Effects of deep and superficial heating in the management of frozen shoulder

Abstract

To determine whether the addition of deep or superficial heating to stretching produces better clinical outcomes than stretching alone in the management of frozen shoulder.
A single-blinded, randomized controlled study.
Thirty subjects suffering from the stiffness phase of frozen shoulder.
Subjects were randomly allocated to receive: (i) deep heating plus stretching; (ii) superficial heating plus stretching; or (iii) stretching alone. Both heating groups received the respective treatments 3 times per week for 4 weeks. All groups received a standard set of shoulder stretching exercises. The American Shoulder and Elbow Surgeons assessment form was recorded at the baseline, sessions 6 and 12, and at the 4-week follow-up session.
A significant improvement was seen in all groups in all outcome measures except for that of shoulder flexion range. The improvement in the shoulder score index and in the range of motion was significantly better in the deep heating group than in the superficial heating group.
The addition of deep heating to stretching exercises produced a greater improvement in pain relief, and resulted in better performance in the activities of daily living and in range of motion than did superficial heating.

Full text

ORIGINAL REPORT
J Rehabil Med 2008; 40: 145–150
J Rehabil Med 40
© 2007 The Authors. doi: 10.2340/16501977-0146
Journal Compilation © 2007 Foundation of Rehabilitation Information. ISSN 1650-1977
Objectives: To determine whether the addition of deep or
supercial heating to stretching produces better clinical out-
comes than stretching alone in the management of frozen
shoulder.
Design: A single-blinded, randomized controlled study.
Subjects: Thirty subjects suffering from the stiffness phase
of frozen shoulder.
Methods: Subjects were randomly allocated to receive: (i)
deep heating plus stretching; (ii) supercial heating plus
stretching; or (iii) stretching alone. Both heating groups
received the respective treatments 3 times per week for 4
weeks. All groups received a standard set of shoulder stretch-
ing exercises. The American Shoulder and Elbow Surgeons
assessment form was recorded at the baseline, sessions 6 and
12, and at the 4-week follow-up session.
Results: A signicant improvement was seen in all groups
in all outcome measures except for that of shoulder exion
range. The improvement in the shoulder score index and in
the range of motion was signicantly better in the deep heat-
ing group than in the supercial heating group.
Conclusion: The addition of deep heating to stretching ex-
ercises produced a greater improvement in pain relief, and
resulted in better performance in the activities of daily living
and in range of motion than did supercial heating.
Key words: shortwave, hot pack, stretching, frozen shoulder,
range of motion.
J Rehabil Med 2008; 40: 145–150
Correspondence address: Gladys Cheing, Department of Re-
habilitation Sciences, The Hong Kong Polytechnic University,
Hung Hom, Kowloon, Hong Kong. E-mail: gladys.cheing@
inet.polyu.edu.hk
Submitted April 27, 2007; accepted October 4, 2007
INTRODUCTION
Frozen shoulder or adhesive capsulitis is a common insidious
condition that is associated with pain and with a restricted range
of motion (ROM) around the shoulder joint. Its prevalence in
the general population has been estimated at between 3% and
5%. It can arise from idiopathic or post-traumatic causes. Fro-
zen shoulder usually involves 3 phases: (i) the painful phase,
which usually lasts for 2–9 months and leads to progressive
stiffness; (ii) the stiffness phase, which usually lasts for 3–9
months, during which the pain gradually subsides but marked
stiffness develops in all planes of the shoulder joint; (iii) the
thawing phase, which usually persists for 12–42 months, dur-
ing which there is a slow gain in motion and comfort (1, 2).
Stretching exercises are a key component of exercise therapy
for musculoskeletal disorders. In addition, heat modalities are
frequently used as an adjuvant treatment to exercise therapy
in order to help the patient regain ROM and restore function
to the affected shoulder.
The rationale for achieving therapeutic goals through heat-
ing is to alter the viscoelastic properties of connective tissues

occurs with a rise in the temperature of soft tissues to between
40°C and 45°C, compared with that recorded at room tempera-


agents are ultrasound (9) or shortwave diathermy (SWD) (10).
SWD can heat up a larger treatment area and volume of tissue
than is possible with ultrasound, while ultrasound can produce
some mechanical effects in addition to the heating effect. Hot
pack (HP) is the most traditional method of providing super-

could produce a greater increase in tissue extensibility than


gain in tissue extensibility than did HP. Peres et al. (11) showed
that the combination of pulsed SWD and stretching exercises
     
with what could be achieved by stretching alone.
      
