To the Editor:
I read with great interest the article entitled " Botulinum Toxin
Injection in the Treatment of Tennis Elbow A Double-Blind, Randomized,
Controlled, Pilot Study" (1). Tennis elbow is a self
limiting condition that burns out in a year(2). Tennis elbow is, however,
symptomatic during that year affecting function and ability to work.
Measures to provide relief during the symptomatic period is required and
we commend the authors for doing an excellent study to see the short term
(3 month) benefit of Botulinum toxin vs placebo.
Currently the terms epicondylitis and tendinitis are not used to
describe tennis elbow which is now more commonly known as tendinosis(3).
Since tennis elbow is not an inflammatory process, rest provided by
botulinum toxin seems to be an excellent alternative(4,5).
The current report however concludes “With the numbers studied, we
failed to find a significant difference between the two groups; thus, we
have no evidence of a benefit from botulinum toxin injection in the
treatment of chronic tennis elbow”.
This conclusion which contradicts earlier reports(4,5) led us to
examine the patient groups, methodology and level of significance used in
this current report. There are a number of issues that require
clarification.
(1) The current study has used 4 outcome measurements. The outcome measurements are:
(a) Grip strength (Table I)
(b) Pain on Visual Analogue Scale (Table II)
(c) Physical function (Table III)
(d) Mental (Table III)
The PRE TREATMENT VALUES of both the Toxin and Placebo show that
in 3 out of the 4 outcome measures tested the Toxin group is worse than
the Placebo group and at least in the SF-12 Physical Function it reaches
nearly clinical significance (p=0.06). p=0.06 is nearly as important as
p=0.05(6). This makes one wonder whether the groups were really randomly
selected and matched for comparison.
(2) Could the authors please mention the gender and age distribution
of each of the Toxin and placebo group and whether they were comparable?
(3) The authors again describe in length the Visual Analogue Scale
stating that it ranges from 0 to 10(7). If 10 is the maximum possible score
on a Visual Analogue Scale how did the authors obtain Mean Post injection
Pain Scores of 11.35 for the Toxin group and 12.46 cm for the Placebo
group (Table II) ?
References
1. Hayton MJ, Santini AJA, Hughes PJ, Frostick SP, Trail IA and
Stanley JK Botulinum Toxin Injection in the Treatment of Tennis Elbow A
Double blind, Randomized, Controlled, Pilot Study (2005 87-A 3 Mar 503
– 507
2. Smidt N, van der Windt DA, Assendelft WJ, Deville WL, Korthals-de
Bos IB, Bouter LM. Corticosteroid injections, physiotherapy, or a wait-and
-see policy for lateral epicondylitis: a randomised controlled trial.
Lancet. 2002 Feb 23;359:657-62.
3. Kraushaar BS, Nirschl RP. Tendinosis of the elbow (tennis elbow).
Clinical features and findings of histological, immunohistochemical, and
electron microscopy studies. J Bone Joint Surg Am. 1999;81:259-78.
4. Keizer SB, Rutten HP, Pilot P, Morre HH, v Os JJ, Verburg AD.
Botulinum toxin in-jection versus surgical treatment for tennis elbow: a
randomized pilot study. Clin Orthop. 2002;401:125-31.
5. Morre HH, Keizer SB, van Os JJ. Treatment of chronic tennis elbow
with botulinum toxin. Lancet. 1997;349:1746.
6. Rosnow RL Rosenthal R Statistical procedures and the justification
of knowledge in psychological science. American Psychologist 44:1276-1284.
7. Scott J, Huskisson EC. Graphic representation of pain. Pain.
1976;2:
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