Mathematical modeling of dynamic loading features of hip joint after resection of proximal femur tumors

Abstract

The problem of achieving positive results in the treatment of patients with tumors of the upper third of the femur remains relevant. Among the methods for studying the functioning of the hip joint and for analyzing the specific loads it is used mathematical modeling method. Purpose: using the method of mathematical modeling, to study the characteristics of dynamic load in hip joint with the presence of bone and soft tissue post-resection defects in the upper third of the femur.Methods: in this study method of mathematical modeling by OpenSim software has been used. Basic muscle-skeletal model and created models with reproduction of hip joint condition after the resection of malignant tumor of the upper third of the femur and proximal femur replacement with and without myoplasty used. Load transmitted from the endoprosthesis head to the acetabulum studied. Results: it is revealed change of load direction from the anterior toward posterior acetabular wall with threefold volume in comparison to basic model was defined during the modeling process and analyzing of significant defects in femoral abduction and flexion muscles with substitution of proximal femur defects using modular endorposthesis. Also, important decline of pressing load to the acetabular bottom noted. This situation results in severe function impairment of the lower extremity and determines hip joint instability. Method of abduction muscles repair at the cost of proximal transposition of m. vests laterals allows to compensate load changes in the acetabulum.Conclusion: reproduction of abduction muscle defects in the model results in load direction changes in anteposterior direction, functional impairment of the lower extremity and increases risk of hip joint instability. Appropriate method of abduction muscle defects repair using m. vastus laterals is presented.