Interact CardioVasc Thorac Surg 2009;9:559-561. doi:10.1510/icvts.2009.212506
© 2009 European Association of Cardio-Thoracic Surgery
Work in progress report - Cardiac general |
Reinforced closure of the sternum with absorbable pins for high-risk patients
Masatsugu Hamaji*,
Yasuto Sakaguchi,
Mitsuhiko Matsuda and
Satoshi Kono
Department of Thoracic and Cardiovascular Surgery, Nagahama City Hospital, Nagahama, Japan
Received 27 May 2009;
received in revised form 9 June 2009;
accepted 12 June 2009
*Corresponding author. 1300-7 Nagara, Gifu City, 502-8558, Japan. Tel.: +81-58-232-7755; fax: +81-58-295-0077.
E-mail address: masamasatsugu{at}nifty.com (M. Hamaji).
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Abstract
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We report our result of the reinforced sternal closure in 51 consecutive patients. We applied a new type of absorbable radiopaque pins (Super FIXSORB®) composed of poly-lactide acid and hydroxyapatite, in addition to conventional stainless steel wires. The risk scores of our patients were calculated from the simplified risk scoring system for major infection based on the Society of Thoracic Surgeons National Cardiac Database. The expected probability of infection is significantly higher than the actual infection rate in our patients. Our procedure may contribute to minimizing the fatal sternal complication particularly in high-risk patients.
Key Words: Sternum; Wound closure
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1. Introduction
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Sternal dehiscence sometimes results from the postoperative mediastinal or local infection or non-infectious dehiscence sometimes occurs. The incidence of this complication is 2.5% and increases up to 5.6% in patients with at least one risk factor such as obesity, advanced age, diabetes, chronic obstructive pulmonary disease and prolonged extracorporeal circulation [1]. Reinforced sternal closure for prevention of sternal dehiscence in high-risk patients is necessary [2, 3].
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2. Material and methods
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We applied new absorbable pins with conventional wires to promote the sternal closure in 51 consecutive patients and evaluated the clinical outcome. The subjects were 51 patients (age: 43 88 years, 70.5 on average) who underwent cardiac or great artery procedures (valve: 15, OPCAB: 20, acute type A aortic dissection: 14, thoracic arch aneurysm: 2) in Nagahama City Hospital from September 2005 to April 2007. Full midline sternotomy was closed with a combination of transsternal stainless steel wires and absorbable radiopaque sternal pin (Super FIXSORB® 3 mmx3 mmx23 mm, 70% of poly-lactide acid and 30% of hydroxyapatite; Takiron Co, Ltd, Osaka, Japan) (Fig. 1). We prefer transsternal wiring to peristernal wiring for fear of injuring internal mammary vessels. We inserted a pin into the bone marrow of the manubrium and two pins into that of the body, with three wires in the manubrium and five in the body (Fig. 2). We adopted a simplified risk scoring system for major infection based on the STS National Cardiac Database [1] and calculated the risk scores of our 51 patients (Table 1).
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Table 1 Risk scoring system for major infection based on the STS national cardiac database and the number of our cases
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3. Results
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The median term of follow-up was 21 months ranging from 1 to 33 months. Deep sternal infection (MRSA osteomyelitis) was complicated in one patient – a 73-year-old female, whose risk score was 13. Semi-emergent off-pump CABG (LITA-8, Ao-SVG-9, Ao-SVG-12-13) was performed for acute myocardial infarction. All the wires and pins were removed and mediastinal drainage was carried out two months after the operation. The mediastinitis was classified as type V mediastinitis; and in terms of pathogenesis, it was caused by local contamination, not by spread from another infection site. MRSA was positive in the wires, while it was negative in the implanted pins. Repeated debridements and continuous irrigation led to spontaneous closure of the sternum. No other patient developed sternal dehiscence or superficial wound infection. Estimated probability of infection by risk score category and the number of our cases in each score category are listed in Table 2. The average risk score was 10.7, and expected probability of infection [1] was 4.08%. Our actual infection rate (1.95%) was significantly lower (P<0.0001) than the expected rate by one sample t-test.
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Table 2 Estimated probability of infection by risk score category and the number of our cases in each risk score category
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4. Discussion
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There have been some previous reports on the sternal closure using poly-lactide-containing absorbable pins with favorable results [4, 5]. We used a new type of pin, Super FIXSORB®, in which hydroxyapatite was added to the previous ingredient of poly-lactide acid. It is expected to be more favorable in view of strength, biocompatibility and osteoconductivity than the former pin containing poly-lactide acid alone [6]. Although the antimicrobial effect of hydroxyapatite is not clear, we experienced only one case of sternal infection. Bioresorption is another advantage in terms of potential late infection or inflammation. Little information is available on how soon hydroxyapatite as well as poly-lactide acid is absorbed in the implanted sites. Shikinami reported that 4–5 years was needed to absorb the composite pin placed into the femur of rabbit and that particles of hydroxyapatite were still microscopically observed [7]. The particles of hydroxyapatite as the remnants of bioabsorbable pins seem to contribute to the strength of the bones into which the pins were inserted, but we should be careful of any future problem of the remnants. A limitation of our study is the fact that it is not a matched case-control study. However, combined use of stainless steel wires with Super FIXSORB® may contribute to minimizing sternal complications.
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References
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Abstract
1. Introduction
