[A biomechanical study in the repairing process of avascular necrosis of the femoral head in dogs].
We report the result of an animal experiment studying the biomechanical, radiological and histological changes during the repairing process of avascular necrosis of the femoral head. At 1/2 month, histology showed complete necrotic changes involving both marrow content and bone trabecula. However, biomechanical tests showed there was no significant difference in material properties between experimental and control sides. A2 2 and 4 months, reparative changes were observed by histology and radiography. The decrease in mean compressive strength in the subchondral bone was 17.5% at 2 months and 35.5% at 4 months. Subchondral bone mean modulus of elasticity decreased by 25.1% at 2 months, 43.0% at 4 months. Greater decrease in mean strain energy in the cancellous bone occurred at 2 months (43.2%) and 4 months (42.9%). In the 6 months group, all necrotic femoral heads showed varying degrees of collapse. The compressive strength and the modulus in the subchondral bone decreased by 73.3% and 76.9% respectively. The strain energy in the cancellous bone decreased by 37.9%. The present study indicates that the biological resorptive cativity of the advancing reparative processes may lead to significant decrease in the mechanical properties. This is probably the most direct cause of late femoral head collapse.
Wang
J X
JX
First Affiliated Hospital of Suzhou Medical College.
D000818:Animals; D001696:Biomechanical Phenomena; D004285:Dogs; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D011859:Radiography