[Experiences with the "Balgrist" cement-free, self-anchoring conical acetabular prosthesis--March 1982 to September 1988].

The advantage over other acetabular sockets for cementless fixation lies in the easier preparation of the acetabulum without endangering neighbouring structures, and in its self-locking ability which ensures firm fixation in the surrounding bone during the critical period of bone-remodelling which occurs during the first three months postoperatively. In over 90% of the 414 sockets, implanted over 6.5 years, with an average follow-up period of four years (3 to 78 months), we have had, clinically and radiologically, good results. Loosened sockets (3.6%) were observed with those made of polyethylene during the early stages mainly due to inadequate experience in implanting them. The titanium model which has been exclusively used from november 1987 has shown no signs of instability neither in the case of primary or revision sockets.