This study aims to determine analgesic and anti-inflammatory effects of dual-wavelength PBM in people with symptomatic knee OA.

Inclusion Criteria:

• Clinically confirmed knee osteoarthritis (OA) based on the American College of Rheumatology (ACR) criteria with symptomatic pain for ≥ 3 months
• Average knee-pain intensity ≥ 30/100 on both the Daily Symptom Diary (DSD) run-in and CATI
• Age ≥ 50 years
• Ability to give informed consent, attend visits, and complete ≥ 4 of 7 DSD entries pre-randomization
• Capacity to perform all study tasks (Timed Up-and-Go, knee OA assessments, blood draw, questionnaires, etc)

Exclusion Criteria:

Systemic and Rheumatic Disease

• Active systemic rheumatic condition (e.g., rheumatoid arthritis, systemic lupus erythematosus)
• Fibromyalgia with pain outside the knee that is equal to or worse than knee pain

Musculoskeletal History

• Clinically significant surgery on the index knee (e.g., arthroplasty, osteotomy)
• Knee surgery within the past 6 weeks
• Intra-articular injection to the index knee within the past 14 days

Medication Use

• Daily opioid therapy
• Hypersensitivity to PBM
• Migraine triggered by light
• Open wounds, skin infections, eczema, burns, or other dermatologic conditions at or near the treatment application site.
• New prescription or OTC analgesic, non-pharmacologic pain therapy, chemotherapy, or radiation therapy initiated ≤ 30 days before screening

Cardiovascular Safety

• Uncontrolled hypertension (SBP > 150 mmHg or DBP > 95 mmHg)
• Unstable or activity-limiting cardiovascular or peripheral arterial disease

Neurological and Psychiatric Conditions

• Diagnosed neurological disorder (e.g., Parkinson's disease, multiple sclerosis, epilepsy)
• History or evidence of stroke or moderate-severe traumatic brain injury
• Serious psychiatric illness requiring hospitalization within the past 12 months
• Active suicidal ideation
• Current substance-use disorder or past hospitalization for substance-use treatment

Dermatologic Conditions

• Compromised skin integrity at or near the treatment site (e.g., open wounds, active rash, dermatitis, burns, ulcers, eczema, infection) interfering with topical treatment or PBM

Other Metabolic Conditions

• Uncontrolled diabetes
• Diabetes-related complications (e.g., peripheral neuropathy, severe nephropathy, chronic ulcers at treatment site)

Other Pain Conditions

• Chronic pain at another body site more severe than knee pain

General Health and Cognition

• Pregnancy or lactation
• Cognitive impairment that precludes informed consent or task participation

This is a small, internally funded pilot study intended to assess feasibility and preliminary outcomes. IPD sharing is not planned at this stage.