Pathological fracture risk (Mirels classification)
Mirels classification is a system used to predict the highest risk of pathological fracture among long bones affected by metastases, and is based on site, location, matrix and/or presence of pain.
Classification
- 1 point
- upper limb
- involving <1/3 of bone diameter
- blastic/sclerotic lesion
- mild pain
- 2 points
- lower limb
- involving 1/3-2/3 of bone diameter
- mixed sclerotic/lytic lesion
- moderate pain
- 3 points
- trochanteric region
- involves >2/3 of bone diameter
- lytic lesion
- functional pain
This will give a minimum score of four and a maximum score of 12. A score of ≥9 suggests that prophylactic fixation should be performed . For score 8 lesions, treatment is based on clinical judgment and for lower scores clinical management and radiotherapy is suggested. The overall sensitivity of the Mirel classification predicting fracture is ~90% but specificity is only 35% (meaning there will be unnecessary fixations) leading to debate about its usefulness .
History and etymology
Hilton Mirels (fl. 2019), a South African-born, American orthopedic surgeon, practising in New York State, described his proposed scoring system in an article published in 1989 .