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Bone metastases and pathological fracture
Metastases are the most common malignant tumour of bone in adults; the goals are to control pain, prevent fracture with prophylactic fixation when the risk is high, and recognise spinal cord compression as an emergency.
Why it matters in the exam
Questions present a patient older than 40 with bone pain and a lytic lesion, or a patient known to have cancer with a fracture from minor trauma, and ask for the next step. The five main sources are breast, prostate, lung, kidney and thyroid, and the common sites are the spine, pelvis and proximal femur. Prostate metastases usually form sclerotic (blastic) lesions, whereas kidney and thyroid metastases are lytic and highly vascular — so embolisation is advised before surgery on a renal metastasis. In multiple myeloma the bone scan may be normal, so low-dose whole-body CT or MRI is used. When the primary is unknown and a solitary lesion is found, it must not be fixed before work-up, because it may be a primary sarcoma that an intramedullary nail would spread. The decision on prophylactic fixation of a long bone is helped by the Mirels score, which weighs site, pain, lesion type and size: a score of 9 or more justifies prophylactic fixation. After fixation, radiotherapy is given to the whole implant area, and drugs such as bisphosphonates or denosumab reduce skeletal events. A patient with back pain and leg weakness or sphincter disturbance is suspected of metastatic spinal cord compression: start dexamethasone, obtain MRI of the whole spine promptly and decide between stabilising surgery with radiotherapy or radiotherapy alone according to the patient's condition. Every surgical decision should also weigh the patient's expected survival, functional status and goals, because the aim of surgery is mainly pain relief and preserved mobility.
Key points
- Metastases are the most common malignant bone tumour in adults.
- Sources: breast, prostate, lung, kidney and thyroid.
- Mirels score 9 or more — prophylactic fixation followed by radiotherapy.
- Solitary lesion without a diagnosis — work-up and biopsy before fixation.
- Spinal cord compression — dexamethasone and urgent MRI.
Summary table
| Mirels component | 1 point | 2 points | 3 points |
|---|---|---|---|
| Site | Upper limb | Lower limb | Peritrochanteric region |
| Pain | Mild | Moderate | Functional (pain on weight-bearing) |
| Lesion type | Blastic | Mixed | Lytic |
| Size relative to cortex | Less than one third | One third to two thirds | More than two thirds |
| Decision | 7 or less — radiotherapy and observation | 8 — clinical judgement | 9 or more — prophylactic fixation |
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Sources
- Campbell's Operative Orthopaedics, 14th ed. (2021) — Metastatic Disease of Bone and Pathological Fractures
- Mirels H. scoring system, Clin Orthop Relat Res (1989) — Metastatic disease in long bones: a proposed scoring system
- NICE Guideline NG234, 2023 — Spinal metastases and metastatic spinal cord compression
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.
See also: Bone metastases — pain, fractures and bone-modifying drugs