A prospective randomized clinical trial to investigate the effect of silicone gel sheeting (Cica-Care) on post-traumatic hypertrophic scar among the Chinese population.

Abstract

This study aimed to determine the efficacy of silicone gel (Cica-Care) on severe post-traumatic hypertophic scars among the Chinese population.
A randomized clinical trial (RCT) was conducted on 45 Chinese patients with post-traumatic hypertrophic scars. Twenty-two subjects were placed in the experimental group with silicone gel sheeting (SGS) applied 24h per day for 6 months while all subjects were taught to massage the scar daily for 15 min serving as the control intervention. Scar assessments were conducted regularly to measure the changes in thickness, pigmentation, vascularity, pliability, itchiness and pain.
Two-way repeated ANOVA showed a significant difference between MT group and SGS group on scar thickness. The post hoc comparison analysis showed that the difference was significant at the post-2-month (p=0.008) and post-6-month (p<0.001) intervention. The SGS group also showed changes in pigmentation which resembled normal skin but no statistical significance was found. Pain, itchiness and pliability were also improved after intervention.
This study indicated that silicone gel sheeting (Cica-Care) was effective to reduce thickness, pain, itchiness and pliability of the severe hypertrophic scar among the Chinese population. The moisturization effect of the tough and hard scar might contribute to the reduction of the skin thickness after 6 month's intervention.

Full text

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A prospective randomized clinical trial to investigate the effect
of silicone gel sheeting (Cica-Care) on post-traumatic
hypertrophic scar among the Chinese population
Cecilia W.P. Li-Tsanga,*, Joy C.M. Laua, Jenny Choia,
Chetwyn C.C. Chana, Li Jiananb
aDepartment of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, HKSAR, Hong Kong
bDepartment of Rehabilitation Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing, China
Accepted 10 January 2006
Abstract
Background: This study aimed to determine the efficacy of silicone gel (Cica-Care) on severe post-traumatic hypertophic scars among the
Chinese population.
Method and materials: A randomized clinical trial (RCT) was conducted on 45 Chinese patients with post-traumatic hypertrophic scars.
Twenty-two subjects were placed in the experimental group with silicone gel sheeting (SGS) applied 24 h per day for 6 months while all
subjects were taught to massage the scar daily for 15 min serving as the control intervention. Scar assessments were conducted regularly to
measure the changes in thickness, pigmentation, vascularity, pliability, itchiness and pain.
Results: Two-way repeated ANOVA showed a significant difference between MT group and SGS group on scar thickness. The post hoc
comparison analysis showed that the difference was significant at the post-2-month (p = 0.008) and post-6-month (p < 0.001) intervention.
The SGS group also showed changes in pigmentation which resembled normal skin but no statistical significance was found. Pain, itchiness
and pliability were also improved after intervention.
Conclusion: This study indicated that silicone gel sheeting (Cica-Care) was effective to reduce thickness, pain, itchiness and pliability of the
severe hypertrophic scar amongthe Chinese population.The moisturization effectof thetough andhardscar mightcontributetothe reduction
of the skin thickness after 6 month’s intervention.
# 2006 Elsevier Ltd and ISBI. All rights reserved.
Keywords: Pressure therapy; Hypertrophic scar; Randomized clinical trial; Chinese population
1. Introduction
Hypertrophic scar was commonly formed after dermal
skin injury [1,2]. The abnormal scar was characterized by
red, rigid and raised appearance associated with pain and
itchiness. It will lead to cosmetic disturbance and affect the
daily activities of a person if the scar is contracted causing
joint stiffness and deformities. The scar maturation process
varies from half a year to several years depending on the
severity of the injuries and complications during the process
of wound healing.
Different treatment methods have been suggested in
treating hypertrophic scar such as cortical steroid injection
and surgical excision. However, side effects were reported
such as extreme pain and high recurrence rate [3]. Perkins
et al. first suggested using silicone gel sheeting (SGS) to
treat the contracture and post-burnhypertrophic scar in 1982
[4]. Its application was then widely used on patients with
hypertrophic scars and keloids. In recent years, it was
advocated for use prophylactically on healed wounds right
after surgery to enhance its effect [5]. However, the
mechanism of how silicone gel sheeting exerted its effect
www.elsevier.com/locate/burns
Burns 32 (2006) 678–683
* Corresponding author. Tel.: +852 2766 6715; fax: +852 2330 5124.
