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Surgical metal plates, pins, screws, staples. etc. - 04/11/13 05:36 PM
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Can Titanium Plates Be Left in the Body Safely?
Patients who have metal plates, pins, and screws in the body are rightfully concerned about the safety and long-term effects of these devices left inside. Surgeons share those concerns but do not want to perform an additional surgery to remove them if unnecessary. And sometimes when plates are used to hold bone together after a fracture, bone grows around them embedding this fixation device too much to remove it easily.
So just how safe are these devices? In this article, Dr. David G. Dennison from the Orthopedic Surgery department of Mayo Clinic in Rochester, Minnesota summarizes what we know from research and clinical studies on this topic. In particular, Dr. Dennison zeroes in on titanium volar plates used to treat distal radius fractures.
Titanium has replaced stainless steel these days for fixation devices. It is more compatible with the human biology, which means it's less likely to cause a reaction. When an inflammatory response does occur, it is mild and limited (doesn't last). Titanium can also be combined with other metals such as cobalt, chromium, and molybdenum to create a lighter but more durable material.
Volar plates refer to the location of fixation devices -- placed on the front or inside of the forearm. Radius fracture tells us the radial bone in the forearm is broken. There are two bones in the forearm: ulna and radius. The radius is on the thumb-side of the forearm. Distal means the break is down toward the hand rather than up by the elbow.
There are all kinds of concerns about metal plates. Animal studies show there is an effect on the immune system. There is evidence that the metal can cause the entire immune system to be suppressed (under functioning). This immune system shut down could result in infections. Some studies have shown that metal implants can cause an increase in white blood cells called lymphocyte reactivity. There is a worry that this effect could cause implant loosening or failure, though it hasn't been proven yet.
Another potential problem with titanium plates is the debris that occurs. Tiny flakes of this metal chip off and enter the bloodstream, nearby soft tissues, and/or joint. Both titanium and stainless steel have been found in all these anatomical areas of the human body (titanium slightly more often and in greater amounts than stainless steel). Metal debris is more likely to develop when the implant is rubbing against another surface. This wearing or rubbing phenomenon is called fretting.
Then the question arises: can this metal debris lead to the formation of cancer? Studies in mice show there is the potential for metal wear debris to damage chromosomes making it a potential carcinogen (cancer producing). Next, developers of these products asked if coating the plate would protect the body from corrosion or metal debris? This question remains unanswered so far.
One thing we do know from studies -- placing a long titanium or metal pin down through the middle of a bone to stabilize it is linked with a much higher increase in the amount of metal found in the bloodstream. Chromium seems to have the highest levels reported for these intramedullary nails. Intramedullary titanium nails also increase the amount of titanium found in blood samples, but not as much as chromium. Evidently, the large surface area of the intramedullary nail exposes the bone to more titanium, thus the higher levels of serum (blood) metal.
Removing titanium plates does slowly reduce the levels of metal in the blood and soft tissues. But it can take a year or more after removal to bring these elevated levels back down to normal. Dr. Dennison reports that there aren't specific studies of the effects of titanium plates (prolonged use or removal) from the treatment of distal volar radial fractures.
Summarizing, Dr. Dennison says that the information found on this topic seems to suggest that the overall level of risk when leaving titanium plates in the forearm is acceptable. The volar surface plate is not a large implant and doesn't usually involve nails down through the bone. Instead, small screws placed perpendicular to the plate to hold it in place are more typical. Still, there are concerns and risks reported that deserve specific study and more conclusive answers. Future studies are needed to address these concerns and questions.
Reference:
David G. Dennison, MD. Distal Radius Fractures and Titanium Volar Plates: Should We Take the Plates Out? In The Journal of Hand Surgery. January 2010. Vol. 35A. No. 1. Pp. 141-143.
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