|A systematic review with procedural assessments and meta-analysis of low level laser therapy in lateral elbow tendinopathy (tennis elbow)
|Bjordal JM, Lopes-Martins RA, Joensen J, Couppe C, Ljunggren AE, Stergioulas A, Johnson MI
The authors concluded that low-level laser therapy administered to the lateral elbow tendon insertions at 904nm or possibly 634nm wavelength, with or without exercise, was associated with pain relief and less disability for people with tennis elbow. The authors' overall conclusions are reasonable but some of their recommendations for practice are not directly based on their results.
To assess low level laser therapy for the treatment of lateral elbow tendinopathy (tennis elbow).
MEDLINE, EMBASE, CINAHL, PEDro and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched without language restrictions. Search terms were provided, but search dates were not. National medical and physiotherapy journals from seven countries were handsearched and researchers in the field were contacted.
Randomised controlled trials (RCTs) assessing the effect of low-level laser therapy on pain intensity or global improvement in people with tennis elbow were included. Tennis elbow was defined as pain from the lateral elbow epicondyle upon finger or wrist extension. Low-level laser therapy with wavelengths ranging from 632 to 1064 nanometres (nm) that irradiated the tendon, acupuncture points or trigger points were included. Parallel or crossover RCTs with a placebo or non-laser intervention control group, blinded outcome assessment, and at least 10 persons per group were eligible.
In addition to the primary outcomes of pain intensity (measured on 100mm visual analogue scale) and global health status at end of treatment, the secondary outcomes of interest were pain-free grip strength, pain pressure threshold, sick leave and results more than one week after the end of treatment.
The majority of included trials used the tendon application technique, although there was variability between trials in the laser wavelength (632 to 1,064nm), the total irradiation time, the number of therapy sessions, and whether participants also received exercise therapy. A small number of included trials used acupuncture point technique at 632 or 904nm. Several trials included patients with a poor prognosis (i.e. long symptom duration and prior steroid injections).
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality
Validity was assessed using the ten point Pedro scale.
The authors did not state how the validity assessment was performed.
The change from baseline to follow-up for the intervention and control groups was extracted for pain intensity and the mean difference (MD) in change between the two groups, with 95% confidence interval (CI), was calculated. For global health status, the number of patients who were classified as improved (e.g. improved, good, better, much improved, pain-free, excellent) was extracted and the relative risk (RR) and 95% confidence interval calculated. The standardised mean difference (SMD) was used for pain-free grip strength and pain pressure threshold due to the variety of outcome measures used.
The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction.
Methods of synthesis
Trials were pooled in a random-effects (for pain) or fixed-effect meta-analysis (for other outcomes), subgrouped by application technique and laser wavelength. Trials that were not pooled were reported in a narrative. Heterogeneity was assessed using the χ2 and I2 statistics. An Egger plot was used to assess publication bias.
Results of the review
Thirteen RCTs (n=730 participants) were included; 12 trials with a placebo control group and one trial with a wrist brace and ultrasound therapy control group. The number of participants in the included trials ranged from 30 to 142. With the exception of one poor quality trial, the included trials fulfilled between 6 and 8 of the 10 quality criteria and were considered as being of acceptable quality.
Pain intensity: There was a statistically significant improvement in pain at the end of treatment with low-level laser therapy compared to control in the overall pooling (WMD 10.2mm, 95% CI 3.0 to 17.5; 10 trials). When the trials were subgrouped by technique and wavelength, there was a significant improvement in pain with tendon application 904nm low-level laser therapy compared to control (WMD 17.2mm, 95% CI 8.5 to 25.9; five trials) and tendon application 632nm compared to wrist brace (WMD 14mm, 95% CI 7.5 to 20.6; one trial). There was no significant difference between tendon application 820nm and 1064nm and control (three trials) or between acupuncture point 904nm and control (one trial). There was statistically significant heterogeneity in the overall pooling and in the pooling of trials of tendon application 904nm, indicating variability in the effect of treatment between the trials.
Global improvement at the end of treatment: There was a benefit in favour of low-level laser therapy in the overall pooling (RR 1.36, 95% CI 1.16 to 1.60, seven studies). When the trials were subgrouped by technique and wavelength, there was a statistically significant benefit in favour of tendon application 904nm compared to control (RR 1.53, 95% CI 1.28 to 1.83; five trials), but not tendon application 820nm or acupuncture point application 904nm compared to control, although these were only single trials. There was statistically significant heterogeneity in the overall analysis.
Treatment was generally well tolerated and no adverse events were reported. There was evidence of publication bias, but this was not in the expected direction: unpublished studies were likely to be those with positive results in favour of low-level laser therapy.
Low-level laser therapy administered directly to the lateral elbow tendon insertions, with an optimal dose of 904nm or possibly 634nm wavelength, either alone or in conjunction with an exercise regimen seemed to offer short-term pain relief and less disability in patients with tennis elbow.
The review had a clearly stated research question and clearly specified inclusion criteria. Relevant databases were searched for studies. There was evidence of publication bias, but this was in the unexpected direction of unlocated unpublished studies being more likely to show a positive benefit with low-level laser therapy; this indicated that the treatment effect was unlikely to have been overestimated due to publication bias. It is unclear whether there was a risk of error and bias in study selection, quality assessment and data extraction as details of the processes used are not reported. The statistical analysis seemed appropriate and clinical and statistical heterogeneity was considered. The authors' overall conclusions are reasonable. However they did not specifically compare low-level laser therapy with and without exercise therapy, so the recommendation that exercise therapy should be considered an adjunct to low-level laser therapy would benefit from further investigation. Also, their suggestion that low-level laser therapy should be considered as an alternative to commonly used pharmacological interventions is not based on evidence from their review.
Implications of the review for practice and research
Practice: The authors stated that low-level laser therapy should be considered as an alternative to commonly used pharmacological agents in the treatment of tennis elbow and should be considered an adjunct rather than alternative to exercise therapy and stretching. However, low-level laser therapy treatment with wavelengths of 820, 830 and 1064nm cannot be recommended until further research establishes their effectiveness.
Research: The authors stated that high quality trials are required directly comparing the short term effects of low-level laser therapy and corticosteroid injections.
Bergen University College.
Bjordal JM, Lopes-Martins RA, Joensen J, Couppe C, Ljunggren AE, Stergioulas A, Johnson MI. A systematic review with procedural assessments and meta-analysis of low level laser therapy in lateral elbow tendinopathy (tennis elbow) BMC Musculoskeletal Disorders 2008; 9:75
Subject indexing assigned by NLM
Elbow Joint; Humans; Laser Therapy, Low-Level; Randomized Controlled Trials as Topic; Tendinopathy /radiotherapy; Tennis Elbow /radiotherapy; Therapeutics
Date bibliographic record published
Date abstract record published
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.