BMJ Open. 2019; 9(10): e031142.
Published online 2019 Oct 28. doi: 10.1136/bmjopen-2019-031142
Efficacy of low-level laser therapy on pain and disability in knee osteoarthritis: systematic review and meta-analysis of randomised placebo-controlled trials
Low-level laser therapy (LLLT) is not recommended in major knee osteoarthritis (KOA) treatment guidelines. We investigated whether a LLLT dose–response relationship exists in KOA.
Systematic review and meta-analysis.
Eligible articles were identified through PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature, Physiotherapy Evidence Database and Cochrane Central Register of Controlled Trials on 18 February 2019, reference lists, a book, citations and experts in the field.
Eligibility criteria for selecting studies
We solely included randomised placebo-controlled trials involving participants with KOA according to the American College of Rheumatology and/or Kellgren/Lawrence criteria, in which LLLT was applied to participants’ knee(s). There were no language restrictions.
Data extraction and synthesis
The included trials were synthesised with random effects meta-analyses and subgrouped by dose using the World Association for Laser Therapy treatment recommendations. Cochrane’s risk-of-bias tool was used.
22 trials (n=1063) were meta-analysed. Risk of bias was insignificant. Overall, pain was significantly reduced by LLLT compared with placebo at the end of therapy (14.23 mm Visual Analogue Scale (VAS; 95% CI 7.31 to 21.14)) and during follow-ups 1–12 weeks later (15.92 mm VAS (95% CI 6.47 to 25.37)). The subgroup analysis revealed that pain was significantly reduced by the recommended LLLT doses compared with placebo at the end of therapy (18.71 mm (95% CI 9.42 to 27.99)) and during follow-ups 2–12 weeks after the end of therapy (23.23 mm VAS (95% CI 10.60 to 35.86)). The pain reduction from the recommended LLLT doses peaked during follow-ups 2–4 weeks after the end of therapy (31.87 mm VAS significantly beyond placebo (95% CI 18.18 to 45.56)). Disability was also statistically significantly reduced by LLLT. No adverse events were reported.
LLLT reduces pain and disability in KOA at 4–8 J with 785–860 nm wavelength and at 1–3 J with 904 nm wavelength per treatment spot.
PROSPERO registration number
Keywords: phototherapy, laser therapy, knee osteoarthritis, systematic review, meta-analysis
Strengths and limitations of this study
- The review was conducted in conformance with a detailed a priori published protocol, which included, for example, laser dose subgroup criteria.
- No language restrictions were applied; four (18%) of the included trials were reported in non-English language.
- A series of meta-analyses were conducted to estimate the effect of low-level laser therapy on pain over time.
- Three persons each independently extracted the outcome data from the included trial articles to ensure high reproducibility of the meta-analyses.
- The review lacks quality-of-life analyses, a detailed disability time-effect analysis and direct comparisons between low-level laser therapy and other interventions.
The influence of irradiation with low-level diode laser on the proteoglycan content in arthrotically changed cartilage in rabbits
Tonio Gottlieba, BjÃ¶rn JÃ¶rgensenb, Ewa Rohdec, Gerhard MÃ¼llerc, Eike Eric Schellera,_
- Ev. Krankenhaus Hubertus, Spanische Allee 10-14, 14129 Berlin, Germany
- Endozentrum Martin Luther Krankenhaus, Caspar-TheyÃ�-Str. 27-31, 14193, Berlin, Germany cInstitut fuÂ¨r Medizinische Physik und Lasermedizin, ChariteÂ´ Campus Benjamin Franklin, Fabeckstr. 60-62, 14195, Berlin, Germany
Received 24 November 2005; accepted 16 December 2005
Abstract: The course of arthrosis was investigated on an animal-experimental arthrosis model considering macroscopic aspects, and the proteoglycan and the glycosaminoglycan contents. Based on these parameters, the influence of a low power diode laser of 692.6nm wavelength on the progress of arthrosis was investigated. Thirty days following joint instability surgery another operation was made during which the femoral condyles were irradiated using different energy densities. Seven days after the second operation, macroscopic findings were made and the proteoglycan content was established based on the quantitative determination according to Taylor and Jeffre. This method is based on various spectrophotometric absorption behaviours of different concentrations of sulphatized glycosaminoglycans in the presence of dimethylmethylene blue.
Macroscopically, a progressively increasing severity of cartilage changes during the course of arthrosis was detected and the proteoglycan content was found to decrease. The changes in the irradiated joints proved to be less severe, with the higher energy density having a greater positive influence of statistical significance.
r 2006 Elsevier GmbH. All rights reserved. Keywords: Cartilage; Laser; Proteoglycans; Spectrophotometry
Low-level laser therapy for zymosan-induced arthritis in rats: Importance of illumination time
- Ana P. Castano MD1,2,
- Tianhong Dai PhD1,2,
- Ilya Yaroslavsky PhD3,
- Richard Cohen MD3,
- William A. Apruzzese PhD3,
- Michael H. Smotrich PhD3,
- Michael R. Hamblin PhD1,2,4,*
Article first published online: 20 JUL 2007
Copyright © 2007 Wiley-Liss, In
- low-level light therapy;
- zymosan-induced arthritis;
- cold laser;
- prostaglandin E2
It has been proposed for many years that low-level laser (or light) therapy (LLLT) can ameliorate the pain, swelling, and inflammation associated with various forms of arthritis. Light is thought to be absorbed by mitochondrial chromophores leading to an increase in adenosine triphosphate (ATP), reactive oxygen species and/or cyclic AMP production and consequent gene transcription via activation of transcription factors. However, despite many reports about the positive effects of LLLT in arthritis and in medicine in general, its use remains controversial. For all indications (including arthritis) the optimum optical parameters have been difficult to establish and so far are unknown.
We tested LLLT on rats that had zymosan injected into their knee joints to induce inflammatory arthritis. We compared illumination regimens consisting of a high and low fluence (3 and 30 J/cm2), delivered at high and low irradiance (5 and 50 mW/cm2) using 810-nm laser light daily for 5 days, with the positive control of conventional corticosteroid (dexamethasone) therapy.
Illumination with 810-nm laser was highly effective (almost as good as dexamethasone) at reducing swelling and a longer illumination time (10 or 100 minutes compared to 1 minute) was more important in determining effectiveness than either the total fluence delivered or the irradiance. LLLT induced reduction of joint swelling correlated with reduction in the inflammatory marker serum prostaglandin E2 (PGE2).
LLLT with 810-nm laser is highly effective in treating inflammatory arthritis in this model. Longer illumination times were more effective than short times regardless of total fluence or irradiance. These data will be of value in designing clinical trials of LLLT for various arthritides. Lasers Surg. Med. 39:543–550, 2007. © 2007 Wiley-Liss, Inc.