Pathophysiology of Intramedullary Nailing

Local Changes

The internal cortical blood supply can be damaged by the reaming of the medullary cavity. In experiments done on animals, it was found to be reversible within 8-12 weeks. Higher risk of infection mainly in open tibia fractures may be caused by the lower blood supply particularly in the early weeks after the injury. In open fractures, the use of reamed intramedullary nails was not advisable, not even on a delayed basis as the infection rate is as maximum as 21%. While some workable bone cells have been seen and bone formation around the remaining dust has also been observed, the frequently mentioned osteoinductive effect of these materials is still contradictory.

Locking nails and tibia femur nails are commonly used for the treatment of femoral shaft fractures. The treatment by intramedullary nailing is simpler and has a low-risk level in the femoral shaft fractures because of the fine soft-tissue envelope in the femur. The same treatment is risky in the case of the tibia fracture. The rate of infection in open fracture of grade I and grade II in the femur which follows reamed intramedullary nailing treatment is 1-2% while the infection rate ranges between 4-5% for the open fractures specifically with a substantial soft-tissue injury of grade III.

General Changes

General changes also need consideration in addition to other effects of reaming. These general changes are temperature-related in the coagulation system and neural, humoral, and other inflammatory reactions and pulmonary embolization. The occurrence of post-traumatic pulmonary failure including acute respiratory distress syndrome in a multiply-bruised patient is correlated with the remaining process where early femoral nailing is followed. This topic is focused on in the studies where post reaming the passage of thrombi into the pulmonary circulation is denoted. 

Intramedullary nailing seems to like tribulation to the patient’s pulmonary system particularly in the case of multi-trauma. Because immediately after the injury, the lung becomes more sensitive to the extra strain. The studies have been going on in various centers and expectantly are going to show the actual risk level of complications related to the pulmonary system.

It is observed that the introduction of the reamer into the canal requires a lot of repetition (upto12 times for a 14mm nail) in the remaining procedure. As compared to it, the thinner solid nail needs just one gentle push to be inserted into the diaphysis. 

However, the emergence in the benefits of reamed nails has been noticed. The device such as a reamer, guidewire, and nail functions like a piston. These devices force the medullary cavity content either through the fracture gap into the adjacent tissue or the venous system. Wenda et al. found the values between 420–1,510 mm Hg with reaming procedures measuring intramedullary pressures intra-operatively in their studies as compared to the cases in which solid nails were applied where the values found were 40–70 mm Hg. Moreover, intraoperative transesophageal echocardiography indicated solid emboli in the cases of the reamed group which were not noticed in the case of unreamed group.

However, there had always been controversy regarding the use of reamed nailing. One group recommended the use of reamed nailing for the patients with a critical injury. On the contrary, the role of reamed nailing in pulmonary impairment in multi-trauma patients is a matter of serious concern for the other group.

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