Mirel's classification to predict possible pathological fracture if boney metastasis

Last edited 01/2021 and last reviewed 01/2021

Mirels classification is a system used to predict the highest risk of pathological fracture among long bones affected by metastases

• 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 judgement and for lower scores clinical management and radiotherapy is suggested

 The overall sensitivity of the Mirel classification predicting fracture is approximately 90%

• however specificity is only 35%
• this means that there will be unnecessary fixations) leading to debate about its usefulness (1,3)

Reference:

• Jawad MU, Scully SP. In brief: classifications in brief: Mirels' classification: metastatic disease in long bones and impending pathologic fracture. Clin. Orthop. Relat. Res. 2010;468 (10): 2825-7
• Rockwood CA, Bucholz RW, M.D. CC et-al. Rockwood and Green's Fractures in Adults. Lippincott Williams & Wilkins. (2010) ISBN:1605476773
• Piccioli A, Spinelli MS, Maccauro G. Impending fracture: A difficult diagnosis. (2014) Injury. 45 Suppl 6: S138-41. doi:10.1016/j.injury.2014.10.038