|Text in Italics is general (instructional) information|
X ray detail
The X rays of the distal femur show a poorly defined sclerotic region in the distal shaft and supracondylar metaphysis. There are no aggressive features such as periosteal reaction or bone destruction.
The nature of a bone infarct changes with the site of involvement:-
Diaphysometaphyseal infarction: due to infection, vasculitis, sickle cell disease, pheochromocytoma, other vascular disease, Gaucher’s disease, pancreatitis, idiopathic, decompression sickness (historically)
Epiphysometaphyseal infarction: same as above, also fractures and dislocations, corticosteroids for collagen vascular diseases, thromboembolic disease, systemic lupus erythematosus, rheumatoid arthritis, Langerhans cell histiocytosis, osteochondrosis
Medullary infarcts: patchy necrosis involving cancellous bone and marrow; cortex has collateral blood flow
Subchondral infarcts: wedge shaped; cartilage remains viable since nutrients are present in synovial fluid
Sites: femoral head or other convex articular surfaces (see aseptic bone necrosis above)
Xray: no changes until third week; then reduced density in areas of dead bone and increased density due to new bone formation; changes appear irregular / mottled; thick, serpentine border
Treatment: Routine biopsy is not advised for an infarct in the metaphyseal region, if a diagnosis can be clearly made on clinical and imaging studies. Another problem with biopsy is that the surrounding bone is dead and stress fracture may occur at the biopsy site as there is little or no healing of the biopsy defect.