Radiation-induced rib fracture

Radiation-induced rib fractures refer to the occurrence of rib fractures following administration of radiotherapy to the region close to a rib or within a path of a rib. They are considered pathological fractures, as they happen in underlying abnormal bone affected by radiation therapy. Please note that this article is focusing on ribs not affected by metastatic disease.

Epidemiology

They are considered a relatively common occurrence, especially after hypofractionated stereotactic body radiation therapy (SBRT) , used for mediastinal or lung malignancies, but they can also occur with external beam radiotherapy to the breast.

Pathology

The toxic effects of radiation reduce osteoblast function and, therefore, decrease bone matrix production . The bones within the radiation portal become weaken, particularly if the primary tumor irradiated is close to the chest wall, and are more prone to fractures.

Another complication affecting the bony thoracic cage is osteoradionecrosis , which may also lead to fractures.

The diagnosis could be considered in the appropriate clinical context where there is rib fracture seen on follow up CT scans following external radiation to the thorax in the absence of surgery, trauma or metastases.