E-mail address: rscecili@inet.polyu.edu.hk (C.W.P. Li-Tsang).
0305-4179/$30.00 # 2006 Elsevier Ltd and ISBI. All rights reserved.
doi:10.1016/j.burns.2006.01.016

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onto the hypertrophic scar is not yet proven. It was
postulated that siliconegel would release silicone molecule
onto the hypertrophic scar, thus help to control the scar [6].
The effect was also suggested to be related to the control of
oxygen tension and effect of occlusion, but it would not
exertany pressure ontothe scar[7]. It wasproposedthat the
staticelectriccurrentgeneratedbysiliconegelcontributeto
the involution of the hypertrophic scar, although the effect
remains inconclusive[8].Its mechanism was assumed to be
due to the control of scar hydration. There was evidence
showing that the water vapor transmission rate of silicone
gel sheeting was about half of the normal skin [9]. The
mechanism that the reduction in water vapor loss by the gel
sheetingishypothesizedtodecreasethecapillaryflowatthe
scar, thus reducing collagen deposition and scar hyper-
trophy [10,11]. This study is therefore designed to
investigate the effect of silicone gel sheeting (SGS) on
the hypertrophic scar resulted from burns or other severe
skin trauma.
Chinese people tend to have a higher prevalence of scar
formation after skin injury [12]. The incidence of scar
hypertrophy was over 70%. Most of these scars were not
treated in the early stage of wound healing, thus resulting in
thick, firm, highly vascular and dark red in appearance. For
most of the cases, theywill cause joint contractures and limb
deformities. In Mainland China, since conservative treat-
ment was uncommon, most of these scars were then treated
by skin grafting or major soft tissue reconstruction.
Unfortunately, hypertrophic scar will grow again after these
surgical interventions and the problems recur. Silicone gel
sheeting (SGS) was recommended by the International
Burns Society [3] for management of hypertrophic scar.
However,previousstudiesmainlyreporteditseffecton early
application on healed wounds or less severe scar among the
Caucasian population.Thisstudy focusedon its effecton the
thick, vascular and firm scar that was developed long after
the wound was healed.
In previous studies, most of the scar assessment were
done by the visual examination of surgeons or therapists
based on their experiences. Some may use photos to
documentthechangesonscarbutitcouldonlyprovidesome
basic information on the size, appearance. Some of the key
factors could not be measured objectively such as thickness
and vascularity. Some used standardized evaluation system
such as the Vancouver Scar Scale (VSS) in grading the
pigmentation, thickness, vascularity, pliability of the scars.
However, previous research also indicated its lack of
reliability (ICC lower than 0.6). In our study, we have used
some objective evaluation tools to quantify the scar
conditions. A spectrocolorimeter [13] has been selected to
evaluate the scar pigmentation in terms of redness (a*),
yellowness (b*) and lightness (L*) based on previous
research on its validity and reliability on scar assessment.
The tissue ultrasound palpation system (TUPS) was used to
measure the entire thickness of scar (including the scar
underneath the skin) [14].
2. Subject selection
Subjects of either sex with age less than 50 years old
and had previous history of burns, scald or other severe
skin trauma resulting hypertrophic scar were recruited into
this study. For standardization, the scar dimension should
not exceed 20 cm ? 20 cm and the scar thickness should
be more than 3 mm. All subjects were consented to join
the study on a voluntary basis and once committed, they
had to complete the 6-month intervention programme. In
order to reinforce their participation of the study, all
treatment fees and materials cost would be waived when
they had completed the course of intervention. The
treatment was implemented by two therapists who
received previous training in scar management in Hong
Kong while the assessment was conducted by a research
assistant who was blind to the subject grouping and was
trained to administer all the assessments in standardized
methods.
