Radial extracorporeal shockwave treatment compared withsupervised exercises in patients with subacromial painsyndrome: single blind randomised study
Kaia Engebretsen, physiotherapist,1,2 Margreth Grotle, research leader,2,3 Erik Bautz-Holter, professor,1,2 LeivSandvik, professor,4 Niels G Juel, MD consultant,1,2 Ole Marius Ekeberg, Research fellow,1,2 Jens Ivar Brox, MDconsultant2,5
inflammatory drugs, and corticosteroid injections.
Objective To compare the effectiveness of radial
Physiotherapy includes a variety of modalities such as
extracorporeal shockwave treatment with that of
electrotherapy, radial extracorporeal shockwave treat-
supervised exercises in patients with shoulder pain.
ment, ultrasound treatment, laser treatment, manual
Design Single blind randomised study.
therapy, supervised exercises, sling exercise treatment,
Setting Outpatient clinic of physical medicine and
and acupuncture.4-7 Some evidence exists for the effec-
rehabilitation department in Oslo, Norway.
tiveness of corticosteroid injections, non-steroidal anti-
Participants 104 patients with subacromial shoulder pain
inflammatory drugs, and exercises for chronic
shoulder pain.8-10 A recent systematic review con-
Interventions Radial extracorporeal shockwave
cluded that surgery and exercises are equally effective
treatment: one session weekly for four to six weeks.
for rotator cuff disease.11 In studies of musculoskeletal
Supervised exercises: two 45 minute sessions weekly for
pain, women report pain that is more severe, more fre-
quent, and of a longer duration than do men.12 13 Stra-
Primary outcome measure Shoulder pain and disability
tification by sex or adjustment for sex is therefore
recommended in the analysis of data from trials.
Results A treatment effect in favour of supervised
In a systematic review, Harniman et al found mod-
exercises at 6, 12, and 18 weeks was found. The adjusted
erate evidence that low energy radial extracorporeal
treatment effect was −8.4 (95% confidence interval −16.5
shockwave treatment was not effective for non-calcify-
to −0.6) points. A significantly higher proportion of
ing rotator cuff tendinosis.6 Additional studies includ-
patients in the group treated with supervised exercises
ing patients with calcifying or non-calcifying tendinosis
improved—odds ratio 3.2 (1.3 to 7.8). More patients in
reported no treatment effect compared with sham or
the shockwave treatment group had additional treatment
control.14 15 Despite these findings, shockwave treat-
between 12 and 18 weeks—odds ratio 5.5 (1.3 to 26.4).
ment is increasingly used for subacromial shoulder
Conclusion Supervised exercises were more effective
pain. To our knowledge, radial extracorporeal shock-
than radial extracorporeal shockwave treatment for short
wave treatment has not been compared with exercises
term improvement in patients with subacromial shoulder
in a clinical trial including patients with shoulder pain.
The purpose of this study was to compare the short
Trial registration Clinical trials NCT00653081.
term effect of radial extracorporeal shockwave treat-ment and supervised exercises in patients with suba-
The shoulder is the fourth most common site of mus-culoskeletal pain reported by patients to general prac-
titioners and physiotherapists.1 Rotator cuff disease,
impingement syndrome, and rotator cuff tendinosis
The study was designed as a randomised single blind
are terms used synonymously with subacromial
clinical study. Participants were recruited by physi-
shoulder pain. The exact source and mechanism of
cians at the outpatient clinic of the Physical Medicine
the pain is unknown.2 Histopathology studies show
and Rehabilitation Department at Ullevaal University
mainly degenerative changes in the rotator cuff ten-
Hospital, Oslo, Norway, between July 2006 and
dons, but other factors also contribute to the pain and
Women and men aged between 18 and 70 years with
Patients with subacromial shoulder pain are often
subacromial shoulder pain lasting at least three months
treated with physiotherapy, non-steroidal anti-
were eligible for inclusion. The following diagnostic
outcome measure was the shoulder pain and disability
index (SPADI), a self report questionnaire for patientswith shoulder pain. The questionnaire consists of 13
Excluded (n=37): Not meeting inclusion criteria (n=31)
questions divided into two domains: pain (five items)
and disability (eight items).18 Answers are scored on
visual analogue scales from 0 cm (best) to 11 cm
(worst) and in accordance with the original scoringsystem.18 The total score ranges from 0 to 100 points,with a higher score indicating worse shoulder pain and
disability.18 A version adapted to Norwegian language
shockwave therapy (n=52)Received allocated intervention (n=51)
