Red Light Therapy for Knee Pain: Scientific Evidence

46 adolescents aged 15 to 18 with pain at the front of the knee took part in a randomized controlled trial published in 2025 that tested whether adding monochromatic infrared energy to standard physical therapy could produce better outcomes than physical therapy alone. The 2 groups were assessed on pain, balance, functional status, and quality of life before and after 12 weeks of treatment: the active group received standard physical therapy plus monochromatic infrared energy (890 nm, 6.24 W) applied to both knees for 40 minutes per session 3 times a week, while the control group received the same physical therapy program without the infrared device. Across all outcomes, the infrared energy group showed significantly better results than the control group, with greater pain reduction, improved balance in multiple directions, better functional status, and higher quality of life scores.

A systematic review and meta-analysis published in 2025 pooled data from 8 randomized controlled trials to evaluate whether photobiomodulation (PBM) could reduce pain and improve function in patients with pain at the front of the knee. The 340 participants across all 8 trials received PBM using a range of wavelengths from 590 to 1064 nm at fluences from 1.53 to 180 J/cm2, combined with exercise, and were compared against control groups on pain and physical function outcomes. The review reported that PBM was associated with significantly greater pain reduction and better physical function than control treatments, though the researchers noted that the overall quality of evidence was very low due to inconsistency across studies, and that larger and better-designed trials are needed before firm conclusions can be drawn.

The active laser group and the sham group both followed the same exercise program in a randomized controlled trial published in 2025, but only the laser acupuncture (LA) group showed greater improvements in pain, knee movement, and function in patients with pain at the front of the knee. The 60 participants, predominantly women aged 18 to 25, were randomly split into 2 equal groups: the active group received LA applied to 6 knee acupoints using a 905 nm laser (100 mW, 4 J per point, 80 seconds per point), while the sham group received an inactive device, with both groups completing the same stretching and strengthening program twice a week for 4 weeks. The study reported statistically significant differences in favor of the laser acupuncture group on all measured outcomes, though the researchers noted the findings may not apply broadly given the predominantly young female sample.

Pain scores, knee movement, and lower limb function all improved more with high-intensity laser therapy (HILT) than with 2 other physical treatments in a single-blind randomized controlled trial published in 2024, testing 3 approaches to patellofemoral pain syndrome. The 45 participants (24 women and 21 men, aged 25 to 45) were split into 3 groups of 15: Group 1 received HILT using a 1064 nm laser (7 to 10 W, 1500 mW/cm2, 25 Hz) applied to the kneecap plus an exercise program, Group 2 received ultrasound plus electrical nerve stimulation plus exercise, and Group 3 received ultrasound plus interferential current plus exercise, with all groups completing 10 sessions over 2 weeks and assessed before treatment, after treatment, and at 3 months. At 3-month follow-up, the HILT group showed reductions in pain, improvements in knee flexion, and better lower limb function than both comparison groups.

Combat soldiers and police officers with anterior knee pain were enrolled in a prospective double-blind sham-controlled randomized trial published in 2021 to test whether photobiomodulation (PBM) added to physiotherapy could outperform physiotherapy alone. Of the 26 participants (15 men, 11 women), half received 4 weeks of active PBM using 660 nm and 850 nm LEDs pulsed at 2.5 Hz and an 810 nm continuous laser applied to the knee, surrounding lymph nodes, lower spine, and trigger points alongside physiotherapy, while the other half received a sham device with the same physiotherapy program. The study reported that the PBM group showed significantly greater pain reduction at the end of treatment and significantly better knee function scores at 3-month follow-up compared to the sham group. All 26 participants completed the protocol without any reported adverse effects.