To ensure early mobilization, minimize suffering, and to prevent postoperative complications postoperative pain should be reduced as soon and as effectively as possible.

A non-pharmacological post-operative intervention in terms of the application of transcutaneous electrical nerve stimulation (TENS), could have the potential to accelerate early mobilization and reduce the use of opioids.

The overall aim is to demonstrate that the addition of TENS to standard postoperative pain management of orthopedic patients can alleviate pain during mobilization and at rest as well as reduce opioid consumption.

TENS for Relief of Postoperative Pain in Orthopedic Patients

Orthopedic Disorder

Post Operative Pain

Hip Fractures

Arthroplasty, Replacement, Hip

Internal Fixation

Hip fracture is most often addressed surgically (Allahabadi et al., 2022; RikshÖFt, 2020), and is commonly associated with a short-term increase in mortality, and long-term reduction in health-related quality of life (Alexiou et al., 2018; Dyer et al., 2016; Gjertsen et al., 2016; Griffin et al., 2015). A large part of this reduction in quality of life can be related to pain and mobility. According to the Swedish National Hip Fracture Registry (RikshÖFt, 2020), 5.8% of the patients registered in 2019 were experiencing severe pain either constantly or during activity at the 4-month follow-up; 42% were experiencing tolerable pain during activity, and 35% were pain-free.

In the larger context of Chronic PostOperative Pain (CPOP), severe pain on postoperative day 1 constitutes an important risk factor (Fletcher et al., 2015). A 10% increase in the amount of time spent in severe pain on postoperative day 1 has been associated with a 30% increase in the incidence of CPOP at a 12-month follow-up. Yet, a 2021 review on the prevention of CPOP (Carley et al., 2021) reported that there were no pharmaceutical pain treatments that could be universally or specifically recommended to reduce the incidence of CPOP.

To effectively manage acute and chronic pain disorders, Transcutaneous Electrical Nerve Stimulation (TENS) has been viewed a safe nonpharmacological addition to standard care (Jafra et al., 2022; Johnson et al., 2022; Vance et al., 2022). Conventional TENS with high frequency (50-100Hz) activates non-noxious afferents considered to inhibit nociceptive transmission at the spinal cord level, i.e., peripheral gate-control. Mixed-frequency TENS adds a low-frequency (mostly 2-10Hz) stimulation that activates small-diameter, high-threshold peripheral afferents considered to trigger brainstem opioid descending pain inhibitory pathways, i.e., central gate-control. Studies have indicated mixed-frequency TENS may be effective to mitigate post-operative pain (Bjordal, Johnson, &amp; Ljunggreen, 2003; Hamza et al., 1999).

A non-pharmacological post-operative intervention in terms of the application of transcutaneous electrical nerve stimulation (TENS), could have the potential to accelerate early mobilization and reduce the use of opioids.

A 2019 study (Elboim-Gabyzon, Najjar, &amp; Shtarker, 2019) demonstrated pain reduction during activity - but not at rest - following hip fracture with a 30-minute TENS intervention daily on the first 5 postoperative days. A more recent (and currently unpublished) study using TENS integrated in TENS-pants (Opolka et al., 2024) demonstrated pain reduction at rest and during activity with a single 2.5-hour intervention carried out around postoperative day 1 (POD1). However, there is there is still a lack of knowledge regarding the possible effect of a longer TENS intervention repeated over several days. Moreover, there is still a lack of statistical evidence for the opioid sparing effect of TENS following hip fracture surgery.

