Patients and methods: Between January 2014 and September 2014, a total of 56 patients were included. The patients were divided into two groups according to the closure modality. The Cable group in whom the sternal cables were used consisted 24 patients, whereas the Wire group included 32 patients. Risk factors such as obesity, chronic obstructive pulmonary disease, diabetes mellitus, reoperation and closure with figure-of-8 were considered in the selection of these patients. The length of intensive care unit and hospital stay, blood drainage, infection and sternal complications were compared between the groups.

Results: Preoperative and perioperative variables between two groups were similar. There was no postoperative sternal complications for the Cable group, however, sternal dehiscence and superficial wound infections were observed in two patients in the Wire group. An inflammatory reaction to the wire developed within one month in a patient.

Conclusion: We recommend using sternal cable system instead of wires in the patients having risk factors for sternal instability.

The predisposing factors which may cause such complications, namely chronic obstructive pulmonary disease (COPD), high body mass index, diabetes mellitus, older age and smoking are defined in several studies.[4] We assume that sternal dehiscence and infection ratios can be reduced by using a reliable closure technique. In this study, we compare the patients in whom we used a sternal cable and sternal wire in aspects of postoperative complications.

Surgical technique
The cables were in the same diameter with the standard wires. They were inserted by using multiple figure-of-8 suturing constructs, each were tightened with a gauged instrument and were fixed in place with a reproducible crimp type device (Figure 1). We provided the 8 figure by passing the wire through the intercostal space and secured it with special clips (Figure 2). Three cables were used for each patient which resulted a tighter and more evenly distributed force than the use of wires. It also eliminated the human variable of determining how tight each wire actually was and the potential for wire fatigue and breakage due to over tightening.

Figure 1: Closure device.

Figure 2: Figure-of-8 suturing (a) X-ray image. (b) Figure-of-8 which made by crossing intercostal spaces.

Statistical analysis
Statistical analysis was performed using SPSS version 15.0 software (SPSS Inc., Chicago, IL, USA). Compliance with the normal distribution of variables were analyzed by visual (histograms and probability graphics) and analytical (Kolmogorov-Simirnov/ Shapiro-Wilk tests) methods. Descriptive analyses were done for categorical variables. Descriptive statistics for categorical data was presented in the mean and the standard deviation of the bionormally distributed samples. Median and interquartile values were used for samples with non-normal distributions. The significance between the Cable group and Wire group for abnormally distributed parameters was assessed with the Mann-Whitney U test. Categorical parameters between the Cable group and Wire group were compared with the chi-square and Fisher's exact test. A p value of <0.05 was considered statistically significant.

Table 1: Demographic data of the patients

Table 2: Surgical procedures

Three cables were used to maintain 8 figures. Hemi-sternums were converged with the use of equal pressure by closure device. Postoperative data of the Wire group and Cable group are presented in Table 3. The drainage amount of the Wire group was less than the Cable group (p=0.001). The hospitalization time was significantly shorter in the Cable group (p=0.004). Sternal dehiscence in three patients and sternal revision in five patients were observed in the Wire group, however, there was no statistically difference among two groups. The closure via cable was longer than the closure time with a wire. The right internal mammary artery was injured by the cable put through the intercostal space in one patient. In the Cable group, one patient in whom cardiovascular resuscitation was performed about 15 minutes had a ventricular fibrillation attack at early postoperative period. This patient was discharged without sternal dehiscence.

Although many materials have been used for the sternal closure so far, a sternal wire has been widely adopted currently. Grapow et al.[7] used a new material namely ZipFix, which had successful results. Permut et al.[8] performed the cable system in pediatric patients and reported that the ratio of postoperative pain and restlessness were relatively low in this patient population. The postoperative pain and painkiller use were relatively low in patients in the Cable group. Corset was not used in any patient. Superficial wound infection was observed in one patient, while dehiscence was not found in any patient. The length of hospital stay was significantly shorter in the Cable group.

In conclusion, although there were no statistically significant difference between two groups, we conclude that sternal cable system can be used safely instead of standard sternal wire in patients whose body mass index are >30 and those with comorbidities. However, further large-scale studies are required to establish a conclusion.

Declaration of conflicting interests
The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding
The authors received no financial support for the research and/or authorship of this article.

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