Patellofemoral Pain SyndromeBFRNCT04086615
Trial of Neurostimulation and Blood Flow Restriction for PFPS in Active Duty
A study testing NMES and exercise supplemented with high BFR and NMES and exercise supplemented with low BFR in people with Patellofemoral Pain Syndrome, run by University of Tennessee at 1 site in United States.
Trial summary
The overall objective of this project is to compare two self-managed treatment regimens for PFPS: (1) NMES-Exercise supplemented with high BFR LOP of 80% and (2) NMES Exercise augmented with a low percentage of BFR LOP at 20 mmHG (BFR-sham). Read more about this study
- Who is it for?
- Ages 18 to 44 years
- Conditions the study is for
- Patellofemoral Pain Syndrome
- What is being tested?
- NMES and exercise supplemented with high BFR and NMES and exercise supplemented with low BFR
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 84 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Aug 2020to 31 Mar 2022
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 44 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Active duty military personnel who are:
- diagnosed with knee pain, categorized as anterior or retropatellar in one or both knees;
- self-reported difficulty performing at least two or more of the following activities associated with knee pain: prolonged sitting, stair climbing, running, jumping, and repetitive movements such as kneeling or squatting or stooping;
- military service member at the time of diagnosis and length of study;
- age ≥18 and <45 years; and
- able to provide freely given informed consent.
Who cannot join
- fracture or injury to external knee structures such that knee extension or flexion is impaired;
- a significant co-morbid medical condition (such as severe hypertension, neurological disorder, sickle cell anemia, or pacemaker/defibrillator) in which BFR, NMES strength training, or unsupervised exercise is contraindicated and would pose a safety threat or impair ability to participate;
- previous knee surgeries (i.e., tibiofemoral, patellofemoral) excluding knee arthroscopy > 3 years;
- knee instability or recurrent patella dislocation or subluxation;
- inability or unwillingness to participate in an exercise or strengthening program;
- reduced sensory perception in the lower extremities;
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- pregnancy;
- Any vascular disorder (varicose veins, Hx of DVT); or
- unwillingness to accept random assignment.
Trial locations and contacts
1 site in 1 country.
United States1 site
Blanchfield Army Community Hospital (BACH)
Fort Campbell North, Kentucky, 42223
About this study
The overall objective of this project is to compare two self-managed treatment regimens for PFPS: (1) NMES-Exercise supplemented with high BFR LOP of 80% and (2) NMES Exercise augmented with a low percentage of BFR LOP at 20 mmHG (BFR-sham). Each of the two treatment arms will perform a fixed exercise protocol singularly and in combination with BFR-NMES, and NMES alone. The specific aims of the study are 1) To determine whether self-managed NMES-Exercise program supplemented with a high BFR of 80% LOP (limb occlusion pressure) is significantly more efficacious than NMES-Exercise with low BFR LOP set at 20 mmHG (sham) in improving muscle strength of the lower extremity, daily physical activity and mobility; and 2) To determine whether NMES-Exercise with high LOP BFR therapy improves QOL and PFPS symptoms significantly more than NMES-Exercise with low LOP BFR.
Read the detailed description
The long-term goal is to identify effective self-managed therapies for military members that will return them to duty as quickly as possible. The overall objective of this project is to compare two self-managed treatment regimens for PFPS: (1) NMES-Exercise supplemented with high BFR LOP of 80% and (2) NMESExercise augmented with a low percentage of BFR LOP at 20 mmHG (BFR-sham). Each of the two treatment arms will perform a fixed exercise protocol singularly and in combination with BFR-NMES, and NMES alone.
The rationale for this study is that by limiting blood flow to an exercising limb using both active and passive exercise is expected to significantly improve lower extremity muscle strength, mobility, quality of life (QOL) and pain. The central hypothesis is that the combination of NMES/exercise of the injured leg supplemented with BFR set at 80% LOP will show significantly greater improvements in muscle strength, mobility, pain, daily activity and QOL than the NMES-Exercise with BFR set at a very low percentage of LOP at 20 mmHG. To test this hypothesis, the investigators will address the following specific aims:
a1. To determine whether self-managed NMES-Exercise program supplemented with a high BFR of 80% LOP (limb occlusion pressure) is significantly more efficacious than NMES-Exercise with low BFR LOP set at 20 mmHG (sham) in improving muscle strength of the lower extremity, daily physical activity and mobility. Muscle strength will be measured by isometric peak torque of the left and right knee and hip posterolateral stabilizers; physical activity will be measured by steps walked and energy (kcal) expenditure/day; and mobility by time to complete a stair climb, step down test, distance walked in 6 minutes, and number of times to complete the chair rise.
