Numerical study of the mechanical behavior of the hip joint under therapeutic acoustic impact

Degenerative diseases are one of the main causes of disability in the middle-aged and older population. One of the most common diseases is osteoporosis and osteonecrosis of the femoral head. For the prevention and treatment of osteoporosis, osteopenia, and osteonecrosis, external mechanical stimulation based on ultrasound and shock wave exposure is used, based on local ultrasonic or shock wave exposure in the area of pathology. The effect of external mechanical action is based on mechanobiological principles, the essence of which is that a certain level of pressure (mechanical stress) and deformation leads to the growth and differentiation of various types of biological tissue. To obtain a therapeutic effect, it is necessary to correctly choose the parameters of exposure and the place of its application. Usually, these problems are solved empirically. In this work, the possibility of creating conditions for bone tissue regeneration under external acoustic impact on a healthy hip joint and a joint affected by osteonecrosis was studied numerically. The study was carried out using the method of mobile cellular automata. The results obtained showed the effectiveness of the use of medium- and high-intensity ultrasound exposure for the prevention of osteopenia and osteoporosis. When exposed to ultrasound on a joint with osteonecrosis of the head, the creation of conditions for osteogenesis and chondrogenesis in the affected area is observed only with high-intensity loading. Thus, the hypothesis that low-intensity ultrasound therapy is effective only in combination with other methods of treatment was confirmed. It was found that shock-wave action of low intensity promotes the division of biological cells and their transfer, thereby creating conditions for the regeneration of bone tissues. This conclusion is consistent with the results of most experimental studies.