Asian Cardiovasc Thorac Ann 2006;14:e41-e42
© 2006 Asia Publishing EXchange Ltd
Managing Sternal Osteomyelitis with Antibiotic Bead Implantation
Kuan-Ming Chiu, MD,
Tzu-Yu Lin, MD1,
Shu-Hsun Chu, MD,
Cheng-Wei Lu, MD1
Department of Cardiovascular Surgery
1 Department of Anesthesiology Far-Eastern Memorial Hospital Taipei, Taiwan
For reprint information contact: Cheng-Wei Lu, MD Tel: 886 2 8966 7000 Fax: 886 2 7738 6057 Email: drlin{at}ms4.hinet.net, Department of Anesthesiology, Far-Eastern Memorial Hospital, 21, Sec 2, Nan-Ya S. Road, Pan-Chiao, Taipei 220, Taiwan.
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ABSTRACT
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Early, aggressive debridement followed by closure with muscle flaps is thought to improve the resolution of deep sternal wound infection that occurs after sternotomy. However, persistently discharging sternal osteomyelitis remains difficult to resolve. We successfully treated 2 patients who developed deep sternal wound infection after cardiac surgery by combining one-stage debridement with implantation of gentamicin beads to fill up the evacuated bone marrow space. This approach provides a simple and effective solution for sternal osteomyelitis.
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INTRODUCTION
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Deep sternal wound infection after sternotomy for cardiac surgery is a serious complication that affects between 1% and 2.8% of patients, with an overall mortality rate between 25% and 52%. The infection always involves the sternum itself. Patients carrying a high risk for mediastinitis usually have an osteoporotic, fragile, and broken sternum. During debridement, all foreign bodies as well as infected and necrotic tissue must be removed, which gives rise to a dead space in the sternal bone. Although muscle flaps and omental flaps have been proposed for covering the dead space to provide a nourished bed for delayed closure, the evacuated bone marrow space is not filled. Sternal osteomyelitis often persists after debridement for mediastinitis. Moreover, efforts to treat deep sternal wound infection sometimes meet with only partial success and result in localized sternal osteomyelitis. The persistently discharging sternal wound may not have systemic consequences, but it does affect the patient’s self-image and physical well-being. We report 2 cases in which the marrow space was filled with antibiotic bead chains in order to eradicate sternal osteomyelitis after debridement of the sternal wound.
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CASE REPORTS
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CASE 1
A 74-year-old man underwent coronary artery bypass surgery (CABG) and 2 subsequent re-operations for postoperative bleeding. Two weeks later, he developed a discharging sternal wound. Computed tomography showed blurred tissue planes in the peristernal area and subcutaneous tissue. Wound culture revealed methicillin-resistant Staphylococcus aureus. Three debridements were performed. The mediastinitis healed with no systemic signs, but locally discharging sternal osteomyelitis persisted for 3 months. We performed another procedure to fill the bone marrow space with gentamicin-impregnated polymethylmethacrylate chains (Septopal®; Merck, Darmstadt, Germany) after extensive debridement before repairing the primary wound. One month after removing the drain tube, the patient showed good healing and no further discharge. The beads remained in the patient 3 years after implantation.
CASE 2
A 64-year-old diabetic woman who had off-pump CABG was discharged with good wound healing on postoperative day 7. She presented with malaise and fever 5 days later. Mild erythema over the sternal wound was observed. Suspecting sternal wound infection, intravenous vancomycin was prescribed, but 3 days later the wound was discharging frank pus. Chest computed tomography revealed some gas space and fluid accumulation both above and behind the sternum. Pus culture showed methicillin-resistant Staphylococcus aureus. On re-opening, the wound was found to be filled with necrotic tissue. All suspected infected and necrotic tissue was excised. Two drain tubes were placed in the presternal and retrosternal spaces. The evacuated bone marrow space was filled with Septopal® chains and the sternum was rewired. The soft tissue was repaired. The wound healed well after 14 days of vancomycin injection. The beads had remained in place for 20 months by the time of this report.
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DISCUSSION
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Deep sternal wound infection after cardiac surgery continues to represent an important complication associated with high morbidity and cost. A multicenter prospective trial has established that the independent risk factors for sternal wound infection include obesity, CABG, re-operation, and postoperative inotropic support.1 Other postoperative variables such as nephrological and pulmonary complications have also been found to be strong predictors of sternal wound infection.2 None of the previously identified risk factors are modifiable, except the use of bone wax and the technique of grafting using bilateral internal mammary arteries in diabetic patients.3 The risk factors for mortality in patients who develop deep sternal wound infection have been determined as bacteremia, intra-aortic balloon pumping, advanced age, and prolonged mechanical ventilation.4 However, the majority of the deaths are secondary to sepsis and multi-organ failure.
Most cardiac surgeons manage deep sternal wound infection with radical debridement, rewiring, and closed drainage, with or without antibiotic saline irrigation. However, our experience with these traditional approaches was unsatisfactory. Some surgeons advocate immediate debridement followed by closure with a bilateral pectoralis major myocutaneous advancement flap with omental transposition.5 This strategy of early, aggressive debridement followed by delayed closure has been reported to reduce early mortality to less than 20%.6
Although various operative techniques have been adopted in the management of this complication, there have been few reports discussing the sternal infection itself. In this report, we present our experience with the use of gentamicin beads to treat sternal osteomyelitis. An important modification of the procedure in case 2 was the placement of the beads at the first debridement operation. The commercially available gentamicin beads are highly efficient in eluting the antibiotic locally, significantly raising the local concentration of the antibiotic that can be achieved through systemic delivery, thereby effectively eliminating the residual infection in the bone cavity. Moreover, the high local gentamicin concentration exceeds the tolerance level of a broad spectrum of bacteria. Another important advantage is cost savings in comparison with multiple debridements. In both our patients, the beads have not been removed. Although there is concern that the retained foreign bodies may cause complications, we have not encountered any problems. However, in case removal is necessary in the future, the last bead was placed superficially so that the chain could be accessed easily from an incision over the xiphoid. Long-term implantation of gentamicin beads without increasing the risk of complications has been reported.7 Our experience with this simple maneuver in 2 patients has been encouraging. However, long-term follow-up is required.
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REFERENCES
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- The Parisian Mediastinitis Study Group. Risk factors for deep sternal wound infection after sternotomy: a prospective, multicenter study. J Thorac Cardiovasc Surg 1996;111:1200–7.[Abstract/Free Full Text]
- Noyez L, van Druten JA, Mulder J, Schroen AM, Skotnicki SH, Brouwer RM. Sternal wound complications after primary isolated myocardial revascularization: the importance of the post-operative variables. Eur J Cardiothorac Surg 2001;19:471–6.[Abstract/Free Full Text]
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- Henry SL, Hood GA, Seligson D. Long-term implantation of gentamicin-polymethylmethacrylate antibiotic beads. Clin Orthop Relat Res 1993;295:47–53.
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ABSTRACT
INTRODUCTION