and culture, translated and back translated by indepen-
dent philologists, was used in this study.19 20
Intensity of pain during rest and activity in the pre-
vious week was measured on a nine point Lickert-type
scale, on which 1 indicates no pain and 9 indicates severe
pain.21 Participants were asked two questions about spe-
cific function of the shoulder: “Can you carry a shopping
bag (5 kg)?” and “Can you take down something from a
wall cupboard?” These questions were scored on a scale
from 1 (easy) to 7 (impossible).21 Active range of motion
was measured bilaterally with an accuracy of 5°.2122 Thepatients decided when the pain condition confined the
Participants reported work status according to a vali-
criteria were used: dysfunction or pain on abduction,
dated questionnaire.23 A status of retired was recorded
normal passive glenohumeral range of motion, pain on
separately. They also recorded use of drug treatment,
two of three isometric tests (abduction at 0° or 30°,
including both daily and weekly treatments for pain,
external or internal rotation), and a positive Ken-
nedy-Hawkins sign.1 16 17 Park et al recommend thesecombined clinical tests for a clinical diagnosis of sub-
acromial impingement syndrome (or rotator cuff ten-
At six weeks the patients completed a postal question-
dinosis) with a post-test probability of 95%.17 Patients
naire, including the outcome measures, at home. The
with rotator cuff rupture were included if they fulfilled
12 week and 18 week follow-ups were done at the hos-
the above criteria. Exclusion criteria were bilateral
pital. A blinded physiotherapist made the baseline and
shoulder pain, previous surgery on the affected
follow-up measurements. The patients were instructed
shoulder, instability, clinical signs of a cervical syn-
not to discuss their treatment with the blinded physio-
drome, rheumatoid arthritis, clinical and radiological
signs of glenohumeral or acromioclavicular arthritis,inability to understand Norwegian, serious psychiatric
disorder, use of anticoagulant drugs (except low dose
Both treatments were given at the Department of Phy-
aspirin), pregnancy, previous experience of one of the
sical Medicine and Rehabilitation. The supervised
study interventions, or unwillingness to accept either
exercise regimen, developed at Ullevaal University
Hospital by Bøhmer in the 1980s,5 was provided bytwo physiotherapists experienced in its performance.
Patients attended two 45 minute sessions weekly for a
The patients were referred to the investigator (KE, a
maximum of 12 weeks. The first session included gath-
physiotherapist), received oral and written informa-
ering medical history and bilateral inspection of align-
tion about the two treatments, and gave their informed
ment, including the scapula and the glenohumeral
consent before the baseline evaluation. A statistician
joint. Movement pattern, the immediate co-contrac-
not involved in data collection or analysis randomly
tion, and timing of the scapula and the arm were
allocated patients to treatment groups in blocks of
observed during elevation to obtain a functional diag-
four to six. Randomisation was stratified by sex. A per-
nosis for individual guidance of treatment.5 24 The prin-
son not involved in the treatments opened the sealed
cipal focus was on relearning of normal movement
envelopes and assigned appointments according to
patterns, which could then be transferred to daily
activities.5 The initial aim was to unload the stress onthe rotator cuff and subacromial structures.5 During
this phase, a mirror for awareness of posture, manual
The participants completed a comprehensive ques-
techniques for loosening tense muscles, an elastic rub-
tionnaire including questions on demographics, edu-
ber band, and a sling fixed to the ceiling were used.5 24
cation, duration of pain, sick leave, emotional
The patients received immediate feedback and correc-
distress, and the outcome measures. The main
tion (supervision) by the physiotherapist.
Table 1 | Baseline characteristics of participant according to treatment group. Values are
time between the start of treatment and the 18 week
numbers (percentages) unless stated otherwise
The study was designed to detect a difference of 10
points in the shoulder pain and disability index score
between groups with α value set at 0.05 (type I error)
and β at 0.2 (type II error).26 After a pilot study, and in
accordance with a previous study, the standard deviation
was estimated to 20.26 The sample size was calculated as
48 in each group for a univariate analysis of covariance.27
This is a linear model using baseline measures of the
primary outcome as a covariate. The ρ was set to 0.5.27
The study has three post-treatment registrations.
