Page 55 - Micro5 Brochure 2017

110 A.F. Ahmed et al.
process of tendon and the polarity of MES could be an important factor to be considered in treating
tendon injuries.
Introduction
Injury of the dense connective tissues as tendons and ligaments,
either from acute trauma or repetitive strain lesions results in
protracted periods of disability. The resolution of such injuries
often fails to restore the normal morphologic and functional
characteristics of the tissue structure and therefore, either com-
promises the future performance of the individual or predisposes
to an increase risk of recurrent injury [1,2]. Tendons are charac-
terized by their slow rate of healing and much debate has been
aroused concerning the intrinsic capacity of tendons to heal after
injury. Tendons have shown a capacity for healing, either alone
or in conjunction with extratendinous structures. Intrinsic heal-
ing results in improved biomechanics and has less complication.
In particular, a normal gliding mechanism within the tendon
sheath is preserved. It was suggested that a means of enhancing
intrinsic repair mechanisms would be highly desirable [3–6].
MES is a low-intensity current that delivers monophasic or
biphasic pulsed microamperage currents usually between 1
microampere (lA) and 1000 lA. MES is thought to mirror
the body’s own natural current as so, it has the privilege of
using electric currents similar to those produced by the body
during tissue healing and it may be a particularly beneficial
where endogenous healing has failed [7,8]. It was reported that
MES plays a significant role in enhancing the healing process
of tissue healing [9]. The proposed mechanisms by which
MES produced its effect are, increasing adenosine triphos-
phate (ATP) concentration, promoting amino acid uptake,
and enhancing protein synthesis in human fibroblasts [4,8,10].
Regarding the effect of MES on tendon healing, many stud-
ies have been conducted using variable current parameters, and
demonstrated that MES improves tendon healing [4,11–15]. The
effect of MES may be related to the selected treatment parame-
ters as current intensity, current density and polarity [11,12,15]. determination of the dose of anesthesia. The rabbits were anes-
An important parameter of electrical stimulation in healing is
the type of applied polarity which may affect protein synthesis,
cell migration, growth of bacteria, electrotaxis, inflammation,
edema, and also the processes of bioelectric events of injury
[10,16–19]. Some studies have reported significant improvement
of tendon healing using negative polarity [11,12], while others
reported significant improvement using positive polarity [13,14].
So, despite the presence of many studies on the effect of
MES on tendon healing, more comparative studies are needed
to compare and standardize the ideal polarity at each stage of
tendon healing. Therefore, the present study investigated the
effect of MES with different polarity on the biomechanical
and histopathological properties of surgically repaired rabbits
Achilles tendon at different stages of healing.
Material and methods
Animal model
The ethical committee of the Faculty of Physical Therapy,
Cairo University approved this study. Ninety six, 4–6 months
ª 2011 Cairo University. Production and hosting by Elsevier B.V. All rights reserved.
old male New Zealand White rabbits, with average weight 2–
2.5 kg, were used in this study. The rabbits were purchased
from the Rabbit Production Unit, Faculty of Agriculture,
Cairo University. The animals were housed individually in a
standard rabbit cage of 15 · 20 · 20 cm. (The size of the cages
did not allow them full activity such as running, but they could
move around freely.) The rabbits were kept at the same condi-
tions of temperature (about 20 °C), humidity (50%) and light
(a 12 h light/dark cycle), and subjected to comprehensive vet-
erinary care. Tap water and balanced diet were given ad libi-
tum throughout the study. The rabbits were assigned to
normal group served as a basic reference and three studied
groups. The normal group included six rabbits with intact ten-
dons five of which were used for biomechanical measurements
and one was processed for histopathological studies. The
remaining ninety rabbits, their right Achilles tendons were
tenotomized, sutured and immobilized. After that, rabbits
were randomly divided into equal three groups (n = 30 in
each) by a technician not involved in the surgery. The studied
groups were cathodal, anodal and control and each group was
further subdivided into three subgroups according to the study
period; 3, 5 and 8 weeks (n = 10 in each). In each subgroup, 7
of the tendons were used for biomechanical measurements and
3 were processed for histopathological studies. Tendons in the
cathodal and anodal groups were treated with MES while
those of the control group did not receive MES treatment.
Surgical procedures
In preparation for surgery, food was withheld 12 h while water
was withheld 3 h before the operation. Immediately before the
surgery the hair was removed from the site of the operation, at
the posterior and medial aspects of the hind limb using hair
removal cream. The remaining hair was short cut using hair
scissor. Each rabbit was weighed before the operation for the
thetized by general anesthesia using combination of intramus-
cular injection of ketamine hydrochloride (35 mg/kg body
weight) (Ketalar (Parke–Davis SA, Barcelona, Spain) and
Xylazin hydrochloride (5 mg/kg body weight) (Rompun 2%
(Bayer, Leverkusen, Germany).
All surgical techniques were done under sterile conditions
according to the following steps (Fig. 1). The animal was
immobilized on the surgical table in a side lying position.
The right Achilles tendon was exposed and dissected using a
longitudinal incision of about 3 cm in length on the medial
aspect of the leg extending from just above the heel to the mid-
dle of the leg. Achilles tendon was sharply transected with a
scalpel, about 1 cm apart from calcaneal insertion. To stan-
dardize the injury mode in both groups, a complete surgical
transection of the Achilles tendon was performed. After that
both ends of the severed Achilles tendon were approximated
and sutured by 4/0 Proline (Ethicon, NY, USA) using modi-
fied Kessler suture technique. The skin was then closed by
interrupted silk sutures. Afterward; the operated limb was
immobilized using Plaster of Paris cast with the knee in flexion