In the OR change-room was a younger surgeon who had taken over my emergency room work. I mentioned that I had just removed a forearm plate.
“I don’t remove plates” he said.
“Why is that?”
“I just don’t do it.”
“There might be some good reasons for taking them out…” I ventured.
“Well there is always the risk of breaking the arm again, adjacent to the plate”
“When that happens I would remove the plate when I put the next on!”
“I don’t think that is quite the point – with a plate still in place even relatively minor trauma might cause the bone to break, which otherwise might not have happened if there had not been a plate.”
“How is that?”
“The plate, with a different distortion factor from the bone acts as a stress rider, and concentrates the stress at the sharp boundary at the end of the plate.”
“Well, I don’t know about that…”
“The screws through the bone also represent a weakness. Imagine fixing a plate on a bamboo by screws, and then bending it. Where will it break? Either through a screw hole or at the end of the plate.”
“But what are the chances of another fall onto the same limb?”
“Quite good. People tend to fall and injure themselves in particular patterns. Further with ageing, and loss of balance and sight and osteoporosis, the risks increase.”
“I can’t do much about that, can I?”
“A further problem is that the plate itself causes a weakening of the bone. The plate redirects the forces which would normally be transmitted through the bone, and the reduced stimulus to the bone and the strengthening mineral in the bone decreases, as per Wolf’s Law. This has been called stress shielding.”
“There is a micro movement between the plate and the screws, even when bone is healed, and this abrasion produces a fine dust from the alloy. This is easily seen, staining and permeating the adjacent tissues.”
“It may not matter, but conceptually the presence of this absorbable alloy may not be a good idea. Some years ago, I was able to demonstrate increased blood level of chromium, cobalt and beryllium in people subject to particles from implanted metal on metal abrasion.”
“There are other reasons – as in this case, there was a danger of rupture to tendons overlying the screw heads because of abrasion. The movement at the adjacent joint was also reduced, because the plate had caused the muscles to glue down. Then there was the discomfort of the ‘cold syndrome’ and pain on knocking against the plate through the skin. A relative reason might be future difficulties with MR imaging caused by residual metal. Some people are distressed by airport metal detector activation.
Implants represent “foreign material” which can act as a nidus for subsequent infection, perhaps years after insertion. Should that happen removal of the metal might become mandatory. This means that whenever metal is inserted a mode of removal must be designed into the initial procedure. This might not be as obvious as it seems. In the child exuberant bone can rapidly cover the metal, and grow make it even more inaccessible. Inserting a curved intermedullary rod into an unhealed fracture, or leaving in place a bent intermedullary rod, before healing is completed, might make extraction impossible, if substantial surgical damage is to be avoided.
Of course all these reasons remain relative to many factors, including cost, time off work and much more which needs be assessed individually, ideally by the surgeon who inserted them”
“Well, I don’t remove plates.”
The study referenced below demonstrate increased risk of breakage of a long bone at screw-holes and simulated “demineralisation” (osteoporosis). It is far from an exact simulation, but it demonstrates a danger. It must be remembered that whether a screw-hole is empty or contains a screw in the hole, the bone is weakened either way. Leaving the screw in place will cause the hole to persist. Following removal of screws the screw-hole may or may not close, but the surrounding bone seems to structurally compensate for the previous weakening by screw holes. Breaks through screw holes do occur years after the screws have been removed, but usually with significant trauma. It is more common in my experience to have a break while the plate and screws are still in place. Said another way plates and screws have a temporary benefit, but once the bone is healed that benefit is replaced by the dangers of demineralisation and persisting screw holes. It is therefore frequently policy to remove the plates once union of bone is assured.
This paper was designed to determine whether there would be a benefit if stabilising plates were flexible. However the key statement in this paper is “We have considered only the relative effects of atrophic changes under a plate and residual screw holes; in the clinical situation the transition zone between plated and unplated bone creates a further potential stress raiser”. It is this phenomenon which enhances the risk of breakage when a plate is left in situ after bone healing is complete.