Results of the Total Hip Prosthesis Design "St. George"

The following statistical investigations deal with the operations carried out from November 1964 to the end of the year 1971. Late results are on operations performed up to the end of 1967. For provisional results, we evaluated the operations from 1968 to 1971. The arithmetical evaluations were derived from an IBM computer 360/65 and 360/75, to which the cardindex concerning the total prostheses was converted. The operations were performed exclusively with a prosthesis named the St. George Design in honor of our hospital. Up to October 1968 we used the Wittebol prosthesis with a head diameter of 38 mm. After 1968 we inserted our own design with a longer neck and various sizes of the shaft without anteversion, but with the same size head.1 We first used a socket manufactured from a polymerization product of formaldehyde. It could be sterilized, but did not have sufficient resistance to wear, and furthermore it only lasted for 5 years. After performance of 20 operations we changed to a socket of a hemispherical shape made of high density polyethylene. There is a difference in circumference of I mm between the diameter of the socket and the head. In October 1968 this socket was supplied with an arched recess in the ventro-medial part in order to protect the tendon of the ileopsoas muscle and the femoral nerve and to guarantee the ability of flexion of more than 90° without dislocation of the prosthesis.2, 8, 9, 13