a2. To determine whether NMES-Exercise with high LOP BFR therapy improves QOL and PFPS symptoms significantly more than NMES-Exercise with low LOP BFR. QOL will be measured by the SF-12 Health Survey and the Center for Epidemiological Studies-Depression (CES-D) scale. Symptoms of PFPS will be quantified by the Anterior Knee Pain Scale and IKDC subjective knee form.
The investigators expect to demonstrate that these combined multimodality therapies of a self-managed NMES-Exercise program supplemented with high (80%) LOP BFR-NMES-Exercise is more efficacious than a low percentage of LOP BFR-NMES-Exercise (sham). Positive results will translate into therapy options for PFPS that can be used by health care providers to accelerate rehabilitation, speed return to world-wide duty status, decrease symptoms, and lower medical costs. Moreover, these approaches are safe, easy to use and non-pharmacological.
- Conditions
- Patellofemoral Pain Syndrome
- Being tested
- NMES and exercise supplemented with high BFR, NMES and exercise supplemented with low BFR
- Medical subject headings
- Patellofemoral Pain Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
NMES and exercise supplemented with high BFRDevice
The BFR-NMES-Exercise training consists of 20-min sessions performed concurrently with NMES and exercise in the clinic 2x a week for a total of 18 in-clinic sessions. Using the Delfi PTS Personalized Tourniquet System for Blood Flow Restriction at 80% of LOP, the participant performs 4 exercise sets of 60 repetitions (5 seconds ea) for 5 minutes, with a 1-minute BFR deflation between sets. The standard exercise rehabilitation protocol for PFPS combines open chain and closed chain quadriceps strengthening exercises: active straight leg raises, quadriceps straightening, step up, and squats. NMES training consists of 20-minute sessions: a 2-min warm-up, 15-min work-out, and a 3-min cool down using the KneeHAB® XP "Multipath" stimulation system which changes the current pathways between the electrodes for preset periods within each pulse, allowing for higher stimulation intensities that maximizes muscle fibre recruitment and minimizes muscle fatigue.
NMES and exercise supplemented with low BFRDevice
The BFR-NMES-Exercise training consists of 20-min sessions performed concurrently with NMES and exercise in the clinic 2x a week for a total of 18 in-clinic sessions. Using the Delfi PTS Personalized Tourniquet System for Blood Flow Restriction at 20mmHG venous pressure (no blood flow restricted), the participant performs 4 exercise sets of 60 repetitions (5 seconds ea) for 5 minutes, with a 1-minute BFR deflation between sets. The standard exercise rehabilitation protocol for PFPS combines open chain and closed chain quadriceps strengthening exercises: active straight leg raises, quadriceps straightening, step up, and squats. NMES training consists of 20-minute sessions: a 2-min warm-up, 15-min work-out, and a 3-min cool down using the KneeHAB® XP "Multipath" stimulation system which changes the current pathways between the electrodes for preset periods within each pulse, allowing for higher stimulation intensities that maximizes muscle fibre recruitment and minimizes muscle fatigue.
| Study group | Role | What they receive |
|---|---|---|
| NMES and exercise supplemented with high BFR | Experimental | All participants receive a standard exercise rehabilitation protocol for PFPS to be performed singularly at home/work, synchronously with NMES and concurrently with NMES/BFR in-clinic. The PFPS exercises teach muscle strengthening exercises and self-management strategies to prevent recurrence. Participants will receive a portable battery-operated device, KneeHAB® XP (Bio-Medical Research, Galway, Ireland) with the thigh garment. NMES training will consist of 20-minute stimulation sessions performed concurrently with the exercise program.
