We examined ten intramedullary rods of similar design after routine
retrieval from patients. Of these ten rods, four were found to exhibit
cracking around their proximal third. This behavior could not be attributed
to the surgical techniques employed or to the length of time in vivo of
these rods. Rather, the cracking was a function of both the metal alloy
used and the method of manufacture, which occasionally allowed a weld zone
to be located at the point of maximum stress with the result that cracking
occurred. A change in alloy composition to a low-carbon form of 316
stainless steel probably would reduce the risk of cracking. Clinical
relevance: In the treatment of orthopaedic disorders, it is important for
the operating physician to appreciate the problems that may be encountered
in using implants. One of the most important of these problems is the
possibility of implant failure. The present report illustrates how a
combination of both metallurgical and fabrication factors may cause such an
event to occur.