Understanding the causes behind coracoid graft osteolysıs in latarjet procedure (finite element analysis and comparison of three fixation methods). BACKGROUND
 Latarjet is one of the most common surgical procedure performed on patients with shoulder instability with osseous defects, some complications include coracoid bone graft osteolysis, osteoarthritis, graft detachment, and malpositioning were previously reported.  Several studies investigated potential causes of graft osteolysis but still, it remains a crucial area of investigation.  We aim to use finite element analysis to examine the potential correlations between three modes of fixation methods used in the Latarjet procedure (screw, wedge plate, and endobutton), and the coracoid graft osteolysis.


 Finite element analysis tested the hypothesis that there is a linear relationship between the compression stress on graft which was generated by fixation methods used in the latarjet and the coracoid graft osteolysis.


 Boundary conditions and inhomogeneous material properties were carefully assigned within the material of the scapula and coracoid interface.  For the screw and wedge plate fixations, an applied torque in the range of 1-1.5Nm was used to characterize the surgeon's insertion torque during the surgical operation, while a 100N compressive force was selected for the endobutton fixation.


 Relatively lesser stress magnitudes were observed with endobutton fixation method rather than screw and the wedge plate fixation.  Statistical analyses revealed significant differences between the groups (p<0.05).


 DISCUSSION
 Excessive compressive stresses within the coracoid graft regions may be responsible for osteolysis due to negative effects over biological factors such as blood flow.  Our study emphasizes the importance of taking into account the fixation method while performing the Latarjet procedure.  We concluded that the mode of fixation used within the Latarjet procedure has a correlation on the coracoid graft osteolysis.


 LEVEL OF EVIDENCE

C