Knee OsteoarthristisSPARKNCT07832669
Stimulation of Peripheral Afferents to Reduce Muscle Inhibition at the Knee
A study testing Peripheral Electrical Stimulation (PES) and Paired Pulse Electrical Stimulation (ppES) in people with Knee Osteoarthristis and Knee Pain Arthritis, run by Northeastern University.
Trial summary
Knee osteoarthritis is a leading cause of disability, and the muscle weakness that limits walking in this population arises not only from the joint itself but from afferent signals that inhibit motor drive to the thigh muscle, which is why exercise alone so often produces incomplete recovery. Read more about this study
- Who is it for?
- Ages 45 years and older
- Conditions the study is for
- Knee Osteoarthristis, Knee Pain Arthritis, Knee Pain Chronic
- What is being tested?
- Peripheral Electrical Stimulation (PES) and Paired Pulse Electrical Stimulation (ppES)
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 50 participants
- Where
- No sites listed yet
- Study dates
- Sep 2026to Sep 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 45 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- >45 years old
- Able to speak and understand English
- Unilateral or bilateral knee OA, per NICE criteria
- Age 45+ AND
- Have activity-related joint pain AND
- Have either no morning joint-related stiffness or morning stiffness that lasts no longer than 30 minutes
- Score > 3/20 on WOMAC pain scale
- If using pain medications, report >4 weeks of stable use without recent adjustments
Who cannot join
- History of lower extremity surgery.
- BMI > 40kg/m^2
- Received an intra-articular knee joint injection within the last 3 months.
- Currently pregnant.
- Currently experiencing heavy menstruation, within one month of an IUD contraceptive device (e.g. coil) being fitted or within 6 weeks after giving birth or at least three months after having a Caesarean.
- Suspected or diagnosed heart problems (e.g. arrhythmia, cardiac disturbances).
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- Use of an implanted electronic device (e.g. a cardiac pacemaker or defibrillator).
- Insulin-dependent diabetes.
- Implants in the lower limb.
- Suspected or diagnosed epilepsy or a familial history of epilepsy.
- History of neurologic or psychiatric condition (e.g. Parkinson's disease, bipolar disorder, epilepsy, etc)
- Implanted cardiac pacemaker, cochlear implant, medication pump, surgical clips or other metal (dental implants excluded).
- Use of alcohol or recreational drugs in the prior 12 hours.
- Frequent or severe headaches.
- Prior adverse reaction to transcranial magnetic stimulation.
- Altered sensation (hypo or hypersensitivity) of the skin of the thigh.
- Swollen, infected, inflamed, or damaged skin of the thigh.
- Current Use of prescription and over the counter medications will be grounds for exclusion except for:
- Contraceptive (birth control) drugs (e.g. those containing ethinyl estradiol and/or norethindrone).
- Seasonal allergy medications (e.g. cetirizine (Zyrtec), fexofenadine (Allegra), and loratadine (Claritin)).
- Antihypertensives
- Statins
- GLP-1 agonists
- Non-insulin diabetes medications (metformin)
- Thyroid medications
- Osteoporosis medications
- Respiratory medications
- Pain medications available over the counter (ibuprofen, acetaminophen, etc)
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
Samantha H Long, DPT contact
About this study
Knee osteoarthritis is a leading cause of disability, and the muscle weakness that limits walking in this population arises not only from the joint itself but from afferent signals that inhibit motor drive to the thigh muscle, which is why exercise alone so often produces incomplete recovery. This project examines whether brief, non-invasive electrical stimulation of a nerve behind the knee can reduce inhibition and restore muscle coordination while walking in adults with knee osteoarthritis. Establishing this effect would identify a modifiable neural target that current rehabilitation does not address, with the potential to improve physical function and independence for the millions of adults living with this condition.
Read the detailed description
Knee osteoarthritis affects more than 14 million adults in the United States and is a leading cause of disability. Its most disabling consequence is not joint degeneration alone but persistent quadriceps dysfunction. Afferent signals arising from the painful joint inhibit the descending motor drive that activates the muscle, so voluntary activation remains incomplete. Exercise therapy, the mainstay of care, therefore produces strength gains of only 10 to 20 percent against the 30 to 40 percent required for meaningful clinical benefit, and patients walk with rigid, co-contracted movement patterns that concentrate joint loading and accelerate degeneration. Existing interventions address either pain or motor retraining; none target the cortical circuits in which the two interact. This study tests whether paired-pulse electrical stimulation (ppES) of the tibial nerve can reduce that inhibition. ppES delivers two stimuli in rapid succession: the first activates sensory afferents projecting to the primary somatosensory cortex, and the second, delivered at a precisely timed interval, induces heterosynaptic depression of that transmission, in turn reducing sensory-driven inhibition of motor output. Applied at the tibial nerve, ppES acts on the sensorimotor integration that governs quadriceps activation during walking. Twenty adults with knee osteoarthritis will each complete two single-session visits separated by at least seven days, receiving active ppES at one visit and sham stimulation at the other in randomized order, with participants and outcome assessors blinded. At each visit, before intervention and again immediately and 30 minutes afterward, we will measure short-latency afferent inhibition of the quadriceps motor pathway and quadriceps-hamstrings co-contraction during treadmill walking, the two primary outcomes. Somatosensory evoked potentials and modular organization of gait will be measured as secondary outcomes. Aim 1 will determine whether ppES reduces sensorimotor inhibition and co-contraction relative to sham. Aim 2 will determine whether baseline pain sensitization, cortical sensory processing, and sensorimotor inhibition predict the magnitude and variability of individual response. Establishing that this circuit is modifiable would identify a rehabilitation target that current care does not address and would provide the mechanistic evidence and effect-size estimates required for a trial of ppES as an adjunct to exercise.
