Analysis of the stress-strain state of a three-dimensional model a shoulder hemiarthroplasty after changing the greater tubercle position on the shoulder

Abstract

Background. The greater tubercle position change in shoulder hemiarthroplasty is of great importance for the shoulder joint contact surfaces’ stress-strain state (SТS). One of the important conditions for restoring a full range of motion in the shoulder joint after hemiarthroplasty and a longer service life of the endoprosthesis is the anatomical location of the greater tubercle. The purpose was to develop a three-dimensional model and study the STS of elements of the shoulder joint and implants of a hemiarthroplasty after changing the greater tubercle position on the shoulder. Materials and methods. The SolidWorks software package was used in order to construct a simulated 3D model of the shoulder joint, taking anatomical and anthropometric data into conside­ration to make the model as close to the real shoulder joint as possible. The ANSYS software package was used to calculate the shoulder joint models of the total load vector at different positions of the total load vector, depending on the greater tubercle of the humerus position. Results. The analysis of the shoulder joint mo­del elements’ STS with different greater tuberosity positioning and a shoulder abduction angle of 60° showed that the maximum increase in stress values is observed on the glenoid cavity subchondral bone when the greater tubercle of the humerus is transposed by 1 cm anterior — in 3.4 times, σmax up to 4.02 MPa. Moving the big tubercle by 1 cm distally is an optimal position in which the subchondral bone of the glenoid cavity undergoes minimum stress and deformation forces. Conclusions. The change in pressure on the contact surfaces is significant when changing the position of the greater tuberosity, which will undoubtedly affect the volume and range of motion in the postoperative period. Taking into account the data of the stress values on the contact surfaces obtained from our simula­ted 3D computer model of the shoulder joint allows improving the quality of preoperative planning and improving shoulder function and possible complications in the postoperative period.