Monday, November 5, 2012

Is a CT scan necessary before doing a shoulder arthroplasty?

Some surgeons routinely obtain a CT scan before proceeding with a shoulder joint replacement. A CT scan adds an estimated $1000 to the cost of evaluating a shoulder for arthroplasty. In 2008, 47,000 shoulder arthroplasties were performed in the US and "The number of shoulder arthroplasties, particularly total shoulder arthroplasties, is growing faster than ever. " If, four years ago, a CT scan was obtained on each of these shoulders, the total cost would have been $47 million.

The effective dose of a computerized tomographic scan of the shoulder is 2.06 mSv. It has been pointed out that "computerized tomographic imaging of the spine or other anatomic structures in close proximity to the axial skeleton such as the shoulders, hips, or pelvis may subject the patient to significantly greater quantities of ionizing radiation. "

For these two reasons we avoid the routine use of CT scans before shoulder arthroplasty, instead relying on properly done AP and Axillary views.

Sometimes patients come to us with CT scans performed elsewhere, giving us the chance to see if additional information could be gained from them.

A recent example:
Here's the preop axillary view we obtained. It clearly shows a Walch B2 glenoid.
Here is the CT scan from elsewhere showing the same.
We performed a ream and run procedure on this shoulder. Two years later the patient rated his shoulder as 12/12 on the SST and had the axillary x-ray shown below - showing the conversion of the biconcave glenoid to a single stable concavity.

Our practice is to obtain CT scans only on the rare shoulder where the anatomy is not evident from plain films.

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