Sternal Reconstruction Following Cardiac Surgery Complicated by Mediastinitis

Mediastinitis represents an uncommon but potentially life-threatening complication following median sternotomy, with incidences ranging from 0.25-5% (1). It may result from direct hematogenous spread of bacteria or from the extension of infection from adjacent structures e.g., esophagus, airways, lungs, or head and neck (descending necrotizing infection). Diagnostic criteria have been described by the Centers for Disease Control and Prevention (CDC) (2) with signs and symptoms typically presenting within 30 days of cardiac surgery; whilst the predominant risk factors for its development include diabetes mellitus and obesity. There remains a lack of consensus regarding the optimal treatment option(s). Definitive management options may involve an array of techniques, depending upon the severity of the infection. The general principles of management aim to bring the infection under control, via removal of all infected/necrotic tissue and foreign material alongside appropriate antimicrobial therapy (3), with subsequent restabilization of the sternum. Techniques may include titanium rib plating, methyl methacrylate, prosthetic patches (synthetic, biological or titanium), or allo/auto-grafts (4).

Custom tridimensional titanium printing provides an effective method for construction of complex prostheses. The authors demonstrate the case of a 49-year-old female with previous sternal dehiscence and deep wound infection following coronary artery bypass grafts, necessitating sternectomy. A year later, she presented with chronic severe pain and audible crepitations of her ribs/clavicles. Lack of identification of a mechanical cause, poor localization, and suboptimal medical pain management culminated in the consideration for a novel approach for sternal reconstruction. By way of bridging the final placement of the titanium prosthesis, the patient underwent placement of a methyl methacrylate spacer. The surgical approach involved the removal of the temporary spacer, with tissue samples taken to guide postoperative antimicrobial therapy. Concurrently, the reaming, irrigation, and aspiration technique of bone marrow harvesting, for seeding of the central web structure of the implant, was employed under fluoroscopic guidance. Following adequate dissection under the pectoral muscle, and debridement of the anterior chest wall, final placement of the prosthesis was made via bicortical fixation to the ribs. Finally, the mobilized pectoral muscles were sutured medially and fixed to the previously placed rectus abdominis flap. 3D printing of a custom prosthesis offers a novel and effective approach to full reconstruction, maintaining pulmonary mechanics and stability of the anterior chest wall.

References

1. Abu-Omar Y, Kocher GJ, Bosco P, Babero C, Waller D, Gudbjartsson T, et al. European Association for Cardio-Thoracic Surgery expert consensus statement on the prevention and management of mediastinitis. Eur J Cardiothorac Surg. 2017;51:10-29.
2. van Wingerden JJ, Ubbink DT, van der Horst CM, de Mol BAJM. Poststernotomy mediastinitis: a classification to initiate and evaluate reconstructive management based on evidence from a structured review. J Cardiothorac Surg. 2014;9:179.
3. Ennker IC, Ennker JC. Management of sterno-mediastinitis. HSR Proc Intensive Care Cardiovasc Anesth. 2012;4:233-241.
4. Sanna S, Brandolini J, Pardolesi A, et al. Materials and techniques in chest wall reconstruction: a review. J Vis Surg. 2017;3:95.

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