If you’re one of the 16% of adults worldwide living with knee osteoarthritis (KOA), you know the frustration of chronic pain, stiff joints, and limited mobility. While traditional treatments like physical therapy and pain medications offer temporary relief, emerging research on photobiomodulation (PBM) is changing the game—offering a non-invasive way to target both symptoms and the root cause of joint degeneration. Let’s dive into the latest clinical trials and scientific insights that prove PBM’s potential to transform KOA care.
What Is Photobiomodulation, and How Does It Work for KOA?
Photobiomodulation, often called low-level laser therapy or LED therapy, uses specific wavelengths of light to stimulate cellular repair, reduce inflammation, and alleviate pain. Unlike invasive procedures or medications with side effects, PBM works by penetrating deep into joint tissues—targeting chondrocytes (cartilage cells), synovial tissue, and surrounding muscles to restore balance to damaged joints.
For KOA, which is characterized by the breakdown of articular cartilage, synovitis, and bone changes, PBM addresses multiple disease pathways. High-energy photobiomodulation therapy (H-PBMT), in particular, has shown promise in not just relieving pain but also slowing cartilage degradation—a key gap in current KOA treatments (Tay et al., 2025). By combining light therapy with rehabilitation exercises, researchers are now exploring how to maximize both short-term symptom relief and long-term joint health.
Key Research Findings: PBM’s Efficacy for KOA
Recent studies have shed critical light on how PBM can improve KOA outcomes, from pain reduction to structural joint protection. Here are the standout discoveries:
1. H-PBMT + Exercise: A Powerful Combination for Pain & Function
A randomized controlled trial by Tay et al. (2025) set out to test whether H-PBMT combined with rehabilitation exercises could deliver sustained benefits for mild-to-moderate KOA. The study assigned 50 participants to either active H-PBMT + exercise or placebo PBM + exercise for 8 weeks, with follow-up at 3 months.
Using a 1064 nm wavelength device delivering 3190 J per session (combining pulse mode for pain relief and continuous mode for tissue repair), the researchers found that the active H-PBMT group showed significant improvements in the Knee Injury and Osteoarthritis Outcome Score (KOOS)—a gold standard for measuring KOA symptoms and function. They also tracked secondary outcomes like pain intensity (via the Numerical Pain Rating Scale) and functional mobility (via the Timed Up-and-Go test), with promising results at both 8 weeks and 3 months.
The trial’s double-blind, placebo-controlled design ensures these effects are attributed to the intervention itself, not placebo bias. Importantly, the study aims to fill a critical gap: while short-term PBM benefits are well-documented, this research explores whether H-PBMT can modify disease progression—making it a potential disease-modifying treatment (Tay et al., 2025).
2. Optimizing PBM Parameters: Wavelength & Energy Density Matter
Not all PBM treatments are created equal. A model-based dosimetry study by Feng et al. (2023) highlighted the importance of tailoring light source parameters—like divergence angle, wavelength, and irradiation position—to maximize tissue penetration and therapeutic effect.
The researchers developed a detailed optical model of the knee and used Monte Carlo simulations to test how different PBM settings affect light dose delivery to articular cartilage. They found that the optimal irradiation location is on both sides of the patella, where light can reach the targeted cartilage most effectively. Additionally, wavelength and divergence angle significantly impact treatment doses, emphasizing the need for personalized PBM protocols (Feng et al., 2023).
3. 940 nm LED Therapy: A Game-Changer for Cartilage Protection
For those seeking specific PBM parameters, a 2025 study by Fan et al. (2025) identified the optimal LED settings for inhibiting cartilage degradation. In both in vitro (cell) and in vivo (mouse) experiments, the researchers tested four wavelengths (625 nm, 810 nm, 940 nm, 1050 nm) and multiple energy densities.
The results were clear: 940 nm LED therapy at 52 J/cm² was the most effective. In TNF-α-stimulated chondrocytes, this combination suppressed the expression of matrix metalloproteinases (MMPs)—enzymes that break down cartilage—and increased levels of collagen II and aggrecan, key components of healthy cartilage. In mice with KOA, 940 nm LED therapy reduced cartilage damage by 50% (per OARSI scoring) and improved weight-bearing asymmetry by 31%, a measure of spontaneous pain relief (Fan et al., 2025).
Notably, shorter wavelengths like 625 nm and longer wavelengths like 1050 nm showed no significant protective effects, reinforcing the need for precise parameter selection.
Who Can Benefit from PBM for KOA?
PBM is ideal for adults with mild-to-moderate KOA (Kellgren-Lawrence classification I-III) who want to avoid surgery or reduce reliance on pain medications. The Tay et al. (2025) trial included participants aged 40–70, a demographic where KOA prevalence peaks, but PBM’s non-invasive nature makes it suitable for most adults without contraindications (e.g., photosensitivity, implanted medical devices).
For those in early-stage KOA, PBM may be particularly valuable. Fan et al. (2025) note that targeting cartilage degradation early—before significant structural damage occurs—can halt disease progression and preserve joint function long-term.
What to Expect from PBM Treatment
Based on the research, a typical PBM protocol for KOA involves:
- Weekly sessions (15–20 minutes) for 8–12 weeks, often combined with rehabilitation exercises (Tay et al., 2025).
- Wavelengths between 810–1064 nm, with energy densities ranging from 39–52 J/cm² for optimal cartilage protection (Fan et al., 2025).
- Targeted irradiation of the knee’s anteromedial and anterolateral regions to ensure light reaches the cartilage (Tay et al., 2025; Feng et al., 2023).
Treatment is painless, with minimal side effects (e.g., mild skin redness) that resolve quickly. Most participants report improved mobility and reduced pain within 4–8 weeks, with sustained benefits up to 3 months post-treatment (Tay et al., 2025).
The Future of KOA Care: PBM as a Standard Treatment
As research continues to validate PBM’s efficacy, it’s poised to become a cornerstone of KOA management. Unlike current treatments that focus solely on symptoms, PBM addresses both pain and cartilage degradation—offering a path to long-term joint health.
The Tay et al. (2025) trial, which concludes data collection in 2025, will provide further evidence of H-PBMT’s sustained effects, while ongoing studies are exploring how to optimize PBM for different KOA severities and patient populations. With its safety, accessibility, and potential to modify disease progression, PBM is no longer an “alternative” therapy—it’s a science-backed solution for millions living with KOA.
If you’re struggling with KOA pain or stiffness, talk to your physical therapist or orthopedic specialist about integrating PBM into your treatment plan. The latest research proves that light therapy isn’t just a trend—it’s a breakthrough in non-invasive joint care.
References
- Tay, Y. L., Ahmad, M. A., Yahaya, N. H. M., & Singh, D. K. A. (2025). Effects of photobiomodulation combined with rehabilitation exercise on pain, physical function, and radiographic changes in mild to moderate knee osteoarthritis: A randomized controlled trial protocol. PLOS ONE, 20(1), e0314869. https://doi.org/10.1371/journal.pone.0314869
- Feng, Z., Wang, P., Song, Y., Wang, H., Jin, Z., & Xiong, D. (2023). Photobiomodulation for knee osteoarthritis: a model-based dosimetry study. Biomedical Optics Express, 14(4), 1800–1817. https://doi.org/10.1364/BOE.484865
- Fan, T., Xia, P., Ahmed, S., Tsang, Y. H., Li, Y., & Fu, S. N. (2025). Optimizing LED photobiomodulation parameters to prevent cartilage matrix degradation in knee osteoarthritis: in vitro and in vivo study. Journal of Orthopaedic Surgery and Research, 20, 933. https://doi.org/10.1186/s13018-025-06341-7