Influence of Noxious Electrical Stimulation on Chronic Pain From Knee Osteoarthritis
Condition: Knee Osteoarthritis
MeSH terms: Osteoarthritis; Osteoarthritis, Knee; Chronic Pain
Study type: Interventional

Summary: 
      Knee osteoarthritis (OA) is the most common lower extremity joint pain condition, and it is
      estimated that 15 million people in the US are living with symptomatic knee OA and that more
      than half (8 million) are under 65 years of age. To that end, the Centers for Disease Control
      and Prevention strongly recommends non-pharmacological treatments for chronic pain including
      physical therapy and weight loss; however, these interventions have significant barriers that
      can prevent their success. An intervention that targets pain specifically is transcutaneous
      electrical nerve stimulation (TENS), which is a low-cost intervention with evidence to
      support pain reduction. As used in the majority of research to date, the intervention called
      "TENS" refers to the application of electricity across the skin that produces a tingling
      sensation that is strong but comfortable. However, electricity is applied at a noxious level
      is thought to result in strong activation of the endogenous pain modulation system, thus
      producing longer-lasting pain inhibition. However, noxious electrical stimulation (NxES) has
      rarely been investigated as a treatment intervention. Recent studies, including our own,
      demonstrate that NxES produces immediate and potentially greater pain relief. Despite some
      promising research, the clinical use of NxES is sparse and more research is necessary to
      demonstrate its effects on resting pain, movement-related pain, physical function, and
      quality of life. The investigators hypothesize that the application of NxES will activate
      pain modulation mechanisms and change the pain modulation profile toward an anti-nociceptive
      state in adults with chronic knee osteoarthritis (OA) pain, and thereby decrease pain (at
      rest and with movement), improve physical function, and improve quality of life. The
      investigators expect individual differences; therefore, participants will be classified at
      baseline and their response to the intervention tracked using psychophysical tests and
      clinical response. The hypothesis will be tested through 2 Specific Aims.

      Aim 1: The investigators will test the magnitude and duration of pain relief and functional
      improvement of a single treatment with NxES in adults with chronic knee OA pain.

      Aim 2: The investigators will determine if repeated NxES treatments show greater pain relief
      and/or functional improvements and if so, whether the gains plateau after a certain number of
      treatments.

      The knowledge gained by this study will be important to physical therapists and other health
      care practitioners who treat people with chronic knee osteoarthritic pain. If noxious
      electrical stimulation is found to be an effective strategy to decrease pain at rest and with
      movement, it may lead to improved patient care, improved function, and decreased chronic pain
      in people with knee osteoarthritis.
    

Detailed description: 
      Up to forty-four participants (22 for Aim 1; 22 for Aim 2) with knee OA will be recruited
      using advertisements, the Legacy Scholars research registry maintained by UNE's Center of
      Excellence in Aging and Health, from participants with knee OA previously involved in the
      investigator's research who indicated their willingness to participate in other studies, and
      from a local orthopedic surgeon group practice. Potential participants will complete a
      per-participation survey online or by phone that will be used to determine eligibility based
      on inclusion/exclusion criteria.

      For Aims 1 and 2, eligible individuals will be asked to defer any plan for knee joint
      injections until after the testing period. Participants will be asked to refrain from taking
      any pain medications for at least 4 hours prior to testing. After giving informed consent,
      individuals who have diabetes will undergo sensory testing to confirm that their sensory
      detection threshold is no lower than the mean (+ 2 standard deviations) of the detection
      threshold of healthy older adults which is 1.4 g of force applied by a size 4.17
      monofilament. This threshold is based on data collected in our laboratory using the 4-2-1-
      method of steps. If the individual is unable to perceive 1.4 g stimulus s/he will not
      continue in the study.

      Protocol for Aim 1- Data collected for Aim 1 will occur over 4 sessions. The purpose of this
      aim is to determine the magnitude and duration of the day-to-day effects on clinical pain
      relief and quantitative sensory tests related to pain after a single NxES treatment.

