Joint pain is one of the uses red light is studied for. For knee osteoarthritis, one review pooled 22 placebo-controlled trials, which makes it a fair test of the claims.
This article covers what those trials pooled together show. It sits under our overview of red light therapy benefits. It is general information, not medical advice: knee pain has many causes, and a doctor should look at yours.
Short answer: a 2019 meta-analysis of 22 placebo-controlled trials with 1,063 people found low-level laser therapy reduced knee osteoarthritis pain by 14.23 mm on a 0 to 100 mm scale, and by 18.71 mm at recommended doses. No trial reported side effects. However, the trials used clinical lasers at set doses, and guidelines didn’t recommend the treatment at the time.
What the meta-analysis found
Stausholm (2019) found a consistent effect. The review in BMJ Open pooled 22 randomized placebo-controlled trials with 1,063 people with knee osteoarthritis. Pain was measured on a visual analog scale (VAS), a 100 mm line where 0 is no pain.
| Measure | Pain reduction vs placebo (VAS, 0 to 100 mm) |
|---|---|
| End of therapy, all trials | 14.23 mm (95% CI 7.31 to 21.14) |
| 1 to 12 weeks after, all trials | 15.92 mm |
| End of therapy, recommended doses | 18.71 mm |
| 2 to 12 weeks after, recommended doses | 23.23 mm |
| Peak, 2 to 4 weeks after therapy | 31.87 mm |
Disability also fell significantly, and no trial reported adverse events. The authors concluded:
“LLLT reduces pain and disability in KOA.”
Stausholm MB, et al., BMJ Open, 2019
The doses that worked
The authors name the effective settings: 4 to 8 joules per treatment spot at 785 to 860 nm, or 1 to 3 joules per spot at 904 nm. Those are near-infrared wavelengths, longer than the 630 and 660 nm red listed for panels like the MitoPRO 1000+. Red Light Therapy Wavelengths explains the difference.
Limitations: why a home panel isn’t the same
The trials used clinical lasers aimed at specific points on the knee, at measured doses. A wall panel spreads light over a wide area from a distance, and most listings don’t give the joules your knee receives. Although the pooled result is positive, it doesn’t transfer to a panel automatically.
The review also has gaps its authors name: no quality-of-life analysis, and no head-to-head comparison with other treatments. At the time, they noted, major guidelines did not recommend low-level laser therapy for knee osteoarthritis.
Cleveland Clinic lists knee osteoarthritis, tendonitis, and carpal tunnel syndrome among conditions under investigation for red light, not established uses.
Here’s what the spec sheet won’t tell you. A panel’s wattage isn’t its dose. Without irradiance and treatment distance, you can’t work out joules per spot.
My rule of thumb: if knee pain is the reason to buy, ask a physical therapist about clinical laser therapy first.
Bottom line: knee osteoarthritis has some of the better evidence for light therapy, from 22 placebo-controlled trials. The trials used clinical lasers at set near-infrared doses, which home panels may not match. For the other claims, see the red light therapy benefits overview linked above.
Sources
- Stausholm MB, et al., “Efficacy of low-level laser therapy on pain and disability in knee osteoarthritis: systematic review and meta-analysis of randomised placebo-controlled trials,” BMJ Open, 2019 (abstract): pubmed.ncbi.nlm.nih.gov
- Cleveland Clinic, “Red Light Therapy,” medically reviewed December 1, 2021: my.clevelandclinic.org