tDCS for Pain Modulation in Knee Osteoarthritis

NCT07291791 | Completed

• 1 other identifier: tDCS121225
• Study Type: interventional
• Target: 102
• Locations: 1 country
• Sites: 1

Brief Summary

Knee osteoarthritis (KOA) is a common condition that causes long-lasting knee pain and difficulty with daily activities. Many patients have pain that is stronger than expected from joint changes because the nervous system becomes more sensitive to pain. Transcranial direct current stimulation (tDCS) is a non-invasive technique that uses a small electrical current applied to the scalp to help reduce pain sensitivity. This study will test whether active tDCS over the primary motor cortex can reduce pain and improve function in people with knee osteoarthritis. A total of 102 participants will be randomly assigned to receive either active tDCS or sham (placebo) stimulation. All participants will receive 15 sessions over three weeks. We will measure pain intensity, pain sensitivity, physical function, depression, cognition, and quality of life before the treatment, after the 3-week treatment program, and again at the 1-month follow-up.

Conditions

Knee Osteoarthritis

Keywords

Knee Pain; Osteoarthritis; tDCS; Neuromodulation; Central Sensitization

Outcome Measures

Primary Outcomes (1)

• Change in Pain Intensity (VAS and BPI Scores)

  Pain intensity will be assessed using the Visual Analogue Scale (VAS) and the Brief Pain Inventory (BPI). The primary outcome is the change in VAS and BPI pain scores from baseline to immediately post-intervention and one-month follow-up.

  Baseline, immediately after the 15-session intervention, and at 1-month follow-up.

Secondary Outcomes (9)

• Change in Pressure Pain Threshold (PPT)

  Baseline, immediately after completing the 15 treatment sessions, and at 1-month follow-up

• Change in Central Sensitization using Central Sensitization Inventory (CSI) Score

  Baseline, immediately after the 15-session intervention, and at 1-month follow-up

• Change in Conditioned Pain Modulation (CPM) Efficiency

  Baseline, immediately after the 15-session intervention, and at 1-month follow-up

• Change in neuropathic-like pain features (PainDETECT Score)

  Baseline, immediately after the 15-session intervention, and at 1-month follow-up

• Change in physical function (WOMAC Score)

  Baseline, immediately after the 15-session intervention, and at 1-month follow-up

Study Arms (2)

Active tDCS

EXPERIMENTAL

Participants in this arm (active tDCS group) will receive active anodal transcranial direct current stimulation (tDCS) applied over the primary motor cortex (M1). Stimulation will be delivered at 2 mA for 20 minutes per session, for a total of 15 sessions (five sessions per week for three consecutive weeks). Electrode placement follows standardized M1 montage protocols.

Device: Transcranial Direct Current Stimulation (tDCS)

Sham tDCS

SHAM COMPARATOR

Participants in this arm (sham tDCS group) will receive sham tDCS using identical electrode placement and device settings as the active tDCS arm. The current will be applied for approximately 30 seconds and then gradually ramped down to zero to mimic the initial tingling sensation of active stimulation while delivering no effective stimulation. A total of 15 sessions will be administered over three weeks.

Device: Transcranial Direct Current Stimulation (tDCS)

Interventions

Transcranial Direct Current Stimulation (tDCS) DEVICE

Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation technique that applies low-intensity direct current to modulate cortical excitability. In this trial, stimulation is delivered over the primary motor cortex (M1) using saline-soaked sponge electrodes. For the active arm, anodal tDCS is applied at 2 mA for 20 minutes per session, for 15 sessions over three weeks. For the sham arm, the same electrode placement and device settings are used, but the current is ramped down after approximately 30 seconds to mimic the sensation of active stimulation without producing neuromodulatory effects.

