A 74-Year-Old With Chronic Chest Pain

Answer: B: Nonunion of the sternum

Sternal nonunion is a rare complication after median sternotomy with an incidence of less than 1%.¹ Nonunion is described as pain in the sternum for a postoperative duration of more than 6 months in the absence of fever, chills, or fatigue.¹ The pain is associated with instability, often presenting clinically as a sternal click.^1,2 Both patient-associated and operation-associated factors play an important role in developing sternal nonunion:¹

• Diabetes mellitus
• Obesity
• Malnutrition
• Osteoporosis
• Chronic use of corticosteroids
• Chronic obstructive pulmonary disease
• Prolonged ventilator support
• Low cardiac output 

While the patient had several of these risk factors – including diabetes, prolonged glucocorticoid exposure, and obesity – the probable musculoskeletal nature of his history and the palpable defect on examination led to suspicion of sternal nonunion.

Diagnostic testing. To further evaluate his symptoms, the patient was referred to a cardiovascular surgeon who ordered a computerized tomography (CT) scan of the chest without contrast. A CT scan is the preferred test for diagnostic imaging in sternal complications.² These complications include sternal nonunion, mediastinitis, and secondary osteomyelitis.^2-4The CT of the chest confirmed fracturing of the cerclage wires along the entirety of the sternotomy with an opening measuring up to 0.6 cm between the margins of the sternum (Figure 2). Surgical intervention is preferred for the management of sternal nonunion.^3,4 Sternal plating is used to stabilize the sternal nonunion and tension band wiring is used for closure of the thorax which simulates the median sternotomy closure.^1,5 

Figure 2. Nonunion along the entirety of the sternotomy with a gap measuring up to 0.6 cm.

Differential diagnosis. Mediastinitis is an inflammation of the mediastinum due to deep sternal wound contamination. This is an uncommon complication of median sternotomy with a stated incidence of 0.4% - 5.0%.⁶ The risk factors include interoperative wound contamination, delayed wound closure, undrained hematoma, or prolonged surgeries.7 A CT of the chest without contrast is considered the best diagnostic imaging.² It may show obliterated mediastinal fat planes, gaps between the sternum, and mediastinal fluid or abscess.⁶ Chronic mediastinitis is considered best treated by first accomplishing wound debridement. Then, wound closure with a muscular or omental flap can be undertaken in a delayed manner.⁸

Dressler syndrome is a pericardial complication which occurs 2 to 3 weeks after acute myocardial infarction (MI).⁹ The etiology includes the development of humoral antibodies against self-myocardial antigens, which are exposed to blood during acute MI or reactivation of latent viruses.^9,10 The patient typically presents with chest pain that worsens with deep breathing and a low-grade fever.^9,10 Early coronary reperfusion therapy using percutaneous transluminal coronary angioplasty or thrombolysis may reduce the risk of developing Dressler syndrome.^9,10 Aspirin is used as a first-line medication, while steroids and colchicine are preferred in patients with refractory pain.¹⁰

Costochondritis is an inflammation of the costochondral junctions of ribs commonly occurring at more than one junction.¹¹ Patients typically present with a sharp or pressure-like pain on the anterior chest wall which aggravates with deep breathing.¹¹ This is a self-limiting condition in which symptomatic treatment is required. This is achieved with acetaminophen or non-steroidal anti-inflammatory drugs.¹¹

Treatment and management. As part of our patient’s preoperative work up, an echocardiogram revealed a decrease in his ejection fraction from 55% in 2018 to 35% in 2021. A cardiac catheterization showed stable coronary artery disease from his last study. It was suspected that this decrease in systolic function was pacemaker-related. An upgrade to a biventricular pacemaker improved his cardiac function, allowing him to proceed with the surgery.

Given his age and medical complications, the patient and surgeon agreed to simply remove all the wire material from the sternum to minimize the operation, as he had some degree of fibrosis in the interspace. He was aware that this option should help alleviate his pain, which was his goal, but would not improve potential instability.

Outcome and Follow-up. The patient underwent successful removal of his sternal wires and had an uncomplicated post-operative course. His sternal pain symptoms remain resolved for more than 1 year of follow-up.

Discussion. In our patient, concern for sternal nonunion was increased due to the prolonged nature of his symptoms, his demonstration of some of the associated risk factors, and a tender, palpable gap in his sternum on examination. While chest X-ray followed by chest CT eventually confirmed the diagnosis, obtaining an appropriate history and completing simple physical examination maneuvers can greatly increase one’s degree of suspicion.

Chronic chest pain is often musculoskeletal in nature, but the diagnostic decision-making process becomes more complex in patients with a known past medical history of coronary artery disease. Appropriate history taking, physical examination, and ancillary testing can help clarify a broad range of diagnostic possibilities for individuals presenting with chronic chest pain.  Primary care physicians and advance practice providers should keep sternal nonunion in mind when seeing patients who have had medial sternotomy incisions.