For the BFR training, the automatic Delfi's PTS Personalized Tourniquet System for Blood Flow Restriction (Delfi Medical, Vancouver, BC, Canada) with variable contour nylon cuff (11.5 cm × 86 cm, 2.5 mm thick) will be used. The Delfi PTS system automatically adjusts pressure around the set occlusion pressure. The High BFR group will have the pressure set at 80% of limb occlusion pressure. Receives: Device: NMES and exercise supplemented with high BFR |
| NMES and exercise supplemented with low BFR | Sham comparator | All participants receive a standard exercise rehabilitation protocol for PFPS to be performed singularly at home/work, synchronously with NMES and concurrently with NMES/BFR in-clinic. The PFPS exercises teach muscle strengthening exercises and self-management strategies to prevent recurrence. Participants will receive a portable battery-operated device, KneeHAB® XP (Bio-Medical Research, Galway, Ireland) with the thigh garment. NMES training will consist of 20-minute stimulation sessions performed concurrently with the exercise program.
For the BFR training, the automatic Delfi's PTS Personalized Tourniquet System for Blood Flow Restriction (Delfi Medical, Vancouver, BC, Canada) with variable contour nylon cuff (11.5 cm × 86 cm, 2.5 mm thick) will be used. The Delfi PTS system automatically adjusts pressure around the set occlusion pressure. The Low BFR group will have the pressure set at 20 mmHg. Receives: Device: NMES and exercise supplemented with low BFR |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Lower Extremity Muscle Strength- Extension
Strength of knee extension muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The participant will be positioned with a small towel roll placed distally to support the femur in 90-degree hip flexion. The participant's knee will be placed in 70º knee flexion using a goniometer. The distance from the tibial tuberosity (TT) to the superior aspect of the medial malleolus will be measured.
For knee extension, the first measurement will be taken using standard NMMT protocol (0.6 X the distance from the tibial tuberosity to the superior aspect of the medial malleolus). Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Measured: Time Frame: 9 weeks
Change in Lower Extremity Muscle Strength- Flexion
Strength of knee flexion muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The participant will be positioned with a small towel roll placed distally to support the femur in 90-degree hip flexion. The participant's knee will be placed in 70º knee flexion using a goniometer. The distance from the tibial tuberosity (TT) to the superior aspect of the medial malleolus will be measured.
For knee flexion, the NMMT will be positioned 0.6X distance from TT to superior border of medial malleolus on the dorsal limb side. Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Measured: Time Frame: 9 weeks
Change in Lower Extremity Muscle Strength- Hip Posterolateral Stabilizer
Strength of hip posterolateral stabilizer muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The hip stability isometric test (HipSIT) will be measured using the NMMT as described by Almeida et al. Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Measured: Time Frame: 9 weeks
Change in Mobility- Timed Stair Climb Test
Tests the activity of stair climbing. The test will begin with participants ascending up four steps (6-inch rise, 11.5-inch run) to a 30-inch square platform, and then descending to the bottom of the stairs. Participants will climb the stairs at a self-selected pace using the handrails if necessary.
Each participant will complete two complete rounds, if possible, and the two times will be averaged to produce one score.
Measured: Time Frame: 9 weeks
Change in Mobility- Forward Step-Down Test
This is a specific function test for PFPS, putting weight bearing stress during a movement that mimics stair descent. The test is performed from a 20 cm (8 inch) high platform. The participant steps forward and down toward the floor from a single-leg stance with a straight knee (hands on hips). The knee of the stance leg bends until the opposite foot lightly touches the floor with the heel and then returns to full knee extension. The heel touching the floor is not to be used to accelerate back onto the platform. This counts as one repetition; the number of repetitions performed in 30 seconds is recorded. Both legs are tested separately.
Measured: Time Frame: 9 weeks
Change in Mobility- 30-Second Chair Stand Test
This assesses lower-body strength mimicking squatting. The participant completes as many full stands as possible in 30 seconds. The participant sits in the middle of the chair, feet flat on the floor with arms crossed at the wrists and held against the chest. When instructed, the participant rises to a full stand, and then returns to a fully seated position. The number of completed rises will be recorded.
Measured: Time Frame: 9 weeks
Change in Mobility- 6-Minute Walk Test
This is a submaximal test of functional capacity and measures the distance a participant walks at a "fast" pace over a 6-minute period. Participants will "walk as quickly as you can" with the opportunity to stop and rest if required. This test measures functional capacity of walking.
