In the short term (a few years), the main reasons to remove an intramedullar nail are:
- You have pain in your knee even when resting or you have pain when you kneel. Removal of the nail seems to get rid of the pain in almost all cases. The incidence of pain is about 50% in people getting an intramedullary nail.
- The screws holding the nail in place irritate the surrounding flesh and produce bursitis type pain. This usually occurs with the screws in the lower leg where they can rub against hiking boots etc. Simple removal of the screws stops this type of irritation.
- The iliotibial band can hang up on the upper screws as it slides back and forth over the side of the knee like plucking a guitar string. Removal of the upper screw set will stop this problem.
- An asymptotic patient just does not like the idea of having a rod in his/her leg for the rest of their life.
- The danger of having the rod in your leg if you ever broke the leg again (the rod gets bent and is difficult to remove or the rod causes addition damage to the bone during the breakage incident).
The average time between the injury and nail removal was 14 months. You have to wait that long for the bone to heal and densify. Operation removal time varied with the type of rod material. It took 105 minutes to remove a titanium rod and 84 minutes to remove a stainless steel rod. The difference in time was caused by the better bonding between the bone and titanium than between bone and stainless steel.
The main surprise in reviewing this literature is that dynamization of the nail (by removing the screws but not the nail) did not result in better bone healing or bone density. Bones heal partly through a piezoelectric effect (i.e. stress on the bone produces an electric field which generates bone growth and an increase in bone density). It had been thought that when a nail is held statically in place by its associated screws, the nail would take a lot of the stress and the bone would not densify or heal properly. Within experimental error, a static nail was as good as a dynamic nail and several studies concluded that routine removal of even just the screws should not be done as a matter of course.
Even though intramedullary nailing was started more than 40 years ago in Germany, there does not seem to be any literature on the long-term results of nailing. It must be very difficult to follow patients for long periods of time. Either the funding for the study evaporates, the patients disappear, or the principal investigator retires or dies.
Intramedullary nails are actually hollow. One study examined what was inside the nail after it had been in the bone for several years. The contents included dead bone fragments, dead tissue and other detritus. They cultured this material but it was inactive. The body apparently could not clean it up because there are no blood vessels inside of the rod to transport phagocytes there.
Another risk of intramedullary nailing in the long run (over several years) is avascular necrosis. This happens when the blood vessels (avascular) that enter and feed the bone at various places along the bone are injured or die. Then the bone is left without life support and it dies (necrosis). The bone becomes weak and brittle and will fracture unexpectedly. It is difficult to determine whether this is happening until the unexpected fracture occurs. However, it seems to be more of a problem if the ends of the bone were injured seriously. Some of the major blood vessel entry points are near the ends of the bone and this is probably why there is an association between injury at the ends and avascular necrosis. They also stick the rod in from the end nearest the knee so it makes sense that this location is most susceptible to avascular necrosis if the operation is not done well. The percentage of cases with this problem is very low, about 1-2%.