The main outcome variable (shoulder pain and disabil-
ity index score) is considered to be a continuous
variable.26 To evaluate the treatment effect (the mean
difference between the groups at six, 12, and 18 weeks),
Median (interquartile range) EQ5D index†
we used the mixed model analysis (repeated
measurements).28 This model includes the interaction
between treatment and elapsed time, baseline values
*0=worst imaginable health state; 100=best imaginable health state.
are adjusted, and we assume that data are missing at
†Evaluates health status: five dimensions with three categories in each.
random.28 The distribution of future values for a parti-cipant who drops out at time t and one who remains in
Once dysfunctional neuromuscular patterns were
at time t is expected to be the same if they have the
normalised, endurance exercises were performed
same covariates and the same history of outcome
with gradually increasing resistance. Principles of
until time t.28 Model assumptions were checked by
closed and open kinetic chain and plyometric exercises
residual plots. We estimated the smallest detectable
were incorporated in the next phase of training.5 24
real difference between two measurements on the
Patients had an adjusted programme at home, which
same person to be 19.6 points on the shoulder pain
consisted of correction of alignment during daily living
and disability index and used this as a cut-off point.19
and simple low loaded exercises with a thin elastic cord
We calculated the number needed to treat (NNT)
to provide assistance and resistance to the movement.
according to the method of Guyatt et al.29
We checked the secondary outcome measures for
Radial extracorporeal shockwave treatment (Swiss
normal distribution and found that parametric statis-
Dolor Clast, EMS) was provided by a physiotherapist
tics were appropriate.30 We used logistic regression
experienced in its use. The treatment was administered
with adjustment for baseline values to compare work
once a week for four to six weeks; three to five tender
status and drug treatment. We analysed data according
points were treated each time. Points were identified
to the intention to treat principle, in which the study
through a patient oriented biofeedback process (inser-
groups are compared in terms of the treatment to
tion of supraspinatus tendon, dorsolaterally below the
acromion, and a maximum of three trigger points inthe rotator cuff muscles).25 The frequency applied
was 12-8 Hertz with from 2000 pulses per session,
A total of 141 patients were eligible for inclusion, and
with a pressure between 2.5 and 4.0 Bar, depending
104 were randomised for study intervention (fig 1).
on what the patient tolerated without local anaesthetic.
The groups were similar at baseline with regard to
Radial extracorporeal shockwave treatment uses
age, education, dominant arm affected, duration of
low to medium energy shockwaves generated when a
pain, sick leave, shoulder pain and disability index
projectile is accelerated by compressed air and hits an
score, and secondary outcome variables (tables 1, 2
applicator.7 These impulses are delivered into the tis-
and 3). Seventeen (33%) patients in the radial extra-
sue and spread as spherical “radial” waves (rather than
corporeal shockwave group and 12 (23%) in the super-
being focused). Patients were informed that the sug-
vised exercise group were on sick leave because of
gested mechanism for pain relief was hyperstimulation
shoulder pain. Five patients in the radial extra-
analgesia and increased neovascularisation that
corporeal shockwave group and two in the supervised
improves regeneration of tissue.625 Patients were
exercise group claimed for disability pension.
advised to avoid activities that elicited pain.
Patients treated with radial extracorporeal shock-
All the patients were asked not to have any addi-
waves (n=52) received a median of five (interquartile
tional treatment except analgesics (including anti-
range 4-6) treatments. One patient had only one treat-
inflammatory drugs) for their shoulder pain for the
ment, and one patient had two treatments. Patients in
Table 2 | Mean (SD) scores and differences in improvement with overall P values at 18 weeks,
two out of 50 (64%) patients treated with supervised
from mixed models linear (repeated measures analysis)
exercises and 18/50 (36%) patients treated with radialextracorporeal shockwaves achieved a reduction in
shoulder pain and disability index score exceedingthe smallest detectable difference of 19.6 points (odds
group of supervised exercises and three (6%) in the
radial extracorporeal shockwave group deteriorated
after treatment. The number needed to treat was 3.2
(95% confidence interval 2.1 to 7.1).
At 18 weeks, results for pain, function, and active range
of motion were not statistically significant (table 2).
More patients in the supervised exercise group
returned to work (P=0.016) (table 3). Six patients in
the supervised exercise group and one in the radial
extracorporeal shockwave group used less drug treat-
One patient in the supervised exercise group reported
a considerable increase in pain and stiffness consistent
with adhesive capsulitis and had only four treatments.
