Stress-strain state of pelvis and hip models on different phases of step

Abstract

The rationale of this scientific paper is stipulated by great amount of complication and negative results after surgical treatment of patients with hip pathology. Issues that can be interesting for surgeons, who deal with pelvis and hip pathology, are shown in the article. Recently, mathematic modeling is widely used in orthopedics and traumatology to improve surgery technique. But investigation of stress-strain state (SSS) of pelvic bones while walking are still lacking. Goal: to analyze SSS in bones of pelvis and hip on different phases of step on the background of human pelvic model designed by the authors. Methods: the method of model creation using geometric cut of CT scans was used to design geometric model of pelvis. The angles of tilting of femur and pelvis were taken into consideration for three phases of step cycle. The geometric model was built in SolidWorks programme. The basic calculations were performed using ANSYS programme. Von Mises stress was chosen to assess SSS. The investigation was performed on three pelvis models: on the phase of breakoff of fore part of nonbearing foot, during the full single-support position and during the touch of nonbearing foot. Results: the biggest strain was observed on I and III step phases. The biggest increase of SSS was noticed in the posterior part acetabulum comparing with single-support standing. On the 1st step phase the anterior and posterior parts of acetabulum occurred to be more pressure-bearing, on the 3d — anterior part. Severe increase of SSS was observed in the greater sciatic notch on I and III step phases. Conclusion: the use of pelvic model, which takes into consideration the changes of SSS while walking, allows equally show SSS in bones of pelvic comparing to the models used before.