- Conditions
- Knee Osteoarthristis, Knee Pain Arthritis, Knee Pain Chronic
- Being tested
- Peripheral Electrical Stimulation (PES), Paired Pulse Electrical Stimulation (ppES)
- Keywords
- quadriceps activation, muscle activation, pain, physical function, neurophysiology, motor control, neuromuscular
- Medical subject headings
- Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Peripheral Electrical Stimulation (PES)Other
Participants will receive a single session intervention of single pulses of electrical stimulation to the tibial nerve at a below motor threshold intensity. These pulses will be delivered with a pulse width of 1000 microseconds, delivered at 20 Hz frequency. This intervention will last approximately 30 minutes and deliver 24,000 stimulation pulses.
Paired Pulse Electrical Stimulation (ppES)Other
Participants will receive a single session intervention of pairs of electrical stimulation pulses delivered to the tibial nerve. These pairs will use pulses of 1000 microseconds duration, separated by a 5 millisecond interstimulus interval, delivered at a frequency of 10Hz. Participants will receive 12,000 stimulation pairs during an intervention lasting approximately 30 minutes.
| Study group | Role | What they receive |
|---|---|---|
| Paired-Pulse Electrical Stimulation Intervention | Experimental | Not described Receives: Other: Paired Pulse Electrical Stimulation (ppES) |
| Peripheral Electrical Stimulation | Sham comparator | Not described Receives: Other: Peripheral Electrical Stimulation (PES) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Short-latency Afferent Inhibition Ratio
Measuring change in short-latency afferent inhibition (SAI) ratio of the motor cortex controlling quadriceps muscle excitability across timepoints
Measured: Before, immediately after, and 30 minutes after intervention at each study session
Change in Muscle Co-Activation Percentage During Treadmill Walking
Measuring change in co-activation percentage of quadriceps and hamstring muscle pairs during treadmill walking across timepoints
Measured: Before, immediately after, and 30 minutes after intervention at each study session
Secondary outcomes (2)
Change in Somatosensory Evoked Potentials Amplitude
Measuring change in somatosensory evoked potentials (SEPs) amplitude measured in the sensory cortex in response to peripheral electrical stimulation across timepoints
Measured: Before, immediately after, and 30 minutes after intervention at each study session
Change in Dynamic Motor Control Index of Gait During Treadmill Walking
Measuring change in the organization of motor control strategies, in terms of dynamic motor control index, during treadmill walking across timepoints
Measured: Before, immediately after, and 30 minutes after intervention at each study session
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Sep 2026
- Study startSep 2026 (estimated)
- Primary completionSep 2027 (estimated)
- Study completionSep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Knee OsteoarthristisStudies 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
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Northeastern University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07832669
- Sponsor's protocol ID
- 25-12-17
- Acronym
- SPARK
- Status last verified
- Sep 2026
- First submitted
- 3 Sep 2026
- Last updated
- 22 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Stimulation of Peripheral Afferents to Reduce Muscle Inhibition at the Knee
- ClinicalTrials.gov ID
- NCT07832669
- Acronym / sponsor ID
- SPARK / 25-12-17
- Conditions
- Knee Osteoarthristis, Knee Pain Arthritis, Knee Pain Chronic
- Keywords
- quadriceps activation, muscle activation, pain, physical function, neurophysiology, motor control, neuromuscular
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- Northeastern UniversityUniversity, hospital or other
- Study start
- Sep 2026 (estimated)
- Primary completion
- Sep 2027 (estimated)
- Study completion
- Sep 2027 (estimated)
- First posted
- 22 Sep 2026 (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.
Knee osteoarthritis is a leading cause of disability, and the muscle weakness that limits walking in this population arises not only from the joint itself but from afferent signals that inhibit motor drive to the thigh muscle, which is why exercise alone so often produces incomplete recovery. This project examines whether brief, non-invasive electrical stimulation of a nerve behind the knee can reduce inhibition and restore muscle coordination while walking in adults with knee osteoarthritis. Establishing this effect would identify a modifiable neural target that current rehabilitation does not address, with the potential to improve physical function and independence for the millions of adults living with this condition.
