Comment on “Efficacy of high-energy, focused ESWT in treatment of lumbar facet joint pain: a randomized sham-controlled trial”

Dear Editor, We read with great interest the article by Nedelka et al[1] titled “Efficacy of high-energy, focused ESWT in treatment of lumbar facet joint pain: a randomized sham-controlled trial.” The lumbar facet joint is a common source of chronic low back pain), and its diagnosis and treatment remain challenging[2]. Extracorporeal shock wave therapy (ESWT), which utilizes externally generated radial or focused acoustic waves, is a treatment modality for musculoskeletal disorders and shows therapeutic potential for facet joint-mediated pain[3]. In this context, the authors’ prospective, randomized, sham-controlled trial is of significant importance. The study is rigorously designed, incorporating ultrasound-guided targeting, strict inclusion and exclusion criteria, and a 12-month follow-up, all of which substantially enhance the reliability of the findings. We particularly appreciate the following highlights: the study not only confirms significant improvements in pain and functional disability following ESWT but also provides the first reported imaging evidence of its effect on resolving lumbar bone marrow edema (BME), offering strong support for its biological mechanisms. Furthermore, the assessment of neuropathic pain components and subgroup analyses based on body mass index extend the potential clinical applicability of ESWT. Despite the rigorous study design, we believe the following issues warrant further discussion. 1. The study used an “air-filled polyurethane interface” to absorb shockwaves for sham therapy. Although this method has been applied in previous literature, the energy attenuation and mechanical transmission of shockwaves in human tissues are highly complex. We recommend supplementing the data with physical validation of the energy attenuation of this interface in a tissue-mimicking model or phantom – for example, by measuring whether the energy delivered to the tissue is reduced to a biologically ineffective level. This would help conclusively demonstrate that the sham treatment is truly “inert,” thereby enhancing the credibility of between-group comparisons and avoiding underestimation of the true treatment effect due to potential low-level bioactive stimulation in the control group. 2. Although a sham-controlled design was employed, the study did not report specific results of blinding assessment (e.g., the proportion of patients correctly guessing their group assignment, analyzed by chi-square test). If a majority of patients could distinguish real from sham treatment, it would suggest possible unblinding, which may affect the interpretation of subjective outcomes such as the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). Patients’ expectation effects could exaggerate between-group differences. We recommend explicitly reporting statistical results of the blinding assessment and discussing their potential impact on outcome interpretation. 3. The observed resolution of BME is an important finding. However, the analysis remained at the level of describing “improvement in some patients within the group.” Individual-level correlation analysis – such as comparing changes in VAS and ODI scores between a “BME resolution subgroup” and a “BME non-resolution subgroup” – was not conducted. If a positive correlation exists between edema resolution and clinical improvement, it would strongly support the biological hypothesis that ESWT alleviates pain by modulating local intraosseous inflammation and edema. Conducting such correlation analyses could uncover deeper insights from the existing data, transforming imaging findings from isolated observations into compelling evidence closely linked to clinical outcomes. In conclusion, we believe that addressing the above issues would further strengthen the persuasiveness of the study’s conclusions and enhance its value in guiding future clinical practice and research. We thank the authors for their valuable contribution and look forward to further academic exchange.