Laser or ultrasound – or both?

A comment on: Manca A, Limonta E, Pilurzi G, Ginatempo F, De Natale E R, Mercante B, Tolu E, Deriu F. Ultrasound and Laser as Stand-Alone Therapies for Myofascial Trigger Points: A Randomized, Double-Blind, Placebo-Controlled Study. Physiother Res Int. 2014 [Epub ahead of print]

By Jan Tunér

 

Ultrasound is one of the most commonly used physiotherapeutic modalities. Is LPT better than ultrasound, or is it the other way around? Or maybe, could they be used together? Studies trying to compare the two therapies are difficult to evaluate, because it is hard to tell if both modalities were applied within the therapeutic window, if the instruments were properly calibrated and so forth. At any rate, most physiotherapeutic modalities have a stronger scientific documentation than ultrasound, but traditionally ultrasound therapy has a long history and is more accepted than LPT – whether better or not.

As already mentioned, a comparison between LPT and ultrasound requires the use of reasonable parameters for both modalities. Let us have a look at a very recent effort to compare the two modalities:

Manca [1] presents the following abstract:

Ultrasound (US) and low-level laser therapy (LLLT) are commonly employed for myofascial trigger points (MTP) despite lack of evidence for usage as stand-alone treatments. The aim of the study was to determine, on MTP of the upper trapezius muscle (uTM), the effects of US and LLLT per se, as delivered in accordance with the procedures reported by surveys about their usage among physiotherapists. Design was set as a double-blind, randomized, placebo-controlled study. Sixty participants with at least one active MTP in uTM (28 women and 32 men; mean age 24.5 ± 1.44 years) were recruited and randomly assigned to one out of five groups: active US (n = 12), placebo US (n = 12), active LLLT (n = 11), placebo LLLT (n = 11) and no therapy (control, n = 14). The participants and outcome assessor were blinded to the group assignment and therapy delivered. Three outcome measures were assessed at baseline, after a 2-week treatment and 12 weeks after the end of the intervention (follow-up): pressure pain threshold, subjective pain on a numerical rating scale and muscle extensibility performing a cervical lateral flexion. All subjects assigned to the intervention groups were treated five times weekly for overall 10 treatments given. Two-way ANOVA was used to compare differences before and after intervention and among groups at each time-point. After the 2-week intervention, all groups showed pressure pain threshold, numerical rating scale and cervical lateral flexion significant improvements, which were confirmed at the follow-up. When performing multiple comparisons, controls scored significantly less than both the active therapies and placebos, whereas no differences were detected between active therapies and placebos. Ultrasound and LLLT provided significant improvements in pain and muscle extensibility, which were superior to no therapy but not to placebos, thus raising concerns about the suitability, both economically and ethically, of administering such common physical modalities as stand-alone treatments in active MTP of the uTM.

At first glance this appears to be an ambitious study. But is it? Here are the laser parameters:

Active low-level laser therapy: A J&S Medical-Cyberlight (J&S, Rome, Italy), Mod. Ls1-Ga/As LLLT machine was used. According to the acknowledged guidelines (WALT, 2004), delivery parameters were: wave-length 904 nM; pulse duration 200 ns; pulse frequency 1953 Hz; peak power 90 mW; average output 30 mW; power density 22.5mWcm2; treatment time 600 seconds; energy dose 18 J per session; spot size 4 cm2 and treatment frequency five times/week. Laser probe (head size: 4 cm2) was applied steady in skin contact with no pressure over the MTP.

The 904 nm laser cannot possibly have a peak power of 90 mW. Let us accept this as a misprint for 90 W. If so, the average output is 35 mW (not 30), which is reasonable for a TP. However, the “spot” is 4 cm2, so the 30 mW is spread over a large area, producing a power density that is very low. And in fact even lower than the one stated in the paper. Assuming that the peak power is 90 watt instead of 90 mW, the average output power can be calculated to 35 mW. Spot size is said to be 4 cm2. Then the power density will become 7.5 mW/cm2 (if 30 mW is used) or 8.8 mW/cm2 (if 35 mW is used). How is the stated 22.5 mW/cm2 calculated? Anyway, both 22 and 8 mW/cm2 are relatively low power densities.