Detailed description
Knee osteoarthritis affects more than 14 million adults in the United States and is a leading cause of disability. Its most disabling consequence is not joint degeneration alone but persistent quadriceps dysfunction. Afferent signals arising from the painful joint inhibit the descending motor drive that activates the muscle, so voluntary activation remains incomplete. Exercise therapy, the mainstay of care, therefore produces strength gains of only 10 to 20 percent against the 30 to 40 percent required for meaningful clinical benefit, and patients walk with rigid, co-contracted movement patterns that concentrate joint loading and accelerate degeneration. Existing interventions address either pain or motor retraining; none target the cortical circuits in which the two interact. This study tests whether paired-pulse electrical stimulation (ppES) of the tibial nerve can reduce that inhibition. ppES delivers two stimuli in rapid succession: the first activates sensory afferents projecting to the primary somatosensory cortex, and the second, delivered at a precisely timed interval, induces heterosynaptic depression of that transmission, in turn reducing sensory-driven inhibition of motor output. Applied at the tibial nerve, ppES acts on the sensorimotor integration that governs quadriceps activation during walking. Twenty adults with knee osteoarthritis will each complete two single-session visits separated by at least seven days, receiving active ppES at one visit and sham stimulation at the other in randomized order, with participants and outcome assessors blinded. At each visit, before intervention and again immediately and 30 minutes afterward, we will measure short-latency afferent inhibition of the quadriceps motor pathway and quadriceps-hamstrings co-contraction during treadmill walking, the two primary outcomes. Somatosensory evoked potentials and modular organization of gait will be measured as secondary outcomes. Aim 1 will determine whether ppES reduces sensorimotor inhibition and co-contraction relative to sham. Aim 2 will determine whether baseline pain sensitization, cortical sensory processing, and sensorimotor inhibition predict the magnitude and variability of individual response. Establishing that this circuit is modifiable would identify a rehabilitation target that current care does not address and would provide the mechanistic evidence and effect-size estimates required for a trial of ppES as an adjunct to exercise.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Paired-Pulse Electrical Stimulation Intervention | Experimental | Other: Paired Pulse Electrical Stimulation (ppES) |
| Peripheral Electrical Stimulation | Sham comparator | Other: Peripheral Electrical Stimulation (PES) |
Who may qualify
- Ages
- 45 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- >45 years old
- Able to speak and understand English
- Unilateral or bilateral knee OA, per NICE criteria
- Score > 3/20 on WOMAC pain scale
- If using pain medications, report >4 weeks of stable use without recent adjustments
Key exclusion criteria (28 listed)
- History of lower extremity surgery.
- BMI > 40kg/m^2
- Received an intra-articular knee joint injection within the last 3 months.
- Currently pregnant.
- Currently experiencing heavy menstruation, within one month of an IUD contraceptive device (e.g. coil) being fitted or within 6 weeks after giving birth or at least three months after having a Caesarean.
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 |
|---|---|---|
| Peripheral Electrical Stimulation (PES)Participants will receive a single session intervention of single pulses of electrical stimulation to the tibial nerve at a below motor threshold intensity. These pulses will be delivered with a pulse width of 1000 microseconds, delivered at 20 Hz frequency. This intervention will last approximately 30 minutes and deliver 24,000 stimulation pulses. | Other | Peripheral Electrical Stimulation |
| Paired Pulse Electrical Stimulation (ppES)Participants will receive a single session intervention of pairs of electrical stimulation pulses delivered to the tibial nerve. These pairs will use pulses of 1000 microseconds duration, separated by a 5 millisecond interstimulus interval, delivered at a frequency of 10Hz. Participants will receive 12,000 stimulation pairs during an intervention lasting approximately 30 minutes. | Other | Paired-Pulse Electrical Stimulation Intervention |
Primary outcome
Change in Short-latency Afferent Inhibition Ratio
Time frame: Before, immediately after, and 30 minutes after intervention at each study session
Measuring change in short-latency afferent inhibition (SAI) ratio of the motor cortex controlling quadriceps muscle excitability across timepoints
Change in Muscle Co-Activation Percentage During Treadmill Walking
Time frame: Before, immediately after, and 30 minutes after intervention at each study session
Measuring change in co-activation percentage of quadriceps and hamstring muscle pairs during treadmill walking across timepoints
2 secondary outcomes
Change in Somatosensory Evoked Potentials Amplitude
Time frame: Before, immediately after, and 30 minutes after intervention at each study session
Change in Dynamic Motor Control Index of Gait During Treadmill Walking
Time frame: Before, immediately after, and 30 minutes after intervention at each study session
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Sep 2026.
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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.
Samantha H Long, DPT contact
Questions about this trial
What is this clinical trial studying?
A study testing Peripheral Electrical Stimulation (PES) and Paired Pulse Electrical Stimulation (ppES) in people with Knee Osteoarthristis and Knee Pain Arthritis, run by Northeastern University.
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 8 inclusion and 28 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: opening soon, as of the sponsor's last update on 22 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact David A Sherman, PhD (401-225-1233, da.sherman@northeastern.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Short-latency Afferent Inhibition Ratio (time frame: Before, immediately after, and 30 minutes after intervention at each study session). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 22 Sep 2026.