Our study objective that DCO strategy in the management of fractures due to ballistic trauma is efficient, with a consolidation rate > 80%, and a relatively low percentage of general complications. These complications had minor severity, and they were easy to manage.
Local complications, mainly sepsis on osteosynthesis material and pseudarthrosis had relatively low rates. Our analyses showed that they were associated with several parameters. These parameters can be divided into non-modifiable risk factors such as the history of smoking, the wound opening, the fracture comminution, and bone loss. And a modifiable risk factors, mainly the delay of conversion from external fixation to internal osteosynthesis. The local complications rate was lower when this delay of conversion was shorter.
Our study is distinguished by strict inclusion and exclusion criteria. It was carried out in an institution that has good experience in the field of ballistics. Its protocol was interested not only at the results of the DCO strategy but also at the parameters which could affect this strategy. However, our study also has some limitations, mainly a selection bias due to its retrospective nature, and the relatively small number of patients.
The DCO is a relatively new concept (3), adopted in the management of ballistic limb trauma, appeared to solve the defects of an older approach, which consists of early stabilization of skeletal lesions called early total care.
The early total care was the principal strategy for management of polytrauma and war wounded in the 1980s and 1990. However, recent studies have shown that adoption of this strategy, in groups of patients with hemodynamic instability, is more associated with significant complications such as pulmonary embolism and acute respiratory distress syndrome, and multiple organ dysfunctions syndrome. And this was exceptionally observed in the intra-medullary femur nailing (4). Studies have associated the occurrence of these complications with changes in pro-inflammatory markers (5). Indeed, the initial accident causes inflammatory and immunological reactions proportional to the severity of the trauma called “First hit” (6). This reaction is characterized by local and systemic proliferation of various pro-inflammatory mediators such as cytokines, complement, coagulation proteins and others. Besides, the prolonged duration of the surgery and the bleeding lead to another significant inflammatory and immunological reactions called “Second Hit”. This second hit potentiates the effect of the first hit, and this may lead to a severe consequence in patients.
From these observations, a new strategy, based on minimizing the impact of the second hit by shortening the initial operating time and delaying the definitive treatment, was adapted to manage limb ballistic trauma. This strategy was called the DCO. Therefore, the treatment of long bone fractures of soldiers wounded on the battlefield is based on the temporary external fixation whose objective is controlling haemorrhage, restoring perfusion of the limb, debridement of necrotic soft tissue and ensuring bone stability. And without disturbing resuscitation care measures (7).
However, after hemodynamic stabilization, control of inflammatory phenomena and improvement of the local wound condition, this external fixation would be better converted into an internal osteosynthesis. Because even though the external fixation does not always allow an anatomical reduction, it is often associated with a high rate of pin-site infection and low-quality bone callus. Respet and al attempted to determine the time between the realization of external fixation and the onset of pin site infection. They found that pins bacteriological cultures were positive in 50% of the cases in 2 weeks and 67% in 4 weeks (8). These results were also confirmed later by Clasper and al (9). Also, Sigurdsen and al (10, 11) experimented on rats. To study the quality of the bone callus after an osteotomy, initially treated with an external fixator and then followed by conversion to internal synthesis, with different delays. This conversion delay was seven days in A group, 14 days in B group, 30 days in C group and the control group D without conversion. All the groups had better consolidation than the control group, but only group A had a significant difference. Biomechanically, the rigidity and quality of the callus in group A were better than other groups.
These studies not only show the interest of the conversion from external fixation to internal osteosynthesis, but it also proves the interest of the delay of this conversion. The shorter it is, the better the quality of bone callus, and the lower the risk of pin site infection and sepsis. This result is consistent with our study, which objectified that the delay of conversion is a risk factor for both septic and non-union complications.
In our study, this conversion time was relatively short compared to other papers in the literature(12–15). It was possible by care aimed at accelerating deferent phases of the wound healing process and fighting infection. Indeed, VAC therapy allows a permanent elimination of exudates from the wound bed. Associated with repetitive debridement, it accelerated the inflammatory phase of the wound healing process. Hyperbaric oxygen therapy improves tissue oxygenation. Also, it enhances fibroblast and collagen synthesis, neovascularization, and the closure of arterial-venous shunts (16), which shortened the time to granulation formation, especially in open wound fracture Gustillo III (17). As well, several studies had proven the effect of VAC therapy to accelerate granulation tissue formation (18–20). With normal haemoglobin and serum protein levels, they hasten the proliferative phase of the wound healing. Furthermore, in addition to adapted antibiotic therapy, hyperbaric oxygen therapy and VAC therapy had a confirmed role against infection.