Optimizing LED photobiomodulation parameters to prevent cartilage matrix degradation in knee osteoarthritis: in vitro and in vivo study

Fan T, Xia P, Ahmed S, Tsang YH, Li Y, Fu SN · Journal of Orthopaedic Surgery and Research

In vitro, 940 nm at 52 J/cm2 was the most effective parameter set, suppressing mmp3 and mmp13 mRNA and raising col2a1 and aggrecan (P < 0.05); 810 nm at 39 J/cm2 inhibited mmp3 and mmp13 only, and 625 nm and 1050 nm produced no significant effect on any matrix marker. In the mice, 940 nm at 52 J/cm2 improved weight-bearing asymmetry by 31 percent at 6 weeks against controls (P = 0.03) and halved cartilage degradation on OARSI score (P = 0.03), with lower mmp3 and higher collagen II protein on immunofluorescence.

Population

TNF-alpha-stimulated RCJ 3.1.C5.18 chondrocytes, and mice with knee osteoarthritis induced by destabilization of the medial meniscus, 5-6 per group

Intervention

LEDs at 625, 810, 940 and 1050 nm, 13-78 J/cm2 at 44 mW/cm2 in vitro; in vivo, 810 nm or 940 nm at 39 or 52 J/cm2, three times weekly for 6 weeks

Comparator

Untreated osteoarthritis controls and sham irradiation

Limitations

Four wavelengths only, so anything between or beyond them is untested, and the mechanism was not examined. The authors note that only part of the delivered energy reaches the joint cavity in an animal and that repeated irradiation may accumulate, leaving the optimal in vivo dose unresolved — the in vitro figure cannot simply be carried across. Sham controls were fully shielded with aluminium foil while treated animals sat in ambient light, which is not a light-matched control. Five to six mice per group, no proliferation or viability endpoints, and no human data. Hong Kong Polytechnic University institutional funding and an endowed professorship in pain management; the authors declare no competing interests.