Intramedullary reaming and nailing of femoral shaft fractures : A study on the procedure-related inflammatory- and cardiopulmonary responses

Abstract

Background: An important part of the early trauma management is stabilization of long bone fractures. The intramedullary reaming and nailing of femoral shaft fractures has, however, been associated with pulmonary complications. These are probably due to the intravasation of bone marrow content as a result of the procedure-related increased intramedullary pressure (IMP). In order to reduce the complications, alternative systems that reduce IMP during reaming have been developed. One focus has been techniques using suction and irrigation during reaming. We wanted to evaluate the effect of using a one-step Reamer- Irrigator-Aspirator (RIA) system and compare it to a traditional reaming (TR) system, with the hypothesis that the RIA system represents a lesser operative burden than the TR system. Additionally, we wanted to evaluate to what extent cardiopulmonary function and inflammation becomes further affected by femoral intramedullary nailing (IMN) in severely injured patients, with the hypothesis that the burden of the procedure to a certain extent will drown in the massive response to the initial trauma.<br><br>

Materials and Methods: In an experimental model including 28 Norwegian landrace pigs the IMP (Paper I), cardiopulmonary alterations (Paper II), numbers of lung embolisms (PE) (Paper II), inflammatory response (Paper III) and the associations between these (Paper IV) were studied during IMN and the first three post procedure days. The animals were divided into three groups, and the left intact femur was operated on either by the use of a traditional reaming (TR) system, a RIA system, or the animals were exposed to a sham operation. In 12 polytraumatized patients with femoral shaft fractures primarily intramedullary stabilized, we investigated prospectively to what extent the cardiopulmonary and inflammatory response was further activated related to reamed IMN (Paper V). The patients were followed for three days after IMN. In the postoperative course the following complications were recorded: SIRS, ALI, ARDS, pneumonia, sepsis and local wound infection.<br><br>

Results: The IMP (Paper I), the numbers of PE (Paper II) and the procedure-related inflammatory response (Paper III) were reduced after RIA reaming compared to reaming with the TR device. Both reaming devices induced a hemodynamic procedure-related effect, but with no significant difference between reaming with the RIA system and reaming with a TR system (Paper II). The lowering of IMP, as obtained with the RIA system, reduced the magnitude and the effects of the bone marrow intravasation (Paper IV). In the severely traumatized patients (Paper V) no additional procedure-related coagulationand fibrinolytic response was found. Increased levels of TNF-a, IL-6 and IL-10, however, were found, and a transient (ns) procedure-related hemodynamic response was observed. All patients except one fulfilled the criteria of SIRS. The postoperative course was prolonged by pneumonia (7/12), ALI (3/12), ARDS (3/12) and sepsis (3/12). All the patients had additional extremity- and chest injuries.<br><br>

Discussion: In healthy human individuals the amount of pulmonary vessels occluded needed to cause hemodynamic alterations has been estimated to be as high as 30 - 50%. In our experimental model the animals were young and healthy, and the embolic load induced by the procedure was probably not sufficiently massive to cause marked alterations. Additionally, the length of the pig femur is relative to body size about 50% shorter than in humans, resulting in a smaller potential volume of bone marrow content that can be extruded into the vascular system of the pigs. In our experimental model the response to reaming with the RIA and the TR systems per se were isolated and thoroughly investigated. In clinical practice, however, femoral shaft fractures are often caused by injuries involving high energy and are therefore associated with multiple and severe injuries. Severely injured patients already have an activated inflammatory system at hospital admission. The procedure-related hemodynamic response seen in the severely injured patients can be interpreted as a response to an embolic load, which may also contribute to the increased inflammatory response. The patients in this study had a high complications rate; the complications on which we focused were related to an increased inflammatory response.<br><br>

Conclusions: Overall, in this work on reamed IMN on intact pig femora without any additional injuries or confounding artifacts, the RIA system seems to represent a reaming method with a lower operative burden than the TR system. The harmful effects of reamed IMN in severely injured patients, however, are difficult to pinpoint.