      Session 1: In this session we will gain informed consent, then perform a sensory screen (if
      necessary), collect demographic data and baseline questionnaire data and familiarize
      participants with the quantitative sensory testing (QST) procedures and to briefly experience
      the NxES treatment.

      Session 2: During this session, participants will experience a single treatment with NxES and
      we will assess changes in pain and function and QST measures before and after the treatment.
      For the NxES Intervention, a pair of 2x3 inch electrodes will be placed on the medial and
      lateral sides of the knee. Pulses of electrical current (400 µs biphasic square wave pulses
      delivered at 50-100 pulses/second; 10-seconds on: 10-seconds off) will be applied for 20
      minutes. The amplitude of the current will be increased until the participant rates the pain
      50/100 on numeric pain rating scale. Pain intensity and unpleasantness will be assessed every
      two-min. and amplitude will be increased to maintain the 5/10 pain intensity level during the
      treatment. QST will be performed immediately after the treatment and 1 hour later. One- to
      two-minute washout periods will be provided between QST test repetitions and a 20-minute
      washout period will be provided after the NxES treatment and the post-treatment test of
      conditioned pain modulation.

      Sessions 3-4: These sessions will occur 24-hours and 72-hours after session 2 and pain and
      function along with QST will be performed.

      Protocol for Aim 2- The purpose of this aim is to determine if there is a cumulative response
      to NxES treatment on clinical pain and quantitative sensory tests related to pain. Data
      collected for Aim 2 will begin at least 1-week after the testing for Aim 1 and take place
      over a 2-week treatment period. Follow-up testing will take place 72-hours and 4-weeks after
      the last NxES treatment session.

      Session 1: This session will be used to re-collect baseline questionnaire data and
      re-familiarize participants with procedures if it has been greater than 2-weeks since
      participation in Aim 1 or if they declined participation in Aim 1.

      Session 2: During this session, participants will receive the first NxES treatment and
      undergo assessment of QST, pain, and function.

      Session 3-7: These sessions are NxES treatment sessions. Pain and QST assessment will be
      collected at the beginning of sessions 3,5 & 7 only.

      Session 8: No treatments will be performed; post-treatment assessments will occur at 72 hours
      after session 7.

      Session 9: No treatments will be performed; post-treatment assessments will be completed 4
      weeks after session 7.

      Sessions 2-7 must be completed within 18 calendar days in order to preserve the fidelity of
      the intervention dosage.
    

Intervention name(s): Noxious Electrical Stimulation (NxES)
Intervention type(s): Device
Intervention description(s): The NxES intervention will be applied with a pair of 2x3 inch electrodes placed orthogonally to the knee joint line with one electrode on the medial and lateral sides of the knee. The device is a commercially available unit(Chattanooga Continuum, DJO Global, Vista CA) and the parameters of the NxES include: 400 μs biphasic square wave pulses delivered at 50-100 pulses/second, using a cycle time of 10-seconds on, with a 2-second ramp-up in intensity, followed by a 10-second off period. The current intensity will be dosed over the first 2-minutes of stimulation to find the sensory perception threshold and the threshold for the first perception of a sharp, prickly buzzing sensation that they would identify as painful. Next, the current intensity will gradually be increased until the participant reports a sharp or prickly buzzing sensation that achieves a pain rating of not more than a 5/10 using a numeric pain rating scale.
Intervention model: Single Group Assignment
Intervention model description: The investigators propose a single arm/pre-post trial to examine the effects of NxES on resting pain (BPI, ICOAP), pain sensitivity (PPT, HTS, CPM), movement-related pain (5xSTS), and physical function (5xSTS, KOOS) for people with knee OA. The investigators plan to examine the potential time-course effects after a single intervention (immediate, 1-hr, 24-, and 72-hours) and due to repeated treatment (3x/week for 2-weeks) at the end of treatment (post 72-hours and 4-weeks).
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: electrical stimulation