Comparison of nerve healing and adhesion-reducing effects of vein and fat graft applications after crush injury in rat sciatic nerve

Objective: Peripheral nerve injuries are one of the important morbidity and mortality conditions frequently encountered in clinical practice as a result of traumas, iatrogenic injuries secondary to surgical interventions, burns and degenerative lesions. As a result of scar tissue that develops due to collagen produced by fibroblasts, macrophages and other cellular structures during the nerve healing process after nerve repairs, nerve structures adhere to surrounding tissues, leading to a decrease in healing processes, decreased mobility during muscle and joint movements and ischemia in nerve structures. Although many treatment modalities have been used in experimental studies and clinical practice to reduce and prevent this scar tissue and adhesions, scar tissue and adhesions are still one of the leading causes affecting the healing process. Compression-type neuropathies due to this scar tissue are very common in practice. In order to prevent this process and increase nerve healing, biomaterials and drugs with antioxidant, anti-inflammatory, antifibrotic and neuroprotective properties are known to contribute to nerve healing. In experimental studies conducted for this purpose, positive results have been obtained after the use of anti-inflammatory drugs such as 5-fluorouracil, doxorubicin, colchicine, synthetic drugs such as hyaluronic acid, carboxymethyl cellulose, amniotic membranes, radiation, biological membranes such as seprafilm to reduce adhesions and scar tissue, but the fact that acces to these drugs and materials are not easy, therefore these limits their use due to their difficult access and high cost. For this, the use of autologous tissues comes to the forefront. For this purpose, tissues such as vein, mucosa, muscle tendon can be used, but donor site morbidity is the most important disadvantage of these autologous tissues. We think that fat and vein autologous tissues, which are frequently used in many areas of plastic surgery such as regeneration, augmentation, tissue healing and stem cell function and have antifibrotic, anti-inflammatory and neuroprotective effects, contribute positively to the sciatic nerve healing process and reduce fibrosis-scar formation. In the experimental study we conducted for these purposes, we created a crush injury model (axonotmesis) in the sciatic nerve in rats and evaluated the nerve healing and scar reducing effects of fat and vein grafts. Materials and Methods: In our experimental study, 24 female Sprague-Dawley rats with an average weight of 300-350 g and 14-16 weeks of age were used. The rats were divided into 3 groups as control, fat graft group and vein graft group. The right sciatic nerves of all rats were accessed after appropriate dissection and crush type axonotmesis type injury was created by applying pressure with the help of aesculap clamp for 60 seconds. No intervention was performed in the control group, fat grafts collected from the left ischial region were wrapped around the crushed nerve segment and sutured in the fat graft group, and femoral vein graft taken from the left side was wrapped as a tube and sutured in the vein graft group. After 4 weeks of close follow-up, all experimental animals were euthanized. Rats were evaluated macroscopically and histopathologically. The sciatic nerve segment was accessed by following asepsis and antisepsis conditions. Macroscopic evaluation was performed according to the staging described by Petersen. The healing and integrity of the skin, muscle and muscle fascia during dissection, the adherence of the nerve tissue to the surrounding structures and the separability of the nerve from the surrounding structures during exploration were evaluated. In histopathologic evaluation, fibrosis, axonal degeneration, inflammation and dilatation parameters were examined in the preparations stained with Hematoxylin-Eosin. Results: According to the results of statistical analysis, no significant difference was observed between the three groups in terms of macroscopic integrity and healing of skin, muscle and muscle fascia. Although nerve adhesion and detachability were better in the vein group than in the control and fat groups, no statistically significant difference was observed when the three groups were compared (p>0.05). In the histopathologic evaluation, a significant difference was observed between the three experimental groups in terms of inflammation, no significant difference was observed between the control and fat graft groups, but a significant difference was observed between the vein graft-control and vein graft-fat graft groups, and it was seen that the group that made the difference was the vein graft group (p<0, 05), neuronal degeneration was statistically significant in both fat and vein groups compared to the control group (p<0.05), but there was no statistically significant difference between the fat and vein graft groups (p>0.05), a significant difference was observed between the three experimental groups in terms of fibrosis. While there was no statistically significant difference between the control and fat graft groups in terms of fibrosis (p>0.05), a statistically significant difference was observed when the vein group was compared with the fat group and the control group (p<0.05). When all three experimental groups were compared in terms of dilatation, no statistically significant difference was observed (p>0.05). Conclusion: In our experimental rat sciatic nerve crush style axonotmesis type injury model study, we obtained macroscopic and histopathologic results showing that autologous fat and vein grafts can positively benefit peripheral nerve healing by reducing scar tissue and related nerve adhesions. Considering the severity and mechanism of trauma, additional traumas, general condition and comorbid conditions of the patient, and surgeon's preference, appropriate graft material can be preferred for these purposes.