Orthopaedic perspective on bone metastasis

Table 1 Mirels classification of metastatic bone lesions

Variable	Score
	1	2	3
Site	Upper Limb	Lower Limb	Peritrochanter
Pain	Mild	Moderate	Functional
Lesion	Blastic	Mixed	Lytic
Size	< 1/3	1/3-2/3	> 2/3

Table 2 Capanna classification, classification according to tumour type

Classification according to tumour type
Class 1	Solitary metastatic lesion
	Primary with good prognosis
	Interval after primary over 3 years
Class 2	Pathological fracture at any site
Class 3	Impending fracture in a major weight bearing bone
Class 4	Osteoblastic lesions at all sites
	Osteolytic or mixed lesions in non-structural bones
	Osteolytic lesion with no impending fracture in major weight-bearing bone
	Lesions of the iliac wing, anterior pelvis or scapula

Table 3 Capanna classification, potential survival

Survival	Sources of metastasis
< 1 yr (1 point)	Unknown Primary
	Melanoma
	Lung
	Pancreas
	Thyroid (undifferentiated)
	Stomach
1-2 yr (3 points)	Colon
	Breast (not responding to adjuvants)
	Liver
	Uterus (responding to adjuvants)
> 2 yr (6 points)	Thyroid (differentiated)
	Myeloma
	Lymphoma
	Breast (responding to adjuvants)
	Rectum
	Prostate
	Kidney

Table 4 Capanna classification, recommended surgical procedure and prosthetic type

Survival	Biomechanics	Size defect	Response to adjuvant therapy
< 1 yr = 1 pts	Tibia = 1pt	Small (1/3) = 1 pt	Yes = 0
1-2 yr = 3 pts	Femur, humerus = 2 pts	Large (1/2) = 2 pts	No = 3
> 2 yr = 6 pts	Subtrochanteric, supracondylar = 3 pts	Defective or pathological fracture = 3 pts
	< 5 points =	Minimal or simple osteosynthesis
	5-10 points =	Reinforced osteosynthesis
	10-15 points =	Megaprosthesis or intercalary spacer