89-91 - Polskie Stowarzyszenie Biomateriałów

emoved. On the day of the planned procedure all animals
underwent the veterinary examination and were recognized
as healthy without clinical symptoms of pathological state.
All implantations of the tested materials were conducted
by the same team in the surgery room with maintenance of
surgical aseptics. Rabbits were anaesthetized by intramuscular
injection of Xylazyne in dose of 5mg/per kg of bodyweight
and Zoletil in dose of 15mg/ per kg of bodyweight.
Skin incision at the length of 4-5cm was made, running
along spinous processes of the spine in thoracic section.
Next, skin was prepared bluntly to the sides of the chest. In
back muscles (thoracic longest muscle and lumbus longest
muscle - mm. longissimus thorascis et longissimus lumborum)
muscle pockets were made by incision in fascia with
the use of blunt ended scissors and blunt prepared. In those
muscle pockets the tested samples were placed. Muscle
pockets were sutured with single resorbable suture Dexon
3-0. Next, the tested samples were placed in subcutaneous
tissue securing them with single suture Dexon 3-0 in order
to avoid displacement.
Samples in total quantity of 12 per rabbit were implanted
according to the below mentioned schema:
- 3 tested samples in back muscle on the right side
- 3 tested samples subcutaneously on the right side
- 3 tested samples in back muscle on the left side
- 3 tested samples subcutaneously on the left side
Samples, both in muscle pockets and in subcutaneous
tissue, were placed in the distance between one another
not smaller than 2cm.
After implantation of all samples the skin was closed
with interrupted sutures with the use of polyamide nonresorbabale
sutures Amifil M 3-0. The postoperative wound
was rinsed with hydrogen peroxide solution and disinfected
with preparation Prevacare. Wounds were not covered with
a dressing. Conditions of postoperative maintenance were
the same as in the preoperative period. On the 10 th day after
the procedure the sutures at all rabbits were removed.
fIg.4.
Subcutaneousimplantation
of hernia
mesh
sample.
fIg.3. Implantation
of hernia
mesh
sample
into back
muscles.
macroscopic autopsy evaluation
In planned testing terms after 2, 4, 12, 26 and 52 weeks
the euthanasia of the rabbits was conducted by intravenous
administration of penthoparbitalum. Before the anaesthesia
was performed the general health state of the animals was
evaluated. During the course of autopsy, firstly, the macroscopic
evaluation of the wound was performed and the
appearance of all places of samples implantation was rated.
Next, the tested material was sampled with surrounding tis-
sues for further histological testing. In the second stage, the
appearance of the chosen internal organs was evaluated,
mainly of the respiratory and digestive system.
microscopic evaluation
Soft tissues namely muscle and subcutaneous with implants
were being fixed for 48 hours in 10% water solution of
formic formaldehyde in phosphatic buffer. Next, the samples
were dehydrated in acetone, transilluminated in xylene and
embedded in paraffin blocks. On microtome sections at
the thickness of 4µm were cut. Preparations were stained
with hematoxylin and eosin (HE) and Van Gieson method
(VG) differentiating connective tissue stroma and then were
closed in Canadian balsam. Histological preparations were
evaluated with light microscope with the use of computer
software for analysis and image activation. The classical
qualitative- quantitative evaluation was made and also
healing in process dynamics was evaluated, next on chosen
and most representative preparations the semi-quantitative
evaluation was conducted (ISO/DIS 10993-6:2004-2005,
Biological evaluation of medical devices – Part 6: Test for
local effects after implantation, Annex E which is comparable
with new revision of PN-EN ISO 10993-6:2007 Standard).
Results
In both groups all animals survived to the planned autopsy
dates without clinical illness symptoms. At all animals
with performed autopsy the following organs were subjected
to examination: hearts, lungs, livers and kidneys; all of them
had proper size and colour, without changed shape, without
visible pathological changes.
macroscopic evaluation
Macroscopic evaluation indicated that the healing process
of the tested mesh Dallop® M and the control hernia
mesh Duramesh TM coursed without any complications.
Symptoms of low irritation (maintaining hyperaemia, and
vascular injection) around the subcutaneously implanted
samples were presented up to 12 weeks due to the constant
movements of the samples. After 26 and 52 weeks neither
in case of tested mesh Dallop® M nor in control hernia
mesh Duramesh TM maintaining inflammation state were
observed. For both evaluated meshes in the testing terms
the macroscopic image looked similarly.
microscopic evaluation
The samples of tested mesh Dallop® M two weeks after
implantation were surrounded by the band of loose rich-cell
connective tissue with presence of numerous eozinophils.
The histological evaluation of hernia mesh Dallop M in
comparison with DurameshTM presented slight irritation in
subcutaneous tissue after two weeks (which disappeared
during next weeks of observation).
The microscopic image of the healing of Dallop® M and
Duramesh TM in testing terms 4,12, 26 and 52 weeks after
implantation was similar and no differences were showed.
Both in subcutaneous and muscle tissue the process led to
formation of thin band of connective tissue with fat infiltration
around the mesh fibres. In 26 week after implantation the
connective tissue band had double-layer structure: fibrous
from the side of surrounding tissues and loose rich-cell
from the side of implant. After 52 weeks from implantation,
in direct vicinity of mesh threads especially in spaces
between filaments, were still present small bands of loose
rich-cell connective tissue in which the following could
be distinguished: fibroblasts, lymphocytes, single giant
cells. Fat infiltration had different degree both around the