Abstract
The range of motion of the hip was analyzed clinically and radiographically after joint replacement with the Bateman UPF prosthesis. A smaller range of motion was obtained with it than with the conventional Austin Moore-type prosthesis, Thompson-type prosthesis, or a prosthesis for total replacement.
In vivo observation of the prosthesis with a image intensifier reviealed that relative motion between the inner head and the bearing insert took place first, and secondarily after the prosthetic neck impinged against the rim of the outer head and acetabulum.
The relative motion along the two bearing surfaces was found to be smaller than expected, due to the scar tissue formed around the prosthesis.
The position of the outer head showed large variation among the implanted prostheses, and a smaller range of motion in hip abduction and flexion was observed in patients with valgus and a retroverted position of the outer head, while a larger range of motion was obtained with varus and an anteverted position of the outer head.
The position of the outer head was controllable by managing the hip position after joint replacement.
