Wearable, noninvasive, pulsed shortwave (radiofrequency) therapy for postoperative analgesia: A randomized, double-masked, sham-controlled pilot study

Abstract

Background: Nonthermal, pulsed shortwave (radiofrequency) therapy (PSWT) is a nonpharmacologic, noninvasive modality that limited evidence suggests provides analgesia. Its potential favorable risk-benefit ratio stems from its lack of side effects and significant medical risks, applicability to any anatomic location, long treatment duration, and ease of application by simply affixing it with tape. Even with a relatively small treatment effect, PSWT might contribute to a multimodal analgesic regimen, similar to acetaminophen. However, widespread clinical use is hindered by a lack of systematic evidence. The current randomized, controlled pilot study was undertaken to determine the feasibility and optimize the protocol for a subsequent definitive investigation and estimate the treatment effect of PSWT on postoperative pain and opioid consumption.

Methods: Within the recovery room following primary knee and hip arthroplasty, cholecystectomy, hernia repair, and non-mastectomy breast surgery, we applied 1-3 PSWT devices (Model 088, BioElectronics Corporation, Frederick, Maryland) over the surgical bandages. Participants were randomized to 28 days of either active or sham treatment in a double-masked fashion. The outcomes of primary interest were the cumulative opioid consumption and the mean of the "average" and "worst" daily pain measured with the Numeric Rating Scale over the first 7 postoperative days.

Results: During the first 7 postoperative days, oxycodone consumption in participants given active treatment (n = 55) was a mean (SD) of 21 mg (24) versus 17 mg (26) in patients given sham (n = 57): difference 4 (95% CI, -5 to 13), p = 0.376. During this same period, the "average" daily pain intensity in patients given active treatment was 2.4 (1.6) versus 2.6 (1.7) in sham: difference -0.2 (95% CI -0.8 to 0.5), p = 0.597. Concurrently, the worst/maximum pain for the active group was 4.6 (2.0) versus 4.7 (2.1) in sham: difference -0.1 (95% CI -0.8 to 0.7), p = 0.888. No device-related systemic side effects or serious adverse events were identified.

Conclusions: Pulsed shortwave (radiofrequency) therapy did not reduce pain scores and opioid requirements to a statistically significant or clinically relevant degree during the initial postoperative week in this pilot study. These results must be replicated with a subsequent study before being considered definitive. Data from this preliminary study may be used to help plan future trials.

Keywords: analgesia; postoperative pain; post‐surgical pain; pulsed electromagnetic fields; surgical analgesia.

FIGURE 1

A wearable pulsed shortwave therapy device with a pulse generator and flexible 12 cm‐diameter antenna. The unit is secured with an included cotton‐based kinesiology or paper tape. The single control is an on/off button on the back of the pulse generator, and the green light emitting diode indicates the unit is activated. Imaged are knee arthroplasty and umbilical hernia repair. Used with permission from the first author.

FIGURE 2

Consolidated Standards of Reporting Trials (CONSORT) diagram.

FIGURE 3

Effects of 28 days of pulsed shortwave therapy on daily pain, opioid consumption, and pain's interference in functioning. Pain severity was measured using a numeric rating scale with 0 equal to no pain and 10 being the worst imaginable pain. Oxycodone is a synthetic opioid and presented in milligrams. Regarding the Brief Pain Inventory, pain interference indicated using a numeric rating scale of 0–70, with 0 and 70 equal to no and maximal interference, respectively. Data expressed as mean (top of box) with standard deviation (whisker). There were no statistically significant differences between the treatment groups at any time point.

FIGURE 4

Effects of pulsed shortwave therapy on the highest worst and average pain level experienced over the entire 28‐day treatment period. Pain severity was measured using a numeric rating scale with 0 equivalent to no pain and 10 being the worst imaginable pain. Data expressed as mean (top of box) with standard deviation (whisker). There were no statistically significant differences between the treatment groups.