Sudden Back Pain in an Older Man: Distinguishing Benign from Pathological Fracture
A 74-year-old man presents with acute mid-thoracic back pain after lifting a box. He has a history of hypertension and gout, and takes allopurinol. He has no known malignancy. Examination shows focal tenderness at T8 with no neurological deficit. A plain radiograph shows a wedge compression fracture of T8 with about 40% height loss. Blood tests show a haemoglobin of 118 g/L, calcium 2.42 mmol/L (upper limit of normal), and a total protein slightly elevated. The radiographer suggests a follow-up radiograph in six weeks. The emergency physician asks whether this is simply osteoporotic and whether imaging can wait.
1. Identify the features that make a benign osteoporotic fracture more or less likely, and explain the significance of the normal calcium and mild anaemia.
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Features favouring a benign osteoporotic fracture include the mechanical trigger, the wedge morphology, the absence of neurological deficit, and the absence of known malignancy. Features that lower confidence include the absence of documented osteoporosis or prior fragility fracture, the mid-thoracic level (T8 is a common site for both osteoporotic and pathological fractures), and the mild anaemia, which is non-specific but can accompany myeloma or a marrow-replacing metastasis. A normal calcium does not exclude malignancy; myeloma classically causes hypercalcaemia but is often normocalcaemic, and many solid tumour metastases are normocalcaemic. The slightly elevated total protein raises the possibility of a paraprotein and warrants serum protein electrophoresis and free light chains. The key judgement is that a single radiograph cannot reliably distinguish acute osteoporotic from pathological fracture, and the patient's age and anaemia justify further investigation rather than simple observation.
2. What imaging would you arrange, and how would you interpret the findings to distinguish benign from malignant causes?
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I would arrange MRI of the thoracic spine with and without contrast. MRI distinguishes acute from chronic fracture by marrow oedema, and helps differentiate benign from pathological fracture by the pattern of signal abnormality. Benign osteoporotic fractures typically show a band-like area of oedema parallel to the endplate, preservation of the posterior cortex, and no soft-tissue mass. Pathological fractures more often show complete replacement of the vertebral body, convex posterior border, epidural or paraspinal soft tissue, and involvement of the pedicle. Contrast can help show enhancing tumour tissue. If MRI is unavailable or equivocal, CT assesses cortical destruction and pedicle involvement. I would also arrange serum protein electrophoresis, free light chains, and a staging CT if malignancy is suspected. A follow-up radiograph in six weeks is inadequate because it delays diagnosis and does not assess the spinal canal or soft tissues.
3. If MRI shows a pathological fracture with epidural soft tissue at T8, what are the immediate priorities?
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The immediate priorities are to assess for cord or cauda equina compromise, obtain urgent neurosurgical or spinal surgical review, and start corticosteroids if there is cord compression, while arranging staging to identify the primary. A pathological fracture with epidural soft tissue at T8 requires urgent MRI of the whole spine to identify other levels, and CT of chest, abdomen, and pelvis plus a myeloma screen to identify the underlying cause. Analgesia and discussion of vertebral augmentation or stabilization depend on the degree of collapse and neurological status. The patient should be discussed at a multidisciplinary meeting including oncology, and the family should be involved in discussions about prognosis. The key point is that a pathological fracture with epidural disease is a time-critical finding, and the initial suggestion of a six-week radiograph would have been unsafe.