Delayed Primary Versus Late Secondary Wound Closure in the Treatment of Postsurgical Sternum Osteomyelitis

1. Background

1.1. Problem of surgical site infection after sternotomy Sternal osteomyelitis and poststernotomy mediastinitis is a severe and life-treating complication after the cardiac surgery. The incidence of sternal osteomyelitis ranges from 1% to 3% (1, 2) with a high mortality rate from 19% to 29% (1, 3).

The most devastating complication of the open sternum is the laceration of the right ventricle which has a very high mortality. Additionally destabilizations of the thoracic cage, prolonged immobilization, or substantial surgical trauma are further complications of the conventional strategy (4). In addition, postoperative infections after sternotomy are associated with prolonged hospital stay, increased healthcare costs and impaired quality of patient life, representing an economic and social burden. The emergence of increasing antimicrobial resistant bacteria augments the importance of postsurgical infections since the antimicrobial choices are becoming limited. Furthermore, the incidence of infection is an indicator for the quality of patient care in the international benchmark studies.

Although several therapy strategies are nowadays there is a lack of evidence based surgical consensus for treatment of this surgical complication. In most case the poststernotomy mediastinitis is involving surgical revision with debridement, open dressing, vacuum assisted therapy or closed irrigation. After the granulation tissue on open chest wound was achieved secondary closure and/or reconstruction with vascularized soft tissue flaps such as omentum or pectoral muscle is performed. Both open therapy and the flap implantations may be used as a single-line therapy or as a combination of procedures.

1.2. Etiology of poststernotomy infections Many mechanisms have been proposed to explain the development of sternal wound infection. These theories include inadequate sternal fixation leading to instability and dehiscence of the overlying skin incision and inadequate surgical drainage. Further theories suggest a localized ischemic osteomyelitis. This theory suggests that sternal wires become loose, leading to sternal instability, which ultimately leads to skin dehiscence and osteomyelitic infection. The most commonly cultured organism is Staphylococcus Aureus.