Primary sternal plating in high-risk patients prevents mediastinitis

Sternal wound infection leading to post-operative mediastinitis is a devastating complication of cardiac surgery carrying nearly a 15% mortality rate despite current treatment methods. Instability of bone fragments pre-disposes a patient to have non-union, mal-union and can subsequently lead to deep sternal wound infections progressing to mediastinitis. Rigid plate fixation has been utilized for acquired and surgically created fractures of virtually every bone in the body to prevent instability. However, the current standard for sternotomy closure remains the method of wire-circlage. Application of rigid plate fixation for sternal osteotomies affords greater stability of the sternum. We report on our preliminary experience with this technique in high-risk patients.

From July of 2000 to December 2001, rigid plate fixation was applied to 45 patients designated as having high risk for sternal dehiscence and subsequent mediastinitis. High risk was defined as patients having 3 or more established historical risk factors, including: COPD, Re-Operative Surgery, Renal Failure, Diabetes, Chronic Steroid Use, Morbid Obesity, Concurrent Infection and Acquired or Iatrogenic Immunosuppression. Intra-operative risk factors included off-midline sternotomy, osteoporosis, long cardio-pulmonary bypass runs (>2 h), transverse fractures of the sternum. Rigid plate fixation was performed using a combination of plates secured by bi-cortical screws, after the cardiac surgical procedure was complete and hemostasis was secured.

Rigid plate fixation was performed on 26 males and 19 females. The average age of patients was 63 (43-88) years. The average follow-up was 15 weeks (range 8-41 weeks). While there were 4 peri-operative deaths unrelated to sternal closure: one from aspiration pneumonia (post-operative day 9), one from a pulmonary embolus (post-operative day 29), one from overwhelming sepsis from pre-existing endocarditis (post-operative day 15), and one for primary respiratory failure (post-operative day 12). All others healed successfully. One patient who had a sterile dehiscence subsequently underwent successful re-operative rigid fixation. Comparing the cohort of patients who received rigid plate fixation to a matched population of high-risk patients during a similar time period who received wire closure, revealed a significant difference in the incidence of post-operative mediastinitis. The wire closed group (n = 207) had 18 deaths unrelated to sternal closure and had 28 patients who developed mediastinitis (14.8%). The rigid plate fixation group had no mediastinitis (Fisher's exact test, P = 0.006). The total incidence of post-operative mediastinitis during the designated study period was 4.2%.

Patients who benefited from sternal closure with rigid plate fixation showed a significant decrease in the incidence of post-operative mediastinitis when compared to similar population of patients whose sterna were closed with wire.