Asian Cardiovasc Thorac Ann 2004;12:16-18
© 2004 Asia Publishing EXchange Ltd
Interlocking Sternotomy: Initial Experience
Raja Joshi, MCh,
Smartin Abraham, MS,
Arkalgud Sampath Kumar, MCh
Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, New Delhi, India
For reprint information contact: Arkalgud Sampath Kumar, MCh Tel: 91 11 2658 8889 Fax: 91 11 2658 8663 Email: asampath_kumar{at}hotmail.com Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
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ABSTRACT
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An interlocking sternotomy using a lazy-S-shaped incision was performed in 91 patients undergoing cardiac surgical procedures (group A). The results were compared with those of 77 patients (group B) who underwent a standard sternotomy by the same surgical team. In group A, the incidence of sternal instability was 2.27% (2/88) versus 8.21% (6/73). No dehiscence or mediastinitis was noted in group A, whereas 6.85% (5/73) in group B had this complication. Analysis of diabetics revealed no sternal complication in group A compared to 50% (3/6) in group B. The interlocking sternotomy significantly reduced the incidence of sternal instability and helped to prevent sternal dehiscence and mediastinitis. Use of this safe, simple, and reproducible technique is strongly recommended, especially in diabetics.
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INTRODUCTION
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Post-sternotomy wound complications are a major cause of cardiac surgical morbidity. Sternal dehiscence with mediastinitis is a dreaded complication. Many attempts to prevent this have been made by altering the methods of approximation using different suture materials and avoiding application of bone wax on the marrow surface.1–4 We describe our initial experience with an interlocking sternotomy designed to reduce postoperative sternal instability and dehiscence.
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PATIENTS AND METHODS
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Between May and September 2001, 91 consecutive patients underwent an interlocking sternotomy (group A). There were 68 males and 23 females, their ages ranged from 10 to 72 years with a mean of 39.06 years. Body weight varied from 23 to 93 kg (mean, 51.5 kg). Of the 91 operations, 73 were valve procedures, 14 were coronary artery bypass graft (CABG) procedures for ischemic heart disease, and 4 were for repair of congenital cardiac defects; 4 sternotomies were for emergency operations (1 CABG, 1 aortic valve replacement, 2 mitral valve replacements). One patient underwent a repeat sternotomy for tricuspid valve replacement for tricuspid stenosis and regurgitation after a previous double valve replacement. There were 8 diabetic patients in this group. They were compared with 77 patients (group B) of comparable demographics who had undergone a standard straight sternotomy by the same surgical team between February and May 2001. There were 50 males and 27 females, with age ranging from 11 to 74 years (mean, 37.6 years). Body weight varied from 20 to 86 kg (mean, 49.2 kg). There were 60 valve operations, 13 CABG, and 4 congenital cardiac defect repairs; 6 operations were repeat sternotomies for valve replacement. There were 6 diabetic patients in this group.
After standard preparation, a midline skin incision was made. A lazy-S-shaped incision was marked on the periosteum of the sternum by scoring with electrocautery (Figure 1
). Care was taken to remain within the lateral confines of the manubrium and body of the sternum. The sternotomy was performed using a sternal saw (Sarns, Terumo Corporation, Tokyo, Japan). Bleeding points of the periosteum and marrow were cauterized for hemostasis. No bone wax was used in either group. The sternum was approximated with 3 or 4 figure-of-eight Ethibond no. 5 (Ethicon, Somerville, NJ, USA) sutures in patients with a body weight less than 60 kg, and using no. 5 steel wires (Davis & Geck, Wayne, NJ, USA) in those above 60 kg. Antibiotics were continued for 48 hours after surgery or until invasive lines and tubes were removed, whichever being later.
