Rigid Plate Fixation for Reconstruction of Symptomatic Sternal Nonunion: A Retrospective Review

Abstract

Background: Median sternotomy, the most common approach to open cardiac surgery, is performed in over 500,000 patients annually in the United States. This approach involves an incision from the manubrium to xyphoid and vertical division of the bony sternum. Wire cerclage remains the standard technique for sternal closure after median sternotomy. Complications following median sternotomy include infection, hematoma, seroma, and sternal nonunion or dehiscence. Sternal nonunion occurs when either significant bony motion, fracture, or separation occurs with the two sternal halves. It is clinically defined as greater than 6 months of pain, clicking, or sternal instability. This represents a failure of primary cerclage “fixation.” Risk factors for nonunion after sternotomy include obesity, bilateral internal mammary artery harvesting, diabetes, and off-midline sternotomy. While sternal nonunion has an incidence of less than 1%, this complication can serve as a nidus for life-threatening infection and can cause significant discomfort for the patient. There is currently no standard-of-care treatment for sternal nonunion after median sternotomy. In fact, sternal nonunion most commonly goes untreated, leaving patients continuously symptomatic. Rigid plate fixation (RPF) has been employed in certain cases for primary sternal closure in patients at higher risk for sternal healing complications. RPF has been shown to significantly reduce the incidence of complications and mortality after median sternotomy in high-risk patients when compared to wire cerclage. We have recently employed traditional orthopedic techniques of bony debridement, anatomic bony reduction, and have extended the use of RPF to patients with symptomatic sternal nonunion.

Objectives: The goal of this retrospective review is to investigate and describe long term clinical outcomes in patients at our institution who have undergone RPF for sternal nonunion after median sternotomy. Our objectives are to investigate long term outcomes and complications in patients at our institution who have undergone rigid plate fixation for sternal nonunion after median sternotomy.

Methods: All patients who underwent sternal reconstruction for sterile sternal nonunion between 2017 and 2023 were reviewed. Patients were excluded if they underwent prophylactic RPF during primary sternotomy or if they did not meet the clinical definition of sternal nonunion. Data regarding demographics, risk factors, initial sternotomy procedure, nonunion presentation, reconstructive procedure, and clinical and radiographic follow up. For sternal reconstruction, all patients underwent debridement of nonviable sternal tissue, rigid fixation with locking plates and screws with or without pectoralis muscle advancement flaps, layered closure, and incisional negative pressure wound therapy (NPWT). A total of 18 eligible patients, 14 male and 4 female, were identified. Average age was 63 years. Preoperative risk factors included obesity (n = 14), smoking (n = 9), diabetes (n = 8), and LIMA harvest (n = 16). Indication for median sternotomy included coronary artery bypass grafting (n = 16) and aortic valve replacement (n = 2). Patients presented with symptoms of sternal nonunion an average of 4.5 months after initial sternotomy. The most common presenting symptoms were pain (n = 17) and sternal clicking (n = 14). 8 patients (44%) showed evidence of fractured sternal wires.

Results: Average time from symptom presentation to sternal reconstruction was 3.2 months. Average time from initial sternotomy to reconstruction was 7.7 months. Regarding the sternal reconstruction procedure, 100% of patients underwent debridement of sternal edges and rigid plate fixation using locking plates and screws. Bilateral pectoralis advancement flaps were performed in 17 patients (94%). The average clinical follow-up period was 3 years, ranging from 39 days to 4.9 years. 100% of patients had sternal nonunion confirmed by CT scan and demonstrated clinical evidence of sternal healing. Complications following RPF included seroma (n=3), hematoma (n = 2), and wound infections (n = 2). One patient presented with osteomyelitis/mediastinitis one month post sternal reconstruction, with full resolution after receiving IV and oral antibiotics. Another patient had all hardware removed after presenting with cellulitis and CT evidence of perihardware infection 3 months post reconstruction. Sternal union was noted at time of hardware removal.

Conclusion: Rigid plate fixation is a reliable method of treatment for symptomatic sternal nonunion and should be offered to all patients demonstrating signs and symptoms of sternal nonunion after median sternotomy.