Comparison of In Vivo Intradiscal Pressure between Sitting and Standing in Human Lumbar Spine: A Systematic Review and Meta-Analysis

Background: Non-specific low back pain (LBP) is highly prevalent today. Disc degeneration could be one of the causes of non-specific LBP, and increased intradiscal pressure (IDP) can potentially induce disc degeneration. The differences in vivo IDP in sitting and standing postures have been studied, but inconsistent results have been reported. The primary objective of this systematic review is to compare the differences in vivo IDP between sitting and standing postures. The secondary objective of this review is to compare effect size estimates between (1) dated and more recent studies and (2) healthy and degenerated intervertebral discs. Methods: An exhaustive search of six electronic databases for studies published before November 2021 was conducted. Articles measuring in vivo IDP in sitting and standing postures were included. Two independent researchers conducted the screening and data extraction. Results: Ten studies that met the inclusion criteria were included in the systematic review, and seven studies with nine independent groups were included in meta-analyses. The sitting posture induces a significantly higher IDP on the lumbar spine (SMD: 0.87; 95% CI = [0.33, 1.41]) than the standing posture. In studies published after 1990 and subjects with degenerated discs, there are no differences in vivo IDP between both postures. Conclusions: Sitting causes higher loads on the lumbar spine than standing in the normal discs, but recent studies do not support this conclusion. Furthermore, the degenerated discs showed no difference in IDP in both postures.