Transcutaneous Electrical Nerve Stimulation Integrated into Pants for the Relief of Postoperative Pain in Hip Surgery Patients: A Randomized Trial

Background. The effect of transcutaneous electrical nerve stimulation (TENS) on pain and impression of change was assessed during a 2.5-hour intervention on the first postoperative days following hip surgery in a randomized, single-blinded, placebo-controlled trial involving 30 patients. Methods. Mixed-frequency TENS (2 Hz/80 Hz) was administered using specially designed pants integrating modular textile electrodes to facilitate stimulation both at rest and during activity. The treatment outcome was assessed by self-reported pain Numerical Rating Scale (NRS) and Patient Global Impression of Change (PGIC) scores at four time points. The ability to perform a 3-meter walk test and the use of analgesics were also evaluated. Group comparison and repeated-measure analysis were carried out using nonparametric statistics. Results. The active TENS group exhibited significantly higher PGIC scores after 30 minutes, which persisted throughout the intervention (all p <= 0.001). A reduction in NRS appeared after one hour of active TENS, persisting throughout the intervention (all p <= 0.05). The median group differences in pain ratings were greater than the minimum clinically important difference, and the analysis of pain trajectories confirmed clinical significance at the individual level. Moreover, patients in the active TENS group were more likely able to perform a 3-meter walk test by the end of the intervention (p=0.04). Analysis of the opioid-sparing effect of TENS was inconclusive (p=0.066). No postoperative surgical complications or TENS-related side effects were observed during the study. Conclusion. Mixed-frequency TENS integrated in pants could potentially be an interesting addition to the arsenal of treatments for multimodal analgesia following hip surgery. This trial is registered with NCT05678101.