Ann Thorac Surg 2007;84:664-666
© 2007 The Society of Thoracic Surgeons
Case Reports
Total Sternal Reconstruction Using a Titanium Plate-Supported Methyl Methacrylate Sandwich
Taek Yeon Lee, MD,
Anthony L. Estrera, MD*,
Hazim J. Safi, MD,
Kamal G. Khalil, MD
Department of Cardiothoracic and Vascular Surgery, The University of Texas at Houston Medical School, Memorial Hermann Heart and Vascular Institute, Houston, Texas
Accepted for publication March 1, 2007.
* Address correspondence to Dr Estrera, Department of Cardiothoracic and Vascular Surgery, The University of Texas Houston Medical School, 6410 Fannin, Suite 425, Houston, TX 77030 (Email: anthony.l.estrera{at}uth.tmc.edu).
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Abstract
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We report a case of total sternal reconstruction using a methyl methacrylate polypropylene sandwich secured by using titanium plates. After previously failed attempts to wean the patient from the ventilator, this reconstruction allowed successful separation from ventilatory support in 6 days.
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Introduction
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Deep sternal wound infection is a rare but devastating complication after cardiac surgery occurring in 1% to 4% of cases [1]. Standard surgical treatment has included aggressive surgical debridement, intravenous antibiotics, and sternal reconstruction often using autologous tissue such as omentum or muscle for flap coverage and stabilization. Despite these aggressive measures, recurrent infection may occur requiring more aggressive debridement and reconstruction. As a result, sternal instability may occur resulting in prolonged ventilatory support.
Sternal reconstruction should support the anterior chest wall to prevent paradoxical movement and provide normal respiratory mechanics. For cases of complete sternal reconstruction, several techniques have been devised, the most common involving the use of methyl methacrylate and polypropylene mesh as a sandwich [2]. Others have reported the use of other materials such as those composed of hydroxyapatite and tricalcium phosphate (Ceratite [NGK Spark Plug Company, Aichi, Japan]), and titanium plates and screws for this purpose [3]. We report a successful sternal reconstruction using a methyl methacrylate polypropylene mesh sandwich supported by titanium plates.
A 67-year-old woman with a known history of coronary artery disease, carotid artery disease, hypertension, diabetes mellitus, and chronic obstructive pulmonary disease underwent three-vessel coronary artery bypass grafting using the left internal mammary artery and autogenous saphenous vein as conduits. Her postoperative course was complicated by Staphalococcus aureus deep sternal wound infection requiring sternal debridement and revision 2 weeks after coronary artery bypass. Despite aggressive wound care and intravenous antibiotics, recurrent infection and mediastinitis manifested by sternal drainage and instability developed necessitating the need to transfer the patient to our institution.
After the patient was transferred and stabilized, re-exploration was performed with aggressive wound debridement requiring sternal and costochondral resection. Open chest management was performed with delayed coverage using omentum and right anterior chest fasciocutaneous advancement flap. The acquired defect in the superior epigastric region of the abdomen was eventually covered with a full-thickness skin graft. The mediastinitis resolved, but the patient required tracheostomy for prolonged ventilatory support. She was eventually transferred to a long-term care facility where she completed her intravenous antibiotic course and received physical therapy. After 6 weeks, she was discharged home requiring home ventilatory support.
During the next year, multiple attempts at weaning from mechanical ventilation failed despite optimization of her physiological status (eg, nutrition, physical therapy, and resolution of sepsis). It was suspected the need for continued mechanical ventilatory support was due to insufficient mechanical chest wall support from paradoxical movement of the anterior chest wall. On physical examination, a 14-cm wide anterior flail segment was present. To stabilize the anterior chest wall, polypropylene mesh reconstruction was performed with direct attachment of the mesh to the mid-rib bodies. This reconstruction dehisced and paradoxical respirations remained with the inability to wean her from mechanical ventilation.
Six months after the attempted sternal mesh reconstruction, the patient underwent sternal reconstruction with composite methyl methacrylate polypropylene sandwich supported by using three sternal titanium plates. At surgery, the previously implanted polypropylene mesh was intact and well incorporated in the subcutaneous tissue. In addition, the underlying pedicled omentum flap was intact and viable with adhesion to the polypropylene mesh. The mesh had separated from the rib attachment sites. After careful dissection, the edges of the ribs were defined and prepared for the reconstruction. We then created a sandwich of methyl methacrylate between two layers of polypropylene mesh. After drying, multiple holes were drilled into the mesh for venting (Fig 1). This was then placed into the chest wall defect. The "neosternum" measured 12 cm by 10 cm x 2 cm in dimension. To secure the neosternum, we used three titanium plates (Synthes [Synthes, Inc, West Chester, PA]). These plates were purposely angulated and contoured to fit anatomically in the bed of the previous sternum and costochondral junctions. Three titanium screws were then used to secure each plate on each side to the corresponding second, fourth, and fifth ribs (Fig 2). After fixation of the plates to each rib laterally, the screws were then embedded though the plates directly into the methyl methacrylate polypropylene sandwich (Fig 1).
