Hydroxyapatite-boric acid in femur diaphyzer fracturesand hydroxiapatite- magnesium coated kirschner wirehistological of its effect on fracture healing, radiological and biomechanic evaluation

Purpose: It is aimed to investigate components produced by biomedical engineering which coated with different materials on fracture healing. In accordance with this purpose; Histological, radiological and biomechanical investigation of the effect of Kirschner wire (K wire) produced from Hydroxyapatite (HA), Boric Acid (BA) and Magnesium (Mg) combinations, on fracture healing and repair in transverse fractures formed in the diaphyseal region of the right femur bone of rats. Material and Method: A total of 60 Wistar Albino rats whose average age was calculated as 3 months included in the study. These rats were divided into 5 groups including 12 rats in each group. Then a transverse fracture created on the right femoral diaphyseal region on each rat. K wires which coated with various materials after collaborative work with biomedical engineering, were applied intramedullary to each group as determined specifically. In order to evaluate the fracture healing after surgery, 6 rats from each group in the early period of the 6th week and 6 rats from each group in the late period of the 12th week, were sacrificed. The number of subjects was determined as at least 6 per group according to previous studies and statistical significance, and the power analysis was determined as 95%. The DNA similarity of Wistar Albino animals used in the study was 99%, which clearly strengthened the power analysis of our study. The groups were sacrificed with high-dose anesthetic injection according to the time of sacrification. After sacrification, rats were evaluated radiologically. Lane-Sandhu radiological scoring was used in the radiological evaluation. Then, the right femurs of the rats were excised and subjected to histopathological study. The materials were hold on 10% diluted formalin for 1 week. After fixation, the materials were decalcified in a solution prepared from 50% formic acid and 20% sodium citrate solutions. After decalcification, bone tissue samples were placed in paraffin blocks and 5-7 μm thick sections were taken on slides with a microtome. These sections were stained with Hematoxylin-Eosin and Masson's Tricrom staining method, and evaluations were made according to the fracture healing scale of Huo et al. Mean, standard deviation, and median values were used while presenting descriptive analyzes The Mann Whitney U Test was used when evaluating variables which non-normally distributed (non-parametric) between the two groups. The Kruskal-Wallis Test was used to compare continuous variables that did not show normal distribution in more than two groups. Pairwise Comparisons test was used as post-hoc analysis when Kruskal-Wallis Test was found to be significant. IBM SPSS.23 program was used in all analyzes and p< 0.05 was accepted as the level of significance. Results: In the direct cytotoxicity test, it was determined that the K-wire materials used in the study did not have a toxic effect on cell proliferation. In the indirect cytotoxicity test, the viability rate of the tubes containing the control group evaluated as 100% according to the results of the study. With these data, it was determined that the K-wire materials used in the study did not have a toxic effect on cell proliferation. There was a significant difference in fracture healing in terms of histological score within the same group in all 6 and 12 weeks old experimental groups. A significant increase in fracture healing was observed in the 12th week experimental groups in the same groups compared to the 6th week experimental groups. When all groups were compared with the averages of the 6th week, it was seen that the 5th experimental group, in which HA + Mg coated K wire was applied, had the highest value and was significant. (p<0.001) When the 6th week experimental groups in all groups were compared with each other in pairs, it was seen that the 5th group made a significant difference in fracture healing compared to the other groups. When all groups were compared with the mean value by the 12th week, the histological scores of fracture healing were found to be the highest and significant in the 5th experimental group. (p<0.001) When the 12th week experimental groups in all groups were compared with each other in pairs, it was seen that the 5th group made a significant difference in fracture healing compared to the other groups. In the radiological evaluation of fracture healing, there was no significant difference between the 6th week and 12th week experimental groups within all groups. In the radiological evaluation of fracture healing, when all groups were compared with the averages of the 6th week, it was seen that the 4th and 5th experimental groups had the highest value and the 3rd experimental group had the lowest value, but no significant difference was found statistically. (p=0.837) Also all these groups were compared with the averages of the 12th week, it was seen that the 2nd and 5th experimental groups had the highest value and the 1st experimental group had the lowest value, but no significant difference was found. (p=0.479) When the histopathological and radiological scores of all groups were compared, it was seen that there was a correlation between each other. (p<0.001 and r= 0.438) When the histopathological and radiological scores of the 6th week and 12th week experimental groups were compared, it was seen that there was a correlation between each other (p=0.047 and r=0.365 for the 6th week, p=0.019 and r=0.426 for the 12th week). The left femurs of the rats in the groups were used after the experiment in the biomechanical tests. Data obtained from these tests showed that, optimal conditions between the tests could not be achieved and the right femurs of the rats in the experimental groups were not subjected to biomechanical tests due to the need for more material. Conclusion: In the light of the data obtained from our experimental study, good histological results can be obtained with the use of Mg-containing implants in early and late fracture healing, and it is thought that Mg coated fixation materials will have positive results in fracture healing. Desired results can be obtained by using HA + Mg coated biomaterials in fracture fixation. Keywords: Fracture healing, Magnesium, Boric acid, Hydroxyapatite