Measured: Time Frame: 9 weeks
Change in Physical Activity- Steps walked
Physical activity will be measured using the Fitbit Charge (San Francisco, CA). The Charge is a wrist-worn, three-axis accelerometer that measures steps walked, distance traveled, energy expenditure and floors climbed. Steps walked will be assessed as the number of steps walked in 24 hours.
Baseline data will be ascertained by wearing the Charge for 3 days while maintaining a typical activity pattern. Subsequently, the device will be worn daily for 9 weeks.
Measured: Time Frame: 9 weeks
Change in Physical Activity- Energy expenditure
Physical activity will be measured using the Fitbit Charge (San Francisco, CA). The Charge is a wrist-worn, three-axis accelerometer that measures steps walked, distance traveled, energy expenditure and floors climbed. Energy expenditure will be assessed as the calories expended in 24 hours.
Baseline data will be ascertained by wearing the Charge for 3 days while maintaining a typical activity pattern. Subsequently, the device will be worn daily for 9 weeks.
Measured: Time Frame: 9 weeks
Secondary outcomes (4)
Change in Symptoms of PFPS- Knee pain limiting actiivty (AKPS)
Pain associated with activity limitations will be measured by the Kujala Anterior Knee Pain Scale, a 13-item knee specific self-report questionnaire. Scores range from 0 to 100 with higher scores indicating better performance.
Measured: Time Frame: 9 weeks
Change in Symptoms of PFPS- Pain at rest and post-activity (VAS)
The Visual Analog Scale (VAS) of pain will be used to assess pain at rest and after activity. Participants will complete this scale following the stair climb, step down test, 6-minute walk and the chair rise test. This VAS pain subscale is a 100-mm horizontal line index with descriptive anchors at each end. At the far left (0.0cm) is "no pain" and at the far right (10 cm) is "worst possible pain". The participant is instructed to place a vertical line at some point between the anchors to describe his/her level of pain. The VAS pain scale shows high correlations with acute pain levels.
Measured: Time Frame: 9 weeks
Change in Symptoms of PFPS- Knee Injury and Disability (IKDC)
Knee Injury and disability will be measured by the International Knee Documentation Committee (IKDC) subjective knee form, a well standardized outcomes questionnaire that is knee-specific and assesses patients with various knee disorders. The 18-item instrument assesses symptoms, function and level of sports participation for those with an injured knee.
Measured: Time Frame: 9 weeks
Change in Quality of Life- Overall: The Short Form Health Survey Version 2.0 (SF-12v2) Health Survey
The Short Form Health Survey Version 2.0 (SF-12v2) Health Survey will be used to determine each participant's overall health-related quality of life. The SF12v2 has two summary scores for physical (PCS) and mental health (MCS). Raw scores for each subscale are computed using the scores of 12 questions ranging from 0-100. Zero score indicates the lowest level and 100 indicates the highest level of health. The PCS and MCS subscales are norm-based for different age groups because of the variance in PCS and MCS scores over the life span.
Measured: Time Frame: 9 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Sep 2019
- Study start4 Aug 2020
- Primary completion31 Mar 2022
- Study completion31 Mar 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Patellofemoral Pain SyndromeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 84 (anticipated) participants will be assigned to one of two parallel groups. Sample size was determined using 1) an alpha level of 0.05 and power of 0.80; 2) review of PFPS literature and data from pilot work; and 3) calculation of effect sizes for key variables from previous studies that addressed the Specific Aims. For the primary outcome variable of strength, the sample size calculated was 35 subjects per groups (70 total subjects) with an effect size of 0.52. For the outcomes measures of function, mobility and pain, assuming that standard errors will be similar to those observed in our previous work, the sample size of 35 per group is sufficient to detect the expected mean changes. To account for dropouts, the investigators inflated the sample size by 20%, for a total of 42 subjects per group and a total sample size of 84.