Further, WALT recommendation for a TP is not 18 J, but 2-4 J per point and certainly not one single TP. 18 J would be inhibitory. In short, this is a paper that will be frequently cited and misunderstood. Manufacturer, therapists, reviewers – where were you?

 

Below is a collection of studies were LPT and ultrasound have been used, separately or in combination.

 

The aim of the study by Yavuz [2] was to compare the effectiveness of LPT and ultrasound therapy in the treatment of subacromial impingement syndrome. Thirty-one patients with subacromial impingement syndrome were randomly assigned to LPT group (n=16) and ultrasound therapy group (n=15). Study participants received 10 treatment sessions of LPT or ultra­sound therapy over a period of two-consecutive weeks (five days per week). Outcome measures (visual analogue pain scale, Shoulder Pain and Disabil­ity Index -SPADI-, patient’s satisfactory level and sleep interference score) were assessed before treatment and at the 1st and 3rd months after treat­ment. All patients were analysed by the intent-to-treat principle. Mean reduction in VAS pain, SPADI disability and sleep interference scores from baseline to after 1 month, and 3 months of treatment was statistically signifi­cant in both groups. However, there was no significant difference in the mean change in VAS pain, SPADI disability and sleep interference scores between the two groups. The results suggest that efficacy of both treatments were comparable to each other in regarding reducing pain severity and functional disability in patients with subacromial impingement syndrome

In a study by Prochazka [3], 40 patients were followed under a period of more than five years. Classic medicamentous techniques (colchi­cine, vitamin E) were combined with laser treatment of the following param­eters: probes 200 and 300 mW, 50 J/cm2 continuous mode + 50 J/cm2 with the beam modulated to a 5 Hz pulse repetition rate in one therapy bout. The therapy was applied 20 times in succession, twice a week as an introductory series of procedures, followed by a maintenance series of three to five proce­dures 2 - 3 times a year. In combination with ultrasound, the total effect was very satisfactory.

Strada [4] has treated nearly 300 patients with Peyronie’s disease. GaAs laser treatment in combination with ultrasound was performed once a week for five weeks. All the patients showed pain reduction at the two-month control. A total of 60% reported a reduction of recurvatio penis. A group of patients underwent phlebocavernosometry, showing a disappearance of patches in 30% of the cases. Strada has also treated more than 200 patients with chronic abacterial prostatitis. A GaAs laser probe was used in an endorectal approach (every second day, 12 sessions) and a 30 mW GaAlAs laser was used in a urethral approach (every third day, 8 sessions). More than 65% of the patients had symptom relief even after six months. Spermatic fluid was analysed before and after therapy. There was an increase in the total germinal cell count, and an improvement in motility and morphology. Prostate ultrasound showed a mean reduction of prostate volume from 29.9 cc to 21.9 cc, probably due to resolution of oedema.

The study by Sari [5] compared the effectiveness of matrix rhythm therapy, ultrasound treatment (UT), laser treatment (LT) used in the physio­therapy of burns. The case series comprised 39 individuals with second- and third-degree upper-limb burns, whose burn traumas ended approximately 1 to 3 months previously. Participants were separated into three groups: matrix rhythm treatment (MRT), UT and LT; each group was also applied a treatment protocol including whirlpool and exercise. Pain, range of motion (ROM), muscular strength, skin elasticity, and sensory functions were evalu­ated before and after the treatment. Pressure sense and passive ROM were higher in the MRT group than in the LT group. Pain was lower in the LT group than in the UT group, and passive ROM was higher in the UT group than the in LT group. Active ROM was found to increase in all treatment groups, whereas passive ROM increased only in the MRT and UT groups; pressure sense increased only in the MRT group, and pain decreased only in the LT group. MRT was found to be more effective in the restoration of sen­sory functions than LT, whereas LT was more effective in reducing pain than UT. No significant difference was observed in terms of skin elasticity accord­ing to the results of three treatment modalities.

Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and a systematic review by Bjordal [6] was aimed at assessing their short-term efficacies for pain relief. The authors performed a systematic review with meta-analysis of efficacy within 1-4 weeks and at follow-ups 1-12 weeks after the end of treatment. A total of 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. Three or more out of five methodological criteria (Jadad scale) were satisfied by 33 trials. The patient sample had a mean age of 65.1 years and a mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultra­sound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and LPT offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LPT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LPT, EA and TENS treatment was stopped. In conclusion, TENS, EA and LPT administered with optimal doses in an inten­sive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK.

A study by Liriani-Galvao [7] aimed to compare the consequences of LPT and low-intensity pulsed ultrasound (LIPUS) on bone repair. Many studies have assessed the effects of LPT and LIPUS on bone repair, but a comparison of them is rare. Male Wistar rats (n=8) with tibial bone osteo-tomy were used. One group had the osteotomised limb treated with LPT (780 nm, 30 mW, 112.5 J/cm2) and the second group with LIPUS (1.5 MHz, 30 mW/cm2), both for 12 sessions (five times per week); a third group was the control. After 20 days, rats were sacrificed and had their tibias submitted to a bending test or histomorphometric analysis. In the bending test, maximum load at failure of the LPT group was significantly higher. Bone histomor­phometry revealed a significant increase in osteoblast number and surface, and osteoid volume in the LPT group, and a significant increase in eroded and osteoclast surfaces in the LIPUS group. In conclusion LIPUS enhanced bone repair by promoting bone resorption in the osteotomy area, while LPT accelerated this process through bone formation.

The results of a study by Andrade Gomes [8] suggest an acceleration of bone mineral density after laser and ultrasound irradiation. Ultrasound irradiation showed the greatest effects and the laser power positively influ­enced the recuperation of the bone density on the side opposite its applica­tion, causing a cross reaction or even exacerbating the inherent action of ultrasound irradiation.

In a two-centre study, Simunovic [9] treated 324 patients, 50 with epicondylitis ulnaris and 274 with epicondylitis radialis. All in all 32% of the patients were acute and 68% chronic cases. All patients had previously been treated with various methods such as TENS, ultrasound, drugs and surgery. The patients were divided into three treatment groups. One received 830 nm laser light on trigger points only, the second was treated only with a scan­ner, and the third group received a combined treatment. The third group was the most successful. In the three groups together, complete relief of pain and restored functional ability were achieved in 82% of the acute patients and in 66% of the chronic cases. One centre had more powerful lasers available. Though the same doses were used at both centres, this latter group was slightly more successful. Another 41 patients with bilateral problems were selected for a cross-over study. Minimal dose in unilateral cases was 20 J, which could be increased step-by-step up to 60 J.

The aims of the study by Oken [10] were to evaluate the effects of LPT and to compare these with the effects of brace or ultrasound (US) treat­ment in tennis elbow. The study design used was a prospective and ran­domised, controlled, single-blind trial. Fifty-eight outpatients with lateral epicondylitis were included in the trial. The patients were divided into three groups: 1) brace group-brace plus exercise, 2) ultrasound group-US plus exercise, and 3) laser group-LPT plus exercise. Patients in the brace group used a lateral counterforce brace for three weeks, US plus hot pack in the ultrasound group, and laser plus hot pack in the LPT group. In addition, all patients were given progressive stretching and strengthening exercise pro­grammes. Grip strength and pain severity were evaluated by visual analogue scale (VAS) at baseline, at the second week of treatment, and at the sixth week of treatment. VAS improved significantly in all groups after the treat­ment and in the ultrasound and laser groups at the sixth week. Grip strength of the affected hand increased only in the laser group after treatment, but was not changed at the sixth week. There were no significant differences between the groups on VAS and grip strength at baseline and at follow-up assessments. The results show that, in patients with lateral epicondylitis, a brace has a shorter beneficial effect than US and LPT in reducing pain, and that LPT is more effective than the brace and US treatment in improving grip strength.