previous study found that deep heat applied before stretching

of hamstring muscles (12). However, the study involved only
a 5-day treatment period, which may have been too short to

Gursel et al. (13) found that true ultrasound brought no further

physical therapy interventions in the management of soft tis-
sue disorders of the shoulder. However, they did not control
the other physical therapy interventions that were delivered
to their patients.

and shoulder stretching exercises in normal subjects concluded

prolonged stretching produced more long-lasting changes in


May S. F. Leung, MSc
1,2
and Gladys L. Y. Cheing, PhD
2
From the
1
Physiotherapy Department, Our Lady of Maryknoll Hospital and
2
Department of Rehabilitation Sciences,
The Hong Kong Polytechnic University, Hong Kong

146
M. S. F. Leung and G. L. Y. Cheing
the extensibility of soft tissue than did stretching alone (14).

to muscle relaxation, thus reducing the resistance to stretches
within and around the muscle, and consequently increasing the
ROM of the shoulder (14). However, some studies found that
stretching exercises alone could increase the extensibility of
rats’ tails (15) and the ROM of human shoulders (1, 16).

the effects of heat treatment in increasing the extensibility
of soft tissues. There is a lack of evidence to support the use
of SWD or HP in combination with stretching in managing
patients with frozen shoulder. Therefore, the aim of this study
was to determine whether the addition of deep heating (using

would produce better clinical outcomes than stretching alone
in the management of frozen shoulder.

Subjects
Thirty subjects (9 men and 21 women, age range 37–79 years, mean
59.87, standard deviation (SD) 12.45) with idiopathic frozen shoul-
der in the stiffness phase participated in this study. The diagnosis of
frozen shoulder was made by an orthopaedic surgeon. Subjects were
included if they had experienced shoulder pain and limited shoulder
movement for at least 8 weeks. Subjects were excluded if they had a
 
the shoulder, intrinsic shoulder pathology, were taking analgesic or
   
hot and cold, were pregnant, or had a cardiac pacemaker. Demographic
data for the subjects are shown in Table I.
Treatment procedures
A single-blinded, randomized controlled study was conducted. The rater
was blinded to the group allocation. The study was approved by a local
ethics committee. After informed consent had been obtained, the subjects
were randomly allocated into one of the following 3 groups: (i) SWD
plus stretching (n = 10); (ii) HP plus stretching (n = 10); or (iii) stretching
exercises alone (n = 10). Randomization was performed using an on-line
randomization plane (http://www.randomization.com). The subjects in
the SWD and HP groups received the respective treatments 3 times per

groups received a standard set of shoulder stretching exercises.

Netherlands) with an operating frequency of 27.12 MHz was used
to deliver the deep heating treatment. The subjects were positioned
comfortably sitting on a wooden chair with their back and affected
arm supported. A pair of disc electrodes was placed on the anterior-
posterior aspects of the affected glenohumeral joint, separated by
a hand’s-breadth from the surface of the body. The intensity of the
current was adjusted according to the subject’s subjective feeling of
comfortable warmth. If the level of perceived heating changed dur-
ing the application, the machine’s output was adjusted to maintain
the sensation of comfortable warmth throughout the treatment. For
the HP group, an electrical hot pack sized 35.5 × 68.5 cm was used

subjects were informed that the only purpose of the heating was to
produce a feeling of comfortable warmth. If they felt that the heat
was excessive, the temperature of the electrical HP was adjusted
immediately to ensure that the heat remained at a comfortably warm
level only throughout the treatment.
Immediately after the heat treatment, subjects were asked to perform


the-back and cross-body adduction. They were asked to repeat the

rest between each stretch. The subjects were asked to perform the
stretching exercises at home every day. Assessments were made prior
to treatment at the baseline, at sessions 6 and 12, and at the 4-week
follow-up session (Fig. 1). A therapist checked for compliance with
the exercise regime.
Outcome measures

was used to measure the treatment outcomes in the present study.


consists of 2 parts: a patient self-evaluation section and a physician
assessment section.
The patient self-evaluation section is designed to measure pain
and functional limitation of the shoulder. The pain score is calculated
from the patient’s response to a single question about pain, using a
10-cm horizontal visual analogue scale (VAS) line. The function score
is calculated from the sum of the 10 questions addressing the activi-
 

