Background: There are many factors are known to increase the risk of sternal wound infection (SWI), some studies have reported that nickel is a risk factor for SWI. Titanium wires have only been used as an alternative to steel wires in patients with known allergy to nickel. However, there is a paucity of literature regarding the safety of using titanium wires compared to that on the safety of steel wires for sternum closure after cardiac surgery. Therefore, this study aimed to demonstrate the non-inferiority of titanium wires, even in patients without a known allergy. Methods: A total of 322 Patients who underwent elective full median sternotomy were randomly assigned to sternal closure either by titanium wires (n=161) or by stainless steel wires. Results: 14 patients had sternal instability, six (3.7%) patients in the titanium group and eight (5%) patients in the stainless steel group (p = 0.585). There was no statistically significant difference between both groups in terms of postoperative wound infection (p=0.147). Patients in the titanium group experienced statistically significant lower postoperative pain than those in the stainless steel group (p = 0.024). The wire type was not an independent risk factor for SI, as shown by univariate and logistic regression analyses. Conclusion: Titanium wires are a good alternative and have been proven to be safe and effective for sternal closure. The surgeon should be aware of the possibility of developing an allergic reaction to the wires especially in patients with previous multiple allergic histories.:Table of Contents 1. Background 5 1.1. Anatomy of the sternum 5 1.2. Blood Supply of the Sternum 6 1.3. Basis and phases of acute Wound healing 7 1.4. Biomechanics of the sternum 7 1.5. Post-sternotomy complications 8 1.5.1. Dehiscence and sternal instability 8 1.5.2. Mediastinitis and Deep Sternal Wound Infection 10 1.5.3. Risk factors 12 1.5.4. Diagnosis 12 1.5.5. Bacteriology of Sterno-Mediastinal fluid and tissues 14 1.5.6. Osteomyelitis 14 1.6. Sternal fixation and Wiring Techniques 15 1.7. Overview of sternal closure techniques in Germany 16 1.7.1 Sternal closure Technique in Heart Center Dresden. 17 1.8. ASEPSIS SCORE 17 1.9. NICKEL Allergy/Suture materials and biocompatibility 19 1.10 Nickel allergy and cardiac surgery 20 1.11 Titanium Allergy 21 1.12. Pathophysiology of Metal Hypersensitivity Reactions 22 1.13. The hypothesis of the study 24 2. Materials and methods 25 2.1. Study Population 25 2.1.1. Inclusion criteria 25 2.1.2. Exclusion criteria 25 2.2. Intervention 25 2.3. Control 26 2.4. Outcome 26 2.5. Time 26 2.6. Sample Size calculation 26 2.7. Sternal closure technique 27 2.8. Handling of the wire 28 2.9. Blinding and randomization technique 29 2.10. Data collection and documentation 29 2.11. Statistics 29 3. Results 31 3.1. Preoperative parameters 31 3.1.1. Entire group 31 3.1.2. Group comparison 32 3.2. Intraoperative parameters 34 3.2.1. Entire group 34 3.2.2. Group comparison 34 3.3. Postoperative parameters 35 3.3.1. Entire group 35 3.3.2. Group comparison 36 3.4. Incidence of postoperative sternal instabilities 38 3.5. Univariate analysis 38 3.5.1. Pre-operative 39 3.5.2. Intra-operative 40 3.5.3. Post-operative 40 3.5.4. Statistically significant data 41 3.5.5. Descriptive presentation of the subgroup analysis (Sternal Instability, wire Classification) 41 3.5.6. Logistic regression 43 3.6. Summary / key result 44 4. Discussion 45 4.1. Sternal Instability 46 4.2. BMI “Obesity” 47 4.3. Wound Infection /ASEPSIS Score 48 4.4. Postoperative Pain 49 4.5. Type of the Wire 51 4.6. The Rising Potential Impact of Metal Hypersensitivity on other specialities 51 4.7. Limitation of the study 52 4.7. Conclusion 55 5. Summary 56 6. Zusammenfassung 58 7. List of figure 60 8. List of tables 60 Bibliography 64

Postoperative Wundheilungsstörungen nach herzchirurgischen Eingriffen sind seltene, jedoch gefürchtete und ernstzunehmende Komplikationen, die zu schwerwiegenden Konsequenzen bis hinzu einer Poststernotomie-Mediastinitis mit möglicherweise letalen Ausgang führen können. In einer prospektiven, monozentrisch angelegten Studie wird angestrebt, ein infektionspräventives Behandlungskonzept herauszuarbeiten, mit dem das Risiko für thorakale Wundinfektionen verringert werden kann. Ob mit der Anwendung eines vor operativen Thoraxverschlusses retrosternal eingelegten Gentamicin-Kollagenschwammes eine Reduktion der Inzidenz von Wundheilungsstörungen nach medianer Sternotomie erreicht werden kann, wird in der vorliegenden Studie geprüft. Dazu kommt eine Kombination aus dem Desinfektionsmittel ChloraPrep® und dem Resorbaschwamm Genta-Coll resorb® zum Einsatz.