A 61-year-old female patient with a body mass index of 29.6 kg/m² and a personal history that includes smoking (80 pack years), poorly controlled type 2 diabetes, hypercholesterolemia, hypertension, ischemic stroke, aortoiliac occlusive disease, and acute myocardial infarction underwent coronary artery bypass grafting (CABG). The procedure utilized the left internal mammary artery to bypass the anterior descending artery and involved a standard sternum closure after median sternotomy using steel wires with a simple suture technique. Additionally, she had a percutaneous angioplasty of the circumflex artery 5 years prior. Postoperatively, she developed a superficial infection of the surgical wound, which was treated by her family physician with 8 days of empiric oral amoxicillin clavulanate (875/125 mg, every 12 hours). The infection was adequately controlled and healed well. No microbiologic culture exam or blood test was performed at that time, and the patient did not find it necessary to return to Cardiothoracic Department of the Coimbra University Hospital for observation. One year later, due to severe chest wall instability, the patient underwent surgery for primary rewiring. The surgery and inpatient period proceeded without any events, and she was discharged on the second postoperative day. However, a few days later, a superficial surgical wound infection was observed again. This time, the patient returned to our outpatient clinic, and a microbiologic exam of the wound exudate revealed the presence of Staphylococcus epidermidis and Staphylococcus lugdunensis, which were interpreted as probable contamination. No blood test was performed since the patient was afebrile, hemodynamically stable, and showed no signs or symptoms suggestive of sepsis. Wound healing was achieved after 8 days of oral empiric amoxicillin clavulanate (875/125 mg, every 12 hours) and negative pressure wound therapy. Two months later, the patient returned to our outpatient clinic, reporting intense mechanical pain in the lower sternal region and bilaterally in the inframammary area, due to sternal non-union. She also experienced 1 episode of loss of consciousness, most likely a vasovagal syncope. During the physical exam, she exhibited thorax instability and crepitus, and fractured sternal fixation wires were evident on the chest radiograph. Chest computed tomography revealed a separation of the sternum segments on the axial plane of about 3 cm and a right ventricular (RV) protrusion into the space between both sternum halves, creating a vaguely aneurysmatic image with a neck of 26 mm (Fig. 1). Bone scintigraphy showed adequate bone mineral density, and echocardiography indicated preserved function with no significant valvular abnormalities.

Figure 1. Chest computed tomography scan showing separation of the sternum segments of about 3 cm and right ventricular protrusion into the space between the 2 halves, causing a vaguely aneurysmatic image with a neck of 26 mm. (A) Sagittal view. (B) Axial view. (C, D) Coronal view.

This case was discussed by a multidisciplinary group that included cardiac and thoracic surgeons and a biomedical engineer from Pagaimo Medical, Lda (Figueira da Foz, Portugal). An anterior chest wall supplementation with a pre-planned titanium prosthesis (Sternal Replacement Implant, Trionyx; Neuro France Implants, La Ville-aux-Clercs, France) was proposed to the patient to protect the protruding RV and stabilize the chest wall. Until that point, the patient had been uncooperative in managing risk factors. Five years after CABG surgery, the patient achieved adequate metabolic control, and conditions were favorable to proceed with surgery. A cardiac surgeon performed the skin incision, subcutaneous dissection, and removal of the broken sternal wires due to concerns about exposing the RV through the sternum edges. Dissection and exposure of both sternum edges were achieved without reaching the myocardium. There was no evident bone destruction. Only fibrotic tissue and bony prominences on the anterior surface of the sternum were found and dissected. Resecting these small bone prominences was crucial to create a flat surface for the perfect fit of the sternal plate. On the back table, the costal anchoring staples were molded based on a 3-dimensional (3D) model (3D-printed and sterilized) and attached to the sternal plate. A Gore-Tex patch was placed over the bony defect, secured with three monofilament nonabsorbable sutures on each half of the sternum, and the sternal plate was positioned over it. Two non-absorbable polyester sutures on the cephalic aspect of the sternal plate held it in place while minor adjustments were made to the molding of the costal staples, followed by their definitive fixation to the second, third, fourth, and fifth ribs bilaterally, on their anterior aspect, adjacent to the costal cartilages (Fig. 2). The postoperative period was uneventful, and the patient was discharged 5 days after surgery. At the 2-month follow-up, the patient exhibited a stable chest wall with a well-placed prosthesis (Fig. 3), was asymptomatic, and expressed satisfaction.

Figure 2. (A, B) Three-dimensional (3D) reconstruction of the patient’s anterior chest wall (based on a thoracic computed tomography scan) and planning of the titanium prothesis: anterior view with resected bony prominences circled in red (A); posterior view (B); 3D-printed model of the patient’s anterior chest wall used on the back table for molding of the titanium prosthesis (C, D); Gore-Tex patch anchored to the sternum, over the bony defect (E); titanium prosthesis placed over the bony defect and the Gore-Tex patch (F).

Figure 3. Postoperative chest radiograph showing the titanium prosthesis and costal staples anchored as planned. (A) Posteroanterior view. (B) Right lateral view.

Statement of informed consent

The patient signed the informed consent document, thereby granting permission for her information to be published in the Journal of Chest Surgery. She understands that the information will be published anonymously, but full anonymity cannot be guaranteed. The patient acknowledges that the text, along with any accompanying images or videos, may be published in the article and thus become freely accessible on the internet. Consequently, they may be viewed by the general public. Additionally, these materials might appear on other websites or in printed materials, be translated into other languages, or be utilized for commercial purposes.