Table I. Demographic data for the subjects in the 3 groups
SWD + stretching
(n = 10)
HP + stretching
(n = 10)
Stretching alone
(n = 10)
Age (years);
mean (SD)
59.80 (12.87) 62.50 (12.13) 57.30 (13.10)
Sex F/M 5/5 8/2 8/2

p < 0.05)
SD: standard deviation; F: female; M: male; SWD: shortwave
diathermy; HP: hot pack.
Fig. 1. Study design. ROM: range of motion; SWD: shortwave diathermy;
HP: hot pack.
SWD group
SWD + daily stretching
exercises (n = 10)
HP group
HP + daily stretching
exercises (n = 10)
Stretching group
Daily stretching
exercises (n = 10)
12 treatment sessions
Re-assessment in session 6 and session 12 before intervention
Pain level
Activities of daily living
Shoulder ROM
Re-assessment in the 4-week follow-up
session
Pain level
Activities of daily living
Shoulder ROM
Baseline evaluation (pre-treatment)
Pain level
Activities of daily living
Shoulder ROM
30 subjects
J Rehabil Med 40

147
Shortwave diathermy for frozen shoulder

Both the pain score and function score are weighted equally (50 points
each) and combined for a total score of 100 points, with a higher score

using the following formula (18):
(10 – VAS pain score) × 5 + (5/3 ×
The physician assessment part involved measuring the joint’s ROM.
The shoulder forward elevation, external rotation with the arm by the
side, external rotation with the arm in 90° abduction was measured
using a standard goniometer. The hand-behind-back position, the dis-
tance between 2 thumb tips (with both shoulders performing the hand-
behind-the-back), was measured by using a tape measure. Cross-body
adduction was measured as the distance between the antecubital fossa
and the opposite shoulder (2). The subjects were positioned standing
for all of the ROM tests. All of the assessments were performed by the
same physiotherapist, who was blinded to each subject and interven-
tion order throughout.
Data analysis
Statistical analyses were performed using the software package SPSS
for Windows, version 10. A repeated measures analysis of variance was
performed to examine the change in each outcome measure among the
treatment groups and across treatment sessions. The analysis of vari-
ance was followed by Tukey’s post hoc multiple comparisons. If the


(alpha) was set at 0.05 and the Bonferroni Correction was used to adjust


None of the participants in any of the treatment groups dropped
out throughout the study period. The exercise compliance of
-
ence (p > 0.05) was found among all of the outcome measures
at the baseline. The changes in the shoulder score index and
shoulder ROM in different directions over time are presented
in Tables II, III and IV.
Shoulder score index
By session 12, the shoulder score index in the SWD group had
increased by 63.4%, compared with 45.2% in the HP group and
38.4% in the stretching alone group (Table II). The improve-
ment was well maintained or a further improvement was noted
at the 4-week follow-up session. The overall within-group dif-

(p < 0.001). A post hoc test showed that the differences came
from the comparisons between the data obtained in session 6
or session 12 to the baseline. The between-group difference
p = 0.046). The post hoc test showed that the
SWD group improved more than the stretching alone group
did (p
the HP group and stretching alone group (p > 0.05).
Flexion range

analyses were conducted separately for the “groups” and the

range had increased by 13.9% in the SWD group and 3.5% in
the HP group (Table III). By contrast, the range in the stretch-
ing alone group decreased by 4.2%. By the 4-week follow-up
session, the effect was maintained or a slight improvement was
seen in the SWD and HP groups. The within-group difference

Table III. Average group mean (SD) of the shoulder exion range of motion (ROM) and shoulder cross-body adduction across the study period
SWD + stretching
(n = 10)
HP + stretching
(n = 10)
Stretching alone
(n = 10) p-value (between-group)
Shoulder exion range (degree)
Baseline 129.0 (18.4) 117.9 (20.3) 137.9 (16.1) 0.068
Session 6 146.9 (13.5) 120.2 (21.0) 134.7 (16.6) 0.007
Session 12 146.9 (14.2) 122.0 (20.9) 132.1 (25.7) 0.049
4-week follow-up 148.2 (14.4) 124.7 (20.3) 137.6 (20.8) 0.031
p-value (within-group)
0.002 0.538 0.247
Shoulder cross-body adduction (cm)
Baseline 29.8 (3.4) 30.3 (3.9) 29.3 (3.7) 0.830
Session 6 25.9 (2.9) 29.0 (3.7) 29.4 (3.7) 0.079
Session 12 25.0 (2.2) 29.0 (3.3) 29.1 (4.4) 0.079
4-week follow-up 24.2 (2.0) 29.1 (3.5) 27.8 (5.1) 0.079
p-value (within-group)
0.000 0.000 0.000

