Sunday, June 28, 2015

Reverse total shoulder - failure by glenosphere dissociation from base plate

A colleague sent us this instructive case:

A patient had a reverse total shoulder as shown below:

At six weeks the shoulder was functioning well and had this x-ray appearance:

Eight months after surgery, while doing some upper extremity exercises, the patient noted pain over the lateral shoulder and clicking on motion. x-rays at that time demonstrated dissociation of the glenosphere from the baseplate:

A CT scan was also obtained:

Comment: The key x-ray view is the one taken at 6 weeks, showing that glenoid bone above the base plate prevented complete seating of the glenosphere allowing it to dissociate as the subsequent films demonstrate.

We have previously discussed the issue of glenosphere dissociation as shown in this link, emphasizing that bone and soft tissue can prevent compete seating of the glenosphere.

Our current reverse total shoulder technique is shown in this link.

Seems as though glenosphere dissociation is being describe more commonly:

Glenosphere disengagement in a reverse total shoulder arthroplasty with a non-Morse taper design.