Ultrasound therapy in musculoskeletal disorders: a meta-analysis

We have reviewed 293 papers published since 1950 to assess the evidence of effect of ultrasound in the treatment of musculoskeletal disorders. Twenty-two clinical papers describing trials comparing ultrasound treatment with sham-ultrasound treated, non-ultrasound treatment and untreated groups were found. These papers were evaluated with respect to a list of criteria which should be met in this type of trial. They were generally found lacking with respect to description of drop-outs, randomisation methods, ultrasound apparatus, sham-ultrasound apparatus, control of apparatus, mode of delivery, size of sound-head, treated area and follow-up time. In 16 of these trials, ultrasound treatments were compared with sham-ultrasound and in 13 cases data were presented in a way that made pooling possible. Two standardized effect sizes (dd/r and dd/s) were applied to the results to enable evaluation of the effect of ultrasound treatment on pain. None of the methods (dd/r = 0.64%, confidence limits -6.7 to 7.5%; and dd/s = 0.24, confidence limits -0.01 to 0.49) gave evidence that pain relief could be achieved by ultrasound treatment. Hence we found no reason to analyze the other papers where ultrasound treatment was compared with another treatment or an untreated control group. We found a significant influence of degree of blinding using the d/s for the analysis (t test, P = 0.009), while when the d/r was used, only a trend was found (P = 0.10). An analysis of the effect of proper randomisation on the result was not possible because of inadequate description of the methods used. We conclude that the use of ultrasound in treatment of musculoskeletal disorders is based on empirical experience, but is lacking firm evidence from well-designed controlled studies. One question remaining is whether ultrasound treatment can augment an effect of exercise therapy with respect to musculoskeletal disorders.