groups. Type I errors are corrected by the Bonferroni method.
SWD: shortwave diathermy; HP: hot pack; SD: standard deviation.
Table II. Average group mean (SD) of the shoulder score index
SWD +
stretching
(n = 10)
HP +
stretching
(n = 10)
Stretching
alone
(n = 10)
p-value
(between-
group)
Shoulder Score Index
Baseline 41.5 (12.1) 38.9 (11.8) 33.3 (12.51)
Session 6 56.3 (15.0) 54.2 (15.4) 45.3 (11.2) 0.046
Session 12 67.8 (15.1) 56.5 (14.1) 46.1 (12.7)
4-week follow-up 71.3 (19.3) 57.8 (16.3) 53.8 (16.5)
p-value
(within-group)
< 0.001

Repeated measures ANOVA showed an overall between-group
difference as 0.046, and within-group difference as < 0.001.
SWD: shortwave diathermy; HP: hot pack; SD: standard deviation.
J Rehabil Med 40

148
M. S. F. Leung and G. L. Y. Cheing
(p = 0.002) and a post hoc test showed that the range achieved

by the HP group (p = 0.025). A between-group difference was
found in session 6 (p = 0.007), session 12 (p = 0.049), and in
the follow-up session (p = 0.031). However, after an adjustment
was made using the Bonferroni Correction (adjusted p-value

in session 6.
Shoulder cross-body adduction
By session 12, the cross-body adduction range of the SWD
group demonstrated a 16.1% cumulative improvement (Table

the HP group, and 0.7% for the stretching alone group. The
treatment effects were more or less maintained in the SWD and
HP groups in the 4-week follow-up session. The within-group
p < 0.001). A post
hoc test showed that the difference came from the data obtained
in session 6, session 12, and the 4-week follow-up session com-

difference was found among the 3 treatment groups.
External rotation with arm by side
By session 12, the SWD group demonstrated a 14.5% gain
in shoulder external rotation, compared with 21.1% in the
HP group and 22.6% in the stretching groups (Table IV). The
overall within-group difference across the study period was
p = 0.008). A post hoc test showed that the differ-
ence came from the comparison made between the 4-week
      
group difference in the external rotation range (p = 0.009). The
post hoc test showed that the SWD group achieved a greater
external rotation range than did the HP group (p = 0.007)
External rotation with arm in 90° abduction
In all 3 treatment groups, the external rotation range of the
shoulder tended to increase during the study period (within-
group p = 0.011) (Table IV). By the 4-week follow-up session,
the SWD group demonstrated a 17.4% cumulative increase,
compared with 14.2% for the HP group, and 15.3% for the
stretching alone group. A post hoc test showed that the differ-
ence came from comparisons made between session 12 and
the baseline, and from the 4-week follow-up session and the
baseline. The between-group difference was statistically sig-
p = 0.021). The post hoc

greater than in the HP group (p = 0.016).
Hand-behind-back
The hand-behind-back distance decreased progressively over
time (Table IV). By the 4-week follow-up session, there was a
cumulative decrease in the group mean of 51.2% in the SWD
group, 26.5% in the HP group, and 18.8% in the stretching
group. The within-group difference across the study period
  p < 0.001). A post hoc test showed that the
difference came from the comparison made between session
6, session 12 and the 4-week follow-up to that of the baseline.

behind-back range (p = 0.004). The post hoc test showed that
the gain in the hand-behind-back range achieved by the SWD