Also known as: tDCS

Active tDCS; Sham tDCS

Eligibility Criteria

• Age: 35 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Diagnosis of knee osteoarthritis (KOA) according to the American College of Rheumatology (ACR) clinical criteria.
• Adults of both sexes aged 35 years or older.
• Clinical knee pain persisting for at least 3 months.
• Average knee pain intensity ≥ 4/10 on the Numerical Rating Scale (NRS; 0-10) during the previous 24 hours, with one dominant affected knee.
• Central sensitization phenotype: impaired conditioned pain modulation (CPM), defined as no change or a reduction in pressure pain threshold (PPT) after the conditioning stimulus, corresponding to a PPT ratio ≥ 1 (pre-to-post stimulus).
• Prior pharmacological pain management with NSAIDs and/or SNRIs discontinued due to adverse effects, intolerance, or contraindications, and able to complete the required washout period (2 weeks for NSAIDs and 4 weeks for SNRIs) before baseline assessment.
• Able and willing to provide written informed consent and comply with study procedures.

You may not qualify if:

• Participants will be excluded if they have any condition that could affect cortical excitability, confound outcome measures, or interfere with tDCS safety, including:
• Other chronic pain conditions associated with central sensitization (e.g., fibromyalgia).
• Inflammatory arthropathies (e.g., rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus).
• Neuropathic pain syndromes (e.g., lumbar or cervical radiculopathy).
• Any clinically significant or unstable systemic disease (cardiovascular, hepatic, renal, or metabolic disorders).
• Pregnancy or active malignancy.
• Neurological or psychiatric disorders including epilepsy, history of syncope, traumatic brain injury with residual deficit, or major depressive disorder.
• Current participation in physiotherapy, electrotherapy, or exercise rehabilitation programs.
• Metallic implants or implanted electrical devices (e.g., pacemakers, cochlear implants, deep brain stimulators).
• Cognitive impairment interfering with understanding instructions or providing informed consent.
• Dermatological contraindications at stimulation or testing sites (e.g., open wounds, infection, irritation).
• History of alcohol or substance abuse, or current use of centrally acting medications that alter cortical excitability (e.g., benzodiazepines).

Sponsors & Collaborators

• Suez Canal University: lead

Study Sites (1)

Suez Canal University Hospitals - Physical Medicine, Rheumatology and Rehabilitation Outpatient Clinics

Ismailia, 41522, Egypt

Location

MeSH Terms

Conditions

Osteoarthritis, Knee; Osteoarthritis

Interventions

Transcranial Direct Current Stimulation

Condition Hierarchy (Ancestors)

Arthritis; Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases

Intervention Hierarchy (Ancestors)

Electric Stimulation Therapy; Therapeutics; Convulsive Therapy; Psychiatric Somatic Therapies; Behavioral Disciplines and Activities; Electroshock; Psychological Techniques

Study Officials

• Nourhan E. Elkaraly, M.B.B.Ch.2015; MSc (PMRR)2020

  Suez Canal University, Faculty of Medicine

  PRINCIPAL INVESTIGATOR

• Aziza S. Omar, M.D.

  Suez Canal University, Faculty of Medicine

  STUDY CHAIR

• Ahmed F. Genedy, M.D.

  Faculty of Medicine, Armed Forces Military Academy

  STUDY CHAIR

• Samah I. Nasef, M.D.

  Suez Canal University, Faculty of Medicine

  STUDY CHAIR

• Maha E. Ibrahim, M.D.

  Suez Canal University, Faculty of Medicine

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: This is a participant- and assessor-blinded, sham-controlled clinical trial. All tDCS sessions will be delivered by a trained physiotherapist who is aware of group allocation, while both participants and the outcome assessor remain blinded. To maintain allocation concealment, the physiotherapist recorded each participant's assignment using coded geometric symbols, the meaning of which remained confidential until completion of data collection. Active and sham tDCS will be applied using identical electrode placements and device settings. In the sham condition, the current will be delivered for approximately 30 seconds and then gradually ramped down to zero to reproduce the initial tingling sensation of active stimulation, ensuring effective participant blinding. After all data are collected, group identities will be unmasked for statistical analysis.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Two parallel arms: active tDCS and sham tDCS.

Study Record Dates

• First Submitted: December 5, 2025
• First Posted: December 18, 2025
• Study Start: December 20, 2025
• Primary Completion: May 20, 2026
• Study Completion: May 31, 2026
• Last Updated: June 2, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

EG (1)