Sternalock plating system for elderly post-sternotomy patients

Sternal nonunion after median sternotomy is very stressful for patients and is counted as one of the major postoperative complications reducing quality of life. Conventionally, sternal fixation using metallic wires, sutures, etc., has long been performed. However, postoperative intermittent stress on these fixative materials can cause breakdown of the materials. There are also cases in which the sternum itself rather than the fixative materials is broken. Such events can lead to mediastinal hematoma, necessitating a second thoracotomy or resulting in nonunion in some joints or sternal osteomyelitis [1]. Possible risk factors for sternal nonunion include severe obesity, insulin-dependent diabetes mellitus, chronic obstructive pulmonary disease, steroid therapy, coronary artery bypass grafting with the bilateral internal thoracic arteries, and the necessity of loading body weight onto the arms at the time of standing up or walking. Recently, the Sternalock plating system was developed for use in such cases, and favorable clinical outcomes have increasingly been reported primarily from Western countries [2]. This system is composed of a titanium plate (for crosslinking between the right and left stumps of the sternum) and screws for fixation of the plate onto the sternum. Six plate shapes are available, and the screws come in 7 sizes (8–20 mm) to accommodate different sternal thicknesses. In 2013, reimbursement from the insurer for use of the Sternalock plating system was started in Japan, allowing treatment with this system under the national health insurance scheme of this country. This system is currently used for patients at high risk for sternal nonunion. For patients with a fragile sternum due to aging, many surgeons still use wires or other materials for sternal closure (the conventional method). Because of postoperative sternal nonunion in elderly patients has a risk for severe worsening during postoperative course, many surgeons still employed the familiar conventional method. Moreover, as demerits of the Sternalock plating system usage, there are the higher costs and the requirement of the special tool for emergent re-open chest. The present study was undertaken to retrospectively review patients in whom the Sternalock plating system had been used and to examine whether or not this system can be safely and effectively employed in elderly patients. Of the patients who underwent surgery on the heart or large thoracic vessels via a median sternotomy at the Department of Cardiac Surgery, Tokyo Metropolitan Geriatric Hospital between December 2012 and March 2014, 60 seemingly at high risk for sternal nonunion, satisfying at least one of the following requirements, were enrolled in this study: (1) severe obesity (body mass index C130), (2) insulin-dependent diabetes mellitus, (3) chronic obstructive pulmonary disease, (4) having undergone coronary artery bypass grafting employing the bilateral internal thoracic arteries, (5) requirement for loading body weight onto the arms at the time of standing up or walking, (6) receiving hemodialysis, (7) having undergone a second thoracotomy, and (8) taking steroids or other immunosuppressant agents. For the 30 patients who had undergone surgery before September 2013 when the Sternalock plating system was introduced, sternum fixation was achieved T. Nishimura (&) C. Kurihara Y. Sakano S. Kyo (&) Department of Cardiac Surgery, Tokyo Metropolitan Geriatric Hospital, 35-2, Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan e-mail: takashin-tky@umin.ac.jp