- Masking
- None (open label)
- Enrolment
- 84 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Tennessee
- Sponsor type
- University, hospital or other
- Collaborators
- Blanchfield Army Community Hospital
- Responsible party
- Sponsor
- Investigators
- Laura A Talbot, PhD, EdD, RN, Principal investigator, University of Tennessee Health Sciences Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04086615
- Sponsor's protocol ID
- N19-B01
- Acronym
- BFR
- Status last verified
- Sep 2021
- First submitted
- 3 Sep 2019
- Last updated
- 6 Jun 2022
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No
Publications
Talbot LA, Webb L, Ramirez VJ, Taylor-Clark TM, Morrell CH, Enochs K, Fagan M, Hillner J Sr, Scallan RM, Metter EJ. Effects of Neurostimulation With Blood Flow Restriction on Physical and Mental Health-Related Quality of Life in Military Personnel With Patellofemoral Pain Syndrome: Secondary Data Analysis. Mil Med. 2026 Aug 1;191(Supplement_1):36-43. doi: 10.1093/milmed/usaf630.
PubMed 42560220Talbot LA, Webb L, Morrell C, Enochs K, Hillner J, Fagan M, Metter EJ. Electromyostimulation With Blood Flow Restriction for Patellofemoral Pain Syndrome in Active Duty Military Personnel: A Randomized Controlled Trial. Mil Med. 2023 Jul 22;188(7-8):e1859-e1868. doi: 10.1093/milmed/usad029. Epub 2023 Feb 20.
PubMed 36807977
Study at a glance
From the registry record, last updated by the sponsor on 6 Jun 2022. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Trial of Neurostimulation and Blood Flow Restriction for PFPS in Active Duty
- ClinicalTrials.gov ID
- NCT04086615
- Acronym / sponsor ID
- BFR / N19-B01
- Conditions
- Patellofemoral Pain Syndrome
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 84 participants (actual)
- Lead sponsor
- University of TennesseeUniversity, hospital or other
- Collaborators
- Blanchfield Army Community Hospital
- Study start
- 4 Aug 2020 (actual)
- Primary completion
- 31 Mar 2022 (actual)
- Study completion
- 31 Mar 2022 (actual)
- First posted
- 11 Sep 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The overall objective of this project is to compare two self-managed treatment regimens for PFPS: (1) NMES-Exercise supplemented with high BFR LOP of 80% and (2) NMES Exercise augmented with a low percentage of BFR LOP at 20 mmHG (BFR-sham). Each of the two treatment arms will perform a fixed exercise protocol singularly and in combination with BFR-NMES, and NMES alone. The specific aims of the study are 1) To determine whether self-managed NMES-Exercise program supplemented with a high BFR of 80% LOP (limb occlusion pressure) is significantly more efficacious than NMES-Exercise with low BFR LOP set at 20 mmHG (sham) in improving muscle strength of the lower extremity, daily physical activity and mobility; and 2) To determine whether NMES-Exercise with high LOP BFR therapy improves QOL and PFPS symptoms significantly more than NMES-Exercise with low LOP BFR.
Detailed description
The long-term goal is to identify effective self-managed therapies for military members that will return them to duty as quickly as possible. The overall objective of this project is to compare two self-managed treatment regimens for PFPS: (1) NMES-Exercise supplemented with high BFR LOP of 80% and (2) NMESExercise augmented with a low percentage of BFR LOP at 20 mmHG (BFR-sham). Each of the two treatment arms will perform a fixed exercise protocol singularly and in combination with BFR-NMES, and NMES alone.
The rationale for this study is that by limiting blood flow to an exercising limb using both active and passive exercise is expected to significantly improve lower extremity muscle strength, mobility, quality of life (QOL) and pain. The central hypothesis is that the combination of NMES/exercise of the injured leg supplemented with BFR set at 80% LOP will show significantly greater improvements in muscle strength, mobility, pain, daily activity and QOL than the NMES-Exercise with BFR set at a very low percentage of LOP at 20 mmHG. To test this hypothesis, the investigators will address the following specific aims:
a1. To determine whether self-managed NMES-Exercise program supplemented with a high BFR of 80% LOP (limb occlusion pressure) is significantly more efficacious than NMES-Exercise with low BFR LOP set at 20 mmHG (sham) in improving muscle strength of the lower extremity, daily physical activity and mobility. Muscle strength will be measured by isometric peak torque of the left and right knee and hip posterolateral stabilizers; physical activity will be measured by steps walked and energy (kcal) expenditure/day; and mobility by time to complete a stair climb, step down test, distance walked in 6 minutes, and number of times to complete the chair rise.
a2. To determine whether NMES-Exercise with high LOP BFR therapy improves QOL and PFPS symptoms significantly more than NMES-Exercise with low LOP BFR. QOL will be measured by the SF-12 Health Survey and the Center for Epidemiological Studies-Depression (CES-D) scale. Symptoms of PFPS will be quantified by the Anterior Knee Pain Scale and IKDC subjective knee form.
