## 4 Discussion
Large animal models are valuable tools in biomechanical engineering, finding applications in both preliminary in vitro testing and in vivo testing. These models, including dogs, rabbits, cows, sheep, and pigs, have been extensively utilized in research on the natural meniscus, the study of its kinematic behavior, the assessment of the biomechanics of knee joint contact, the validation of engineered tissues proposed for total or partial replacement of the meniscus, and the evaluation of the efficacy of surgical meniscal repairs. The canine model, historically employed in studies, has experienced a decline in usage, potentially due to increasing pressure from animal advocacy groups. Moreover, from a technical perspective, the majority of surgical procedures on the canine meniscus require arthotomy, often accompanied by medial collateral ligament rupture, deviating from arthroscopic procedures in humans. The rabbit model exhibits significant differences in vascularity, collagen orientation, and glycosaminoglycan content of the meniscus compared to human menisci. Additionally, the kinematics of the rabbit's femorotibial joint significantly differ from those of the human knee [31; 34; 50]. The bovine model, significantly larger than the human meniscus, has limited application in biomechanical studies due to the size discrepancy [34; 50]. The ovine meniscus, while anatomically similar to the human meniscus, differs in kinematics and contact force distribution, making it unsuitable for non-isolated studies of the repaired meniscus [30; 31; 34]. Regarding the porcine model, it closely resembles the human model in terms of anatomical structure, vascularity, volume, and weight [30; 31; 34], although the width of the meniscus is greater, as demonstrated in the present study. The kinematics of the porcine knee reasonably approximate those of the human knee. As a result of the aforementioned arguments, the porcine model is the predominant surrogate for in vitro tests of the young human meniscus [12; 15; 16; 17; 18; 19; 21; 23; 26; 27; 28; 29], widely applied in biomechanical testing for meniscal repair and replacement techniques, allowing for effective translation to clinical applications. Surgical repair of meniscal root avulsions has been traditionally limited to patients under the age of 35-40. However, there is a paradigm shift, with a contemporary inclination towards meniscus preservation through the utilization of repair techniques whenever feasible. The 2019 consensus of the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) [42], drawing from a compilation of studies encompassing patients from 9 to 58 years of age, 'clearly states that numerous meniscus tears that were considered irreparable should be repaired, e.g., older tears'. This shift is substantiated by recent follow-up studies that report the advantages of extending the range for surgical intervention to over 60 years of age [41; 51]. Hence, this matter was carefully considered, and we decided to expand the age range of the young group to 75 years old, aligning with the aforementioned findings and to conform to the criteria of the orthopedic surgeons who are part of our research team. We consider that menisci from donors who are older than 75 years of age are representative of a group of patients who are too advanced in age to be routinely considered eligible for meniscal root repair surgery. The experimental design involved testing isolated meniscus-suture constructs instead of menisci attached to tibial bones. This setup is consistent with prior works on the same topic [29; 37; 38; 52]. It was selected to specifically focus on the behavior of the tissue-suture interface, excluding factors dependent on tibial fixation. Also in line with previous studies [29; 37; 38; 52], the suture was oriented with the loading direction, eliminating shear friction and concentrating the tensile effect on the meniscus-suture interface, which was our area of interest.