What Characteristics of the Acetabular Defect Influence the Choice of the Acetabular Component During Revision Hip Arthroplasty?

The purposes of the retrospective cohort study were: 1) to determine the severity of defects in the acetabulum and the probable causes of their formation in patients who underwent revision hip arthroplasty (RHA), as well as an assessment of factors that exacerbate the severity of the defects; 2) identifying the proportion of severe defects in the overall structure of acetabular revisions and determining the effectiveness of using serial implants in comparison with individual constructions made by 3D printing; 3) the rationale for rational indications for the use of individual constructions. Materials and Methods. The structure and reasons for the formation of bone defects in the acetabulum were evaluated in 726 cases of revisions performed from 2004 to 2018. In addition, the results of revision operations in a group of patients with severe defects (type 3 according to Paprosky and pelvic discontinuity) were evaluated. Results. The most frequent cause of defect formation was iatrogenic (53.2%), and the share of severe defects was 39.5% (287 observations). A factor aggravating the severity of the defect is the lack of its limitation by the support bone. The results of RHA in patients with severe defects were assessed in 186 cases out of 287 (64.8%). In 73 (39.2%) cases, individual constructions were used, the average follow-up was 26 months. (from 12 to 50), and in 113 (60.8%) cases, serial implants were used, the average follow-up period was 62 months. (12 to 186). Individual constructions were more often implanted in patients with 3B acetabular defects (p<0.05) and its uncontained defects (p<0.001). The number of cases of aseptic loosening in the group of patients undergoing endoprosthetics using serial implants was greater than in the group of patients with individual constructions for the entire period (p<0.05) and in the early stages of observation (p<0.05). Conclusion. In case of RHA in patients with severe acetabular defects, individual implants, in comparison with serials, demonstrate better survival with an average follow-up of 26 months and due to design features, they can count on great long-term effectiveness. This study needs to be continued to increase follow-up.