3. Methodology
This study adopted a prospective randomized clinical
trial (RCT) research design to compare the treatment effect
of silicone gel therapy with a control group. The rater of the
assessment was blind to the selected subject group but the
subjects were aware of the intervention programme that they
adopted. Forty-five subjects were randomly allocated into
the silicone gel sheeting group (SGS group) and the control
group (MT group). Patients in the MT group would be
instructed to have a 15-min lanolin deep massage two times
a day, while those subjects in the SGS group would be
instructed with the same protocol plus the application of
silicone gel sheeting (Cica-Care) for 24 h daily for a period
of 6 months. The silicone gel sheeting was stabilized at the
edges with micropore tape to prevent slipping and
displacement during body movements.
3.1. Assessment protocol
The progress of scar was assessed monthly in the first 2
months, then bi-monthly on the fourth and sixth months
after intervention. The spectrocolorimeter and the tissue
ultrasound palpation system (TUPS) were employed to
measure the pigmentation and thickness of scar, respec-
tively. The scar pigmentation was reported in terms of
lightness (L), redness (a) and yellowness (b) in the
international expression CIE. (CIE is short for Commission
Internationaledel’Eclairage,whichistheFrenchtitleofthe
international commission on light.) The TUPS has been
validated as a reliable assessment tool for measuring scar
thickness with high inter-rater (ICC = 0.98) and test-retest
reliability(ICC = 0.84)[14].TheVancouverScarScalewas
used to assess the scar appearance using a standard rating
scale. Subjective feelings of pain and itchiness were
C.W.P. Li-Tsang et al./Burns 32 (2006) 678–683679

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recorded using the Visual Analog Scale (VAS) at each
follow up assessment. The digital image of each scar was
also recorded using a digital camera each time when the
assessment was conducted. The procedure of taking photos
was standardized with fixed distance, lighting and the same
digital camera to ensure that the digital images were
comparable.
4. Data analysis
Independent t-test was used to analyze if there is any
baseline difference between the SGS and the MT group.
The thickness measured by TUPS, the color parameters
measured by the spectrocolorimeter, the Vancouver Scar
Scale, the VAS pain and VAS itchiness ratings were
analyzed by two-way repeated ANOVA in a mixed
mode. Turkey test for post hoc comparison analysis was
used to analyze the difference over time between two
groups and Bonferroni adjusted alpha levels of 0.0167 per
test (0.05/3).
5. Results
5.1. Demographic data
There were altogether 45 subjects with 29 males and 16
females and the mean age was 29.65 ? 17.60 years old.
Causes of scar problems were mainly due to burn and scald
injuries (44.5%), trauma (24.4%) and chemical or electrical
burns (15.5%). There were 24 subjects allocated to the
silicone gel sheeting (SGS) group and 21 subjects in the
control (MT) group. Three subjects from the control group
have dropped out due to long traveling incurred for re-
assessment (Table 1).
5.2. Severity of hypertrophic scar of subjects
The mean total score of Vancouver Scar Scale among all
subjects was 10.87 ? 1.55 (maximum score being 15). The
hypertrophic scar in both groups were considered moderate
to severe as shown from the individual scores of VSS in
Table 3. When compared to the hypertrophic scar and
adjacent normal skin prior to the intervention, there were
significant differences on three color parameters on all
subjects, in terms of lightness
(p < 0.01) and yellowness (p < 0.01) showing that there
are great changes in pigmentation, vascularity between the
scar and the adjacent skin. This is very common among the
Chinese since the skin pigmentation is normally yellowish
while the scar looked more reddish, darker and less
yellowish. The mean scar thickness measured by TUPS
was 5.97 ? 1.82 mm (Tables 2 and 3).
(p < 0.01), redness
5.2.1. Scar conditions between the two groups after
intervention
5.2.1.1. Changes in thickness of scar. Two-way repeated
ANOVA in mixed model reflected that there was a
significant difference between two groups in scar thickness
over the 6-month intervention (d.f. = 4, F = 5.54, p < 0.01).
Post hoc comparison analysis showed that the significant
difference was at the post-4-week (p = 0.007) and post-24-
week assessments (p < 0.001) (Fig. 1).
