- Email: [email protected]
Negative Approach
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during isonation, verifying that viscous heating errors had been eliminated. The axial temperature profile along the test cell indicates that in a bounded medium, more even heating can be achieved at depth using 45 kHz radiation than 1 MHz. These results are perhaps not surprising when, as pointed out by Ward and Robertson, long-wave ultrasound penetrates more deeply due to low absorption. They also correctly observe that greater dispersion due to beam divergence would lead to rnore refraction and reflection of the transmitted beam, which may therefore pass through the same tissue more than once. We do not believe that we are any more justified in claiming that our diathermy model is relevant to in vivo treatment than that of Ward and Robertson. However, we can at least claim to have carried out our tests under scientific discipline which ensured for example that both treatment machines were calibrated before and after the experiment. The 45 kHz machine is known to have had a maximum output capability of 0.95 watts total power and not 12.0 watts as stated by them. Such blatant inattention to detail is inexcusable when the machine display clearly indicated the correct treatment data, and furthermore casts doubt on the validity of the experimental techniques in general. Ward and Robertson re-analysed the outcome data from the sole longwave clinical paper that has been published (Bradnock et a/, 1996). What they have failed to recognise is the elegance of the statistical analysis that was performed in the original paper. By measuring the percentage improvement of each individual, a more accurate statistical analysis can be performed. It is obvious even to a casual observer that the gait pattern of someone who is 4 ft 3 in tall is different from that of someone who is 6 ft 6 in tall and this is reflected in the gait parameters that were measured using Gaitway - this height discrepancy is eliminated using the percentage improvement as a statistical tool. Clearly, if other statistical analyses were to be employed, it would be necessary to randornise patients according to height and weight using a computerised micro streaming technique and a much greater number of patients would be required. Using this
Physiotherapy, May 1997, vol 83, no 5
elegant method, smaller numbers can be used and statistically significant results can be obtained. Ward and Robertson stated that there is an analgesic effect with longwave ultrasound but in Bradnock’s opinion this analgesic effect is secondary to reduced tissue tension. When sprained ankles are treated using longwave ultrasound, wrinkles re-appear in the skin and the joint movement increases in range. It may be that the reduction in tissue tension affords analgesia and allows better mobility. While we welcome serious debate on the important issues of ultrasound therapy, it is clear to us and many other members of the scientific community that this must be based on good science. We believe that this paper has widened the debate and that there is need for serious academic support, perhaps in the form of a multi-disciplinary study which would seek to combine our knowledge of the
biology, physics and physiologyof this important subject.
Brian Bradnock FRCSEd FRCSOrth Royal National Orthopaedic Hospital Stanmore
M Young MSc PhD Orthosonics Ltd Asburton, Devon
References Dyson, M, Pond, J, Woodward, J and Broadbent, J (1974). ‘The production of blood cell stasis and endothelial cell damage in the blood vessels of chick embryos treated with ultrasound in a stationary wave field’, Ultrasound in Medicine and Biology, 1, 133-1 48. Robertson, V J and Ward, A R (1997). ‘Longwave ultrasound reviewed and reconsidered’, Physiotherapy, 83, 3, 123-130. Bradnock, B, Law, H T and Roscoe, K (1 996). ’A quantitative comparative assessment of the immediate response to high frequency ultrasound and low frequency ultrasound (“longwave therapy”) in the treatment of acute ankle sprains’, Physiotherapy, 82, 2, 78-84.
Negative Approach MADAM - I found the article ‘Longwave ultrasound reviewed and reconsidered’by Robertson and Ward (fhysioherapy,March) very negative. It criticises the use of longwave (45 KHz) ultrasound because of a lack of research. However, there is also a scarcity of quality research to condone the continuing use of MHz frequency ultrasound,and support the writers’ claim of ‘therapeutic adequacy’. The clinical study which compared the outcomes of using 45 KHz and 3 MHz ultrasound on ankle sprain patients (Bradnock et a/, 1996) measured function, not physiological effects. Surely such a comparison is valid, even if the results suggest that the physiological effects may differ? I have used 45 KHz ultrasound for three years and would not dispute the visible heating effects on many patients, viz reddening of the skin. I do not believe this superficial heating is the only effect of 45 KHz ultrasound; otherwise I would be using a heatpack which costs less. Results suggest that there is a deeper analgesic effect (perhaps by stimulation of A beta fibres, triggering pain modulation by the ‘gate mechanism’) which enables patients with acute ankle sprain to demonstrate immediate improvement in gait parameters after
treatment. This increased weightbearing activates the venous foot pump with resultant hastening of healing time. This mediates a quicker response than 3 MHz ultrasound is likely to achieve through its gradual influences on inflammation and collagen repair. Clearly there is a need for further research with a larger sample and longer-term observations than in the above trial. With a larger sample there would be less chance of random allocation producing unmatched groups. Incidentally, the 45 MHz and sham KHz groups were matched, and the 45 KHz effected significantly better results in outcome measures. This important research finding should not be ignored. In the meantime I shall continue to use 45 KHz ultrasound because I find my patients get quicker and better results than with MHz ultrasound.
