Pain Management Following Total Hip Arthroplasty With Percutaneous Auricular Stimulation (Neuromodulation): A Randomized, Double-Masked, Sham-Controlled Pilot Study

Objectives Percutaneous auricular neuromodulation involves implanting electrodes around the ear and administering an electric current. A device is currently available in the United States, cleared to treat symptoms from opioid withdrawal, with multiple reports suggesting a possible postoperative analgesic effect. This randomized, controlled pilot study aimed to (1) assess the feasibility of a postoperative auricular neuromodulation protocol and (2) provide an estimate of its treatment effects on postoperative pain and opioid consumption following total hip arthroplasty. Methods Adults undergoing unilateral, primary, total hip arthroplasty received an auricular neuromodulation device (NSS-2 Bridge^TM, Masimo, Irvine, California) applied following surgery. Participants were randomized to five days of either electrical stimulation or sham in a double-masked fashion and discharged home with their devices <i>in situ</i>. Participants or their caretakers removed the devices at home. Results One participant randomized to active treatment removed the device the morning of postoperative day one and withdrew from the study prior to any data collection. The remaining 29 participants were included in the analysis. For the first primary outcome measure, the median (IQR) pain level in the first five days for those receiving active stimulation (n=14) was 2.5 (1.0, 3.8) versus 3.0 (1.9, 4.0) for the sham group (n=15) (P=0.721). Concurrently, the median oxycodone use for the active stimulation group was 3.5 mg (0.1, 9.5) compared to 9.0 mg (2.0, 15.3) for the sham group (P=0.263). No statistically significant differences between treatments were identified for any of the secondary outcome measures. The protocol was successful regarding participant recruitment, intervention administration, data collection, outcomes assessment, and analysis. Six participants (three from each treatment group) removed their device prior to postoperative day five due to either difficulty sleeping while using the device or pain at one of the electrode sites. Conclusions While this randomized, controlled pilot study demonstrated the feasibility of using percutaneous auricular nerve stimulation following total hip arthroplasty for both the inpatient and outpatient portions of the postoperative period, it failed to identify improvements in analgesia, opioid-sparing, or pain interference in psychological and physical functioning. Therefore, it remains unclear whether a definitive clinical trial is warranted to investigate its use following total hip arthroplasty. Further research is advisable, possibly with a different auricular neuromodulation device and larger sample sizes.