Insufficiency fracture of the sternum caused by osteopenia: plain film findings in seven patients

Sternal stress fracture presenting as acute chest pain

Sternal fractures are rare and are typically caused by major trauma such as motor vehicle collisions. However, sternal insufficiency fractures can occur with minimal to no trauma in patients with exaggerated thoracic kyphosis from multiple thoracic compression fractures, especially in the setting of osteoporosis. We describe a case of a sternal insufficiency fracture that presented as chest pain resembling a myocardial infarction. As sternal insufficiency fractures may vary in clinical presentation, this case demonstrates that radiologists should carefully evaluate the sternum, especially when risk factors are present. Furthermore, awareness and identification of these fractures can prevent unnecessary cardiac workups.

Machine learning for the prediction of osteopenia/osteoporosis using the CT attenuation of multiple osseous sites from chest CT

PURPOSE

To use machine learning and the CT attenuation of all bones visible on chest CT scans to predict osteopenia/osteoporosis.

METHOD

We retrospectively evaluated 364 patients with CT scans of the chest, and Dual-energy X-ray absorptiometry (DXA) scans within 6 months of each other. Studies were performed between 01/01/2015 and 08/01/2021. Volumetric segmentation of the ribs, thoracic vertebrae, sternum, and clavicle was performed using 3D Slicer to obtain the mean CT attenuation of each bone. The study sample was randomly split into training/validation (80 %, n = 291 patients) and test (20 %, n = 73 patients) datasets. Univariate analyses were used to identify the optimal CT attenuation thresholds to diagnose osteopenia/osteoporosis. We used penalized multivariable logistic regression models including Least Absolute Shrinkage and Selection Operator (LASSO), Elastic Net, and Ridge regression, and Support Vector Machines (SVM) with radial basis functions (RBF) to predict osteopenia/osteoporosis and compared these results to the CT attenuation threshold at T12.

RESULTS

There were positive correlations between the CT attenuation between all bones (r > 0.6, P < 0.001 for all). There were positive correlations between CT attenuation of the bones and the L1-L4 BMD T-score, total hip T-score, and femoral neck T-scores (r > 0.4, P < 0.001 for all). A CT attenuation threshold of 170.2 Hounsfield units (HU) at T12 had an AUC of 0.702, while a threshold of 192.1 HU at T4 had an AUC of 0.757. The SVM with RBF had the highest AUC (AUC = 0.864) and was better than the LASSO (P = 0.011), Elastic Net (P = 0.011), Ridge regression (P = 0.011) but was not better than using the CT attenuation at T12 (P = 0.060).

CONCLUSIONS

The CT attenuation of the ribs, thoracic vertebra, sternum, and clavicle can be used individually and collectively to predict BMD and to predict osteopenia/osteoporosis.

Uncommon cause of chest pain in a postoperative spinal patient

An 84-year-old woman with previous spinal operations including vertebroplasty and lumbar decompressions was admitted electively under the spinal team for right-sided L4/5 decompression for worsening back pain which she undergoes using a posterior approach. Postoperatively, she develops stabbing upper central chest pain and given unremarkable chest X-ray, ECG and cardiac troponin, she undergoes a CT pulmonary angiogram which shows a fracture of the upper part of sternum but no pulmonary embolism. There is no history of recent trauma and this is deemed to be secondary to prolonged spinal surgery in the prone position in a patient with osteopenic bones. To date, we have not come across a case of spontaneous sternal fracture as a complication of spinal surgery at our regional spinal unit. Most cases of sternal fractures are secondary to blunt anterior chest wall trauma with spontaneous fractures and stress fractures being rare.

Atraumatic sternum fracture

The spine, pelvic bones and long bones of the lower extremities are common sites for insufficiency fractures. Cases of sternum insufficiency fractures have rarely been reported among elderly patients. Insufficiency fractures tend to occur in bones with decreased mechanical strength especially among elderly patients, in postmenopausal women and patients with underlying diseases. We describe a case of spontaneous sternum insufficiency fracture in a healthy man, with no known risk factors to fracture, or previous history of fractures. Sternum insufficiency fracture is a rare cause of chest pain. This case serves to remind the emergency physician to remain vigilant for other non-cardiac, non-pulmonary and non-traumatic causes of chest pain, especially among patients with known risk factors such as osteoporosis, chronic obstructive pulmonary disease, rheumatoid arthritis, systemic lupus erythematosus and patients on long-term steroid treatment. If diagnosed correctly, these patients can be discharged and treated as outpatients as this case emphasises.

Biomechanical contribution of the rib cage to thoracic stability

STUDY DESIGN

In vitro assessment of rib cage biomechanics in the region of true ribs with the ribs intact then sequentially resected in 5 steps.

OBJECTIVE

To determine the contribution of the rib cage to thoracic spine stability and kinematics.

SUMMARY OF BACKGROUND DATA

Previous in vitro studies of rib cage biomechanics have used animal spines or human cadaveric spines with ribs left unsecured, limiting the ability of the ribs to contribute to stability.

METHODS

Eight upper thoracic specimens that included 4 ribs and sternum were tested in special fixtures that disallowed relative movement of the distal ribs and their vertebrae. While applying 7.5 Nm pure moments in 3 planes, angular motion at the middle motion segment was studied in intact specimens and then (1) after splitting the sternum, (2) after removing the sternum, (3) after removing 50% of ribs, (4) after removing 75% of ribs, and (5) after disarticulating and completely removing ribs.

RESULTS

During flexion/extension, the sternum and anterior rib cage most contributed to stability. During lateral bending, the posterior rib cage most contributed to stability. During axial rotation, stability was directly related to the proportion of ribs remaining intact. On average, intact ribs accounted for 78% of thoracic stability. An intact rib cage shifted the axis of rotation unpredictably, but its position remained consistent after partial resection of the ribs. During lateral bending, coupled axial rotation was mild and unaffected by ribs.

