The purpose of this study was the evaluation of the relative merits of RIN versus URIN in the treatment of femoral shaft fractures. This analysis indicated that RIN improved the union rate of fractures, decreased the time to union, and decreased the incidence of non-union or delayed-union; furthermore, it did not correlate with increased blood loss or the risks of ARDS, implant failure, and mortality. Although there was no obvious difference in implant failure between the 2 groups, the incidence of secondary procedures (implant exchange) was higher in the URIN group than in the RIN group.
Intramedullary nailing is the standard treatment for fractures of the femoral shaft in adults. Titanium alloy or stainless steel is often used as the material for nails. The biomechanical properties of the materials can affect fracture healing. Titanium alloy has a lower elastic modulus, which is close to the human bone elasticity and is more biocompatible than stainless steel. Therefore, the insertion of a Titanium nail enhances callus formation and shortens time to bone union, resulting in a high healing rate. In addition, compared with unreamed intramedullary nailing, reamed intramedullary nails of larger diameters can be inserted and their fatigue strength or bending stiffness is higher. We noted a shorter time to union for the RIN group and the time to union was shorter in patients in whom a Titanium nail was inserted. However, Trompeter and Newman reported no significant difference in time required for union and failure rates for the 2 materials. Due to the relatively small size of samples in this study, these results should still be interpreted with caution. The differences between titanium or steel nails should be further verified by additional prospective randomized clinical trials with larger sample sizes.
El Maraghy et al reported that reaming might destroy the nutrient artery and decrease bone blood flow in the diaphysis. Based on this, researchers predicted that bone blood supply that was reduced due to reaming damage could influence fracture healing and increase the risk of infection. However, this is not supported our analysis. Instead, we found that fracture union was significantly slower in the URIN group and the incidences of nonunion and delayed-union were significantly lower in the RIN group. The blood supply of long bones was well-characterized by Rhinelander who showed that the medullary arteries supply the inner two-thirds of the cortex, and that the outer third is supplied by the periosteal vasculature via its soft tissue attachments to the bone. When a fracture occurs, the medullary vessels are disrupted, leading to 50% to 70% necrosis of the cortex near the fracture site. Some researchers have speculated that the debris produced by reaming may include osteoblasts and multipotent stem cells placed at the fracture site to act as an autologous bone graft. Reaming may damage the blood supply of the inner cortical bone, but in response, the periosteal blood flow can increase 6-fold, which may stimulate fracture healing.
The treatment methods for delayed-union or nonunion after bone fracture include dynamization, bone grafting, implant exchange, and electrostimulation. Clatworthy et al concluded that fracture stability was an important determinant of rapid union. A larger nail is inserted into the medullary cavity after reaming to improve cortical contact and provide greater stability.[34,35] Grundnes et al reported a tightly fitting nail increased the periosteal reaction. However, it is still unclear if RIN, thought to provide increased mechanical stability, will reduce the need for implant exchange compared to the URIN group. By subgroup analyses, our study found no obvious differences in the risks of bone grafting and dynamization between the 2 groups, but the risk of implant exchange was lower for the RIN group. Our findings indicate RIN may provide greater stability and reduce the risk of implant exchange. In the treatment of femoral fractures, economic costs must also be considered. Secondary procedures are very expensive and are correlated with high rates of complications and mortality. Our study found a high rate of secondary procedures in the URIN groups, which would require higher costs. Therefore, the treatment of femoral fractures using reamed intramedullary nailing is recommended.
From a technical point of view, implant failures include clinical screw or nail failure. Screw failures are more common than nail failures. Screw failure and nail failure correlated with a higher risk of implant failures. However, we observed no obvious differences between RIN and URIN groups for the risk of implant failures. By subgroup analyses, we also found that reamed intramedullary nailing, in contrast with the URIN group, did not increase the incidences of screw failure and nail failure. Consistent with the conclusions of a separate analysis, our results suggest that the time to union, the presence of an open wound, and the configuration of the fracture were the most critical predisposing factors of implant failures. This conclusion should be further verified by additional prospective randomized clinical trials with larger sample sizes.
Various clinical studies have suggested that reaming increased intramedullary pressure of the femur, releasing more bone marrow components and fat emboli into pulmonary circulation compared to treatment without reaming. Potential clinical adverse events include FES, ARDS, multiple organ dysfunction syndrome (MODS), and sudden death. However, the rates of FES and ARDS were low in our analysis. Only 8 cases of ARDS were reported in these studies. No cases of FES were documented in any of the included studies.[7,8,14–16,23–25] We found no obvious differences in ARDS or mortality rate between the 2 groups.
Alho et al concluded that the risk of infective complications was higher in the RIN group when compared to the URIN group. However, some studies found that there was no obvious discrepancy in infection rates between the groups.[40,41] In all included studies, the rate of infective complications was low and only 2 studies reported infective complications.[8,23] In 1 study, there were 4 cases with infection (3 superficial and 1 deep infection).[8,23] However, the number of infections for each group was not reported. Another study described a superficial infection in the RIN group.[8,23] Due to insufficient data, we did not perform meta-analysis of the rate of infection.
Unreamed femoral nailing may have a potential advantage of less blood loss. Less blood loss can reduce the need for transfusion, eliminating complications of blood transfusion and reducing costs.[42,43] The reduced intraoperative blood loss will benefit elderly patients with multimorbidity, as other diseases may take precedence. However, we did not observe significant differences in blood loss for the 2 groups. Due to high heterogeneity, these results should be interpreted with caution. In practice, surgeons usually estimate the blood loss and different assessment methods of intraoperative bleeding were used in different hospitals, such as collection from a plastic bag taped to the surgical drapes, suction drain, or from the weight of swabs. These differences may mask any differences in blood loss for these methods. That could explain the statistic significant difference of heterogeneity.
Most studies compared reamed and unreamed intramedullary nails for closed femoral fractures, but a few studies compared the reamed and unreamed intramedullary nails for treatment of both closed femoral fractures and open femoral fractures. However, any complications that occurred were not distinguished by fracture type, precluding our ability to perform subgroup analysis according to different types of fractures.
Several limitations of this analysis should be noted. First, this article only focused on the rates of nonunion, delayed-union, mortality, implant failure, reoperation, ARDS, blood loss, and the time to union. We did not assess outcomes such as functional results or satisfactory outcomes or time to definitive treatment because these parameters were not always reported or were reported in various forms and not directly comparable. Second, this study did not evaluate quantitative outcome measures such as weight-bearing time, operative time, and hospital stay. Finally, only 8 studies with 1078 participants were included in the review, which might weaken the reliability of this meta-analysis. Despite these limitations, our quantitative evaluation of the rates of complications, blood loss, and the time to union provide an important foundation for surgical treatment decisions.
Reamed intramedullary nailing is correlated with shorter time to union and lower rates of delayed-union, nonunion, and reoperation. Reamed intramedullary nailing did not increase blood loss or the rates of ARDS, implant failure, and mortality compared to unreamed intramedullary nailing. Therefore, the treatment of femoral fractures using reamed intramedullary nailing is recommended.
The authors thank all the anonymous reviewers and editors for their helpful suggestions on the quality improvement of our paper.
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Keywords:Copyright © 2016 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
femoral shaft fracture; meta-analysis; randomized controlled trials; reamed intramedullary nailing; unreamed intramedullary nailing