Pathological fracture risk (Mirels classification)

Dr Daniel J Bell and Dr Henry Knipe et al.

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 1,2. 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 1,4.

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 6.

Bone tumours

The differential diagnosis for bone tumors is dependent on the age of the patient, with a very different set of differentials for the pediatric patient.

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Article information

rID: 40745
Synonyms or Alternate Spellings:
  • Mirels' score
  • Mirel's classification
  • Mirel score
  • Pathological fracture risk: Mirel's classification

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