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Kanevsky et al. Stretch device for scar therapy

have similar concerns about scarring and value even A B
small improvements in scarring. [6-11] Changes in
texture, coloration and elevation of scar are of equal
concern to patients with minor and severe scars. [5,12]
In addition to scars on the face, patients are often
dissatisfied with scars from donor graft sites used
for breast reconstruction, heart surgery, and elective
procedures such as abdominoplasty. [13,14]

Scar prevention and reduction is an area of therapeutic
opportunity and unmet medical need. There is no
single therapy that is accepted as the standard of
care for treatment of scars. [15-17] Many patients seek
surgery for scar revision but surgeons often turn away
patients, as they believe that improved results cannot Figure 1: (A) Application of stretch device in vivo. Stretch
be obtained with current techniques and therapies. [12] In treatments lasted 20 min once a day for 10 days. Mice were
anesthetized under isoflurane for each stretch treatment; (B) the
the US alone, 45 million patients undergo procedures actual design of the stretch device
yearly that would benefit from scar reduction therapy. [18]
formation by applying mechanical stress to oppose
Current scar therapies lack a clear mechanism of wound edges. [33,34]
action and have unpredictable efficacy. Non-surgical
therapies include topical creams and preparations, Langevin et al. [26-28,35] and Bouffard et al. [29] have
wound dressings, laser treatments, and skin substitutes. published a series of studies that demonstrate the
Additional therapies such as massage and mechanical decreased collagen and transforming growth factor
manipulation have also been often recommended to beta 1 (TGF-β1) expression, major contributors to scar
patients for treatment of scars with variable results. [19-21] formation, after longitudinal stretch parallel to a wound.
Based on these data, the present study aims to develop
To better understand then mechanism behind scar a longitudinal stretch device that might enhance
formation, the role of mechanical force in scar formation aesthetic outcome of scarring through modulation of the
has been explored extensively. [22-25] Studies have cellular processes involved in scar formation.
shown that tension resisting wound closure can worsen
scar formation. [25] However, recent data suggests METHODS
that the timing, duration, and direction of force on
a scar plays an important factor in scar formation, Device development and standardization
and properly aligned and timed mechanical forces AutoCAD was used to design a scar stretch device
could potentially decrease scar formation. [26-29] A that could easily attach and detach from skin. The
previous study by Alenghat and Ingber [30] showed that components of the device include a skin adhesive
mechcanotransduction directly affects a variety of mechanism and an extension force mechanism,
cellular processes involved in scar formation. Although allowing for reliable attachment and detachment of
direct manipulation of these cellular processes is still the device [Figure 1]. The device prototypes were
being investigated, there has been an assortment constructed using inert materials purchased from
of models examining the effects of direct skin Small Parts Inc. (www.smallpartsinc.com): steel spring
manipulation on scar formation. A randomized-control
trial (RCT) showed that using tape after surgery helped (Stainless Steel 316 Compression Spring), polyvinyl
prevent hypertrophic scar formation in 70 patients. [31] tubing (White Translucent Miniature PTFE Tubing),
Another study showed using a mouse model that when Teflon rods (PTFE Round Rod), and an adhesive.
an incision is under mechanical stress, inflammatory Three different spring strengths for the scar stretch
cells become activated and apoptosis of the healing devices were created and labeled as 0.5×, 1× and 2×
[32]
cells increases. Additionally, a review on all currently to investigate a dose response (1× = 0.96 Newton, as
hypothesized physical treatment modalities for scar per manufacturer specifications). The devices were
prevention and found that the success of compression standardized to ensure similar extension force using a
therapy, silicone therapy, adhesive tape, and occlusive small force gauge (Jonard Industries, Tuckahoe, NY).
dressing therapy, relies on mechanotransduction
mechanisms. Furthermore, recent studies evaluating Animal model
[24]
tension on wounds in a pig model formed the foundation The experimental protocol was approved by the McGill
for the Embrace device, which functions to reduce scar University Animal Care Committee and Institutional
352 Plastic and Aesthetic Research ¦ Volume 3 ¦ November 15, 2016