All patients were followed up by the surgical team during hospital stay and in outpatient clinics. The dressing was changed on the 3rd postoperative day and removed on the 5th postoperative day. Skin stitches were removed on the 9th postoperative day in the outpatient clinic. Thereafter, patients were recalled after 1 week, 1 month, 3 months, and then on a 6-monthly basis. Members of the resident staff who examined the wounds were blinded to the type of sternotomy. Sternal instability was defined as a clicking sound on coughing or laughing, anteroposterior movement of the sternal edges elicited with mild pressure, and a discernible but small gap between the sternal edges. Sternal dehiscence was defined as complete separation of the two sternal halves with an open wound and/or frank mediastinitis. Superficial wound infection was defined as redness, elevation, or discharge from the skin wound in the leg or in the main sternal incision or drain sites. Patients in group A were followed up from 1 to 5 months (mean, 3.8 months), and those in group B have been followed up for 4 to 7 months (mean, 5.6 months). The chi-squared test with Yates’ correction factor was used for statistical analysis to compare the results in each group. A p value of < 0.05 was considered to be statistically significant.
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RESULTS
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In group A, all patients survived the operation. Early postoperative mortality was 3.3% (3/91). Four patients were re-explored for bleeding. Of the surviving patients, 5 had superficial wound infections requiring daily dressing in the outpatient clinic for a maximum period of 10 days. Two patients in group A had sternal instability which was detected at the 2 weeks follow-up; one of these was a chronic smoker with an emphysematous chest, both were managed by external chest binder and were doing well at their latest follow-up, 6 weeks and 3 months after surgery. There was no incidence of sternal dehiscence, mediastinitis or other sternal complications in this group. No diabetic patient had a sternal wound complication.
In group B, all patients survived the operation. Operative mortality was 5.19% (4/77). Among the survivors, 7 developed superficial wound infection requiring a daily dressing change in the outpatient clinic for a maximum period of 14 days. Six patients developed sternal instability; they were managed conservatively using a sternal binder. All patients recovered without surgical intervention. Sternal dehiscence developed in 5 of the 73 surviving patients; all were managed by wound dressings and appropriate antibiotics. One patient required rewiring of the sternum. These patients had a prolonged hospital stay. In this group, 5 of the 6 diabetic patients developed sternal complications (sternal dehiscence in 3 and superficial wound infection in 2).
A comparative analysis of the two groups is shown in Table 1. There was no difference noted in the time taken, exposure obtained, the amount of bleeding or ease with which it was controlled in either group. No difficulty was faced at closure in placing the sutures or in approximating the sternal edges. The reduction in sternal dehiscence in group A was statistically significant.
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DISCUSSION
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The technique of an interlocking curved sternotomy was first described by Williams5 who had used it for more than 2 years. It is interesting to note that the idea was provided by one of his patients, an orthopedic surgeon. In our study, a reduction in the incidence of unstable sternum and absence of sternal dehiscence was observed. Remarkably, there was no mediastinitis in the interlocking sternotomy group, whereas almost 7% suffered sternal dehiscence and/or mediastinitis in the straight sternotomy group. None of the 8 diabetic patients had sternal problems after the interlocking sternotomy, but 50% had sternal dehiscence and mediastinitis after a straight sternotomy; the lack of a statistically significant difference may be attributed to the small number of diabetics in each group. We recommend an interlocking sternotomy as a safe technique that should be preferred in this subset in particular, as well as in general for all patients undergoing a sternotomy. To eliminate an additional risk factor, none of the patients in either group A or group B required internal mammary artery grafts.
The lazy-S shape of the sternal cut edges provides interlocking facets that fit into each other exactly and avoid vertical slippage between the two parts. McGregor and colleagues6 showed that rostrocaudal slippage was responsible for a substantial number of cases of sternal dehiscence, although less commonly than anteroposterior slippage. Furthermore, the strong splint-like effect of the interlocking sternotomy leads to firmer immobilization, promoting faster healing of the bone.6,7 We wish to emphasize that one should exert caution and control while negotiating the curved part of the incision to remain well within the confines of the manubrium and body of the sternum. Use of force at these points may lead to excessive thinning or fractures in that region, which may be troublesome during closure. The interlocking sternotomy was found to be a simple, safe, and reproducible technique which helps to reduce sternal instability and dehiscence.
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REFERENCES
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ABSTRACT
INTRODUCTION
