Laser Therapy/ Photobiomodultion

Preliminary clinical experience of low-level laser therapy for the treatment of canine osteoarthritis-associated pain: A retrospective investigation on 17 dogs

Summary:

Laser therapy (aka photobiomodulation) is often used to treat OA in veterinary patients, but the evidence to support this treatment is weak. At the time of this publication, there was one single prior publication investigating laser therapy for dogs with elbow OA (Looney et. al, Can Vet J 2018). This study found that with the laser and protocol studied (980 nm, 5-12 W, CW, 1-2.4W/cm2, 10-19 J/cm2, non-contact mode, scanning method; treatment 2x week for 3 weeks then once a week for 3 weeks), laser-treated dogs (n=11) showed significantly (p=0.001) greater reduction in lameness compared to sham (n=9) treated dogs. NSAID dose was also able to be decreased in 9 of the 11 laser-treated dogs. The authors of the current study (Barale et. al) aimed to report the clinical outcomes following a different laser therapy protocol in dogs with OA.

Conclusion:

This retrospective report provides a basis for future investigations, needed to clarify whether laser therapy may be beneficial to treat canine OA-associated pain. The preliminary findings are promising and suggest that LLLT may help to reduce the analgesic administration and improving client satisfaction and the quality of life of dogs with OA.

Author & Journal:Loris Barale, Paolo Monticelli, Massimo Raviola, and Chiara Adami, Open Vet J., April 2020

Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

Summary:

To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells.

Conclusion:

Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering.

Author & Journal:Augusto Galvão Barboza,Carlos, et al, eintstein, 2014

Preoperative low level laser therapy in dogs undergoing tibial plateau levelling osteotomy: A blinded, prospective, randomized clinical trial.

Summary:

To evaluate the influence of preoperative low-level laser therapy (LLLT) on therapeutic outcomes of dogs undergoing tibialplateau levelling osteotomy (TPLO).

Conclusion:

Twenty-seven dogs (27 stifles) were included and no major complications occurred. At eight weeks postoperatively, a significant difference in peak vertical force analysis was noted between the LLLT (39.6% ± 4.7%) and sham groups (28.9% ± 2.6%), (p <0.01 Time, p <0.01 L). There were no significant differences noted between groups for all other parameters. The age of dogs in the LLLT group (6.6 ± 1.6 years) was greater than that for the sham group (4.5 ± 2.0, p <0.01). Although not significant, a greater proportion of LLLT dogs (5/8) had healed at the eight-week time point than in the sham group (3/12) despite the age difference (p = 0.11) Clinicalsignificance: The results of this study demonstrate that improved peak vertical force could be related to the preoperative use of LLLT for dogs undergoing TPLO at eight weeks postoperatively. The use of LLLT may improve postoperative return to function following canine osteotomies and its use is recommended.

Author & Journal:Rogatko CP, et al, VCOT 2017:30:46-53

Photobiomodulation directly benefits primary neurons functionally inactivated by toxins: role of cytochrome c oxidase.

Summary:

Far red and near infrared (NIR) light promotes wound healing, but the mechanism is poorly understood. Our previous studies using 670 nm light-emitting diode (LED) arrays suggest that cytochrome c oxidase, a photoacceptor in the NIR range, plays an important role in therapeutic photobiomodulation. If this is true, then an irreversible inhibitor of cytochrome c oxidase, potassium cyanide (KCN), should compete with LED and reduce its beneficial effects. This hypothesis was tested on primary cultured neurons. LED treatment partially restored enzyme activity blocked by 10-100 microm KCN. It significantly reduced neuronal cell death induced by 300 microm KCN from 83.6 to 43.5%. However, at 1-100 mm KCN, the protective effects of LED decreased, and neuronal deaths increased. LED significantly restored neuronal ATP content only at 10 microm KCN but not at higher concentrations of KCN tested. Pretreatment with LED enhanced efficacy of LED during exposure to 10 or 100 microm KCN but did not restore enzyme activity to control levels. In contrast, LED was able to completely reverse the detrimental effect of tetrodotoxin, which only indirectly down-regulated enzyme levels. Among the wavelengths tested (670, 728, 770, 830, and 880 nm), the most effective ones (830 nm, 670 nm) paralleled the NIR absorption spectrum of oxidized cytochrome c oxidase, whereas the least effective wavelength, 728 nm, did not.

Conclusion:

The results are consistent with our hypothesis that the mechanism of photobiomodulation involves the up-regulation of cytochrome c oxidase, leading to increased energy metabolism in neurons functionally inactivated by toxins.

