Effectiveness of combined therapy in physical therapy for the management of musculoskeletal pain: a systematic review and meta-analysis

Introduction. Therapeutic ultrasound and electrotherapy are commonly used in physical therapy for musculoskeletal pain (MSP) management. Combined therapy (CT) is a resource that merges both techniques, enhancing the analgesic effects of both treatments, although studies are limited. Objective: To determine the effectiveness of CT in physical therapy for the management of MSP. Methods. The PubMed, Web of Science, Scopus, Cinahl, Science Direct, and PEDro databases were searched for randomised clinical trials (RCTs) (updated June 5, 2024). RCTs comparing CT with other physical therapy treatments for MSP were included. Thirteen studies met the eligibility criteria, including those of the qualitative synthesis and meta-analysis types. The Cochrane Rob2 tool was used to assess the articles’ quality. Results. RCTs were assessed as having a low risk of bias for all RoB2 domains. Although the qualitative synthesis reports a reduction in pain, an increase in ROM, and less disability in favour of CT, the quantitative analysis only shows large, statistically significant effect sizes (Cohen’s d) (p < 0.05) for the standardised mean differences (SMD) in pain (SMD = 0.9; CI = 0.8, 1.1) and ROM (SMD = –0.93; CI = –1.1, –0.8). These analgesic and ROM benefits improve when CT is applied with interferential currents (Pain: SMD = –1.54; IC = –1.8, –1.3) (ROM: SMD = 2.28; CI = 1.8, 2.7). Although the analgesic evidence was qualified as important, the heterogeneity obtained in the studies (I² > 75%) moderates its degree of recommendation. Conclusions. This SR shows that CT has better analgesic effects than TENS, interferential currents, or therapeutic ultrasound alone, which supports the idea of a combined analgesic effect. The researchers propose dosage recommendations for clinical practice and future research.