The investigators expect to demonstrate that these combined multimodality therapies of a self-managed NMES-Exercise program supplemented with high (80%) LOP BFR-NMES-Exercise is more efficacious than a low percentage of LOP BFR-NMES-Exercise (sham). Positive results will translate into therapy options for PFPS that can be used by health care providers to accelerate rehabilitation, speed return to world-wide duty status, decrease symptoms, and lower medical costs. Moreover, these approaches are safe, easy to use and non-pharmacological.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- 84 (anticipated) participants will be assigned to one of two parallel groups. Sample size was determined using 1) an alpha level of 0.05 and power of 0.80; 2) review of PFPS literature and data from pilot work; and 3) calculation of effect sizes for key variables from previous studies that addressed the Specific Aims. For the primary outcome variable of strength, the sample size calculated was 35 subjects per groups (70 total subjects) with an effect size of 0.52. For the outcomes measures of function, mobility and pain, assuming that standard errors will be similar to those observed in our previous work, the sample size of 35 per group is sufficient to detect the expected mean changes. To account for dropouts, the investigators inflated the sample size by 20%, for a total of 42 subjects per group and a total sample size of 84.
| Arm | Type | Receives |
|---|---|---|
| NMES and exercise supplemented with high BFR | Experimental | Device: NMES and exercise supplemented with high BFRAll participants receive a standard exercise rehabilitation protocol for PFPS to be performed singularly at home/work, synchronously with NMES and concurrently with NMES/BFR in-clinic. The PFPS exercises teach muscle strengthening exercises and self-management strategies to prevent recurrence. Participants will receive a portable battery-operated device, KneeHAB® XP (Bio-Medical Research, Galway, Ireland) with the thigh garment. NMES training will consist of 20-minute stimulation sessions performed concurrently with the exercise program. For the BFR training, the automatic Delfi's PTS Personalized Tourniquet System for Blood Flow Restriction (Delfi Medical, Vancouver, BC, Canada) with variable contour nylon cuff (11.5 cm × 86 cm, 2.5 mm thick) will be used. The Delfi PTS system automatically adjusts pressure around the set occlusion pressure. The High BFR group will have the pressure set at 80% of limb occlusion pressure. |
| NMES and exercise supplemented with low BFR | Sham comparator | Device: NMES and exercise supplemented with low BFRAll participants receive a standard exercise rehabilitation protocol for PFPS to be performed singularly at home/work, synchronously with NMES and concurrently with NMES/BFR in-clinic. The PFPS exercises teach muscle strengthening exercises and self-management strategies to prevent recurrence. Participants will receive a portable battery-operated device, KneeHAB® XP (Bio-Medical Research, Galway, Ireland) with the thigh garment. NMES training will consist of 20-minute stimulation sessions performed concurrently with the exercise program. For the BFR training, the automatic Delfi's PTS Personalized Tourniquet System for Blood Flow Restriction (Delfi Medical, Vancouver, BC, Canada) with variable contour nylon cuff (11.5 cm × 86 cm, 2.5 mm thick) will be used. The Delfi PTS system automatically adjusts pressure around the set occlusion pressure. The Low BFR group will have the pressure set at 20 mmHg. |
Who may qualify
- Ages
- 18 to 44 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Active duty military personnel who are:
- diagnosed with knee pain, categorized as anterior or retropatellar in one or both knees;
- self-reported difficulty performing at least two or more of the following activities associated with knee pain: prolonged sitting, stair climbing, running, jumping, and repetitive movements such as kneeling or squatting or stooping;
- military service member at the time of diagnosis and length of study;
- age ≥18 and <45 years; and
Key exclusion criteria (9 listed)
- fracture or injury to external knee structures such that knee extension or flexion is impaired;
- a significant co-morbid medical condition (such as severe hypertension, neurological disorder, sickle cell anemia, or pacemaker/defibrillator) in which BFR, NMES strength training, or unsupervised exercise is contraindicated and would pose a safety threat or impair ability to participate;
- previous knee surgeries (i.e., tibiofemoral, patellofemoral) excluding knee arthroscopy > 3 years;
- knee instability or recurrent patella dislocation or subluxation;
