Invited commentary

Abstract

The midline sternotomy is a commonly used incision, especially for cardiac surgery. Approximately 1,000,000 patients have cardiac surgery worldwide each year, with 500,000 patients per year in the United States. Despite this large volume of sternotomies, relatively little research has been done on methods for closure to achieve stable internal fixation. This is an important area in which real progress that can change clinical outcome can be made. The incidence of early sternal dehiscence and infection continues to be in the range of 1% to 2%, with another 1% to 2% of developing nonunion or late dehiscence in long-term follow-up. These problems are always difficult for patients and can be associated with significant mortality when mediastinitis develops. Several years ago we published an article that analyzed the biomechanics of routine sternal closure with interrupted stainless steel wires using a cadaver model [1McGregor W.E. Payne M. Trumble D.R. Farkas K.M. Magovern J.A. Improvement of sternal closure stability with reinforced steel wires.Ann Thorac Surg. 2003; 76: 1631-1634Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar]. Two observations were made that are worth emphasizing. First, movement occurs at the closure site due to the wires digging into the sternal bone. This occurs at physiologic levels of intrathoracic pressure, such as that generated during coughing. Second, movement of the sternum occurs primarily in the lateral direction and predominantly at the caudal aspect of the sternum. The upper sternum remains stable, but the lower sternum can open several millimeters when stressed. Subsequent bench testing using a polyurethane bone analog confirmed these findings and showed that reinforcement of the lower sternum significantly reduces this problem [2Trumble D.R. McGregor W.E. Magovern J.A. Validation of a bone analog model for studies of sternal closure.Ann Thorac Surg. 2002; 74: 739-745Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar, 3Dasika U.K. Trumble D.R. Magovern J.A. Lower sternal reinforcement improves the stability of sternal closure.Ann Thorac Surg. 2003; 75: 1618-1621Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar]. All of this data was obtained from experimental studies and has not been duplicated in humans due to lack of a simple, noninvasive, and inexpensive method for measuring sternal separation in patients. The article by El-Ansary and colleagues [4El-Ansary D. Waddington G. Adams R. Measurement of non-physiological movement in sternal instability by ultrasound.Ann Thorac Surg. 2007; 83: 1513-1517Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar] describes a method for detecting sternal dehiscence using existing ultrasound equipment [4El-Ansary D. Waddington G. Adams R. Measurement of non-physiological movement in sternal instability by ultrasound.Ann Thorac Surg. 2007; 83: 1513-1517Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar]. This is primarily a methods article, and the value of this technique in clinical practice has not been shown. El-Ansary and colleagues [4El-Ansary D. Waddington G. Adams R. Measurement of non-physiological movement in sternal instability by ultrasound.Ann Thorac Surg. 2007; 83: 1513-1517Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar] studied only patients with a history of sternal instability. It is not known what would be found in patients without an obvious problem. Nonetheless this ultrasound method provides a potentially useful clinical tool for evaluation of the sternotomy closure. This method may allow earlier detection of dehiscence in obese patients in whom a physical examination can be ambiguous. In addition, this method provides a way to compare the stability of different sternal closure methods and a way to determine how much motion occurs in routine, uncomplicated patients. Perhaps patients would have less pain and faster recovery if the sternal closure were completely stable. This is certainly true in orthopedics in which secure internal fixation is the preferred method for treatment in most situations. There is much to be learned about how to improve sternotomy closure. The use of a minithoracotomy for cardiac operations is believed to be less invasive than a sternotomy, but these incisions can also be very painful. I believe that, with improvements in sternal closure, the midline sternotomy might also be considered a minimally invasive incision in the future. Measurement of Non-Physiological Movement in Sternal Instability by UltrasoundThe Annals of Thoracic SurgeryVol. 83Issue 4PreviewSternal instability, a complication arising for some patients after sternotomy for cardiac surgery affects their later quality of life and cost of care. However, there are currently few guidelines for its diagnosis, quantification, and monitoring. Ultrasound equipment with associated software for calculating selected video-monitor distances provides one way of quantifying the extent of sternal separation. Full-Text PDF