[BIOMECHANICAL EVALUATION OF PRIMARY REPLACEMENT ARTHOPLASTY FOR UNSTABLE INTERTROCHANTERIC FRACTURES].

Aim - to study peculiarities of changes of stress-strain state in the proximal femur around the implanted femoral component of hip prosthesis in case of inter-trochanteric fracture on the background of involutive osteoporosis in connection with functional loading by numeral analysis on a mathematical model. Using program SolidWorks 2 variants of finite element models of inter-trochanteric fractures were built, including type 31-A2, with the implantation of the femoral component of hip prosthesis - without restoration and with the restoration of the intertrochanteric region and calcar with a ring-shaped graft. The simulated load is single-support standing and the action of the musculo-ligamentous apparatus in the vertical position of the body. Stress analysis was performed at control points in comparison with the calculated data for the model with unaltered bone tissue (without osteoporosis). In the presence of osteoporosis, the values of stresses in the bone in the places of contact with the implant increase. For models with an osteoporotic inter-trochanteric fracture and an implanted femoral component of hip prosthesis, the maximum stress values are determined in the bone tissue of the proximal metaphysis, especially in the region of the destroyed posterior and medial walls. The simulated reconstruction of the intertrochanteric region with a ring-shaped graft with the restoration of the calcar demonstrates a significant decrease in the stress state at the level of the proximal metaphysis and in the area of predominant destruction of the bone marrow canal. This can contribute to the achievement of primary stability of the femoral component of hip prosthesis.