In the group treated with radial extracorporeal shock-
waves, one patient dropped out after one treatment
and one after two treatments because of the aggrava-
tion of pain; one of them crossed over to the supervised
We found a small but statistically significant difference
in favour of supervised exercises over radial extra-corporeal shockwave treatment for the primary out-
the supervised exercise group (n=51) received a med-
come (shoulder pain and disability index) at six, 12,
ian of 14 (11-16) treatments. One patient did not
and 18 weeks in patients with subacromial shoulder
receive supervised exercises because of depression,
pain. The difference was consistent after adjustment
and another had only four sessions because of an
for education and duration of pain. In addition, more
increase in pain and a suspected adhesive capsulitis.
patients from the radial extracorporeal shockwave
One patient crossed over to the supervised exercise
group (13 v 3) had additional treatment after
group after one treatment with radial extracorporeal
12 weeks, suggesting that they were less satisfied. The
shockwaves (fig 1). Fourteen patients did not return
results for the differences in secondary outcomes were
the questionnaire at six weeks. Two patients rando-
in favour of exercises, but differences were not
mised to supervised exercises did not attend follow-up at 12 and 18 weeks, and two patients in the radialextracorporeal shockwave group did not attend the
18 week follow-up (fig 1). Thirteen patients in the radial
extracorporeal shockwave group and three patients inthe supervised exercise group received additional
treatment (cortisone injections, chiropractic treatment,
physical therapy/supervised exercises) between 12and 18 weeks (odds ratio 5.5, 95% confidence interval
Radial extracorporeal shockwave treatment
The treatment effect was in favour of supervised exer-
cises at six, 12, and 18 weeks. At 18 weeks the treatment
effect was −8.4 (95% confidence interval −16.5 to −0.6;
Fig 2 | Mean shoulder pain and disability index scores with
P=0.047) points (table 2, fig 2). The treatment effect
95% confidence intervals for supervised exercises and radial
was consistent when adjusted for sex (P=0.049). Thirty
Table 3 | Work status and drug treatment. Values are numbers (percentages) unless stated
Supervised exercises and arthroscopic surgery are better
Moderate evidence suggests that low energy radial
extracorporeal shockwave treatment is not effective for non-
Supervised exercises are better than radial extracorporeal
shockwave treatment for short term improvement in
*Old age pension not included (four in supervised exercise group and two in radial extracorporeal shockwavegroup at all follow-ups).
More patients treated with supervised exercises returned to
†Includes drug treatments for pain, sleep problems, and depression.
significant except for change in work status after
18 weeks, which may indicate that supervised exercise
Our results are in agreement with results from previous
is a more comprehensive rehabilitation intervention.
trials recommending exercise therapy9-1131 and do notstrengthen the evidence for extracorporeal shockwave
treatment.6 7 14 15 32 The difference in shoulder pain and
The advantages of this study are the randomised
disability index score of 8.4 points at the 18 week fol-
design, stratification by sex, treatments provided by
low-up was somewhat smaller than the difference (10
physiotherapists experienced in the use of the meth-
points) the study was designed to detect. For inter-
ods, high compliance, blinded observer, large number
preting the effectiveness of the treatment, we must con-
of patients attending follow-up, and intention to treat
sider not only statistical significance but also whether
the improvement (or deterioration) is relevant for the
At least three possible limitations must be taken into
patients or clinicians.33 By using the smallest detectable
account when interpreting the results. Firstly, we did
real difference for an individual patient of 19.6 points
not include a placebo group and cannot exclude the
as a cut-off point, we found that a larger proportion of
possibility that the observed results reflect a placebo
patients in the supervised exercise group than in the
effect or the natural course of the condition. A previous
radial extracorporeal shockwave treatment group
trial reported that a supervised exercise regimen was
improved.19 This suggests that more patients receiving
superior to placebo, so we found it difficult to justify the
inclusion of a placebo group.21 On the other hand, two
improvement.19 34 The number needed to treat to ben-
trials found no difference between sham and extra-
efit from supervised exercises was three, which is con-
corporeal shockwave treatment.7 14 We did not include
sidered clinically important.29 However, the estimate
a placebo radial extracorporeal shockwave group and
of number needed to treat has to be interpreted with
cannot substantiate the placebo effect in our study. Sec-
caution because of possible differences in the study
ondly, local anaesthetics were not injected into the sub-
population recruited from a university hospital and
acromial space to improve diagnostic accuracy. On theother hand, rotator cuff disease or subacromial
the population in primary care to which we wish to
shoulder pain is a clinical diagnosis and we used the
recommended combination of clinical tests to improve
The shoulder pain and disability index is a combined
patient selection.17 Thirdly, the study may be under-
score reported to be one of the most responsive
powered for detecting differences in the secondary out-
shoulder specific questionnaires available and more
come variables. We used a univariate analysis of
responsive than single subjective evaluations of pain
covariance to calculate the sample size with regard to
and function or objective measures of range of
motion.19 The observed improvements were largestat six weeks, suggesting that a reduction of mechanicalsubacromial stress and normalisation of movement
Table 4 | Patients who changed treatment or diagnosis within first 18 weeks
patterns had occurred within a relatively short treat-
ment period. The content of the supervised exercise
intervention was slightly different from the study of
Brox et al.21 Fewer patients used a sling for home exer-
cises in our study; all supervision was finished within
12 weeks; and separate lessons on functional anatomy,
Crossed over to supervised exercises before 18 weeks
pain management, and ergonomics were not included.
