Wednesday, October 28, 2015

'New' humeral prostheses and associated problems leading to revision.

Implant designers seem to have great interest in trying to invent new solutions to problems that have already been solved. One example is shortening the humeral stem. We've posted on the problems of 'shorty' implants in the past. As shown in a revision case we did yesterday, the risk of a short stem is that it increases the risk of its being positioned in varus, resulting in overstuffing of the joint, loss of range of motion and glenoid component failure. 

We revised the shoulder by removing the humeral and glenoid components, inserting a new glenoid component, punching through the pedistal at the stem tip and inserting a standard length prosthesis with impaction allograft as shown in the post operative film below.

 Another example is the questionable idea that a flat head is better than a round humeral head, as illustrated by a second case from yesterday as shown below. This prosthesis resulted in a stiff, painful shoulder.

The stem removal was difficult requiring humeral osteotomy because of the excessively tight diaphyseal incarceration, but the reconstruction was straightforward - again using an impaction allografted stem as shown below.

We continue to be pleased with impaction graft fixation of the tried and true implant we've been using for decades as shown here. Note that the revisions from yesterday were performed using this method. Our hope is that in the future there will be less emphasis on attempting to improve what is already working very well - the humeral side of the arthroplasty - and more focus on optimizing the glenoid side of the arthroplasty where the challenges lie.


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