Ultrastructural investigation of traumatic avascular necrosis of femoral-head.
OBJECTIVE: To investigate ultrastructurally into traumatic avascular necrosis of femoral head. METHODS: Femoral heads were procured during endoprosthetic replacement for 8 cases of intracapsular fracture of femoral neck, which had been subjected to internal fixation and developed Stage II avascular necrosis. The specimens were processed and studied under transmission electron microscope. RESULTS: In the normal bone tissues of the avascular necrotic femoral heads, the collagen fibrils constituting the collagen bundles of the bone matrix were of uniform diameter, and were regularly arrayed with orientation. In the necrotic bone tissues of the avascular femoral heads, the collagen fibrils were of unequal diameter, and were haphazardly arrayed without orientation. From the trabeculae of the avascular femoral heads emerged three different conditions of osteocytes: (1) In the trabeculae of normal bone tissues, the osteocytes belonged to both degenerative phase and formative phase osteocytes with the latter showing signs of degeneration; (2) In the necrotic trabeculae, the osteocytes perished leaving behind empty lacunae; (3) Over the trabeculae of the interface region could be discerned many active osteogenic cells, which were on their way of transformation into osteoblasts. In the trabeculae here, the osteocytes belonged to both formative phase and degenerative phase osteocytes. CONCLUSIONS: These results suggest that in the femoral heads with traumatic avascular necrosis, there is active osteogenetic activity around the necrotic bone tissues, amply implying a local reparative response following partial bone necrosis.
Chai
Benfu
B
Shanghai Institute of Traumatology and Orthopaedics, Shanghai 200025, China.
Tang
Xueming
X
Li
Hui
H