A cementless system of total hip prosthesis. Experimental studies on total hip prosthesis in dogs.

It is essential that the prosthetic material should not be harmful to the human body, it should be strictly fitted to the body and it should have sufficient durability. To investigate those conditions of an artificial joints as mentioned above, it is important to have experimental studies using a model of the artificial joint in animals instead of a simulator. The authors have developed their own total hip prosthesis for a dog since 1970. These prostheses were fixed to the bone without bone cement. These dogs were killed periodically from 8 weeks to 3 years after surgery of total hip replacement. Not only were pathohistological studies on the joint capsule and bony tissue of the femur surrounding the prosthesis performed, but also scanning electron microscopic examination on capsule and the surface of the prosthetic head were performed. The results were excellent. Ther was no loosening or wear when the new type of acetabular socket with large spikes was used. On the other hand, in the case of the old type socket with its smooth surface and smaller spikes, loosening of the socket and prosthetic stem occurred within one year after surgery.