Follow-up in Brox et al’s study was at three and six
*One after a single treatment, and one after four treatments.
13 Zheng Z, Simpson JA, van der Windt D, Elliott AM. Data from a study
After 18 weeks, supervised exercises were better than
of effectiveness suggested potential prognostic factors related to thepatterns of shoulder pain. J Clin Epidemiol 2005;58:823-30.
radial extracorporeal shockwave treatment in terms of
14 Speed CA, Richards C, Nichols D, Burnet S, Wies JT, Humphreys H,
the primary outcome variable—the shoulder pain and
et al. Extracorporeal shock-wave therapy for tendinitis of the rotatorcuff. J Bone Joint Surg Br 2002;84:509-12.
disability index—and one secondary outcome variable
15 Schmitt J, Haake M, Tosch A, Hildebrand R, Deike B, Griss P. Low-
—work status. We found no significant differences for
energy extracorporeal shock-wave treatment (ESWT) for tendinitis of
the other secondary outcome variables of pain, func-
the supraspinatus: a prospective, randomised study. J Bone JointSurg Br 2001;83:873-6.
tion, active range of motion, and use of drug treatment.
16 Michener LA, Walsworth MK, Burnet EN. Effectiveness of
More patients in the supervised exercise group
rehabilitation for patients with subacromial impingement syndrome. J Hand Ther 2004;17:152-64.
improved, probably owing to a treatment effect.
17 Park HB, Yokota A, Gill HS, El Rassi G, McFarland EG. Diagnostic
We thank Stine O Eriksen for doing all the assessments, Roald Danielsen
accuracy of clinical tests for the different degrees of subacromialimpingement syndrome. J Bone Joint Surg Am 2005;87:1446-55.
for administering radial extracorporeal shockwave treatment, and Mona
18 Roach KE, Budiman-Mak E, Songsiridej N, Lertratanakul Y.
Mortensen and Helene Skaara for leading the supervised exercises. We
Development of a shoulder pain and disability index. Arthritis Care
also thank Egil Knag, Enimed, for lending us the Swiss Dolor Clast. A
special thanks to all the patients who made this study possible.
19 Ekeberg OM, Bautz-Holter E, Tveita EK, Keller A, Juel NG, Brox JI.
Contributors: KE contributed to the study design; data collection, analysis,
Agreement, reliability and validity in 3 shoulder questionnaires in
and interpretation; and writing of the manuscript. MG and JIB contributed
patients with rotator cuff disease. BMC Musculoskelet Disord
to the study design, data analysis and interpretation, and writing of the
manuscript. EB-H contributed to the study design and data collection and
20 Tveita EK, Tariq R, Sesseng S, Juel NG, Bautz-Holter E.
interpretation. LS contributed to data analysis and interpretation. NGJ and
Hydrodilatation, corticosteroids and adhesive capsulitis: a
OME contributed to the study design and data collection and
randomized controlled trial. BMC Musculoskelet Disord 2008;9:53.
interpretation. KE is the guarantor.
21 Brox JI, Staff PH, Ljunggren AE, Brevik JI. Arthroscopic surgery
compared with supervised exercises in patients with rotator cuff
Funding: The study was supported by Health Region East, Norway.
disease (stage II impingement syndrome). BMJ 1993;307:899-903.
22 Triffitt PD, Wildin C, Hajioff D. The reproducibility of measurement of
Ethical approval: The study protocol was approved by the ethics
shoulder movement. Acta Orthop Scand 1999;70:322-4.
committee for Medical Research Region 1 of Norway.
23 Holm I, Friis A, Storheim K, Brox JI. Measuring self-reported functional
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