Introduction

The inflammatory response has been recognized as a physiologic reaction to injury. Surgery was shown to be the cause of a systemic response, the extent of which is moderated by different parameters such as the health and nutritional status of the patient, the severity of recent trauma and the presence of any preexisting physiologic derangement, and the magnitude, duration, and technique of surgery [14]. It has been shown that hip fracture and surgery in aged rats induced a systemic inflammatory response and lung injury correlated with increased susceptibility to infection during the acute phase after injury and surgery. It has been shown that long bone fractures are correlated with the development of the systemic inflammatory response syndrome and are strongly associated with multi-organ failure, sepsis, hospital length of stay, and mortality [57]. Different components of the immune system have been demonstrated to be involved in this process, such as inflammatory cytokines, leukocyte adhesion molecules, growth factors, nitric oxide, platelet-activating factors, and the activation of local and systemic polymorphonuclear neutrophils (PMNs), lymphocytes, and macrophages. This complex response arises from the interplay between various mediators produced at the site of injury, including cytokines [8]. These mediators can regulate gene transcription, and modify intracellular signaling pathways [9]. In the initial injury, surgical reduction and fixation of fractures induce the immunoinflammatory response [10]. Therefore, modulation of cytokine release has been considered a tempting strategy [11]. This study aimed to evaluate serum variation of inflammatory markers in patients undergoing surgical treatment for early and delayed femoral fractures.

Material and methods

Patients and serum parameters

This study is a randomized clinical trial and all samples were conducted among patients with femoral fractures, between 2014 and 2015 in Rasol Hospital of Tehran. This study was approved by the Ethical Committee for Clinical Research of the Hospital, and informed consent was obtained from all the patients. It is worth noting that the criteria included ages of 20 to 50 years, and patients with femoral shaft fractures without injury in other parts of the body were recruited for our study. The patients were randomly divided into two groups using the method of block randomization including early surgery (within 24 h) and delayed surgery (after 48 h). Serum levels of inflammatory markers in both groups including interleukin (IL)-1, 5, 6, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were determined by specific kits. From each patient 10 ml of blood was collected for cytokine assay in their serum.

Patients with the following criteria were excluded from the study: patients who had chronic inflammatory disease or a history of trauma in the last month, patients who had suffered multiple organ damage in their recent trauma, and patients with complex fractures.

ELISA analysis

Serum was also separated from blood using centrifugation (2000×g for 15 min at 4°C). All samples were frozen at –20°C in sterile tubes until used for cytokine measurements by the ELISA method using commercial kits (BIORBYT).

Statistical analysis

All variables were analyzed using the software SPSS version 16.0 (SPSS Inc, IL, USA). To compare levels of inflammatory markers including IL-1, IL-5, IL-6, TNF-α and IFN-γ the independent t-test was used. Differences were considered statistically significant when p was less than 0.05.

Results

Our findings suggest that serum levels of IL-8 were markedly decreased from 12 h until 48 h postoperatively (p < 0.05). Moreover, the results indicated that serum levels of TNF-α were significantly increased in the early hours, but after 48 h a decreasing trend was detected (p < 0.05). Furthermore, serum levels of IL-10, IFN-γ, and IL-6 were significantly increased from 12 h until 48 h postoperatively (p < 0.05) (Table I).

Table I

Comparison of serum levels of inflammatory markers in patients with different times

Number of patientGenderSampling dates and timesIL-8 concentrationTNF-α concentrationIL-6 concentrationIFN-γ [ng/µl]IL-10 [ng/µl]
1M00
2M24 h
3M48 h046.439
4M0032.874
5M24 h0
6M48 h0
7M48 h0088.27108.474258.598
8M24 h028.871374.8360164.614
9M001.67956.695141.466572.878
10F48 h57.992135.058393.762104.554395.093
11F24 h0029.4662.842130.332
12F035.064176.806314.6978.371576.652
13M00076.80211.52118.66
14M48 h0055.63611.5286.575
15M24 h0067.1271.066167.327
16M0037.27579.3166.946580.454
17M24 h033.39364.0270416.276
18M48 h0060.90316.44113.428
19M48 h07.83948.1180492.988
20M24 h22.465131.38861.03159.263
21M48 h0066.6124.82223.186
22M24 h0318.514128.10919.0131479.571
23M00357.436107.24141.7721476.714
24M00028.27767.388
25M48 h0020.9354.41832.107
26F24 h01.67946.48293.0631346.595
27F002.54921.55896.848943.885
28M24 h0070.7164.82211.433
29M24 h0058.8056.9469.475
30M000612.36211.5224.638
31M48 h0228.051202.5199.1841441
32M48 h00148.10129.93935.193
33M24 h00214.57489.32294.726
34M000180.94174.81174.866
35M24 h028.8714.063196.52685.576
36M48 h091.92185.0034.822315.489
37M00
38M24 h066.171115.36264.406230.739
39M0
40M24 h0072.753015.458
41M0 h00155049.781
42M48 h00350.6724.82261.946
43M00
44M24 h024.823253.13674.81186.575
45M24 h0117.261201.42837.545
46M48 h077.30674.811197.418
47M24 h00.72270.205145.795237.491
48M001.67986.7870279.141
49M0020.06759.856017.522
50F48 h00127.64024.638
51F24 h00148.562011.433
52F00038.14111.5232.874
53M48 h00123.879120.50680.645
54M24 h0066.097137.18274.866
55M002.54946.482037.545
56M48 h0039.27011.433
57F24 h00108.68012.759
58F00031.234017.522
59M24 h00113.45816.44138.335
60F24 h020.067177.32354.418253.198
61F0011.90529.46651.18355.772
62M0019.46142.06954.41835.973
63M48 h0050.28529.93921.748
64F48 h0072.75316.44119.619

