These authors used finite element analysis (FEA) to conduct an in vitro comparison of 2 augmented glenoid designs—wedge and step—created per the manufacturers’ specifications and virtually implanted in a scapula model to correct 20° of retroversion. Simulation of shoulder abduction was performed using the FEA shoulder model.
Both components showed high levels of stress measured on the cement mantle, which exceeded the endurance limit for cement fracture.
Comment: As demonstrated in this study, the constraint provided by posteriorly augmented glenoid components results in excessive levels of stress in the cement mantle, potentially predisposing the cement to fracture with loosening of the component.
The authors present the example below as a "type B2 glenoid based on Walch classification showing bone loss in posteroinferior quadrant". However, the measured glenoid retroversion in this case is <15 degrees. Thus, this is the type of glenoid that many surgeons would manage with a conventional, non-augmented component without attempting to change glenoid version.
Two studies recent studies demonstrate the successful management of B2 glenoids using a standard glenoid component with minimal change of version. (see this link and this link)
It would have been interesting to see the results of this model for a standard glenoid component inserted with minimal reaming (i.e. just enough to enable a close bony fit with the back of the component).
At present it seems that the role of posteriorly augmented glenoid remains undefined.
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