- inability or unwillingness to participate in an exercise or strengthening program;
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| NMES and exercise supplemented with high BFRThe BFR-NMES-Exercise training consists of 20-min sessions performed concurrently with NMES and exercise in the clinic 2x a week for a total of 18 in-clinic sessions. Using the Delfi PTS Personalized Tourniquet System for Blood Flow Restriction at 80% of LOP, the participant performs 4 exercise sets of 60 repetitions (5 seconds ea) for 5 minutes, with a 1-minute BFR deflation between sets. The standard exercise rehabilitation protocol for PFPS combines open chain and closed chain quadriceps strengthening exercises: active straight leg raises, quadriceps straightening, step up, and squats. NMES training consists of 20-minute sessions: a 2-min warm-up, 15-min work-out, and a 3-min cool down using the KneeHAB® XP "Multipath" stimulation system which changes the current pathways between the electrodes for preset periods within each pulse, allowing for higher stimulation intensities that maximizes muscle fibre recruitment and minimizes muscle fatigue. | Device | NMES and exercise supplemented with high BFR |
| NMES and exercise supplemented with low BFRThe BFR-NMES-Exercise training consists of 20-min sessions performed concurrently with NMES and exercise in the clinic 2x a week for a total of 18 in-clinic sessions. Using the Delfi PTS Personalized Tourniquet System for Blood Flow Restriction at 20mmHG venous pressure (no blood flow restricted), the participant performs 4 exercise sets of 60 repetitions (5 seconds ea) for 5 minutes, with a 1-minute BFR deflation between sets. The standard exercise rehabilitation protocol for PFPS combines open chain and closed chain quadriceps strengthening exercises: active straight leg raises, quadriceps straightening, step up, and squats. NMES training consists of 20-minute sessions: a 2-min warm-up, 15-min work-out, and a 3-min cool down using the KneeHAB® XP "Multipath" stimulation system which changes the current pathways between the electrodes for preset periods within each pulse, allowing for higher stimulation intensities that maximizes muscle fibre recruitment and minimizes muscle fatigue. | Device | NMES and exercise supplemented with low BFR |
Primary outcome
Change in Lower Extremity Muscle Strength- Extension
Time frame: Time Frame: 9 weeks
Strength of knee extension muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The participant will be positioned with a small towel roll placed distally to support the femur in 90-degree hip flexion. The participant's knee will be placed in 70º knee flexion using a goniometer. The distance from the tibial tuberosity (TT) to the superior aspect of the medial malleolus will be measured. For knee extension, the first measurement will be taken using standard NMMT protocol (0.6 X the distance from the tibial tuberosity to the superior aspect of the medial malleolus). Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Change in Lower Extremity Muscle Strength- Flexion
Time frame: Time Frame: 9 weeks
Strength of knee flexion muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The participant will be positioned with a small towel roll placed distally to support the femur in 90-degree hip flexion. The participant's knee will be placed in 70º knee flexion using a goniometer. The distance from the tibial tuberosity (TT) to the superior aspect of the medial malleolus will be measured. For knee flexion, the NMMT will be positioned 0.6X distance from TT to superior border of medial malleolus on the dorsal limb side. Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Change in Lower Extremity Muscle Strength- Hip Posterolateral Stabilizer
Time frame: Time Frame: 9 weeks
Strength of hip posterolateral stabilizer muscle groups will be measured using the Nicholas Manual Muscle Tester (NMMT). The hip stability isometric test (HipSIT) will be measured using the NMMT as described by Almeida et al. Participants will perform three maximal efforts holding contractions for 4 seconds, separated by 30-sec rest; the highest value of the will be accepted (kg).
Change in Mobility- Timed Stair Climb Test
Time frame: Time Frame: 9 weeks
Tests the activity of stair climbing. The test will begin with participants ascending up four steps (6-inch rise, 11.5-inch run) to a 30-inch square platform, and then descending to the bottom of the stairs. Participants will climb the stairs at a self-selected pace using the handrails if necessary. Each participant will complete two complete rounds, if possible, and the two times will be averaged to produce one score.
