Risk factors for aseptic necrosis of femoral head after femoral neck fractures: experimental study

Summary

Objective:
Our experimental study presents the results of an experiment carried out on a miniature pig model. The aim of our experiment was to prove whether hematoma in the hip joint may lead to obturation of the vessels supplying femoral head by means of the compression mechanism and thus induce avascular necrosis. In the initial stage of experiment, we set a null hypothesis presupposing the absence of differences in results between group A (iatrogenic intracapsular hematoma in the right hip joint) and B (control group without hematoma).

Materials and methods:
In all animals in this group, surgical injection of their own venous blood into the hip joint was performed peri-operatively to simulate intracapsular hematoma. Group B also comprised 10 miniature pigs of the corresponding weight (15.2±4.2 kg) and age and was used as a control group. In these animals, the hip joint was left intact. All animals were kept in identical conditions, with the same freedom of movement.

Results:
Over the period of our 8-week observation no clinical complications were documented in most animals in group A and in all animals in group B. X-ray images revealed no signs of avascular necrosis in both group A and B. Histological examination did not show signs of necrosis in any section of the femoral head in both group A and B. The null hypothesis presupposing the absence of differences in the incidence of avascular nec-rosis of femoral head between group A and B was confirmed using a high significance level.

Conclusion:
Our experimental study proves that the presence of intracapsular hematoma in the hip joint does not necessarily lead to the development of avascular necrosis of femoral head in miniature pigs.

Key words:
hip joint, intracapsular hematoma, capsulotomy, proximal femur, avascular necrosis, child.