Hemodynamics of the femoral head
Launder, W.J.; Hungerford, D.S.; Jones, L.H.
Journal of Bone and Joint Surgery. American Volume 63(3): 442-448
1981
ISSN/ISBN: 0021-9355 PMID: 7204444 Document Number: 174021
Pressure-flow relationships of the canine femoral head were determined during venous tamponade of the hip capsule. Intra-osseous pressures were determined before and after infusion of the joint with saline solution to a pressure of 65 cm H2O. Femoral head blood flow was simultaneously determined by the indicator-dilution technique utilizing isotopically labeled microspheres. In puppies pressure in the femoral head rose 248% while flow dropped by 60% after inflation of the capsule. In adults no statistically significant change in pressure or flow was seen. In the immature animal venous tamponade results in increased pressure and decreased blood flow. In the mature animal venous tamponade does not alter intra-osseous pressures or blood flow rates due to the intact intramedullary venous drainage of the adult femoral head. In the immature patient venous tamponade may well be involved in the development of Legg-Perthes disease. A bout of non-specific synovitis may elevate intracapsular pressure sufficiently to obstruct venous outflow. This creates an increase in intra-osseous pressure and a decrease in femoral head flow flow. Hemodynamic changes of this magnitude do not induce Legg-Perthes disease, but such alterations may be linked to the disease. In the adult venous tamponade probably is not involved in the pathogenesis of avascular necrosis. The maintenance of intramedullary venous drainage of the epiphysis into the metaphysis may explain why avascular necrosis of the femoral head rarely develops in adult patients with osteoarthritis or rheumatoid arthritis plus an inflammatory synovitis of the hip.