May titanium spiral tacks contribute to intra-abdominal adhesion formation ?

PURPOSE: To verify if titanium spiral tacks may contribute to intra-abdominal adhesion formation in rabbits. METHODS: Ten New Zealand white rabbits were used. Through videolaparoscopic surgery two titanium spiral tacks (ProTack®, Covidien®) were applied in the right flank. After 30 days the animals were submitted to evaluate peritoneal cavity by videolaparoscopy. RESULTS: No adhesion was found where the titanium spiral tacks were placed. CONCLUSION: Titanium spiral tacks for fixation do not cause adhesions in rabbits.


Introduction
Inflammatory response and adhesions formation of synthetic mesh prostheses inserted inside peritoneal cavity has been our research line [1][2][3] .
Other authors bring into question if adhesions are provoked by prostheses or by the fixation procedure.
Karahasanoglu et al. 4 compared formation of adhesions between titanium spiral tacks and suture to fixed mesh in pigs, showing significant incidence of adhesion with the metallic tacks.
Eriksen et al. 5 compared the fixation of mesh with fibrin sealant and titanium in pigs.They did not find statistic significant differences in adhesions.
Gungor et al. 6 realized a comparative evaluation of adhesions on intraperitoneal fixation materials by a laparoscopic study in rats.They observed that after 15 days adhesions were greater with nickel titanium clips than with polilactic acid stitches or with titanium spiral tacks.No adhesions with fibrin sealant were found.
In general prostheses are fixed with metallic tacks.
Our goal is to investigate if titanium spiral tacks may contribute to intra-abdominal adhesion formation in rabbits.

Methods
Ten New Zealand (Oryctolagus cuniculus) white rabbits, three month age, weighting between 2000 and 2500g, were used.After recovery, animals returned to their cages with food and water ad libitum, with daily follow up for 30 days.
All events were registered.After the period of observation the animals were anesthetized again and submitted to a new videolaparoscopy procedure to find the occurrence of adhesions.
A periumbilical incision (1cm) was made to craft pneumoperitoneum using a Verres needle puncture (8mmHg steady pressure).A 5mm trocar was placed and introduced a 5mm 30° scope.
Abdominal cavity was evaluated and tacker's sites investigated.
The whole procedure was documented.
After laparoscopy the animals were euthanized by anesthetic drugs.

Results
All animals had good postoperative recovery without any complications.
The duration of surgeries was between 10 and 20 minutes with no difficulty to place the tacks.
No adhesions were observed through laparoscopy where the clips were implanted (Figure 1).

Discussion
Mesh fixation in abdominal cavity is important to avoid dislocation 7 , but may cause adhesions 8 .
There are few studies about fixation materials without the presence of prostheses 6 .
Non-use of prosthesis takes away the influence of adhesions formation.adhesions with prostheses in contact with viscera, independent of the type and protection of the mesh [1][2][3] .

Our experimental studies always observed important
Rabbits are used in research to evaluate types of mesh and it is a satisfactory biological model [1][2][3] .
Only one author studied four different types of fixation without the use of meshes in rats 6 .
We applied two titanium spiral tacks in each animal simulating fixation of the mesh.
The clips were positioned in the same place and both were near each other.
Thirty days are enough to evaluate adhesions formation.
We did not find any adhesions at this time.Adhesions find in our previous studies must be considered due to prosthesis other than to the fixation procedure.

Conclusion
Titanium spiral tacks do not contribute to intra-abdominal adhesion formation in rabbits.
This investigation was approved by the Committee of Ethics in Research with animals of Albert Einstein Teaching and Research Institute, cared by specialized veterinarians.The surgical procedures were done at the experimental laboratory of this Institute.All rabbits were kept in abstinence from food for 12 hours and under standard conditions.Anesthesia was induced using intramuscular acepromazina (Acepran® 1%) ten minutes before the procedure.Then, intramuscular ketamine plus xylazine were used.Abdominal wall was completely clipped and disinfected with povidone-iodine and all procedures were performed under sterile technique.A periumbilical incision (1cm) was made to craft pneumoperitoneum using a Verres needle puncture (8mmHg steady pressure).Two 5mm trocars were placed: 30° scope (umbilical incision) and tacker device (left flank).Titanium spiral tacks (ProTack ® , Covidien ® ) were used.Two titanium spiral tacks were applied in the right flank.Aponeurosis was closed with poligalactine 2-0 and skin with nylon 4-0.The peritoneum was left open.

FIGURE 1 -
FIGURE 1 -No adhesion found and peritonealization of the titanium tacks was observed.