PAST LETTERS FROM THE PRESIDENT
Depts.
of Orthopaedics, *Aarhus University Hospital, Denmark, and +University
Hospital Kiel, Germany
wolfdrescher@hotmail.com
In the pathogenesis of steroid induced femoral head necrosis only intra-
and extravascular factors have been discussed. This study investigates
the effect of long term glucocorticoid treatment on contraction of intraosseous
femoral head arteries in a porcine model.
From 24 immature female Danish Landrace pigs from 12 litters, 12 animals received 100 mg methylprednisolone daily for 3 months. Their 12 sister pigs served as controls and received no steroid. Resistance arteries (diameter approximately 250 µm) were isolated from the femoral head epiphyseal cancellous bone and mounted as ring preparations on a small vessel myograph for measurement of isometric force development.
Increasing doses of endothelin-1 evoked significantly stronger vasoconstriction after 3 months of methylprednisolone treatment. The vasocontractory response to increasing doses of noradrenaline was not altered by the previous methylprednisolone treatment. After submaximal precontraction by noradrenaline, vasorelaxation by bradykinin was not altered by methylprednisolone treatment.
The vasocontractory response of isolated intraosseous femoral head epiphysial arteries to endothelin-1 after long term glucocorticoid treatment in the pig is enhanced. Enhanced contraction of FH lateral epiphyseal arteries can diminish femoral head blood flow as vessel diameter decreases. This may be a relevant cofactor in the early pathogenesis of steroid induced femoral head necrosis.