A total of 2 reviews and 20 RCTs were included in the literature anal­ysis by Dingemanse [11]. Different electrophysical regimes were evalu­ated: ultrasound, laser, electrotherapy, ESWT, TENS and pulsed electromagnetic field therapy. Moderate evidence was found for the effec­tiveness of ultrasound versus placebo on mid-term follow-up. Ultrasound plus friction massage showed moderate evidence of effectiveness versus laser therapy on short-term follow-up. On the contrary, moderate evidence was found in favour of laser therapy over plyometric exercises on short-term follow-up. For all other modalities only limited/conflicting evidence for effectiveness or evidence of no difference in effect was found. Potential effec­tiveness of ultrasound and laser for the management of LE was found.

Kannan [12] aimed to study the effect of therapeutic ultrasound, LPT and ischemic compression in reducing pain and improving cervical range of motion among patients with MTPt. Experimental study comparing three groups was designed as a 5 days trial. VAS for pain, provocative pain test using “soft tissue tenderness grading scheme” and active cervical lateral flexion using inch tape.  Patients were divided into 3 groups, Gr 1 underwent treatment using therapeutic ultrasound, Gr 2 with LPT and Gr 3 with ischemic compression. Assessments were done on day 1 and day 5 of treat­ment respectively. ANOVA revealed improvement among all 3 groups as sta­tistically significant difference between the start and end of trial. Analysis using Chi square test shows a statistically significant difference in the improvement between laser and the other 2 groups. Mean difference in the change of scores between the assessments showed laser therapy to have a tendency towards progressive improvement over the treatment period and a better improvement than the other 2 groups.

Hronková [13] irradiated the place of maximum pain with a 200 mW, 870 nm laser, energy density 9 J/cm2, 10 sessions every other day. Sixty-one patients had this therapy while fifty-two patients had a non-active placebo laser. In the laser group, 64% had a complete remission of pain, 26% experi­enced an improvement, and in 10% this therapy brought no effect at all. In the placebo group, 18% reported a full remission of pain, 42% reported an improvement and 40% felt no effect. In a separate study, ultrasound was used for 60 patients - 1 W/cm2 applied for 5 minutes, 10 applications. All in all 50% of the patients had a complete remission of pain, 16.6% were improved and 33.3% reported no effect. Eight of the patients who had not experienced any effect from ultrasound were given LPT, no earlier than two weeks after ending the ultrasound treatment. Six of these patients evaluated their treatment as successful while the additional LPT had no effect in two patients.

Kim [14] found improvement in maximum mouth opening and increase in the pressure pain threshold after irradiating tender points in the masseter and trapezius. Laser was more effective than ultrasound.

Gray [15] performed a clinical study where the effects of shortwave diathermy, megapulse, ultrasound and laser were compared in TMD ther­apy. There was no significant difference in success rate between the four therapies but all were better than placebo. The laser used was Space IRCEB-Up, 904 nm, and the reported dose was 4 J/cm2, 3 minutes application, 3 times weekly for 4 weeks. There is no information in the text making a verifi­cation of this dose possible. This laser typically had 4 mW of power in con­trast to pamphlet values and only at maximum pulsing. Nor is there any information on the therapeutic technique for either arthritis/arthrosis or myosis. This makes an evaluation of the laser part of the study difficult.

 

The literature is inconclusive, but for an evaluation to be performed, reasonable laser parameters must have been applied in a study.

