An interventional study of 810 nm Light Therapy and Sham Light Therapy in Knee Pain Chronic, Synovitis of Knee and Light Therapy, sponsored by The Hong Kong Polytechnic University. Recruiting at 2 sites in 2 countries. Open to participants aged 40 Years to 80 Years. Per ClinicalTrials.gov, last updated 2025-11-26.
Sponsored by The Hong Kong Polytechnic University · Not applicable, Interventional, and Treatment
Background: Knee pain is a common complaint among middle-aged and older adults, often leading to reduced mobility and diminished quality of life. Synovitis is a major underlying cause, present in up to 80% of individuals with moderate knee pain. While light therapy has shown anti-inflammatory and analgesic effects in preclinical studies, our prior animal experiments revealed that light therapy at 810 nm significantly alleviated inflammation and pain-like behaviors. These findings suggest a potential wavelength-specific therapeutic effects. However, it remains unclear whether such effects can be replicated in humans. This study aims to evaluate the efficacy of 810 nm light therapy, compared to sham treatment, in reducing knee pain and synovitis in patients with chronic knee pain and knee synovitis.
Methods/design:
This is a randomized, placebo-controlled clinical trial involving 90 participants with chronic knee pain and ultrasound-detected synovitis. Participants will be randomized into two groups to receive 810 nm light therapy, or sham therapy, delivered twice weekly over five weeks. Primary outcomes include knee pain assessed by the Visual Analogue Scale (VAS) and synovitis assessed by ultrasound. Secondary outcomes include the Knee injury and Osteoarthritis Outcome Score (KOOS), the 30-second chair stand test, and the 40-meter fast-paced walk test. Outcome assessments will be performed at baseline, post-intervention (week 5), and at 1 month and 6 months after treatment completion. Linear mixed-effects models will be used to compare outcome changes between groups.
Discussion:
This trial will assess whether 810 nm light therapy provides clinically meaningful benefits for reducing knee pain and synovitis in humans, building on promising preclinical findings. Results from this study may support the use of near-infrared light as a safe, non-invasive, and effective intervention for synovitis-related knee pain.
53 studies on the registry are indexed under Synovitis; 12 are open to participants now.
This study's planned enrollment of 80 is above the median of 70 across 29 interventional studies indexed under Synovitis.
Browse Synovitis studies →The Hong Kong Polytechnic University is the lead sponsor of 679 studies on the registry; 257 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants receive 810 nm light therapy using a wearable device, twice per week for 5 weeks.
Device: 810 nm Light Therapy
Participants receive sham therapy with the same device that emits no therapeutic light, twice per week for 5 weeks.
Device: Sham Light Therapy
Light therapy at 810 nm, 39 J/cm², delivered via wearable device.
Identical device, no light output, delivered via wearable device.
Knee pain (Visual Analogue Scale, VAS)
Knee pain severity will be assessed using a 100-mm Visual Analogue Scale (VAS), based on average pain over the past week.
Time frame: Baseline, Week 5, 1-month follow-up, 6-month follow-up
Knee synovitis grade (Ultrasound assessment)
Knee ultrasound will be performed by an ultrasound physician with over 8 years of experience, following the published protocol (Bruyn GAW, Naredo E, Damjanov N, et al (2016) An OMERACT reliability exercise of inflammatory and structural abnormalities in patients with knee osteoarthritis using ultrasound assessment. Ann Rheum Dis 75:842-846. https://doi.org/10.1136/ann). The items measured included the maximal score for synovitis obtained at the suprapatellar or parapatellar recesses, with a range of 0-3. Grade 0 indicates no synovitis; Grade 1 represents minimal distension of the recess by abnormal internal hypoechoic or anechoic material (relative to subdermal fat tissue); Grade 2 signifies moderate distension or enlargement of the recess by abnormal internal hypoechoic or anechoic material with a flat or concave superficial limit; and Grade 3 denotes severe distension or enlargement of the recess by abnormal internal hypoechoic or anechoic material with a bulging superficial limit.
Time frame: Baseline, Week 5, 1-month follow-up, 6-month follow-up
Knee Injury and Osteoarthritis Score (KOOS)
Knee Injury and Osteoarthritis Score (KOOS) that includes subdomains of pain (9 items), other symptoms (7 items), function and daily living (short PS version 7 items), and knee-related quality of life (4 items) will be used in this study. A Likert scale is used and all items have five possible answer options scored from 0 (No problems) to 4 (Extreme problems) and each of the five scores is calculated as the sum of the items included. Scores are transformed to a 0-100 scale, with zero representing extreme knee problems and 100 representing no knee problems as common in orthopaedic scales and generic measures. Scores between 0 and 100 represent the percentage of total possible score achieved.
Time frame: Baseline, Week 5, 1-month follow-up, 6-month follow-up
Lower limb function (30-second chair stand test)
A standard chair without arms will be used for the chair stand test (Dobson F, Bennell KL, Hinman RS, et al (2013) Recommended performance based tests to assess physical function in patients with hip/knee OA. Osteoarthr Cartil 8:1042-52). Participants will begin the test seated with their arms crossed over their chest. They will be instructed to stand up fully, so hips and knees are fully extended, and return to the seated position as many times as possible within 30 seconds, while keeping their arms crossed. The total number of chair stands (up and down equals one stand) completed in 30 seconds will be recorded. If a full stand has been completed at 30 seconds (i.e. standing fully erect or on the way down to the sitting position), then this final stand is counted in the total.
Time frame: Baseline, Week 5, 1-month follow-up, 6-month follow-up
Walking speed (40-meter fast-paced walk test)
The 40-meter walk test will be conducted on a marked 10-meter walkway, with cones placed 2 meters beyond each end to facilitate turning. Participants wore comfortable walking footwear. After a brief practice trial to ensure understanding, participants will be instructed to walk as quickly and safely as possible, without running, along the walkway. They turned around the cones at each end and repeated the process until completing a total distance of 40 meters, involving three turns. Timing started when participants began walking and stopped when they crossed the start line after completing the full distance. Walking speed (m/s) will be calculated by dividing 40 meters by the recorded time (Dobson F, Bennell KL, Hinman RS, et al (2013) Recommended performance based tests to assess physical function in patients with hip/knee OA. Osteoarthr Cartil 8:1042-52).
Time frame: Baseline, Week 5, 1-month follow-up, 6-month follow-up
Adverse events monitoring for light therapy
Participants will be closely monitored for adverse events (AEs) at each treatment and visit throughout the study. If any AEs occur (e.g., cutaneous irritation, redness, or itching at the treatment site), they will be documented on a separate form and reported to the principal investigators (PIs) within 24 hours. This monitoring will ensure that any adverse events are promptly addressed and that the safety of participants is prioritized throughout the study.
Time frame: Throughout the intervention period and at all follow-up visits (up to 6 months)
Plan to share: Yes — Individual participant data (IPD) that underlie the results reported in this article, after de-identification, will be shared. Data will be available upon reasonable request from qualified researchers, subject to ethics approval and data use agreement. The data will become available after the publication of the main results and will be accessible for a period of 5 years.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: De-identified individual participant data and supporting documents will be available beginning 6 months after publication of the primary results, and will be available for 5 years thereafter.
Access criteria: Data will be available to qualified researchers whose proposed use of the data has been approved by an independent review committee. Access will be provided after signing a data access agreement. Interested researchers should contact the Principal Investigator by email.
Started Jul 2025 (actual). Primary completion is estimated for May 2026, 10 months after the start.
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