Effects of Orthopedic Manual Therapy on Pain Sensitization in Patients With Chronic Musculoskeletal Pain: An Umbrella Review With Meta-Meta-analysis.

Objective: The aim of this umbrella review with meta-meta-analysis was to assess the effectiveness of orthopedic manual therapy in isolation on pain sensitization in patients with chronic musculoskeletal pain.

Design: A systematic search was performed in different databases including systematic reviews with or without meta-analysis. The outcome measures included were pressure pain threshold, temporal summation, and conditioned pain modulation. The results of the different reviews were statistically synthesized through a random-effect meta-analysis, of all standardized mean differences and the corresponding 95% confidence interval reported by each study.

Results: For mechanical hyperalgesia, the meta-meta-analysis of three meta-analyses revealed a statistically significant small-moderate effect of orthopedic manual therapy, with no evidence of heterogeneity and moderate-quality evidence. In terms of temporal summation, one meta-analysis revealed a statistically significant small effect of orthopedic manual therapy intervention, with moderate heterogeneity and low quality of evidence. Finally, one review without meta-analysis found that orthopedic manual therapy improved endogenous analgesia with low-quality evidence.

Conclusion: Orthopedic manual therapy in isolation improved mechanical hyperalgesia with moderate-quality evidence, as well as temporal summation and conditioned pain modulation with low-quality evidence. However, its effects are limited only to immediate and short-term.