to the probability of resorption. METHODS: We strictly refer to the standard established in the PRISMA (Preferred Reporting Items for a Systematic Review and Meta-analysis) statement, comprehensively searched electronic databases using the terms related to the spontaneous resorption of LDH. Two reviewers independently evaluated the potential studies, extracted, and analyzed the enrolled data. RESULTS: Thirty-one studies with 2233 patients who received conservative treatment were included for this analysis. We found that the pooled overall incidence of disk resorption was 70.39%, 87.77% for disk sequestration, 66.91% for disk extrusion, 37.53% for disk protrusion, and 13.33% for disk bugle, respectively. The resorption incidence in of 25%≤ reduction of disk herniation (RDH) 50%, RDH≥50%, and RDH=100% were 40.19%, 43.62, and 36.89%. The resorption incidence was 66.98% in Japan, 61.66% in the United States, 83.52% in Korea, 60.68% in China, 78.30% in the UK, 56.70% in Italy, and 83.68% in Turkey, respectively. Subgroup analysis showed that there was no significant difference in resorption incidence among prospective, retrospective studies and randomized controlled trials (P=0.77), and there was no significant difference in evaluation method among qualitative and quantitative studies (P=0.05). CONCLUSIONS: The existing evidence shows that the overall resorption incidence of LDH was 70.39%, the resorption incidence of ruptured LDH is higher than that of contained LDH. There are significant differences in the resorption incidence among countries. The resorption process mainly occurred within 6 months of conservative treatment.