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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
80
Light therapy at 810 nm, 39 J/cm², delivered via wearable device.
Identical device, no light output, delivered via wearable device.
Buji Community Service Center, Longgang District
Shenzhen, China
RECRUITINGThe Hong Kong Polytechnic University
Hong Kong, Hong Kong
NOT_YET_RECRUITINGKnee 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)
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.