Results of the static load test:
The graph in Fig.2 shows the measurement results of the static load tests: the first stage of the load-deflection curve can be described as an almost straight increasing line, which represents the flexible range of the rib. After the maximum force exerted, even a smaller force was sufficient for further deflection.
Mean maximum force (and standard error) was 298,9±30,95 N in the control, 287,1±25,93 in the pre-drilled and 280,29±27,51 N in the implanted group. No significant differences were found in the data (p =0.979, Kruskal-Wallis test).
The area under the curves on the 1st diagram (S) describes a quantity, which correlates with the toughness of the ribs, and can be calculated with the following formula:
![](https://myfiles.space/user_files/58890_add8f4303ffe25fa/58890_custom_files/img1601455321.png)
Figure 4 shows the S values in Nmm registered during the test.
Mean S value was 1701,37±166,335 Nmm in the control, 1175,77±128,832 Nmm in the pre-drilled and 1235,56±248,392 Nmm in the implanted group. There is no significant differences between the groups in the calculated S toughness related values (p=0,16, Kruskal-Wallis test).
Results of the dynamic fatigue test:
To analyze the results of the dynamic fatigue tests the Kruskal-Wallis statistic test (control vs. 1, 2) was performed on the measured force values measured for maximum deflection (2,5mm) at specified times (100th, 2000th, 9000th cycles). The results are shown in Fig. 5.
At the 100th cycle the average measured force values were: 0,5766±0,033 kN in the control, 0,4030±0,081 kN, in the pre-drilled, 0,4991±0,073 kN in the implanted group. The statistic test showed significant difference for the measured values between the groups (p=0,014, Kruskal-Wallis test).
At the 2000th cycle the average measured force values were: 0,3896±0,027 kN in the control, 0,2800±0,056 kN, in the pre-drilled, 0,3530±0,049 kN in the implanted group. The statistic test showed a significant difference for the measured values between the groups (p=0,015, Kruskal-Wallis test).
At the 9000th cycle the average values were: 0,2999±0,015 kN in the control, 0,2227±0,042 kN, in the pre-drilled, 0,2840±0,042 kN in the implanted group. The statistic test showed a significant difference for the measured values between the groups (p=0,026, Kruskal-Wallis test).
The difference between the groups was tested with Mann-Whitney test. This showed a significant difference in the measured force values between the control and drilled ribs 100th cycle (p = 0.001, Mann-Whitney U test), which difference remains consistent at the 2000th cycle (p = 0.002, Mann-Whitney U test) and 9000th cycle (p = 0.005, Mann-Whitney U test).
The difference between the control and the implanted ribs in terms of mechanical properties (that is related to the measured force values) is not significantly different in any of the cycles examined (100th cycle p = 0.243, 2000th cycle p =0.447, 9000th cycle p =0.72, Mann-Whitney U test), furthermore the summary graph, figure 5, shows that they exhibit very similar mechanical properties from cycle 9000.
No significant difference was found between the drilled and implanted ribs in the post-hoc test at 100th cycle (p = 0.33, Mann-Whitney U test) 2000th cycles (p = 0.136, Mann-Whitney U test), at 9000th cycles (p = 0.094, Mann-Whitney U test).