group (p = 0.003).
Table IV. Average group mean (SD) of the shoulder external rotation (arm by the side and arm in 90° abduction) and hand-behind-back range of
motion (ROM) across the study period
SWD + stretching
(n = 10)
HP + stretching
(n = 10)
Stretching alone
(n = 10)
p-value (between-
group)
Shoulder external rotation range (arm by side) (degree)
Baseline 50.4 (14.1) 28.2 (23.4) 39.5 (21.7)
Session 6 59.3 (19.8) 27.6 (18.7) 39.5 (20.6) 0.009
Session 12 60.9 (14.5) 32.6 (21.1) 43.3 (22.6)
4-week follow-up 62.1 (11.5) 32.6 (21.7) 41.1 (23.2)
p-value (within-group)
0.008
Shoulder external rotation range (arm in 90˚ abduction) (degree)
Baseline 51.6 (18.2) 26.7 (26.0) 42.5 (18.7)
Session 6 57.8 (22.7) 27.0 (26.5) 43.4 (20.8) 0.021
Session 12 59.6 (19.3) 30.1 (26.8) 45.7 (23.3)
4-week follow-up 60.6 (11.0) 30.5 (24.4) 49.0 (27.2)
p-value (within-group)
0.011
Hand-behind-back (cm)
Baseline 12.3 (4.8) 24.9 (11.5) 16.0 (9.6)
Session 6 7.2 (6.1) 22.2 (11.5) 14.7 (8.1) 0.004
Session 12 7.6 (5.7) 18.5 (8.9) 14.7 (8.0)
4-week follow-up 6.0 (7.3) 18.3 (7.5) 13.0 (6.7)
p-value (within-group)
< 0.001

difference for each outcome.
SWD: shortwave diathermy; HP: hot pack; SD: standard deviation.
J Rehabil Med 40

149
Shortwave diathermy for frozen shoulder
DISCUSSION
The popularity of the deep heating agent SWD has declined
in recent years. This may be partly due to a shortage of qual-
ity controlled studies (19–21), or because the SWD machine
may cause radio-interference with other medical devices. The



       -
cantly greater increase in the shoulder score index than did

gain in the ROM of most shoulder movements than did HP.

heat is just as effective as deep heat therapy in the management
of joint disorders such as frozen shoulder.
Pain relief

The improvement in the shoulder score index observed in the
present study could have resulted from a reduction in pain,


to patients with wrist pain stemming from various causes (22).
Previous studies have demonstrated that both deep and super-
   


within the group across the study period. Interestingly, our

the shoulder score index than the HP group. The deep heating
effect produced by SWD increases the temperature of localized
tissue, with the result that vascular dilation is promoted and
the pain threshold elevated. Such vascular improvement also

and oxygen supply, and by removing metabolites and waste
products. This leads to a decrease in pain and swelling.
Extensibility of soft tissues
When temperature is increased, the stress-relaxation property


-
ies have reported that 15 minutes of SWD treatment increased
the temperature of soft tissue (3 cm deep) by 4.58
± 0.87°C
(28, 29). By contrast, an HP treatment elevated muscle
temperature by only 1°C (30). This implies that SWD could
produce deeper penetration than did HP, thus increasing the
extensibility of tissue. Studies have found that a deep heating
agent (shortwave and ultrasound) in combination with stretch-
 
(9, 11). Robertson et al. (10) found that SWD could increase


gain in shoulder range than did HP.
        -
ence was found in cross-body adduction among the groups.
The postero-inferior part of the shoulder joint is covered by
     
penetrate deep into the tight structures of the muscle, as the
layer of muscle is thick. As a result, the rise in temperature may
not be enough to produce therapeutic effects. Therefore, in our

between-group differences.
According to previous studies, the gain in therapeutic tem-
perature after SWD can be maintained for around 7 min (28,
29). The subjects in our study spent at least 8 min completing

adduction was done, it may not have been possible to maintain
-
perature level. This could have been another reason why the

between the groups.
Previous researchers studied the effect of heat on tissue
extensibility with different treatment frequencies. The treat-
ment frequencies that were tried varied from one treatment per
day to 2 treatments per week (9–14, 22, 32). Further studies

frequency of shortwaves on increasing the extensibility of
tissue.
In the present study, all subject groups received training of a
standard set of shoulder stretching exercise by an experienced
   
-
pist checked for compliance with the exercise regime for all
subjects. As we aimed to determine whether the application of
various heat treatments enhanced the effectiveness of stretching
exercise, the group receiving SWD or HP had more contact
with the therapist compared with the exercise-alone group,
which may affect the treatment outcome. This is a limitation

to take this factor into consideration.

heating (using SWD) to stretching exercises is more effective

-
proving shoulder pain and function. Also, the addition of deep


side, external rotation with the arm in abduction and in the


heating to stretching will not produce a further enhancement
of the shoulder score index or a gain in shoulder ROM for
patients with frozen shoulder.

1. Goldberg BA, Scarlat MM, Harryman DT. Management of the stiff
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