Jenny Wigram
MSc MCSP
Exeter
Reference Bradnock, B, Law, H T and Roscoe, K (1 996). ‘A quantitative comparative assessment of the immediate responseto high frequency ultrasound and low frequency ultrasound (“longwave therapy”) in the treatment of acute ankle sprains’, Physiotherapy, 82, 2, 78-84.
during isonation, verifying that viscous heating errors had been eliminated. The axial temperature profile along the test cell indicates that in a bounded medium, more even heating can be achieved at depth using 45 kHz radiation than 1 MHz. These results are perhaps not surprising when, as pointed out by Ward and Robertson, long-wave ultrasound penetrates more deeply due to low absorption. They also correctly observe that greater dispersion due to beam divergence would lead to rnore refraction and reflection of the transmitted beam, which may therefore pass through the same tissue more than once. We do not believe that we are any more justified in claiming that our diathermy model is relevant to in vivo treatment than that of Ward and Robertson. However, we can at least claim to have carried out our tests under scientific discipline which ensured for example that both treatment machines were calibrated before and after the experiment. The 45 kHz machine is known to have had a maximum output capability of 0.95 watts total power and not 12.0 watts as stated by them. Such blatant inattention to detail is inexcusable when the machine display clearly indicated the correct treatment data, and furthermore casts doubt on the validity of the experimental techniques in general. Ward and Robertson re-analysed the outcome data from the sole longwave clinical paper that has been published (Bradnock et a/, 1996). What they have failed to recognise is the elegance of the statistical analysis that was performed in the original paper. By measuring the percentage improvement of each individual, a more accurate statistical analysis can be performed. It is obvious even to a casual observer that the gait pattern of someone who is 4 ft 3 in tall is different from that of someone who is 6 ft 6 in tall and this is reflected in the gait parameters that were measured using Gaitway - this height discrepancy is eliminated using the percentage improvement as a statistical tool. Clearly, if other statistical analyses were to be employed, it would be necessary to randornise patients according to height and weight using a computerised micro streaming technique and a much greater number of patients would be required. Using this
Physiotherapy, May 1997, vol 83, no 5
elegant method, smaller numbers can be used and statistically significant results can be obtained. Ward and Robertson stated that there is an analgesic effect with longwave ultrasound but in Bradnock’s opinion this analgesic effect is secondary to reduced tissue tension. When sprained ankles are treated using longwave ultrasound, wrinkles re-appear in the skin and the joint movement increases in range. It may be that the reduction in tissue tension affords analgesia and allows better mobility. While we welcome serious debate on the important issues of ultrasound therapy, it is clear to us and many other members of the scientific community that this must be based on good science. We believe that this paper has widened the debate and that there is need for serious academic support, perhaps in the form of a multi-disciplinary study which would seek to combine our knowledge of the
biology, physics and physiologyof this important subject.
Brian Bradnock FRCSEd FRCSOrth Royal National Orthopaedic Hospital Stanmore
M Young MSc PhD Orthosonics Ltd Asburton, Devon
References Dyson, M, Pond, J, Woodward, J and Broadbent, J (1974). ‘The production of blood cell stasis and endothelial cell damage in the blood vessels of chick embryos treated with ultrasound in a stationary wave field’, Ultrasound in Medicine and Biology, 1, 133-1 48. Robertson, V J and Ward, A R (1997). ‘Longwave ultrasound reviewed and reconsidered’, Physiotherapy, 83, 3, 123-130. Bradnock, B, Law, H T and Roscoe, K (1 996). ’A quantitative comparative assessment of the immediate response to high frequency ultrasound and low frequency ultrasound (“longwave therapy”) in the treatment of acute ankle sprains’, Physiotherapy, 82, 2, 78-84.
Negative Approach MADAM - I found the article ‘Longwave ultrasound reviewed and reconsidered’by Robertson and Ward (fhysioherapy,March) very negative. It criticises the use of longwave (45 KHz) ultrasound because of a lack of research. However, there is also a scarcity of quality research to condone the continuing use of MHz frequency ultrasound,and support the writers’ claim of ‘therapeutic adequacy’. The clinical study which compared the outcomes of using 45 KHz and 3 MHz ultrasound on ankle sprain patients (Bradnock et a/, 1996) measured function, not physiological effects. Surely such a comparison is valid, even if the results suggest that the physiological effects may differ? I have used 45 KHz ultrasound for three years and would not dispute the visible heating effects on many patients, viz reddening of the skin. I do not believe this superficial heating is the only effect of 45 KHz ultrasound; otherwise I would be using a heatpack which costs less. Results suggest that there is a deeper analgesic effect (perhaps by stimulation of A beta fibres, triggering pain modulation by the ‘gate mechanism’) which enables patients with acute ankle sprain to demonstrate immediate improvement in gait parameters after
treatment. This increased weightbearing activates the venous foot pump with resultant hastening of healing time. This mediates a quicker response than 3 MHz ultrasound is likely to achieve through its gradual influences on inflammation and collagen repair. Clearly there is a need for further research with a larger sample and longer-term observations than in the above trial. With a larger sample there would be less chance of random allocation producing unmatched groups. Incidentally, the 45 MHz and sham KHz groups were matched, and the 45 KHz effected significantly better results in outcome measures. This important research finding should not be ignored. In the meantime I shall continue to use 45 KHz ultrasound because I find my patients get quicker and better results than with MHz ultrasound.
Jenny Wigram
MSc MCSP
Exeter
Reference Bradnock, B, Law, H T and Roscoe, K (1 996). ‘A quantitative comparative assessment of the immediate responseto high frequency ultrasound and low frequency ultrasound (“longwave therapy”) in the treatment of acute ankle sprains’, Physiotherapy, 82, 2, 78-84.