HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Francis Robicsek Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Robicsek, F. Articles by Fokin, A. A. Search for Related Content PubMed PubMed Citation Articles by Robicsek, F. Articles by Fokin, A. A. Related Collections Cardiac - other Chest wall

Editorials

Search for a better mousetrap. The quest for an ideal method of sternal closure

^a Carolinas Heart and Vascular Institute, Carolinas Medical Center, 1001 Blythe Boulevard, Suite 300, Charlotte, NC 28203, United States
^b Heineman Medical Research Laboratory, Charlotte, NC, United States

^_* Corresponding author. Tel.: +1 704 444 3911; fax: +1 704 373 0781. (Email: francis.robicsek{at}carolinashealthcare.org).

Different methods designed to re-unite the surgically divided sternum remain among the favorite subjects of professional literature. The past three decades witnessed an excess of about 20 modifications to our original parasternal ‘weaving’ technique of sternal closure [1]. Sadly most, if not all of these recommendations, were based either on clinical material which was scarce in numbers and divergent in composition, or on incomplete mechanical modeling. Some of these testing methods, for example, compare the effects of transverse forces acting on rubber hemisternums to those applied upon vertical dislocation of cadaver bones. Such methodology inevitably leads to unfounded claims and would be unacceptable even in everyday commercial product testing. It is clear that today in the era of evidence-based medicine, such a stance is no longer sustainable and we are obliged to establish acceptable standards of comparison.

At first consideration, a well-designed, prospective clinical trial would appear as the appropriate process for the evaluation of the merits and shortcomings of different methods of sternal closure. However, considering that regardless which closure technique is chosen, the rate of disruption is relatively small and occurs in a patient population laden with a great variety of risk factors, the expectation of a large-scale, prospective, multivariant clinical study is rather wishful. For this reason, a well-conducted mechanical modeling may still be the way to find, if not the final solution, a better path to it.

We should gather an expert consensus of surgeons and biomedical engineers and design a biomechanical model, in which forces acting upon the re-united sternal halves may be reproduced and measured. These forces should not be applied separately but in a simultaneous and repetitious way as they naturally occur. Their height and interaction should be adjusted to recreate various clinical stresses, such as coughing, to which the sternum may be exposed in the postoperative period. Some of the experiments should last for as long as 3–4 weeks, a time period during which the reunited human sternum is expected to heal.

To make this testing system more relevant to ‘real life’, special consideration should be given to the composition of the artificial ‘sternum’ used in the experiments. Presently applied materials, such as rubber, silicone or ceramics, all intended to imitate the consistency of the human sternum are unacceptable for obvious reasons. Several studies used freshly harvested cadaver sternums to imitate clinical conditions as close as possible. This approach, however, poses a difficult dilemma: If multiple cadaver sternums are used, their variation in anatomical and structural properties makes them hardly comparable. On the other hand, if the same cadaver-sternum is used over-and-over again, it becomes progressively less resilient to stresses, thus unsuitable for meaningful comparative analysis.

As we see it now, for practical reasons ‘artificial bone’ commonly used in orthopedics appears to be the most suitable material to reproduce various anatomical, structural and material properties of the normal, as well as the weakened, sternum that one may expect in patients of different sizes and genders. These replica sternums should be interchangeable to be readily tested against similar disruptive forces.

With the help of such a system, one should be able to analyze and compare methods and devices designed either for primary closure of the surgically divided sternum, or for repair of disruption if the primary repairs fail. These devices (sutures, plates, etc.) may vary in composition, volume, shape the way they are applied and, whether and how they may be buttressed. Such an arrangement will yield not only more accurate results but also may reveal unexpected outcomes; like a particular method of closure which may appear the strongest under static conditions but fails if subjected to repetitious stress-loads. Or, that a particular technique may work well on solid sternal models but not on weakened sternums. Also, while a relatively simple method may prove to be highly effective to prevent sternal separation, a more complex technique may become necessary to repair if disruption has already occurred.

A testing system, as described above, may indeed establish a ‘mechanical’ line of priority, but certainly will not fully reproduce a situation that may exist in the post-sternotomy patient. Clinical factors of sternal healing such as obesity, low hemoglobin, diabetes, altered blood-supply, as well as possible long-term harmful effects of retained closure-material will need to be looked upon separately. One of these days such integration of mechanical and biological research may give us the final answer. But such a clinical inquiry should be preceded; proper mechanical testing should come first. We have to develop a standardized, up-to-date bioengineering method to find the most appropriate sternal closure. Now.

References

1. Robicsek F, Daugherty HK, Cook JW. The prevention and treatment of sternum separation following open-heart surgery. J Thorac Cardiovasc Surg 1977;73:267-268.[Abstract]

This article has been cited by other articles:

				C. W. Snyder, L. A. Graham, R. E. Byers, and W. L. Holman Primary sternal plating to prevent sternal wound complications after cardiac surgery: early experience and patterns of failure Interactive CardioVascular and Thoracic Surgery, November 1, 2009; 9(5): 763 - 766. [Abstract] [Full Text] [PDF]

				S. Franco, A. M. Herrera, M. Atehortua, L. Velez, J. Botero, J. S. Jaramillo, J. F. Velez, and H. Fernandez Use of steel bands in sternotomy closure: implications in high-risk cardiac surgical population Interactive CardioVascular and Thoracic Surgery, February 1, 2009; 8(2): 200 - 205. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Francis Robicsek Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Robicsek, F. Articles by Fokin, A. A. Search for Related Content PubMed PubMed Citation Articles by Robicsek, F. Articles by Fokin, A. A. Related Collections Cardiac - other Chest wall