Trochanteric intra-osseous venography in femoral neck fractures in the dog.

This study of the healing of femoral neck fractures in dogs clearly indicates: 1. that the restoration of the intra-osseous flow through the fracture site occurs first followed by the appearance of venous drainage in the medial femoral circumflex vein and the vein of the ligamentum teres. 2. That if the intra-osseous flow is restored to the head through the fracture callus, normal fracture healing will proceed. 3. That avascular necrosis following a femoral neck fracture is also dependant on fracture union, and 4. that the incidence of traumatic avascular necrosis can be minimised by adquate fracture treatment. Thus accurate reduction and rigid immobilisation of the fracture promotes early formation of good endosteal callus and the restoration of intra-osseous venous blood flow and so early fracture union. The diagnosis of avascular necrosis of the femoral head may be established by measuring the clearance time of contrast medium flowing into the head via the crossing veins. If the contrast medium is cleared rapidly by the draining veins, it suggests that the head is viable.