 

1. Manca A, Limonta E, Pilurzi G, Ginatempo F, De Natale E R, Mercante B, Tolu E, Deriu F. Ultrasound and Laser as Stand-Alone Therapies for Myofascial Trigger Points: A Randomized, Double-Blind, Placebo-Controlled Study. Physiother Res Int. 2014 [Epub ahead of print]

2. Yavuz F, Duman I, Taskaynatan M A, Tan A K. Low-level laser therapy versus ultra­sound therapy in the treatment of subacromial impingement syndrome: A randomized clinical trial. J Back Musculoskelet Rehabil. 2013 [Epub ahead of print]

3. Prochazka M, Koci K. Non-invasive laser therapy of morbus peyronie - induratio penis plastica. Abstracts of 7th Int Congr European Medical Laser Assn, Dubrovnik, Croatia 2000, p. 39.

4. Strada G et al. Semi-conductor laser ray therapy for the treatment of abacterial chronic prostatitis, induratio penis plastica and urethral stenosis. In: Lasers in Medicine and Dentistry. Ed. Simunovic Z. 2000. European Medical Laser Assn. ISBN 953-6059-30-4.

5. Sari Z, Polat M G, Ozgul B, Aydogdu O, Camcioglu B, Acar A H, Yurdalan S U. A Comparison of Three Different Physiotherapy Modalities Used in the Physiotherapy of Burns. J Burn Care Res. 2013 [Epub ahead of print]

6. Bjordal J M, Johnson M I, Lopes-Martins R A, Bogen B, Chow R, Ljunggren A E. Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials. BMC Musculoskelet Disord. 2007; 8:51.

7. Lirani-Galvao A P, Jorgetti V, Lopes Da Silva O. Comparative Study of How Low-Level Laser Therapy and Low-Intensity Pulsed Ultrasound Affect Bone Repair in Rats. Pho­tomed Laser Surg. 2006; 24 (6): 735-740.

8. Andrade Gomes do Nascimento L E, Sant’anna E F, Carlos de Oliveira Ruellas A, Issamu Nojima L, Goncalves Filho A C, Antonio Pereira Freitas S. Laser Versus Ultrasound on Bone Density Recuperation After Distraction Osteogenesis - A Cone-Beam Computer Tomographic Analysis. J Oral Maxillofac Surg. 2013 [Epub ahead of print]

9. Simunovic Z, Trobonjaca T, Trobonjaca Z. Treatment of medial and lateral epi­condylitis - tennis and golfer’s elbow with low level laser therapy: a multicenter double blind, placebo-controlled clinical study on 324 patients. J Clin Laser Med & Surg. 1998; 16 (3): 145-151.

10. Oken O, Kahraman Y, Ayhan F, Canpolat S, Yorgancioglu Z R, Oken O F. The short-term efficacy of laser, brace, and ultrasound treatment in lateral epicondylitis: a prospective, randomized, controlled trial. J Hand Ther. 2008; 21 (1): 63-67.

11. Dingemanse R, Randsdorp M, Koes B W, Huisstede B M. Evidence for the effective­ness of electrophysical modalities for treatment of medial and lateral epicondylitis: a system­atic review. Br J Sports Med. 2013 [Epub ahead of print]

12. Kannan P. Management of myofascial pain of upper trapezius: a three group compari­son study. Glob J Health Sci. 2012; 4 (5): 46-52.

13. Hronková H, Navrátil L, Krymplová J, Knizek J. Possibilities of the analgesic therapy of ultrasound and non-invasive laser on plantar fasciitis. Laser Partner. No 21. May 2001. www.laserpartner.org.

14. Kim S-Y, Park J-S. The effect of low level laser therapy at the trigger points in mas­seter and other muscles. J Korean Acad. Oral Med. 1996; 21 (1): 1-3.

15. Gray R J M, Quale A A, Hall C A et al. Physiotherapy in the treatment of temporoman­dibular joint disorders: a comparative study of four treatment methods. Br J Dent. 1994; 176: 257-261.