Effect of Physical Therapy on Inflammatory Biomarkers in Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Background/Objectives: Knee osteoarthritis (OA) is increasingly recognized as a condition with an inflammatory component. Elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are associated with disease severity. However, the effects of physical therapy on inflammatory biomarkers remain unclear. This review aimed to evaluate the effects of physical therapy interventions on CRP and ESR in adults with knee OA. Methods: Following PRISMA 2020 guidelines, PROSPERO (CRD42024590843), PubMed, MEDLINE, Embase, Scopus, Web of Science, and Google Scholar were searched from inception to 3 November 2024. Randomized controlled trials comparing any physical therapy intervention with a control condition were included. Risk of bias was assessed using the Physiotherapy Evidence Database (PEDro) scale, and certainty of evidence was evaluated using the GRADE approach. Random-effects meta-analyses were performed using standardized mean differences (SMDs) with 95% confidence intervals (CIs). Results: Seven RCTs (n = 523 participants) were included. Pooled analysis showed a statistically significant reduction in CRP (SMD = −1.05; 95% CI: −1.80 to −0.31; p = 0.006); however, substantial heterogeneity was observed (I2 = 93%), limiting confidence in the pooled estimate. Certainty of evidence for CRP was rated as moderate. No significant effect was observed for ESR (SMD = −0.20; 95% CI: −0.84 to 0.45; p = 0.56; I2 = 63%), with low certainty. Conclusions: Physical therapy may reduce CRP levels in knee OA; however, substantial heterogeneity limits confidence in the precision and generalizability of this effect. These findings should be interpreted cautiously and considered exploratory. Further well-designed RCTs are required.