Effects of implants with coatings based on superhard compounds on weight indices of rats' internal organs

Introduction . Despite the undoubted progress in the treatment of fractures based on osteosynthesis, which was achieved with the use of modern materials and technology, many questions of bones consolidation remain open and are the most urgent problems of traumatology and orthopedics. The prospect and profitability of this area of scientific and practical activities is determined by the amount of large research centers and healthcare companies engaged in the development and production of metal implants for osteosynthesis. Earlier research show that the implantable materials, depending on their biocompatibility, can reduce the threshold dose causing infectious inflammation [3].

The purpose of the study is to examine the effects of implants made of copper (Cu), medical steel 12X18H9T, steel 12X18H9T coated with titanium and hafnium nitrides (TiN + HfN), as well as implants made of steel 12X18H9T coated with titanium and zirconium nitrides (TiN + ZrN) on indicators of weight indexes of experimental rats by transosseous administration.

Materials and methods . The studies were conducted at the Department of Veterinary Surgery of Kazan State Academy of Veterinary. The work was performed on 100 nonpedigreed white male rats weighing 250300 g., which were selected on analogues principle. We divided the animals into four groups depending on the material from which the implant was made. Two comparison groups: №1 - with steel 12X18H9T implants (n = 20) and №2 - with implants made of copper Cu (n = 20). Two experimental groups: №3 -implants 12X18H9T steel coated with a combination of hafnium and titanium nitrides TiN + NHf (n = 20), №4 - implants 12X18H9T steel coated with titanium and zirconium nitrides TiN + ZrN (n = 20). 20 animals were also used as a control group.

Implantation was performed in observance of aseptic and antiseptic rules under general anesthesia in the middle third of the tibia after preliminary reaming. At the end of each period, i.e. 10, 30, 60 and 90 days, the test rats were taken out of the experience by decapitation, then were weighed and we determined the mass of internal organs: liver, spleen, heart, lung and kidney using an electronic scales VLTE-150 with accuracy up to 10-3 g. We performed statistical evaluation by the Student's method using software packages SPSS v.13.0. Differences were considered significant at a significance level of p<0,05.

OrganIndex or relative masswas calculated by the formula:

OI = (AM / L.M.) * 100, where

A.M.- absolute mass of the test organ,

L.M.- mass of live rats from which the organ was removed.

Results and discussion. Investigation of changes in the indices weighted indexes main internal organs in different groups of experimental rats in the study gave the following results. 10 days after implantation the greatest increase in the relative liver weight was observed in the group of TiN + ZrN and it was 7.42% contrast to 4.76% of intact specimens. Difference between the groups is significant (p <0,05).We suppose that this increase can be caused by proliferative liver enlargement. For a period of 30 days, this trend is maintained, and the highest value observed in the same group with implants coated with titanium nitride and zirconium (M = 5.48%), where the value has tended to decline, significantly different from those in the group of Cu (in 0.49%), steel (M = 4.69%) and the intact group (M = 4.18%). As shown in hematological studies, zirconium nitride and copper affect the body of the experimental animals in the opposite way. At all subsequent stages (60 and 90 days) there is normalization of these indicators in all groups.

For a period of 60 days no significant difference between groups was revealed (p<0,05). For a period of 90 days there is a significant decrease in the index of the liver in the group with 12X18H9T steel regarding to all the other groups that may be related to conditions of detention and the feeding of rats, especially compared with a group with implants coated with titanium nitride and hafnium. In groups of Cu and TiN + ZrN this normalization is considered conditional, given the fact that the clinical study found a negative of the local (Cu, TiN + ZrN) and systemic effects (TiN + ZrN) on the body of laboratory animals.

For a period of 10 days, the relative mass of the spleen in the group with implants coated with zirconium insignificantly was higher than the same indicator in the other groups, and it amounted to 0,69% (p<0,05). For a period of 30 days, the value of the spleen weight fell in all groups to levels lower than intact animals, but the highest value observed in the group with zirconium and it was 0,46% (p<0,05). For a period of 60 days, we found no significant difference in the spleen weight index between the groups. For a period of 90 days nonsignificant (p> 0.05) increased the weight index observed in the Cu group (M = 0.42%) and the intact group compared with the others. The weighted index of the heart after 10 day of the experiment showed no significant differences, however, it can be seen that we observed the increased value of this indicator in the group coated with zirconium. A significant difference between the groups TiN + ZrN and TiN + NHf (p = 0,01) indicated on the 30 and 60 day of the observation. In the last stages (90 days), no significant differences were found between the groups. We assume that the post-mortem dilation of heart cavities and walls during his post-mortem blood filling distorts the real experimental data.