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Fig 1. Intraoperative photograph depicting the completed rigid reconstruction of the sternum with composite methyl methacrylate-polypropylene sandwich supported with three titanium plates.
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Fig 2. Postoperative chest roentgenogram (anteroposterior view) demonstrating the titanium plates secured into the ribs.
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The patient’s postoperative course was uneventful with complete weaning from mechanical ventilation by postoperative day 6. Four months after sternal reconstruction, the patient remains free of mechanical ventilation in good condition.
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Comment
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Mediastinitis after cardiac surgery represents an infrequent but serious problem with a reported incidence ranging from 1% to 4% [1]. Currently, wide debridement of bone and cartilage, treatment of infection, and tissue flap coverage are considered the mainstay of treatment. However, when complete resection of the sternum is required, reconstruction can become problematic. Goals of sternal reconstruction include providing external protection of the mediastinal structures and maintaining chest wall stability to prevent paradoxical chest wall movement that may hamper respiratory mechanics. Various autogenous and prosthetic materials have been described for this purpose. Small anterior chest wall defects can be repaired using muscle or myocutaneous flaps, and autogenous ribs have been used as fresh nonvascularized grafts or even vascularized rib grafts in conjunction with muscle flaps [2].
Although autogenous flaps may prevent paradoxical movement, they are often not adequate in providing protection of mediastinal structures from external trauma. Moreover, such flaps (rectus) may be dependent on the internal mammary artery blood supply, which is often harvested during coronary artery bypass, possibly compromising the blood supply of the autogenous flap. Prosthetic woven meshes, as polypropylene meshes, which are doubled over and sutured to the adjacent ribs and fascia to cover the surface, have been previously described. Although woven mesh reconstruction may be helpful with small lateral defects, its use for sternal reconstruction may not be as effective. This was observed in our case in that the mesh reconstruction did not allow adequate chest wall stabilization and dehiscence.
The methyl methacrylate sandwich first reported in 1972 for reconstruction of large anterior chest wall defects is the most widely applied technique for total sternal reconstruction [4]. In this technique, methyl methacrylate is sandwiched between two layers of polypropylene mesh, and then this matrix is sutured to the chest wall to fill in the defect. The challenge in our case was to provide rigid chest wall coverage as well as adequate stabilization. We modified the methyl methacrylate polypropylene sandwich by using titanium plates to secure both directly into the adjacent ribs as well as directly into the methyl methacrylate matrix. We believe that the use of the titanium plates would assure fixation and chest wall stabilization. The success of the technique was confirmed when the patient could be weaned from the ventilator in 6 days. Although it was possible that the methyl methacrylate polypropylene sandwich may have worked alone, achieving a stable attachment to the ribs with sutures or even wires alone was suspect. Moreover, weaning from the ventilator in such a short time would have been unlikely with the methyl methacrylate sandwich alone.
We want to emphasize that most sternal dehiscence due to sternal infection can be managed using local debridement, antibiotics, and either primary reconstruction or autogenous flap coverage. In addition, titanium plates with locking screws may be useful for limited fractures or primary sternal instability that needs local stabilization [5]. In the rare situation that extensive anterior chest wall and sternal resection is required, this modified technique of the titanium supported methyl methacrylate sandwich may provide another option for reconstruction.
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References
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- Francel TJ, Kouchoukos NT. A rational approach to wound difficulties after sternotomy: the problem Ann Thorac Surg 2001;72:1411-1418.[Abstract/Free Full Text]
- Chapelier A, Macchiarini P, Rietjens M, et al. Chest wall reconstruction following resection of large primary malignant tumors Eur J Cardiothorac Surg 1994;8:351-357.[Abstract]
- Watanabe A, Watanabe T, Obama T, et al. New material for reconstruction of the anterior chest wall, including the sternum J Thorac Cardiovasc Surg 2003;126:1212-1214.[Free Full Text]
- Harrington KD, Johnston JO, Turner RH, Green DL. The use of methylmethacrylate as an adjunct in the internal fixation of malignant neoplastic fractures J Bone Joint Surg Am 1972;54:1665-1676.[Abstract/Free Full Text]
- Cicilioni OJ, Stieg FK, Papanicolaou G. Sternal wound reconstruction with transverse plate fixation Plast Reconstr Surg 2005;115:1297-1303.[Medline]
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Abstract
Introduction