5.2.1.2. Changes in scar pigmentation. Although there was
no significant difference among three color parameters as
measured by the spectrocolorimeter in the two-way ANOVA
in mixed model, it was noted that subjects in the SGS group
showed a higher percentage of changes in terms of lightness
and redness when compared to the control (MT) group. The
scar in the SGS group was found paler, less reddish and
appeared to look more yellowish that resembled the yellow
skin pigmentation among the Chinese population. However,
the improvement was not significant statistically (Figs. 2–4).
C.W.P. Li-Tsang et al./Burns 32 (2006) 678–683680
Table 1
Causes of hypertrophic scar formation
Reason Number of scarsPercentage
Trauma
Burn
Scald
Chemical burn
Electrical burn
Other
11
16
4
6
1
7
24.4
35.6
8.9
13.3
2.2
15.6
Total 45100
Table 3
Each parameter scoring of Vancouver Scar Scale
Parameter of Vancouver Scar ScaleMean score
Pigmentation
Height
Vascularity
Pliability
1.98 ? 0.50
3.53 ? 0.73
2.29 ? 0.70
3.07 ? 0.81
10.87 ? 1.55 Total score of VSS
Table 2
The color of scar and the adjacent normal skin measured by the spectrocolorimeter
Color parametersHypertrophic scar (n = 45) Normal skin (n = 45)d.f.p-value
Lightness
Redness
Yellowness
45.74 ? 3.50
8.82 ? 2.38
9.37 ? 2.72
57.09 ? 4.71
4.94 ? 2.35
14.54 ? 2.61
44
44
44
<0.01
<0.01
<0.01

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5.2.1.3. Changes in subjective pain and itchiness. Again,
there was no statistical significant difference between the
two groups in pain and itchiness after 6-month intervention,
it was noted that all subjects in the SGS group did not report
pain while some subjects in the control group still reported
occasional pain (Table 4).
5.2.1.4. Changes in scar pliability. There was a significant
difference between two groups in scar pliability over 6-
month intervention when measured by VSS. The improve-
ment was more significant in SGS group F(3, 100) = 6.27,
p < 0.01. Thescar inthe SGS groupbecamesofter andmore
pliable after 2 months (mean of SGS = 2.62 ? 0.11, mean of
MT = 2.94 ? 0.12), 4 months (mean of SGS = 2.37 ? 0.11,
mean of MT = 2.78 ? 0.15), and 6 months of intervention
(mean of SGS = 1.99 ? 0.11, mean of MT = 2.72 ? 0.15).
The improvement between two groups were significant in 2-
month (p = 0.008), 4-month (p = 0.004) and 6-month
(p < 0.001) assessment (Figs. 5 and 6).
5.3. Summary of results
In summary, subjects with 6-months’ silicone gel
intervention showed a reduction of scar thickness measured
by TUPS. The scar in the experimental group was softer and
more pliable as measured by The Vancouver Scar Scale and
there was improvement on pain and itchiness from patients.
The effect was seen at the 1-month assessment and steadily
reached to an optimal state until 6 months after intervention.
Though the results from the pigmentation and vascularity
did notshowanystatistical significant difference, subjectsin
the SGS groups reported that the scar became paler, less
reddish and more resembled normal adjacent skin. Subjects
in the SGS group also showed faster rate of recovery from
pain and itchiness when compared to the control group
though the outcomes at the 6-months’ assessment were
similar between the two groups.
6. Discussion
SGS was used in western countries as a prophylactic
measure after wound healing to prevent hypertrophic scar.
Therefore, the effect on the long term thick, firm and highly
vascular hypertrophic scar was not clear. This is the first
RCT study conducted on a group of Chinese patients to
C.W.P. Li-Tsang et al./Burns 32 (2006) 678–683681
Fig. 1. The changes in thickness between the two groups during the
intervention.
Fig. 3. The change in redness (vascularity) between two groups during
intervention.
Fig. 2. The changes in lightness between two groups during intervention.
Fig. 4. The changes in yellowness between two groups during intervention.
