MATHEMATICAL MODELING OF GRAFT FIXATION VARIANTS TO THE ANTERIOR MARGIN OF THE GLENOID PERFORMING LATARJET PROCEDURE

Abstract

Latarjet procedure is a common standard in the treatment of anterior and anterior-inferior shoulder instability with a significant glenoid defect. However, like any other surgical technique, it has a list of certain intra- and postoperative complications, including mistakes in the positioning of the bone block. A necessary guarantee of prevention and reduction of the frequency of possible complications associated with graft positioning is a well-performedpreoperative planning with an understanding of the biomechanical functioning of the shoulder joint with the translated bone block. Objective. According to the mathematical modelling we studied the changes that occur in the stress-strain state of the shoulder joint model depending on the options for graft fixation and may occur during the Latarjet procedure. Methods. To solve this problem, a finite element model of the shoulder was created. The simulationswere performed using the SolidWorks computer-aided design system. The following situations were simulated: variants of fixing screws relative to the plane of the articular surface of the glenoid (parallel to the plane, at an angle of 10° and 20°) and variants of graft fixation height at the anterior edge of the glenoid (at the lower edge of the glenoid, 10 mm and 20 mm upper edge). Calculations of the stress-strain state of the models were performed with the CosmosM software package. Results and conclusions. The presence of a bone graft fixed with metal screws at the area of the defect at the anterior edge of the glenoid, leads to an increase in stress levels in the bone elements of the model. Changes in the stress-strain state of the shoulder model also occur, depending on the angle of the screws that secure the graft. The highest stress level was determined when providing the fixing screws at an angle of 10°, the lowest — when providing the screws parallel to the articular surface of the glenoid. The stresses on the locking screws increased slightly with increasing angle of the screws. When studying the height of graft fixation, the most favorable option, in terms of stress distribution on the articular surface of the glenoid and fixing screws, is its location in the lower part of the anterior edge of the glenoid.