Change in Mobility- Forward Step-Down Test
Time frame: Time Frame: 9 weeks
This is a specific function test for PFPS, putting weight bearing stress during a movement that mimics stair descent. The test is performed from a 20 cm (8 inch) high platform. The participant steps forward and down toward the floor from a single-leg stance with a straight knee (hands on hips). The knee of the stance leg bends until the opposite foot lightly touches the floor with the heel and then returns to full knee extension. The heel touching the floor is not to be used to accelerate back onto the platform. This counts as one repetition; the number of repetitions performed in 30 seconds is recorded. Both legs are tested separately.
Change in Mobility- 30-Second Chair Stand Test
Time frame: Time Frame: 9 weeks
This assesses lower-body strength mimicking squatting. The participant completes as many full stands as possible in 30 seconds. The participant sits in the middle of the chair, feet flat on the floor with arms crossed at the wrists and held against the chest. When instructed, the participant rises to a full stand, and then returns to a fully seated position. The number of completed rises will be recorded.
Change in Mobility- 6-Minute Walk Test
Time frame: Time Frame: 9 weeks
This is a submaximal test of functional capacity and measures the distance a participant walks at a "fast" pace over a 6-minute period. Participants will "walk as quickly as you can" with the opportunity to stop and rest if required. This test measures functional capacity of walking.
Change in Physical Activity- Steps walked
Time frame: Time Frame: 9 weeks
Physical activity will be measured using the Fitbit Charge (San Francisco, CA). The Charge is a wrist-worn, three-axis accelerometer that measures steps walked, distance traveled, energy expenditure and floors climbed. Steps walked will be assessed as the number of steps walked in 24 hours. Baseline data will be ascertained by wearing the Charge for 3 days while maintaining a typical activity pattern. Subsequently, the device will be worn daily for 9 weeks.
Change in Physical Activity- Energy expenditure
Time frame: Time Frame: 9 weeks
Physical activity will be measured using the Fitbit Charge (San Francisco, CA). The Charge is a wrist-worn, three-axis accelerometer that measures steps walked, distance traveled, energy expenditure and floors climbed. Energy expenditure will be assessed as the calories expended in 24 hours. Baseline data will be ascertained by wearing the Charge for 3 days while maintaining a typical activity pattern. Subsequently, the device will be worn daily for 9 weeks.
4 secondary outcomes
Change in Symptoms of PFPS- Knee pain limiting actiivty (AKPS)
Time frame: Time Frame: 9 weeks
Change in Symptoms of PFPS- Pain at rest and post-activity (VAS)
Time frame: Time Frame: 9 weeks
Change in Symptoms of PFPS- Knee Injury and Disability (IKDC)
Time frame: Time Frame: 9 weeks
Change in Quality of Life- Overall: The Short Form Health Survey Version 2.0 (SF-12v2) Health Survey
Time frame: Time Frame: 9 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jun 2022.
- Derived from this study: PubMed 42560220Talbot LA, Webb L, Ramirez VJ, Taylor-Clark TM, Morrell CH, Enochs K, Fagan M, Hillner J Sr, Scallan RM, Metter EJ. Effects of Neurostimulation With Blood Flow Restriction on Physical and Mental Health-Related Quality of Life in Military Personnel With Patellofemoral Pain Syndrome: Secondary Data Analysis. Mil Med. 2026 Aug 1;191(Supplement_1):36-43. doi: 10.1093/milmed/usaf630.
- Derived from this study: PubMed 36807977Talbot LA, Webb L, Morrell C, Enochs K, Hillner J, Fagan M, Metter EJ. Electromyostimulation With Blood Flow Restriction for Patellofemoral Pain Syndrome in Active Duty Military Personnel: A Randomized Controlled Trial. Mil Med. 2023 Jul 22;188(7-8):e1859-e1868. doi: 10.1093/milmed/usad029. Epub 2023 Feb 20.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Laura A Talbot, PhD, EdD, RN principal investigator
University of Tennessee Health Sciences Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing NMES and exercise supplemented with high BFR and NMES and exercise supplemented with low BFR in people with Patellofemoral Pain Syndrome, run by University of Tennessee at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 Jun 2022. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Lower Extremity Muscle Strength- Extension (time frame: Time Frame: 9 weeks). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04086615, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Jun 2022; AzTrials last refreshed its copy on 8 Nov 2026.