Condition category
Musculoskeletal Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The knee is the largest weight-bearing joint in the body. It is a complex joint where the shin bone (tibia) and thigh bone (femur) meet creating a “hinge”. One of the most common causes of knee pain is Osteoarthritis (OA). This occurs when the protective cartilage on the end of bones wears away. The bones then rub against one another, causing stiffness, pain and a reduction in the range of movement, causing abnormal gait (instability while walking). The primary aim of healthcare professionals treating patients with knee pain is to relieve pain and help people to recover their normal range of movement. A transcutaneous electrical nerve stimulation (TENS) machine is a device designed to provide pain relief using electrical stimulation. It is attached to sticky pads (electrodes) which are placed on the skin around the area where pain is felt. Small electrical pulses are then delivered to the body through these electrodes, which can help to ease pain by affecting the way that nerves send pain signals to the brain. Studies have shown that TENS can help to relieve pain and restore movement in a number of conditions. More evidence is needed to find out if it can help to restore abnormal gait due to knee pain however. The aim of this study is to find out if TENS treatment is an effective way of reducing pain and restoring normal gait in experimental knee pain (knee pain which is created for the purpose of the study).

Who can participate?
Health adults aged between 18 and 45 who take part in regular exercise.

What does the study involve?
Participants attend three study visits in order to cause knee pain for the experiment. In the first visit, hypertonic saline solution (salt water which is more concentrated than in the blood) is injected into the space surrounding the knee joint. In the second and third visits, isotonic saline solution (salt water with the same salt concentration as the blood) and water are used in order to show the specific effects caused by the hypertonic solution. After the experimental knee pain sessions, participants are randomly allocated to one of two groups. Those in the first group are connected to a TENS machine using electrodes, which are evenly spaced around the knee. The machine then delivers continual electrical pulses to the knee for 20 minutes. Those in the second group are connected to a placebo (dummy) device which is not designed to have any pain-relieving effects for 20 minutes. At the start of the study, during the infusion and after the treatment, participants in both groups are asked to rate their level of pain on a scale of 1-10, and have are filmed walking so that their gait (manner of walking) can be analysed.

What are the possible benefits and risks of participating?
There are no direct benefits of taking part in this study. Participants are expected to experience pain and discomfort during the infusion however these affects will wear off quickly.

Where is the study run from?
Brigham Young University (USA)

When is the study starting and how long is it expected to run for?
August 2013 to December 2013

Who is funding the study?
Brigham Young University (USA)

Who is the main contact?
Mr Seong Jun Son

Trial website

Contact information



Primary contact

Mr Seong Jun Son


Contact details

Department of exercise sciences
Brigham Young University
106 SFH
UT 84602
United States of America
+1 801-422-9156

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Effects of transcutaneous electrical nerve stimulation on perceived knee pain and gait characteristics in individuals with experimental knee pain


Study hypothesis

1. Experimental knee pain would result in altered gait characteristics during various portions of stance
2. Compared to placebo treatment, TENS treatment would reduce perceived knee pain and restore gait characteristics that were altered due to experimental knee pain

Ethics approval

Brigham Young University's Institutional Review Board for Human Subjects, 15/08/2013, ref: F130284

Study design

Single-center controlled cross-over laboratory intervention trial

Primary study design


Secondary study design

Randomised cross over trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Knee pain


Participants are randomly allocated to one of two groups. During the study, participants are required to participate in at least 90 min/week of cardiovascular, resistance and/or other sport-related physical activity, and are not allowed to do strenuous exercise or take any analgesic/anti-inflammatory medication 24 hours before data collection.

Participants are then given 3 separate experimental knee pain sessions which involve hypertonic saline infusion, isotonic saline infusion, and control. Regarding experimental knee pain procedures, after prepping the skin with an alcohol wipe and iodine, a 20-gauge flexible catheter was inserted into the right infrapatellar fat pad. A 30-ml syringe, connected to the catheter, was attached to a portable infusion pump, which produced a continuous saline flow of 0.154 ml/min for 50 minutes (7.7 ml) into the fat pad. Isotonic saline infusion was used for the sham session, allowing us to differentiate potential mechanical effects (catheter insertion and fluid pressure) from effects of the hypertonic saline infusion (pain session). No catheter was involved in the control session. After the infusion initiation, subjects lay supine for three minutes, sat upright for three minutes, and stood for two minutes, so that the subjects could become familiar with the saline infusion effects. Subjects were required to lie, sit, and stand for equivalent time during a control session to maintain consistency over all three experimental data collection sessions.

TENS Group: Following the experimental knee pain sessions, self-adhesive square electrodes are placed around the borders of the patella with approximately 5 to 7 cm distance between them. The TENS device then delivers continuous (normal mode) asymmetric biphasic square-pulse wave with a pulse width of 120 microseconds and a pulse rate of 180 Hz. Electrical stimulation intensity is increased until a visible contraction of the vastus medialis is seen, and then manually decreased until no contraction is seen or felt by the investigator. The treatment lasts for 20 minutes, while the patient is in a seated upright position.

Placebo Group: Following the experimental knee pain sessions, participants are attached to a placebo device not designed to provide significant electrical stimulation. The treatment lasts for 20 minutes, while the patient is in a seated upright position.

Intervention type



Drug names

Primary outcome measures

1. Perceived knee pain is measured using a visual analogue scale (VAS) at baseline and every two minutes throughout the study
2. Gait characteristics (joint angle and torque) are measured using high-speed video and a force plate with 59 reflective markers at baseline (0 minute), infusion (8 minutes), and treatment (38 minutes)

Secondary outcome measures

1. Perceived knee pain is measured using a visual analogue scale (VAS) under hypertonic saline infusion
2. Gait characteristics (joint angle and torque) are measured using high-speed video and a force plate with 59 reflective markers under hypertonic saline infusion

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Aged between 18 and 45 years
2. Participating in at least 90 minutes/week and 3 days/week of sport-related weight-bearing physical activity

Participant type

Healthy volunteer

Age group




Target number of participants


Participant exclusion criteria

1. History of cardiovascular, resistance and/or other sport-related physical activity (at least 90 min/week and 3 days/week in the past 3 months)
2. History of lower-extremity orthopedic surgery, fracture, or neurological disorders in their lifetime
3. History of sport-related lower extremity orthopedic injury in the past 6 months

Recruitment start date


Recruitment end date



Countries of recruitment

United States of America

Trial participating centre

Human Performance Research Center at Brigham Young University
Human Performance Research Center 116 Richards Building
United States of America

Sponsor information


Brigham Young University

Sponsor details

A-285 ASB
United States of America
+1 801 422 3841

Sponsor type




Funder type


Funder name

Brigham Young University

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Planned publication in Arthritis Research and Therapy journal.

Intention to publish date


Participant level data

Available on request

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes