Here's an instructive case.
The patient had bilateral total shoulder arthroplasties, each of which went on to fail because of rotator cuff rupture and rocking horse loosening of the glenoid component.
The x-rays below show that the on each side the humeral component was placed so that the head was too high in relation to the tuberosity placing extra stress on the cuff tendons and preferentially loading the superior aspect of the glenoid component.
Why did this happen?
The answer is found on the films of the entire humerus, where it is seen that the the distal tip of the prosthesis is wedged in the diaphysis preventing more distal seating. Attempting to drive the stem down further would have risked fracture.
In our practice of revision for failed arthroplasties performed elsewhere we encounter this problem frequently as shown again here.
This problem can be avoided by using a smaller stem along with impaction grafting as shown here.
To see the topics covered in this Blog, click here
Use the "Search" box to the right to find other topics of interest to you.