Table 4
Changes of scar thickness between two groups over 6 months based on the
modified population marginal mean
AssessmentsGroups Mean ? S.D.
6.12 ? 0.17
5.77 ? 0.16
5.94 ? 0.24
5.29 ? 0.16
6.17 ? 0.20
4.76 ? 0.17
5.82 ? 0.25
4.47 ? 0.18
6.16 ? 0.25
4.17 ? 0.17
Initial assessmentControl group
Pressure therapy group
Post-1-month assessment Control group
Pressure therapy group
Post-2-month assessmentControl group
Pressure therapy group
Post-4-month assessmentControl group
Pressure therapy group
Post-6-month assessment Control group
Pressure therapy group
Fig. 5. The changes in scar pliability score during the intervention.

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verify its efficacy on the Chinese population with very
severe scar problems using a randomized clinical trial. From
our study, we also found that the SGS is effective on scar
developed after 1–4 years of onset. Most of the problems
with established hypertrophic scar are its insightful, hard,
stiff, dry texture associated with uneven thickness.
Silicone gel sheeting (SGS) was found effective in
reducing scar thickness and improvement in the pliability of
the scar tissue. The mechanism of SGS was postulated as
hydration of the hypertrophic scar, eventually reducing the
fibroblast’s activity and decreased collagen formation. The
silicone gel may have hydrated the stratum corneum and
lubricatedthe surface ofthescar,thushelpingtoremodel the
collagen fibers which are deposited onto the surface of the
skin. This hydration effect on the stratum corneum reduced
the activity level of fibroblasts and collagen synthesis as
suggested by Quinn and Suetake et al. [10,15]. Further
investigation on exploring how silicone gel sheeting is
effective would need to be done.
Our study also found that a period of 6 months seemed to
be the optimum period of silicone gel to exert its effect on
scar. From the trends of improvement in scar thickness,
pigmentation and pliability, the silicone gel was shown to
exert its maximum effect in the first 2 months of
intervention, then gradually plateau after the 4 months of
intervention until the end of the sixth month. In view of the
rather costly material cost of the silicone gel sheet (Cica-
Care), it is therefore recommended that the course of
application should be around 2–6 months depending on the
responseoftreatment.Itwaseasytoapplyandrelativelyless
side effect when compared to other conservative manage-
ment methods.
Previous studies reported the effectiveness of silicone gel
using very subjective evaluation based on clinical examina-
tion and subjective rating on scar parameters such as
pigmentation, thickness, pliability, vascularity. Ahn et al.
[16] and Gold [17] demonstrated the effectiveness by
comparing the scar with gel intervention with the other half
without gel intervention. However, he only described the
change of scar using very subjective observation methods
such as feedback from the assessor of the patients. Cruz-
Korchin [18] and Borgognoni’s study [19] used similar
descriptive manner to report the prophylactic effect of
silicone gel sheeting also but no objective findings were
reported. In our study, we employed more objective
evaluation methods, such as the use of the spectro-
colorimeter which can document the pigmentation changes
using quantitative evaluation system, TUPS can document
the thickness of the scar using the sensitive ultra sound
device specially adapted for scar measurement. In this way,
the improvements could be made evident through the
objective measures.
7. Conclusion
Research using randomized clinical trial design provides
the most objective evidence to demonstrate the efficacy of
treatment. This is an RCT study to evaluate the effect of
silicone gel therapy on Chinese subjects with severe
hypertrophic scar. Subjects in this study were assigned
randomly without bias to either the experimental or control
group and the baseline characteristics of the two groups did
not show any difference. Results showed that was SGS an
effective treatment for the relatively more severe hyper-
trophic scar resulting from scald, burn and skin trauma.
There was significant difference in scar thickness between
the experimental and control group. The scars in the
experimental group became thinner (less hypertrophic),
more pliable and less vascular after intervention. Patients
also reported less pain and itchiness after intervention and
that the color of scar became paler and resemble the normal
C.W.P. Li-Tsang et al./Burns 32 (2006) 678–683 682
Fig. 6. The effectiveness of silicone gel sheeting on scar over abdomen.