Evaluating Manual Therapy in Musculoskeletal Pain: Why Certain Trial Designs May Overestimate Effectiveness-A Scoping Review.

BACKGROUND AND

OBJECTIVE

Atraumatic musculoskeletal pain, regardless of the affected body region, is a highly prevalent condition impacting over 25% of the global population and contributing significantly to the burden of disease. A common study design compares physiotherapy or exercise therapy alone to the same intervention combined with MT (A vs. A + B). This study design is inherently flawed due to its inability to isolate the effect of treatment B, the potential for interaction effects, and the lack of control for non-specific contextual factors. The goal of this study was to compile studies using that approach and to examine the short-, medium-, and long-term effects of the addition of MT to a control treatment.

DATABASES AND DATA TREATMENT: This scoping review identified 95 randomised controlled trials (RCTs) with a systematic literature search in the electronic bibliographic databases MEDLINE (via PubMed), EBSCO, and PEDro.

RESULTS

Long-term effects were absent, and medium-term effects were infrequent. Approximately half of the studies reported statistically significant effects in the immediate or short-term follow-up; however, these effects were of limited clinical relevance and susceptible to methodological issues. Furthermore, studies with lower methodological quality were more likely to report significant effects (85%), whereas medium- and high-quality studies showed positive results in only 50% of cases.

CONCLUSIONS

This review highlights significant research gaps and provides methodological insights. The study design in question is therefore methodologically problematic, as it tends to generate positive short-term results without providing clear answers or meaningful clinical implications for researchers and clinicians.

SIGNIFICANCE STATEMENT: This scoping review summarizes studies using an 'A vs. A+B design', where manual therapy is added to usual care, with or without a sham control. The review identifies a lack of medium- or long-term effectiveness and highlights a methodological bias toward generating positive short- or immediate-term results of questionable clinical relevance. Based on these findings, we provide several recommendations to improve future research and to support clinicians in interpreting the current evidence base.