A rare cause of chest pain: spontaneous sternum fracture

Introduction

Three to eight percent of the patients admitted to Emergency Departments with chest trauma have sternum fractures. Spontaneous sternum fracture is a rare condition which can be seen especially among patients with known risk factors such as osteoporosis or multiple myeloma (1). Diagnosis and observation are important because it can be a sign of cardiac injury. We have discussed that spontaneous sternum fracture can be the diagnosis of patients admitted to Emergency Departments with chest pain and gone through the underlying causes.

Case presentation

An 80-year-old female patient presented to the Emergency Department with chest pain. Patient described the pain as a sudden onset sharp pain radiating through the chest. The patient was admitted to a hospital the day before with the same type of chest pain and a serial follow up tests of cardiac marker enzymes and a posteroanterior chest X-ray were obtained, both interpreted as normal.

The patient’s vital signs were stable at admission to the Emergency Department, with a blood pressure of 135/75 mmHg, pulse rate: 85/min, respiratory rate: 13/min, SpO₂: 99%, temperature: 36.5 °C. An ECG test is obtained and interpreted as normal. Medical history of the patient showed hypertension and coronary artery disease, without coronary angiography. She had no lifestyle risk factors; including cigarette smoking, or alcohol consumption. Skin screening after full exposure of the chest did not show any abnormal signs. Auscultations of the heart and respiratory system were normal. Patient suffered from pain with the palpation of the sternum. Hemogram, cardiac marker enzymes (troponin T and creatine kinase), coagulopathy tests were measured. Posteroanterior and lateral chest X-rays of the patient were taken. Lateral chest X-ray (Figure 1—right) showed displaced fracture line on the sternum while posteroanterior chest X-ray (Figure 1—left) showed no pathological signs. CT scan of the chest showed the fracture lines clearly (Figure 2). Blood test results were normal. Troponin T level was <0.003.

Figure 1 Posteroanterior (left), and lateral (right) chest X-rays of the patient. Fracture line is marked with red circle.

Figure 2 Chest CT scan images of the patient. Fracture line marked with arrows, and can be clearly seen in multiplanar reconstruction view (right).

The patient was discharged after a short period of observation, with analgesics for pain relief, and planned to be treated as outpatient.

Discussion

We describe a case of spontaneous sternum fracture in an 80-year-old female with no known risk factors related to fracture and no medical history of fractures.

Fractures of the sternum have been mainly reported as resulting from trauma, specifically due to traffic accidents, secondary to malignancy, myeloma and rarely secondary to osteoporosis compounded by thoracic kyphotic deformity without any trauma. The latter fracture was defined as an “insufficiency fracture of the sternum” (2).

Stress fractures which occur due to repetitive minor trauma, and its subtype insufficiency fractures which occur in bones with decreased mechanical strength and pathological fractures can be classified as “spontaneous sternum fractures” (3). All diseases that induce osteoporosis are prone to develop insufficiency fractures. Huang et al. analyzed 17 cases of post-menopausal women who had sternal insufficiency fractures. They found that all cases had osteoporosis as suspected and 13 cases had thoracic vertebral fractures. Other associated diseases were chronic obstructive pulmonary disease (7 cases), rheumatoid arthritis (3 cases), systemic lupus erythematosus (1 case) and asthma (1 case) (4).

The spine, pelvis, and lower extremities are commonly affected by insufficiency fractures. Horikawa et al. found that there were only 41 cases of insufficiency sternum fractures reported in the literature as of 2007 (2). Our literature review shows that there are 68 cases of spontaneous sternum fractures, including this case (2,3,5-14) (Table 1). Fifty-four (79.4%) of these cases were females. Forty-six (67.6%) of them presented with chest pain mimicking Myocardial Infarction. Ages of the patients were ranged between 31 and 88. Osteoporosis was seemed as the associated condition for most of the cases, while corticosteroid therapy for different illnesses was the associated condition for relatively younger patients. While osteoporosis, and corticosteroid therapy are easy to be thought of as associated conditions; there are some more eye-catching conditions: Stubert and Gerber reported a case of a young patient who had atraumatic sternum fracture while spontaneous delivery (15), and Aleskerov et al. reported an atraumatic sternum fracture secondary to forceful coughing (11). Most of the spontaneous sternum fractures which are presented in the literature occurred in the sternal body as seen in our case (3).

Table 1 Sex, age and associated conditions of spontaneous sternum fractures reported in the literature
Full table

Although spontaneous sternum fracture is rare as a diagnosis for patients presented to the Emergency Departments with chest pain, they can mimic cardiac and pulmonary emergencies, and it is important to consider this in the differential diagnosis (2). However, on the contrary, chest pain is the most common presentation of sternum fractures (16). Perez et al. argued that increase in the availability of the CT scans around the globe increased the frequency of sternum fracture diagnosis (17).

In the literature; the ribs, sternum, and vertebrae have been described as the most important stabilizing structures of the thorax. Some resources listed sternocostal joints as a fourth structure. Failure of one of these structures puts additional stress on the others and causes insufficiency fractures (18,19). These fractures may cause cardiac injuries which can be fatal (20).

Regular lateral sternum X-ray imaging is sufficiently enough to diagnose sternum fractures. For the patients with a normal ECG, and normal cardiac marker enzyme levels; a short observation period at the emergency department is sufficient, and hospitalization is not needed (3).

Conclusions

It is important to remember that sternum fracture with unidentified etiology is one of the rare causes of chest pain. They can mimic cardiac and pulmonary emergencies and should be in the differential diagnosis of chest pain, especially for elderly patients even if they aren’t diagnosed with osteoporosis. Lateral chest X-ray is sufficient in diagnosis but sometimes this imaging method can be neglected or hard to obtain due to patient’s discomfort during the initial evaluation of the cases with chest pain. For these patients, chest CT scan is an effective method in diagnosis.

Acknowledgements

None.

Footnote

Conflicts of Interest: The authors have no conflicts of interest to declare.

Informed Consent: The patient has given consent for this case report to be published.

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