Author & Journal:Wong-Riley MT, et al, J Biol Chem 2005;280: 4761-4771

The thermal effects of therapeutic lasers with 810 and 904 nm wavelengths on human skin.

Summary:

To investigate the effect of therapeutic infrared class 3B laser irradiation on skin temperature in healthy participants of differing skin color, age, and gender.

Conclusion:

The thermal effects of LLLT at doses recommended by WALT-guidelines for musculoskeletal and inflammatory conditions are negligible (<1.5°C) in light, medium, and dark skin. However, higher LLLT doses delivered with a strong 3B laser (200 mW) are capable of increasing skin temperature significantly and these photothermal effects may exceed the thermal pain threshold for humans with dark skin color.

Author & Journal:Joensen J, et al, Photomed Laser Surg 2011:29(3):145-153

Effect of Pulsing in Low-Level Light Therapy

Summary:

Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen.

Conclusion:

There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures.

Author & Journal:Hashmi JT, et al, Lasers Surg Med 2010;42:450-466

Low level laser therapy for tendinopathy: evidence of a dose-response pattern

Summary:

This review assessed the effects of low-level laser therapy (LLLT) on pain from tendinopathy. The authors concluded that LLLT can reduce pain in subacute and chronic tendinopathy if a valid treatment procedure and location-specific dose is used. Differences among the studies were not examined and only the short-term outcomes were assessed. The authors’ conclusions may not be reliable.

Conclusion:

Thirteen RCTs with sixteen treatment comparisons were included (n approximately 789).

Nine RCTs using optimal laser treatment dose and power density found that LLLT reduced pain in patients with sub-acute and chronic tendinopathy compared with control (WMD 32%, 95% CI: 23, 41).

Nine RCTs using optimal laser treatment dose and power density and 4 RCTs not using optimal treatment parameters found that LLLT reduced pain compared with control (WMD 22%, 95% CI: 5.9, 36.1). There was a statistically significant difference between RCTs using optimal laser treatment dose and power density and those RCTs not using optimal treatment parameters (P<0.001).

The funnel plots suggested there was potential for some publication bias.

Author & Journal:Bjordal JM, et al, Phys Therapy Rev 2001;6:91-99

Inhibitory effect of low-level laser irradiation on LPS-stimulated prostaglandin E2 production and cyclooxygenase-2 in human gingival fibroblasts.

Summary:

It has been reported that lipopolysaccharide (LPS) from periodontal pathogens can penetrate gingival tissues and stimulate the production of prostaglandin E2 (PGE2), which is known as a potent stimulator of inflammation and bone resorption. Although biostimulatory effects of low-level laser irradiation such as anti-inflammatory results have been reported, the physiological mechanism is not yet clarified. The purpose of the present study was to determine the effect of laser irradiation on PGE2 production and cyclooxygenase (COX)-1 and COX-2 gene expression in LPS-challenged human gingival fibroblast (hGF) cells in vitro.

Conclusion:

In conclusion, low-level laser irradiation inhibited PGE2 by LPS in hGF cells through a reduction of COX-2 mRNA level. The findings suggest that low-level laser irradiation may be of therapeutic benefit against the aggravation of gingivitis and periodontitis by bacterial infection.

Author & Journal:Sakurai Y, et al, Eur J Oral Sci 2000;108: 29-34

Low-level laser therapy induces dose-dependent reduction of TNFalpha levels in acute inflammation.

Summary:

The aim of this study was to investigate if low-level laser therapy (LLLT) can modulate acute inflammation and tumor necrosis factor (TNFalpha) levels.

Conclusion:

LLLT can reduce TNFalpha expression after acute immunocomplex lung injury in rats, but LLLT dose appears to be critical for reducing TNFalpha release.

Author & Journal:Aimbiro F, et al, Photomed Laser Surg 2006;24:33-37

A meta-analysis of the efficacy of laser phototherapy on pain relief.

Summary:

Laser phototherapy has been widely used to relieve pain for more than 30 years, but its efficacy remains controversial. To ascertain the overall effect of phototherapy on pain, we aggregated the literature and subjected the studies to statistical meta-analysis.

Conclusion:

Fifty-two effect sizes were computed from the 22 articles that met the inclusion criteria. The resulting overall mean effect size was highly significant; d = +0.84 (95% confidence interval = 0.44-1.23). The effect size remained significant even when a high outlying d value was conservatively excluded from the analysis; d = +0.66 (95% confidence interval = 0.46-0.86). The fail-safe number associated with the overall treatment effect, that is, the number of additional studies in which phototherapy has negative or no effect on pain needed to negate the overall large effect size of +0.84, was 348.

Author & Journal:Fulop AM, et al, Clin J Pain 2010;26:729-736