We have never seen this in HRA, except one broken femoral stem in an implant that is still functioning many years after we saw this on x-ray. The implant is fixed to the bone by cement under the bearing; the stem did not provide any fixation.

Implant breakage was a known cause of failure when THR stems were made of stainless steel. It is rarely seen with cobalt chrome stems. It is exceedingly rare with the titanium stems that I have been using for years. I have never personally seen one fracture. But if young athletic patients run on these for years, it is possible that this may become a late failure mode. Extracting a broken stem is quite difficult. Therefore I recommend no running more than 1-2 miles at a time with a stemmed THR.