CONCLUSION

Because of testing methodology, the rib cage accounted for a greater percentage of thoracic stability than previously estimated. Different rib cage structures resisted motion in different loading planes.

Multidetector CT scan in the evaluation of chest pain of nontraumatic musculoskeletal origin

Acute nontraumatic chest pain is a common presenting symptom to the emergency department. Often, it is evaluated by MDCT with PE, aortic dissection, or coronary artery protocols. The parameters used for these MDCT protocols are very similar to those used in protocols for dedicated imaging of the musculoskeletal system. Thus, these studies are not only effective in evaluating for these traditional vascular causes of chest pain, but also in evaluating musculoskeletal causes of chest pain, including those of infectious, rheumatologic, and systemic causes. In essence, every MDCT of the chest is also a musculoskeletal examination of the chest and anyone interpreting these images must be familiar with the MDCT-imaging appearance of common musculoskeletal causes of acute nontraumatic chest pain.

Sternal fractures

Sternal fractures are relatively common and range from simple unicortical cracks to displaced fractures associated with life threatening injuries. This paper describes the relevant anatomy, biomechanics, mechanism of injury, clinical presentation, investigation, treatment and complications and also includes associated and concomitant injuries. A management flow chart including criteria for discharge from the emergency department is presented.

Fracture of maternal sternum during spontaneous delivery

We report of a maternal sternal fracture during a spontaneous delivery in a 31-year-old primipara without a suitable trauma. The putative mechanism of fracture was strong hyperflexion of the thoracic spine and additional cervical flexion with pushing the chin to the thorax due to active management of labour. The history of the healthy woman was free of related risk factors. A possible promoting factor might be pregnancy-induced bone loss. Although there were clear symptoms, the diagnosis of the fracture was delayed by a week because nobody took account of such a possibility.

Fractures of the upper transthoracic cage

We have reviewed our experience in managing 11 patients who sustained an indirect sternal fracture in combination with an upper thoracic spinal injury between 2003 and 2006. These fractures have previously been described as 'associated' fractures, but since the upper thorax is an anatomical entity composed of the upper thoracic spine, ribs and sternum joined together, we feel that the term 'fractures of the upper transthoracic cage' is a better description. These injuries are a challenge because they are unusual and easily overlooked. They require a systematic clinical and radiological examination to identify both lesions. This high-energy trauma gives severe devastating concomitant injuries and CT with contrast and reconstruction is essential after resuscitation to confirm the presence of all the lesions. The injury level occurs principally at T4-T5 and at the manubriosternal joint. These unstable fractures need early posterior stabilisation and fusion or, if treated conservatively, a very close follow-up.

Sternum insufficiency fracture presenting as acute chest pain: a case report and review of the literature

The spine, pelvic bones and long bones of the lower extremities are common sites for insufficiency fractures. Cases of sternum insufficiency fractures have been rarely reported in an elderly patient. Insufficiency fracture tends to occur in bones with decreased mechanical strength. It tends to occur in elderly patients, especially in postmenopausal women, with underlying diseases. We describe a case of sternum insufficiency fracture in a patient with rheumatoid arthritis and systemic lupus erythematosus on long-term corticosteroid therapy diagnosed in an emergency setting. Sternum insufficiency fracture is a rare cause of chest pain. This case serves to remind the emergency physician to remain vigilant for other noncardiac and nontraumatic causes of chest pain. If diagnosed accurately, these patients can be discharged and treated as outpatients.

Insufficiency fractures of the sternum

Insufficiency fractures occur within weakened bones that are unable to withstand the stress of every day normal activities. The spine, pelvis, and lower long-bone extremities are common sites of insufficiency fractures. Spontaneous sternal insufficiency fracture (SIF) has rarely been reported in elderly patients. To recognise a sternal insufficiency fracture is important in selecting the adequate diagnostic procedures.

Association of posterior rib fractures with exaggerated kyphosis and sternal collapse

The ribs, sternum, and vertebrae all play an important role in stabilizing the thorax. Failure of one of these components places additional stress on the other supporting structures. We present a case of a 62-year-old man with multiple myeloma and osteopenia who sustained fractures to all three components.

A case of sternal insufficiency fracture

We report a case of insufficiency fracture of the sternum in a 70-year-old female patient with a review of the literature. She complained of sudden onset chest pain and aggravating dyspnea. She has been managed with corticosteroid due to chronic obstructive pulmonary disease for 15 years. Diagnosis of sternal insufficiency fracture presented with thoracic kyphosis was made on the basis of absence of trauma history, radiologic findings of lateral chest radiograph, bone scintigraphy and chest computed tomography. Thoracic kyphosis and osteoporosis secondary to menopause, corticosteroid therapy and limited mobility due to chronic obstructive pulmonary disease were considered as predisposing factors of the sternal insufficiency fracture in this patient.

Insufficiency stress fractures

Bones weakened by osteopenia have insufficient elastic resistance to withstand even the minimal mechanical stresses of normal daily activity. Repetitive subthreshold injury to these susceptible bones results in insufficiency-type stress fractures. The spine, pelvis, and lower extremities are commonly affected by these fractures. Insufficiency fractures create a diagnostic challenge for clinicians and radiologists alike. The radiographic evidence of the fracture is often so subtle that it escapes detection. Conversely, findings on other studies may be so striking that they suggest metastatic disease. Insufficiency fractures are often subjected to unnecessary biopsies, and they have been treated unwittingly with chemotherapy and radiation therapy. Radiologists are in a key position to prevent these errors. A thorough familiarity with the characteristic appearance and location of these fractures assures the correct diagnosis.