Effects of cyanoacrylate in rabbits with experimental achilles tendon injury

In our study, we aimed to effects of cyanoacrylate not studied previously on tendon healing in both biomechanical and histopathological manner by inducing a rabbit model of Achilles tendon injury. This study was conducted on 36 rabbits at Experimental Animal Application and Research Center of Bolu Abant İzzet Aysal University. Tendon injury was induced on all animals. The animals were assigned into 2 groups as study and control groups. Tendon repair alone was performed in rabbits in the control group while tendon injury was repaired by end-to-end simple suture and 0.1 cc tissue glue N-butyl-2-cyanoacrylate (Histoacryl, B. Braun, Melsungen AG, Germany was dropped in the study group. In each group, 9 of 18 rabbits were randomly selected on week 4 and histopathological and biomechanical assessments were performed. At the end of week 6, remaining rabbits (9 in the study group and 9 in the control group) were assessed. In the histopathological assessment, no granulation tissue formation was detected in any of animals in the control group while granulation tissue formation was found in all animals in the study group on week 4, indicating significant difference (p<0.001). On week 6, granulation tissue formation was observed in one animal in the control group and in seven animal in the study group, indicating significant (p=0.010). In this study granulation tissue formation rate was significantly higher in the study group when compared to controls on both weeks 4 and 6. On week 4, no foreign body giant cell (FBGC) formation was detected in any of the animals in the control group while FBGC formation was detected in all animals in the study group, indicating significant difference (p<0.001). On week 6, FBGC formation was observed in seven animals in the study group but in none of the animals in the control group, indicating significant difference (p=0.001). In this study, it was found that FBGC formation rate was significantly higher in the study group when compared to controls on both weeks 4 and 6. When inflammation level was considered, inflammatory cells were observed in 6 animals in both study and control groups on week 4. No significant difference was detected between groups (p=1.00). On week 6, inflammatory cells were detected in 4 control animals while in 7 animals in the study group, indicating no significant difference between groups (p=0.282). In this study, no significant difference was detected between groups regarding presence of inflammatory cells on weeks 4 and 6. When neovascularization was assessed, grade 3 neovascularization was observed in 6 animals in each group on week 4. There was grade 2 neovascularization in 2 animals in the control group while there was grade 1 neovascularization in one and grade 2 neovascularization in two animals in the study group. No significant difference was observed between groups regarding neovascularization on week 4 (p=1.00). On both weeks 4, no significant difference was detected in collagen fibril alignment between study and control groups (p=1.00). In addition, no significant difference was found on week 6 (p=1.00). ). In this study, no significant difference was detected between groups regarding collagen fibril alignment on weeks 4 and 6. When fibroblastic activity rate was assessed, it was found that there was marked fibroblastic activity at repair site in 7 animals in the control group and in all animals in the study group on week 4, indicating no significant difference (p=1.00). There was marked fibroblastic activity at repair site in 5 animals in the control group and in all animals in the study group on week 4, indicating no significant difference (p=0.20). In this study, no significant difference was detected between groups regarding fibroblastic activity on weeks 4 and 6. In biomechanical assessment, it was found that maximum rupture strength was significantly higher in the study group when compared to controls on week 4 (239.0±36.5 vs. 193.5±56.9; p<0.05). Between groups, no significant difference was detected in elasticity and stiffness on week 4. As similar to week 4, maximum rupture strength was found to be significantly higher in the study group than controls on week 6 (177.6±49.6 vs. 223.6±42.0; p<0.05). In addition, stiffness was found to be significantly higher in the study group (14.6±5.3 vs. 20.6±7.0; p<0.05) but no significant difference was detected in elasticity between groups. In conclusion, we think that cyanoacrylate can be used in the surgical repair of tendon injuries in clinical practice as it enhances tendon durability at early phase in both histopathological and biomechanical manner and that early rehabilitation can be started more safely in tendon healing where cyanoacrylate was used. Keywords: Cyanoacrylate, Achilles tendon rupture