After 10 days of post-implantation the greatest relative weight of the lungs occurred in the group with copper implants (M = 1.2%), which was significantly (p = 0.01) higher by 0.25% than the group with intact animals. Additionally, significantly increased value of lung weight index was observed in the group with Cu compared to that in groups 12X18H9T (p = 0,013) and TiN + NHf (p = 0,046). In the group of TiN + ZrN this value was also insignificantly slightly increased (M = 1.05%). Significant difference relative to the weight index of lung in the group of intact rats were found in the group with zirconium (M = 0.74%). The fact that the higher values are observed in the groups with implants that are already clinically adversely local and systemic effects on the organism of experimental rats may touch up to the conclusion that these implants cause pathological process through the lung tissue particularly.

Particularly illustrative results were obtained on the 30th day of the experiment. Insignificant differences (p> 0.05) were found only in the comparison of groups with steel and zirconium, as well as the group of intact animals and the groups with coated with titanium nitride and hafnium. For instance, the greatest measure of the relative mass of the lungs occurred in the group of copper implants. This increase in mass connected with infiltration interalveolar septum and detection in the lumen of some alveolar edema fluid.

On the 60th day, a significant difference between groups with implants made of steel 12X18H9T occurred with all the other groups. The relative mass of the lungs of these animal units was higher by 0.55% than in intact animals. On the 90th day, the differences between groups were insignificant. For a period of 10 days we obtained insignificant, slightly increased value of the kidney weight index in the group of TiN + ZrN (M = 1,08%) compared to the indices in intact animals equal to (M = 0.88%). For a period of 30 days, a group of Cu was significantly different from the intact group by 0.12%; the group of implants coated with titanium nitride and hafnium - from the animals with implants made of steel and the intact group. On the 60th day, there was no significant difference between groups. On the 90th day, Cu and 12X18H9T were significantly different (p = 0,038). Kidney weight indicesin these groups were as follows: 0.92% and 0.75%. The value of the index in the group with copper implants was also significantly different from the group with TiN + ZrN (p = 0.045), and equaled to 0.92% and 0.76%.

According to the results of the above studies on kidney weight index, we can argue that changes to the negative highest or lowest values were observed in the groups with copper implants and implants coated with titanium nitride and zirconium.

Conclusions . The highest and abnormal values of weight indices of liver, spleen, kidney, and lung infarction have been identified in the group of rats with implants coated zirconium and titanium nitrides as compared to intact animals, indicating the negative effects of this coating. The use of implants with titanium and hafnium nitrides does not lead to significant changes in the studied parameters, confirming neutrality and biocompatibility of these coating.

These statistical data analysis of weight indexes of internal organs (liver, spleen, kidneys, heart, lungs) has identified that the calculated value can be sufficiently reliable criterion for assessing the impact of the studied implants on the organism of experimental rats, and to determine the correlation between the various indicators themselves.

Turilina K.A., Shakirova F.V. Summary

This article addresses the problem of the effect of implants coated super-hard compounds on the value of weight index of the experimental rats. The study results have showed a positive effect of the coating based on titanium nitride and hafnium nitride and a negative effect of titanium and zirconium.

ОЦЕНКА ВОЗДЕЙСТВИЯ ИМЛАНТОВ С ПОКРЫТИЯМИ НА ОСНОВЕ СВЕРХТВЕРДЫХ

СОЕДИНЕНИЙ НА ПОКАЗАТЕЛИ ВЕСОВЫХ ИНДЕКСОВ ВНУТРЕННИХ ОРГАНОВ КРЫС

Турилина К.А., Шакирова Ф.В. Резюме

В данной статье рассматривается проблема влияния имплантов с покрытиями на основе сверхтвердых соединений на показатели весовых индексов у подопытных крыс. Результаты исследования выявили положительное влияние покрытия на основе нитридов титана и гафния и отрицательное влияние нитридов титана и циркония.