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Effect of local anesthesia on clinical outcome after repetitve low-energy ESWT

Posted by Jan R. on 10/20/04 at 02:40 (161823)

Recently repetitive low-energy extracorporeal shock wave treatment (ESWT) has been widely used to treat a number of musculoskeletal conditions, including insertional disorders such as plantar fasciitis.

In clinical practice, the application of a local anesthesia prior to low-energy ESWT became subject to criticism therefore calling in question the negative results of a multicenter trial on ESWT in patients suffering from chronic plantar fasciitis. In this trial local anesthesia had been applied for reason of blinding.

Labek et al.(1) reported they had enrolled 60 patients with a chronic plantar fasciitis in a triple-arm (20 patients per group), prospective randomized and observer-blinded pilot trial. Patients were randomly assigned to receive either active ESWT without local anesthesia, given daily for three days (Group I, 3 x 1500 pulses, total energy flux density per shock 0.09 mJ/mm²), or ESWT with local anesthesia (Group II, 3 x 1500 pulses, total energy flux density per shock 0.18 mJ/mm²) or ESWT with local anesthesia (Group III, 3 x 1500 pulses, total energy flux density per shock 0.09 mJ/mm²). Main outcome measures were: Pain during first step in the morning (measured on a 0-10 point visual analog scale) and number of patients with >50% reduction of pain and no further therapy needed, measured at six weeks after the last ESWT. At six weeks, there was significant improvement in pain during first steps in the morning in all groups, by 4.2 points in Group I, by 2.6 points in Group II, and by 2.4 points in Group III. The mean between-group difference of improvement was statistically significant, between Group I and Group II, and between Group I and Group III. A reduction of pain of at least 50% was achieved in 60% of patients of Group I, in 36% of patients of Group II, and in 29% of patients of Group III. In conclusion, at six weeks success rates after low-energy ESWT with local anesthesia were significantly lower than after identical low-energy ESWT without local anesthesia.

Our confirmatory randomized-controlled study(2)on 86 patients confirmed their observation. The average pain score for patients who received ESWT without local anesthesia (Group I) was 6.9 points at baseline, and 2.2 points at 3 months. The average pain score for patients who received ESWT with local anesthesia (Group II) was 6.7 points at baseline, and 4.1 points at 3 months. At 3 months in Group I 67% of patients achieved at least a 50% reduction of pain, compared with 29% of patients in Group II. At 3 months in Group I 67% of patients achieved an excellent or good result, compared with 24% patients in Group II. Not all patients were satisfied, of course, in Group I. But with two third of them presenting with either no pain, full movement, and full activity, or with only occasional discomfort, full movement, and full activity, the results were not only statistically impressing. The results were clinically significant as well.

Obviously, accurate targeting of the pathology at the spot of maximal point tenderness, as described to the examiner by the patient, is crucial for optimal application of low-energy shock waves.

We conclude that there is a positive treatment effect of repetitive low-energy ESWT as applied at 3-month follow-up in subjects with chronic plantar fasciitis. This positive treatment effect may be reduced by application of a local anesthetic to the painful area prior to low-energy ESWT. Until further experimental and clinical research has developed evidence for this effect, a local anesthetic should not be used for blinding in randomized-controlled trials evaluating the clinical efficacy of repetitive low-energy ESWT for musculoskeletal disorders.

(1)Labek et al., Z Orthop Ihre Grenzgeb, in press
(2)Rompe et al., J Orthop Res, in press

Re: Effect of local anesthesia on clinical outcome after repetitve low-energy ESWT

Mark Evans on 10/21/04 at 14:38 (161906)

Dr Jan,

Interesting findings.

1. Please detail your and Labeks' criteria used to define 'chronic' PF in the studies.
2. Did the studies attempt to identify those patients with evidence of plantar fasciitis as opposed to fasciosis or was no distinction made between those entities.
3. Are you planning to follow up patients beyond 3 months?
4. In what way does your study protocol differ from Buchbinders'?

Thanks

Re: Effect of local anesthesia on clinical outcome after repetitve low-energy ESWT

Ed Davis, DPM on 10/22/04 at 11:07 (161980)

Mark:

I don't want to 'butt in' here but for more immediate information, you may want to look at Dr. Rompe's papers on the http://www.ismst.com website as I feel that they will answer most of your questions. Also, if you have the time, read some of the other papers on the http://www.ismst.com website too because I feel that it is the cumulative knowledge that you will gain by doing so that will really clarify some of the concepts that you are looking at. The term 'fasciosis' is a term akin to 'tendinosis' that is intuitively understood but not in general usage. The terms tendinosis and fasciosis are terms that should be better defined and used more commonly because they really are the key to differentiating those cases that stand to benefit from ESWT.

I would encourage practitioners to utilize the terminologies of fasciosis and tendinosis more commonly and as appropriate as those terms better describe what we are truly treating.
Ed

Re: Effect of local anesthesia on clinical outcome after repetitve low-energy ESWT

Mark Evans on 10/23/04 at 07:29 (162016)

Ed,

I have visited the website before but none of the articles relating to ESWT/heel can be dowloaded. (or I am missing something?)

On the topic of the term fasciois:

1. From previous posts you have suggested the term is useful to describe abnormal thickening of the fascia.

2. You have stated that ESWT is not useful when there is active inflammation. Is this concept validated through research and widely supported? Does this apply to both high and low energy ESWT? And if it is so, what measures are taken to screen patients prior to treatment? Is it possible to detect edema around the enthesis on ultrasound?

3. It was also said that fasciosis and inflammation can co-exist.

4. Do you believe the hallmark feature of PF - post static dyskinesia - is found only in fasciitis and not fasciosis ? (except when the conditions co-exist) What feature of the condition causes the pain?

Re: Effect of local anesthesia on clinical outcome after repetitve low-energy ESWT

Ed Davis, DPM on 10/25/04 at 14:26 (162112)

Mark:

I will have to look at the ismst.com website and see what you may be encountering.

If you want some validation of the uselessness of ESWT for acute PF, I think that Buchbinders study actually does that. Nevertheless, one must recognize exactly what ESWT accomlpishes -- it causes controlled microtrauma. In other words, it actually creates acute inflammation based on the theory that our bodies handle acute inflammation far better than chronic inflammation. As such, it is a means to convert chronic inflammation to acute inflammation.

Going further back, the concept originated when biopsies noted that some of the healthiest tissue in diseased kidneys occurred in the path of the shockwave. As such, it was hypothesized that there is a tissue level effect to the microtrauma caused by ESWT. Next, ESWT was experimented on rabbit tendons to look for tissue effect. The key is to understand the tissue level effect and that is where there is a lot of basis information on the http://www.ismst.com website. Dr. Rompe has posted a number of his papers on another website that I can refer you to only by email. Also, Dr. Z can provide confirmatory research. The society itself, ISMST, does contain quite a large information repository and much of that is on their website.
Ed
Ed