## 3 Results  
Firstly, we investigated the tendon's fracture behavior. Optical images of a typical failure process are presented in Figure 1. The typical force-elongation curves of each type of tendon are presented in Figure 2.  
Figure 1: Typical damage process of a tested tendon (optical images—left, force–elongation curve—right, note the formation of longitudinal cracks separating the fiber bundles). The failure process is visible from the images presented in Figure 1. In most of the tests, longitudinal fractures formed in the tendons during the elongation, so the co-working of the adjacent fiber bundles was hindered, and the modulus of elasticity (slope of the curve) decreased after every fracture step. When comparing different tendons, the main failure process is the same; only the severity of each force-drop is different. Some differences can also be seen, which can be connected to crack propagation. While in the curve of STG presented in Figure 2, ductile failure with quasi-plastic deformation occurs, for example, in the case of the quadricp tendon's curve, the cracks and partial fractures are more severe. In the case of the quadricp tendon, the process is also worth investigating: irreversible damage progresses even from relatively low elongation, the loss of connection between the fiber bundles is not so critical, and the force required to elongate the tendon further increases. In Table 1, the numerical data of tensile modulus, maximum load, strain at maximum force and fracture strain are summarized and compared. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Tendon Types and** & \multicolumn{3}{c}{**Group A**} & \multicolumn{3}{c}{**Group B**} & \multicolumn{3}{c}{**Group C**} \\ \cline{2-10}
**Mechanical Properties** & **Median** & **25\%** & **75\%** & **Median** & **25\%** & **75\%** & **Median** & **25\%** & **75\%** \\ \hline \multicolumn{10}{c}{**Quadriceps**} \\ Tensile modulus (MPa) & 191.31 & 138.13 & 2922.42 & 120.24 & 90.13 & 299.29 & 83.20 & 30.65 & 137.05 \\ Maximum load (N) & 1939.75 & 1121.97 & 2727.15 & 2803.68 & 1653.26 & 3591.97 & 2564.77 & 1835.38 & 3265.92 \\ Strain at maximum force (-) & 0.1540 & 0.1340 & 0.2485 & 0.1841 & 0.1467 & 0.2299 & 0.2729 & 0.1949 & 0.3472 \\ Fracture strain (-) & 0.3370 & 0.2766 & 0.6900 & 0.3231 & 0.2481 & 0.4885 & 0.4392 & 0.3574 & 0.5909 \\ \hline \multicolumn{10}{c}{**Semiemioms + g+axis (STG)**} \\ Tensile modulus (MPa) & 186.46 & 142.82 & 229.26 & 210.28 & 137.08 & 244.11 & 222.66 & 128.59 & 255.73 \\ Maximum load (N) & 1922.96 & 1501.00 & 2374.84 & 2171.41 & 1330.37 & 2414.74 & 2357.61  
In group A (no freezing, no irradiation), we found no difference in maximum loads, strain at maximum force and tensile modulus among the tendons (Table 1, Figures 3-5). Fracture strain of the quadricp tendons was significantly inferior to the TA (\(p\) = 0.0016) tendons in this respect (Table 1, Figure 6--green color). Figure 4: Minimum, maximum, median, 25% and 75% percentile values of strain at maximum force. Red color: quadricp 21 kGy inferior to the STG 21 kGy. Blue color: quadricp 42 kGy better than the STG 42 kGy, TA 42 kGy, and the PL 42 kGy. Green bracket: quadricp 42 kGy significantly higher than the quadriceps fresh and quadricp 21 kGy. Figure 3: Minimum, maximum, median, 25% and 75% percentile values of maximum load. Red color: STG 21 kGy significantly lower than the quadricp 21 kGy and TA 21 kGy. Blue color: TA 42 kGy significantly higher than the STG 42 kGy and PL 42 kGy. In group B (frozen and irradiated with 21 kGy), the maximum loads of the STG tendons were significantly lower compared to the maximum loads of the quadricep (\(p\) = 0.0193) and TA tendons (\(p\) = 0.0272) (Table 1, Figure 3--red color). The strain at maximum force of the quadricep tendons was inferior compared to the STG tendons (\(p\) = 0.0022) (Table 1, Figure 4--red color). The tensile modulus of the quadricep tendons was significantly inferior to that of the TA (\(p\) = 0.0313) and PL tendons (\(p\) = 0.0201) (Table 1, Figure 5--red color).