Interferential Current Therapy and Spray-And-Stretch in Musculoskeletal Disorders: A Narrative Review of Mechanisms, Evidence, and Clinical Positioning in the Absence of Direct Comparative Trials

Background: Interferential current therapy (ICT) and spray-and-stretch are two low-cost, non-invasive modalities that coexist on the treatment menus of outpatient musculoskeletal clinics, yet no published study has directly compared them, and no guidance document provides principled criteria for choosing between them. Objective: To characterise the mechanistic basis, clinical evidence, safety profile, and practical implementation of each modality across the full range of musculoskeletal disorders, and to propose a hypothesis-generating framework for modality positioning in the absence of direct comparative trials. Methods: A narrative review of literature retrieved from PubMed/MEDLINE, Embase, Scopus, the Cochrane Library, PEDro, and Google Scholar from database inception to 1 August 2026, using the search logic (musculoskeletal condition terms) AND (ICT terms OR spray-and-stretch terms), supplemented by hand-searching. The combined search retrieved 3241 records across six databases; 46 primary studies were included after two-reviewer sequential screening. Risk of bias was assessed using the PEDro scale (RCTs) and the Downs and Black checklist (observational studies). No quantitative synthesis was performed. Results: For ICT, multiple randomised trials and meta-analyses across at least four anatomical regions show that stand-alone ICT produces a small and inconsistent analgesic effect versus sham, whereas ICT as a co-intervention yields modest short-term improvements in pain and disability in chronic non-specific low back pain and knee osteoarthritis. For spray-and-stretch, a small number of predominantly fair-quality RCTs, almost all limited to the upper trapezius, show a real but brief effect of the combined procedure; the independent contribution of the vapocoolant has not been isolated in any dismantling study. Conclusions: The two modalities address mechanistically distinct clinical problems and are not directly comparable on the current evidence. We propose a hypothesis-generating positioning framework—unvalidated and intended to guide future comparative trials rather than to serve as a clinical decision rule—in which ICT is considered for deep, regional, multi-session analgesic adjunction, and spray-and-stretch for single-session restoration of range of motion around a discrete taut band. Direct comparative trial data are needed to test this framework.