Investigation of histopathological and biomechanical durability of scafold in the treatment of achilles tendon ruptures

Object: Achilles tendon is the thickest and strongest tendon in the human body. Even though the tendon is so strong, it is one of the most frequently injured tendons. After achilles tendon rupture the patients can be treated conservatively or surgically. Conservative treatment and follow up is preferred for patients who are old and live sedentarily. Surgical treatment can be done via percutaneous tendon repair or open surgical repair. These include PRP injection, hyaluronic acid application, vitamin C application, and addition of growth factors. In our study, we applied scaffold (type 1 collagen impregnated polylactic-co-glycolic acid membrane) around the tendon in open surgical repair of rabbit Achilles tendons. Then, we aimed to statistically examine the histopathological and biomechanical results. Methods: In our study, twenty-four rabbits were randomly distributed into two groups. Modified Kessler suture was applied to the control group after Achilles tendon rupture was created. In the scaffold group, Modified Kessler suture was applied after Achilles tendon rupture was created and Type 1 collagen PLGA scaffold was applied to the tendon injury area. At the end of the sixth week, the rabbits' Achilles tendons were taken as a whole. Histological examinations were performed, and biomechanical tests were applied by randomly distributing four groups. Bonar and Modified Movin scores were used in histological examination. In biomechanical tests, the maximum endurance force and rupture time of the tendon were measured. Results: Biomechanical tests showed that the rupture force was 110.17±15.35 Newton in the scaffold group and 100.67±13.93 Newton in the control group. Although the rupture force was higher in the scaffold group, the difference between the two groups was not statistically significant (p=0.288). The rupture time was 6.17±1.16 seconds in the scaffold group compared to 4.83±0.75 seconds in the control group, with the scaffold group showing a statistically significant longer rupture time (p=0.041). Histological evaluations revealed that vascularity and ground appearance scores on the Bonar scoring scale were significantly lower in the scaffold group compared to the control group (p=0.010 and p=0.022, respectively). When comparing total Bonar scores, the scaffold group had a score of 5.33±0.51, while the control group scored 7.67±0.51, with the control group showing significantly higher values (p<0.001). In the modified Movin scoring system, fiber structure, fiber alignment, and increased vascularity scores were significantly lower in the scaffold group than in the control group (p=0.002, p=0.001, and p=0.010, respectively). The total Movin score was 10.50±1.04 in the scaffold group and 13.67±1.50 in the control group, with the control group showing a statistically significant higher score (p=0.002). Conclusion: If surgical intervention is decided for Achilles tendon ruptures, there remains no consensus in the literature regarding the preference for open surgery or minimally invasive techniques. Biotechnology is increasingly being utilized to improve surgical outcomes and reduce post-operative complications. Based on our study on rabbit Achilles tendons, we believe that using collagen-impregnated PLGA membranes can positively influence tendon healing. Keywords: Achilles tendon, Rupture, Rabbit, Scaffold, Surgery