My knee hurts

A 45 y.o.  female presents with knee pain

 Our patient had a bone infarct.  These often occur at shoulder , knee , talus, scaphoid, and hip.  When it occurs in children at the hip  it is known as Legg-Calve-Perthes disease. 

Legg calve perthes on the R

 It begins with normal appearing xraysand in later stages appears more radiopaque as marrow fat calcifies after medullary infarcts.  This central lucency surrounded by sclerosis with a serpiginous border is described as “smoke up a chimney.”  It is often diagnosed on MRI where the key feature is that central signal remains of normal marrow with peripheral low signal due to granulation tissue or sclerosis on T1 while  T2  images may show an acute infarct.


There are many causes for bone infarcts. Although it can often by an incidental finding with no pain; when the bone infarcts lead to collapse of the cortex, the infarcts are painful. 

In our patient,  the infarct was painful and she was referredto ortho.    Her infarcts were thought to be secondary to alcoholism. Treatments include core decompressionwith implantation of a living bone chip and an electrical device to stimulate new growth or a free fibular graft in which part of the femur and its blood supply  are transplanted.



 Jacob MA, Loeb PE. Core decompression of the distal femur for avascular necrosis of the knee. 1989 Journal of bone and jointsurgery. British volume 71 94), 583-7.

Simkin PA, Franey DO. Roman arches, human joints and disease: differences between convex and concave sides of joints.  Arthritis Rheum 1980;23:1308-1311.

Judet H, Gilbert A. Long term results of free vascularized fibular grafting for femoral head necrosis. 2001. Clinical orthopaedics and related research 386(386) 114-9