Discussion

The complex inflammatory response arises from the interplay between various mediators produced at the site of injury, including cytokines [8]. These mediators can regulate gene transcription, and modify intracellular signaling pathways [9]. In the initial injury, surgical reduction and fixation of fractures induce the immunoinflammatory response. Therefore, modulation of cytokine release has been considered a tempting strategy [10]. Zhang et al. reported that hip fracture and surgery in aged rats induced a systemic inflammatory response and lung injury correlated with increased susceptibility to infection during the acute phase after injury and surgery [11].

In the present study, our findings suggest that serum levels of IL-8 were markedly decreased from 12 h until 48 h postoperatively. Moreover, the results indicated that serum levels of TNF-α were significantly increased in the early hours, but after 48 h a decreasing trend was detected. Furthermore, serum levels of IL-10, IFN-γ, and IL-6 were significantly increased from 12 h until 48 h postoperatively.

Neumaier et al. [12] reported that the C-reactive protein (CRP) values were significantly lower in early surgery within 24 h after trauma than in delayed surgery. Moreover, they found that a lower postoperative inflammatory reaction after early surgery of hip fractures provides a better outcome when treated with arthroplasty. Findings of Harwood et al. [13] support the continued use of damage control procedures in severely injured patients and complement data already available, suggesting that a damage control orthopedics (DCO) approach reduces the subsequent inflammatory response. Moreover, they concluded that the inflammatory status of the patient may be important in clinical decision making regarding the timing of conversion to an intramedullary device. In agreement with our study, they found that the pattern of serum IL-6, keratinocyte, IL-10, and IL-1 release was dynamic, but no significant elevation in TNF-α was detected. The early hepatic and pulmonary infiltration of polymorphonuclear cells occurred in the absence of significantly elevated serum cytokine levels, indicating that either early minor changes with an imbalance in inflammatory mediators or locally produced cytokines may initiate this process. Nakamura et al. in Japan reported that IL-1 and IL-6 and TNF-α were increased after femoral fractures and that they originated from synovial cells [14]. It has been reported that intramedullary nailing fixation resulted in an increase in the level of inflammatory cytokines in animal models. As a matter of fact, it has more adverse effects on the inflammatory response, system stress, and multiple organs [14].

A previous study found that the serum levels of IL-6 and IL-8 in the cerebrospinal fluid were increased, and it raises the possibility that IL-8, acting in the central nervous system (CNS), plays a role in the postinjury syndrome. The mechanism by which CNS IL-8 is produced in trauma is unclear, but a physiological role is supported by the known ability of the CNS to produce IL-8 and the presence of receptors for its action in the CNS [15, 16].

In an animal model, it has been reported that immune cell performance can be increased, and this phenomenon results in an increase in cytokine secretion levels [17]. A previous study evaluated the change in IL-6 levels perioperatively in patients treated for femoral shaft fracture. It was reported that damage control procedures provoked a significantly smaller increase in IL-6 levels when compared with those observed after primary intramedullary nail (IMN). Furthermore, similar studies on bone fracture were conducted previously by other authors [1820]. In conclusion, the inflammatory status of the patient may be a useful adjunct in clinical decision making. With an improved understanding of the molecular basis of the inflammatory response, and by identifying relevant clinical markers of inflammation, surgeons can better manage the timing of surgical stabilization.

Conflict of interest

The authors declare no conflict of interest.