Prospective cohort study of six hundred and sixty four revisions of loose failed acetabular implants.

Abstract

The purpose of the study was to determine the optimal technique of revision surgery according to the deficiency of acetabular bone to ensure maximum survival of the implant and reduce the risk of complications. From January 1992 through May 2012, 664 revisions of failed acetabular total hip components were performed in the joint replacement department of the Moscow Central Scientific and Research Institute (CITO). The patients were divided into three major groups based on the type of the revision implant: group I--cemented polyethylene cups only, group II--acetabular cages and rings, and group III--non-cemented metal cups. In each of these groups, further subdivisions were made based on the Paprosky Classification of the acetabular defects. Failures were classified as early mechanical instability, chronic pain, and deep wound infection. The most satisfactory results--91% were obtained in patients of groups I and III with relatively minor bony acetabular defects (Paprosky classification types 1, 2A and 2B). The most unsatisfactory results--25% were in the cases with greater bone loss (Paprosky classification type 3B in group I and type 2C in group III)-of the unsatisfactory results. Infection was a significant problem in all the groups, but was the highest (8%) in group II. The study showed that the success of acetabular revisions was directly related to the severity of the bony defects at the time of the operation and to the reconstruction technique applied.