Pathologic Fracture

General Considerations

• By definition, a fracture that occurs through bone which was previously abnormal
• Most frequent through a metastatic lesion or multiple myeloma
• May also involve enchondroma, unicameral bone cysts
• Suspect when there is an avulsion fracture in an unusual location, spontaneous avulsion of lesser trochanter in adult
• May occur in osteoblastic as well as osteolytic metastases

Clinical Findings

• Acute pain without antecedent trauma
• Soft tissue swelling or mass which may pre-date fracture
• Most common primary sites are breast, prostate and lung

Imaging Findings

• Fracture line extending through a destructive lesion in the bone
• Usually transverse in direction
• Surrounding bone may demonstrate
• Endosteal scalloping
• Cortical destruction
• Permeative pattern
• Frequently associated with a soft tissue mass

• Chondroid or osseous tumor matrix

• MRI
• Decreased T1 marrow signal in lesion
• Soft tissue mass and infiltration of the muscle

Differential Diagnosis

• On MRI, non-pathologic fracture-related hematoma
• Insufficiency fractures are seen with osteoporosis, not associated with a visible focal abnormality
• Fatigue fractures occur with repetitive stress in normal underlying bone

Treatment

• If the bone is weight-bearing, such as the femur, intramedullary rodding is frequently used
• Radiation if lesion is radiosensitive
• While radiation may help pain, it may also delay osseous healing
• Cement or bone graft may be used to fill a significant defect

Pathologic Fracture of Humerus. There is a permeative, lytic, and destructive lesion (black arrows) in the midshaft of the humerus with endosteal scalloping. There is a transverse pathologic fracture (white arrows) through the lesion.
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Pathologic Fracture of Femur. There is a permeative, lytic, and destructive lesion in the proximal femur with endosteal scalloping. There is a transverse pathologic fracture through the lesion.

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Pathologic Fracture. E. David Weinberg, M.D. February 1931 Radiology, 16, 282-287.

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