The primary aim of this study is to assess pain reduction and patient global impression of change following mixed-frequency TENS treatment (or placebo TENS) at rest and during activity on postoperative days 1 to 3, following hip fracture surgery. A secondary aim is to assess improvement in mobility and to test the opioid-sparing effect associated with TENS treatment. Moreover, to simplify TENS application, empower the elderly patients and improve compliance during mobilization, the authors chose to administer TENS using wearable TENS-pants with modular textile electrodes. We hypothesize that a mixed-frequency TENS intervention, carried out on POD1 to POD3, with a daily treatment duration of 3 hours, can lead to a significant opioid sparing effect, more durable pain reduction, and improve the patients' overall perception and recovery.

transcutaneous electrical nerve stimulation (TENS)

Sham transcutaneous electrical nerve stimulation (TENS)

Transcutaneous Electrical Nerve Stimulation (TENS) Integrated Into Pants for Relief of Postoperative Pain in Orthopedic Patients

A 11-point numeric pain rating scale (Minimum 0, Maximum 10, higher score means worse outcome, i.e more pain) assessment will be performed during inactivity

The patient's belief about the efficacy of treatment, which ranged from 1 (minimum, "no change") to 7 (maximum, "a great deal better") will be assessed by PGIC.

A 11-point numeric pain rating scale (Minimum 0, Maximum 10, higher score means worse outcome, i.e more pain) assessment will be performed during activity after the Standardized three-meter Walking test (WALK3m)

Professor, MD, PhD

The Standardized three-meter Walking test (WALK3m). With a stopwatch, the patient will be instructed to walk a 3 meters distance beginning from a marked position, in comfortable steps, to a stop position, turn around and walk back to the marked position where he or she started. The timing will begin when the patient starts on the word go, and the timing will end when the patient stopped at the marked position where they started. Patients will be asked whether or not they were mobilized prior to the intervention.

Extra analgesic consumption will be documented to assess and evaluate the effect of the intervention during the following: (1) Only intervention (POD 1,2, and 3). In each day there will be three 30x2-minute long rounds of TENS-application with two interposed 30-minute breaks equalling 4 hours x 3 = 12 hours. (2) Totally during post-operative days 1, 2, and 3 equalling 24 x 3 = 72 hours.

At the start of each day, before the first intervention round the duration of putting on the TENS-pants will be logged. The timer will start once the first NRS at rest has been taken and the TENS-pants are ready to be applied to the patient and it will stop once the pants are worn and ready for TENS-application.

A short follow-up will be performed after the intervention.

The patients in both active and placebo groups will be asked to answer a questionnaire on their attitude toward TENS and the intervention. Answers will be provided on a five-level Likert-type scale on the following statements:

1. I think TENS therapy is comfortable for me.
2. I would like to use TENS again if I were to undergo another surgery in the future.
3. I think the TENS-pants were comfortable to wear.
4. I would feel confident to put on and take off the TENS-pants by myself.
5. I would feel confident to put on and take off the TENS-pants with the help of a family member or care assistant.
6. If you ever need to use TENS-PANTS at home, would you prefer to use "diaper-like" pants or "normal" pants?

In addition, patients will be asked to provide free-form general comments on the product and study.

The Chattanooga Physio TENS (DJO Global, Vista, CA) will be applied with mixed burst / TENS alternated, which is a 30-minute long program where the stimulation frequencies of alternate in 3 second intervals, producing a combined stimulation of 80 Hz and 2 Hz. Two programs/sessions ('a' and 'b') will be applied in succession for a total of 60-minutes (one round). In total, each day will have 3 rounds.

The energy intensity level will firstly be adjusted for 80 Hz (TENS) until a tingling sensation is felt but no discomfort, and then the procedure will be repeat for 2 Hz.

The patient will use a pair of pants with integrated stimulation electrodes, to which the CE-marked TENS device (Chattanooga Physio, DJO Nordic, Malmö, Sweden) will be connected and used to provide pain relief, in addition to usual postoperative care.

The TENS device will be connected to the textile electrodes of the pants which are located 5cm in front and behind the hip incision dressing respectively.

The control group will also receive the TENS-pants described above with integrated stimulation electrodes, connected to TENS treatment. However, the TENS treatment to the control group will be set such that no electricity will be applied to the patient. In all other regards, the control group will follow the same protocol as the intervention group.

TENS for Relief of Postoperative Pain in Orthopedic Patients

About this trial

Study ID

Status

Type

Phase

Placebo

Accepting

Trial Timing

What is this trial about?

What are the participation requirements?