Median sternotomy is the standard approach for most cardiac operations, and sternal closure is typically performed using steel wires [1]. Generally, this is a safe method; however, the incidence of healing complications such as instability, non-union, or dehiscence—with or without infection—ranges from 0.3% to 5.0%, and is associated with increased morbidity and mortality rates [1]. The main risk factors for these complications include obesity, diabetes, osteoporosis, chronic obstructive pulmonary disease, corticosteroid intake, and off-midline sternotomy [1-3].

Managing sternal dehiscence may require surgical interventions such as sternal debridement and rewiring (or Robicsek’s technical modification). However, when the classical approach of rewiring fails, rigid fixation systems may be used for sternal reconstruction [2]. While there is an increasing number of reports on titanium fixation systems for chest wall reconstruction, most of these cases involve primary reconstructions following chest wall tumor resections. To our knowledge, there has been limited experience with these systems in complex sternal dehiscence following cardiac surgery.

After undergoing a median sternotomy, patients may experience either complete or partial symptomatic non-union due to inadequate osteosynthesis with traditional steel wires. Injury to the RV following sternal non-union is a rare but potentially catastrophic event. Possible mechanisms include laceration of the RV by fractured sternal wires or sharp edges of the sternal halves, as well as avulsion resulting from adhesion of the RV to the underside of the sternum [4].

As argued by Arbulu et al. [4], if the sternum remains unclosed, it is crucial to detach the anterior RV from the underside of the sternum, as these adhesions are likely a significant factor in the subsequent rupture of the ventricle. The separated and unstable halves of the sternum move outward and inward with each breath, a motion that worsens with sudden increases in intrathoracic pressure, such as during coughing. This movement may exert a pulling force on a localized section of the anterior RV, placing strain on the myocardium. The opposing forces may then create disruptive impacts on the anterior wall of the RV [4]. Furthermore, in the reported case, the myocardial wall’s vulnerability due to a previous infarct and the absence of pericardial cover could increase the likelihood of avulsion. However, the adhesions of the RV to the underside of the sternum were not divided because the supplementation of the sternum with a titanium prosthesis stabilizes its 2 halves, allowing them to move as a single unit and preventing movement in different directions.

Another described mechanism of RV anterior wall lesion is trauma caused by the sharp edges of the sternum, which tends to protrude between gaping sternal halves [4]. In this case, although the RV did protrude, 4 years had passed since the sternal refixation surgery. Therefore, a myocardial lesion due to sharp sternal edges was unlikely, and the chest wall stabilization provided by the prosthesis would further confer protection.

The primary objectives of chest wall reconstruction include protecting the mediastinal structures from external trauma, preventing paradoxical breathing patterns, and preserving the chest wall’s shape [5]. The materials used in this procedure must possess several key qualities: biocompatibility, radiolucency, and MRI compatibility, along with sufficient rigidity and malleability to be shaped appropriately during surgery. Additionally, these materials should facilitate quick and easy access to the mediastinum in emergencies, promote fibrous tissue ingrowth to reduce infection risks, and be amenable to sterilization [5,6].

Among the most common methods of sternal reconstruction in cardiac surgery are the use of pectoralis, rectus, or latissimus flaps, omental grafts, and allogeneic bone transfers [5]. Additionally, a variety of alloplastic materials are available for reconstruction. These include synthetic meshes such as Gore-Tex soft tissue patches, Prolene mesh patches, and Marlex mesh, which encourage tissue growth but lack strength and rigidity. There are also osteosynthesis systems and plastic or metallic prostheses, including stainless steel nets, titanium mesh, titanium plates, or plexiglass. These materials generally provide good chest wall rigidity; however, their inelasticity and pre-manufactured shapes can complicate the restoration of the chest wall’s original shape, particularly in more extensive defects [5].

In this case, we utilized a standard titanium sternal plate and costal staples, which are biocompatible, radiolucent, magnetic resonance imaging-compatible, rigid, mendable, and easy to sterilize. During the surgery, we shaped these materials to fit the patient’s chest wall using a 3D-printed model. This approach proved effective for chest wall reconstruction. However, the procedure could have been streamlined with the use of a custom-made 3D-printed titanium prosthesis. There are several promising reports on the application of custom-made 3D-printed titanium prostheses, primarily for repairing defects in the chest wall following tumor resection. Nevertheless, this technique also shows potential for addressing post-sternotomy complications in cardiac surgery, particularly when other methods do not achieve satisfactory outcomes [5].

In the case presented herein, we observed an excellent functional outcome. The primary drawback is the anticipated time-consuming removal of the prosthesis if an emergent approach to the mediastinum becomes necessary. More cases and a longer follow-up period are required to better evaluate this approach.

Author contributions

Conceptualization: LALG. Data curation: LALG. Validation: RSL, CB, RP. Formal analysis: RP. Thoracic surgeons who performed the prothesis implantation: LALG, RSL, RP. Cardiac surgeon who performed the dissection of the subcutaneous tissue to avoid lesion of the right ventricle: CB. Writing–original draft: LALG. Writing–review and editing: RSL, CB, RP. The head of the Thoracic Surgery Unit: RP. Supervision: RP. All authors have read and approved the manuscript.

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Acknowledgments

We thank the operating room and ward nursing teams and Filipe Pagaimo, MSc, PhD, from Pagaimo Medical, Portugal, for his role in the development and expert assistance in molding the prothesis intraoperatively.