Radical sternectomy for osteomyelitis without reconstruction post-coronary artery bypass graft: 10 years on

In 2014, we reported on a case of late presentation of a deep sternal wound infection (DSWI) that was treated with total sternectomy and removal of all associated costal cartilages.¹ The patient had extensive sternal osteomyelitis and breast abscesses, requiring a prolonged hospital stay and antibiotic treatment, which precluded sternal reconstruction with mesh or titanium plates. The long-term outcome of patients who have had radical sternal removal, without reconstruction, for osteomyelitis is largely unknown due to the sporadic nature of this radical treatment for DSWI. We wish to further report on this patient 10 years following radical sternectomy for osteomyelitis of the sternum to highlight some of the anatomical and physiological changes that the patient has undergone.

Case report

Patient consent

The patient gave written informed consent for the use of information and imaging; the form is available on reasonable request. No institutional review board approval is required for case reports at our institution.

The case

A 58-year-old female patient had presented, in 2010, as a case of late deep sternal wound infection with multiple breast abscesses six months following coronary artery bypass graft (CABG) surgery performed in another country. She was treated with intravenous antibiotics, radical sternectomy, removal of the costal cartilages and 1cm of the ribs. At that time, this was followed up with negative pressure wound therapy and drainage of the left breast abscesses. She was eventually discharged in a stable condition after 3 months with the wounds completely healed by secondary intention.

In 2019, the patient (now 67 years old) presented with chest pain and shortness of breath on exertion and she was diagnosed with non-ST-elevation myocardial infarction. At that time, she refused to undergo coronary angiography. She again presented, in 2020, with longstanding breathlessness on exertion. Physical examination revealed a completely healed median chest wound with a central depression in the sternal region due to the absent sternum (Fig 1) surrounded by the palpable edges of the ribs bordering the depressed area. The cardiac pulsation was easily visible within the bony defect. Upon inspiration there was diminished chest expansion, particularly at the lower part of the chest wall.

On this occasion, the patient agreed to undergo coronary angiography, which showed patent left internal mammary artery graft to the left anterior descending artery, patent saphenous vein graft to the posterior descending artery and diseased obtuse marginal artery; an attempt at balloon dilatation of the obtuse marginal artery and stent placement failed due to excessive calcification.

Also, the patient underwent axial computerised tomography (CT) scan of the chest (Fig 2). This radiological study was compared to her previous CT scan (Fig 3) that was performed just prior to her radical sternectomy 10 years previously; in this early CT scan one can discern the destroyed sternum and associated costal cartilages.

There was an appreciable reduction in the size of the chest cavity, as well as a change in the geometry of the chest cavity from being wider in a lateral plane than the antero-posterior to being almost circular. This is in part due to the gradual approximation of the anterior edges of the chest wall to the midline due to the absent sternum (Fig 2). Furthermore, when we measured the area of the chest wall in both CT scan images (present and 10 years ago) and standardised it to the size of the vertebral body to eliminate any variation due to unforeseen technicalities, we determined that the chest cavity had decreased in volume by about 10% over the intervening years. We theorise that the decrease in size of the chest cavity is mainly due to wound contracture, chest wall remodelling and healing, and the approximation of the free edges of the anterior chest towards the midline, as can be seen in Figs 2 and 3. Also, the anterior edges of the chest wall have undergone ossification (Fig 4) as part of the healing process. The patient also performed pulmonary function tests and these showed a forced vital capacity of 59% of the predicted value, forced expiratory volume in one second of 56% of the predicted value, and reduced lung capacity. (Predicted values are used to convert raw lung function results into clinically useful data. Predicted data are based on age, sex and height of the patient.²)

Discussion

Radical sternectomy without sternal reconstruction is a rare form of surgical treatment of DSWI. Sternal removal for DSWI and replacement with either titanium plates³ or mesh reconstruction, with or without muscle flap, following mediastinitis has been performed with good results.⁴ However, radical removal of the sternum for severe mediastinitis and osteomyelitis is unusual,¹ and the follow-up many years after the procedure has been of considerable interest to us in order to gain insight into what happens to a patient following this procedure.

Our patient had had a good quality of life since her initial procedure, but with some limitations in her exercise tolerance. The cross-sectional axial CT scans (Figs 2, 3) performed at the time of presentation (10 years previously) and again in 2019 show that there had been a gradual contraction of the chest cavity over time, and approximation of the anterior chest borders to the midline. This had undoubtedly led to a reduction in the absolute volume of the chest as well as reduction in the respiratory mechanics as her anterior chest wall was effectively fused with no movement (usually occurring via the costal cartilages (Fig 4)).

We had performed a radical sternectomy for our patient 10 years previously and, due to the breast abscesses, reconstruction was not possible (declined by the plastic surgeons) with muscle flaps and skin grafts; but the patient had done well, with only some life limitations (limited exercise capacity).

Mediastinitis is a potentially life-threatening complication of cardiac surgery, and is associated with prolonged hospitalisation, increased cost of care, significant morbidity and an increase in short and long-term mortality.⁵ Multiple risk factors have been identified as predictors of sternal wound infections and include obesity, diabetes and the use of bilateral internal mammary artery grafts.⁶

Braxton et al.⁷ conducted a study in which they examined the survival of 15,406 consecutive patients undergoing isolated CABG surgery from 1992–1996; mediastinitis occurred in 193 patients (1.25%). After multivariate adjustment for the risk factors, the first year post-CABG survival rate was 78% with mediastinitis and 95% without mediastinitis; and the hazard ratio for mortality during the entire follow-up period was 3.09 (95% confidence interval 2.28–4.19; p<0.0001).

Conclusion

In this report we highlight that radical sternectomy without reconstruction may be compatible with near-normal quality of life and is associated with anatomical changes to the chest wall due to remodelling.

Reflective questions

• Could more have been done at the time of the original presentation with reconstructive surgery?
• How does lack of patient adherence complicate providing optimal care?
• Is there anything more that can be offered to this patient?