Thirty-two patients in whom Legg-Perthes disease apparently involved
only one hip were examined with venography, measurement of intraosseous and
intra-articular pressures, arthrography, and dynamic triphasic bone-imaging
with 99mTc methylene diphosphonate. The arterial flow of blood in the
affected femoral head was slightly decreased, but the difference from that
on the normal side was not statistically significant. However, there was
marked disturbance of the venous drainage in the diseased hip, elevated
intraosseous pressure in the affected femoral neck, and increased
intra-articular pressure in the involved hip compared with the normal side.
An animal model was then created in twenty immature dogs, venous drainage
was obstructed, and intraosseous pressure of the femoral head and neck was
elevated by injection of four milliliters of semiliquid silicone into the
femoral neck. In eleven of the dogs, areas of avascular necrosis resembling
those associated with Legg-Perthes disease developed in the femoral
head.