Definition of the procedure
Laser therapy is a therapeutic non-invasive modality that is supposed to have analgesic effects, anti-inflammatory effects, effects on nerve regeneration, and effects on regeneration of muscular and bone tissues (de Bie et al 1998).
Wavelength, dosage and dose-intensity are reported to determine the magnitude of the effects.
Lasers with different wavelengths are used in the treatment of musculoskeletal disorders. The wavelengths vary from 632 to 904 nm. The physical properties of the interaction between laser light and tissue can be distinguished in the processes of absorption and scattering. By means of absorption, light energy will transformed into another form of energy which results in warmth dissipation (de Bie et al 1998). By scattering, the direction of light propagation will be changed. Absorption and
scattering are dependent on the wavelength and determine the loss of laser energy into the irradiated tissue. The electromagnetic energy that is applied to the body tissues by means of laser therapy is thought to stimulate or inhibit biochemical, physiological and proliferative activities in the cell (de Bie et al 1998). In general, controversy exists with regard to the appropriate treatment parameters for the different treatment indications.
Results of search Systematic reviews
Two SRs were found (Bjordal et al 2003, de Bie et al 1998) that were not specifically aimed at assessing the evidence for laser therapy in chronic low back pain. One SR aimed at reviewing the effectiveness of 904 nm laser therapy in various
musculoskeletal disorders (de Bie et al 1998). It included one trial on the effects of laser therapy for chronic low back pain (Klein and Eek 1990). The other SR reviewed the effects of low level laser therapy with location-specific doses for pain from chronic joint disorders (Bjordal et al 2003) and included three other relevant trials on the effects of laser therapy in chronic low back pain patients (Basford et al 1999, Soriano and Rios 1998, Toya et al 1994).
Additional trials
One additional trial was found (Gur et al 2003). Quality assessment of the evidence
The two SRs (Bjordal et al 2003, de Bie et al 1998) and the four trials they contained (Basford et al 1999, Klein and Eek 1990, Soriano and Rios 1998, Toya et al 1994) were all rated as high quality.The additional study (Gur et al 2003) was rated as low quality.
Effectiveness
Effectiveness of laser therapy vs sham procedure
The SRs did not separately assess the effectiveness of laser therapy in chronic low back pain. Therefore, the results of the four individual trials are examined here, in order to then summarise the evidence.
One study compared 904 nm laser therapy with placebo laser (Klein and Eek 1990). There were no statistically significant differences in pain improvements between the groups.
One study compared 830 nm laser therapy with placebo laser and reported statistically significant improvements in health status in favour of the laser group when compared with the placebo group (Toya et al 1994). However, no results were reported for pain, functional status or work absenteeism.
when compared with the placebo group (Soriano and Rios 1998). Results regarding pain, functional status and work absenteeism were also lacking in this study.
One study compared NdYag laser therapy (1064 nm) with a placebo laser and found statistically significant differences in pain improvements between the groups (Basford et al 1999).
The two trials that reported pain measurements (Basford et al 1999, Klein and Eek 1990) were both triple blinded (patient, therapist and observer). One of them did (Basford et al 1999) and the other one did not (Klein and Eek 1990) report statistically significant differences between the groups in favour of laser therapy. There is conflicting evidence that laser therapy is effective for chronic low back pain with regard to pain improvement (level C).
Effectiveness of laser therapy vs. other treatments
One low quality trial found that there was no difference between laser, laser therapy and exercise and exercise alone in terms of pain and function (Gur et al 2003) There is limited evidence that there is no difference in effectiveness between laser therapy, laser therapy and exercise and exercise (level C)
Cost-effectiveness
Unknown (no studies were found on this issue) Safety
Unknown (no studies were found on this issue) Subjects (indications)
Not having shown evidence of effectiveness, it is not possible to define indications for interferential therapy.
Comments
The application of laser therapy in the aforementioned trials was heterogeneous with respect to wavelength, dose-intensity and dosage. Future studies on the effects of laser therapy should apply similar treatment parameters in order to increase the homogeneity among studies.
Summary of evidence
There is conflicting evidence that laser therapy is effective for chronic low back pain with regard to pain improvement (level C).
There is limited evidence that there is no difference in effectiveness between laser therapy, laser therapy and exercise and exercise (level C)
Recommendation
We cannot recommend laser therapy for the treatment of patients with chronic low back pain.
References
1. Basford JR, Sheffield CG, Harmsen WS (1999) Laser therapy: a randomized, controlled trial of the effects of low-intensity Nd:YAG laser irradiation on
musculoskeletal back pain. Arch Phys Med Rehabil, 80(6): 647-52.
2. Bjordal JM, Couppe C, Chow RT, Tuner J, Ljunggren EA (2003) A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders. Aust J Physiother, 49(2): 107-16.
3. de Bie RA, Verhagen A, de Vet HCW, Lenssen T, van den Wildenberg FAJM, Kootstra A, Knipschild PG (1998) Efficacy of 904 nm laser therapy in musculoskeletal
4. Gur A, Karakoc M, Cevik R, Nas K, Sarac AJ (2003) Efficacy of low power laser therapy and exercise on pain and functions in chronic low back pain. Lasers Surg Med, 32(3): 233-8.
5. Klein RG, Eek BC (1990) Low-energy laser treatment and exercise for chronic low back pain: double-blind controlled trial. Arch Phys Med Rehabil, 71(1): 34-7.
6. Soriano F, Rios R (1998) Gallium Arsenide Laser Treatment of chronic low back pain: a prospective randomised and double blind study. Laser Therapy, 10: 175-80. 7. Toya S, Motegi M, Inomata K, Ohshiro T, Maeda T (1994) Report on a computer- randomized double-blind clinical trial to determine the effectiveness of the GaAIA (830 nm) diode laser for attenuation in selected pain groups. Laser Therapy, 6: 143- 8.