CONSTRAINED LINERS AND DUAL MOBILITY SYSTEMS FOR PREVENTION OF INSTABILITY IN REVISION HIP ARTHROPLASTY

Abstract

Purpose.Instability is a challenging complication of revision hip arthroplasty and a frequent cause of repeatrevisions. Constrained liners and dual mobility systems have gained major attention among the options of dislocation prophylaxis. The aimof this study is to compare the outcomes of revision hip arthroplasy with use of constrained liners and dual mobility systems. Materials and Methods.We used DePuy Duraloc (inner diameter 28 mm) and Zimmer Trilogy (inner diameter32 mm) systems in the constrained liners group (N 78, mean follow-up — 66.2 month, 54-82), Serf Novae and Biomet Avantage systems in the dual mobility group (N 58, mean follow-up — 17.8 month, 10-41). The two groups were comparable in age, sex and different potential dislocation risk factors, however, dual mobility cups were used more frequently in revisions due to unreduced and recurrent dislocations and in patients with the history of instability following total hip arthroplasty. There were also differences in the structure of primary diagnosis. Results.We observed 14 (17.9%) dislocations, 10 (12.8%) of which occurred within 2 years after surgery, and also3 (3.8%) cases of aseptic loosening of the acetabular component, 4 (5.1%) cases of locking mechanism damage without dislocation and 8 (10.3%) cases of deep infection in the constrained liners group. In the dual mobility group we observed 3 (5.17%) large articulation dislocations, 1 (1.7%) case of aseptic loosening of the acetabular component and 4 (6.9%) cases of deep infection. The difference in dislocation rates in two groups was significant (p<0.05). The analysis of the constrained liners group revealed an increased risk of dislocation in cases when a constrained system was implanted into a retained acetabular component compared to cases with acetabular shell revision (p<0.01; RR = 7.2, 95% CI: 2.05-25.26), as well as a trend for increased risk of dislocation in cases when DePuy Duraloc liners (inner diameter 28 mm) were used compared to Zimmer Trilogy (inner diameter 32 mm) (p= 0.07; RR = 4.97, 95% CI: 1.03-24.04). Conclusion. Dual mobility systems proved to be more effective than constrained liners in revision hip arthroplastyalthough being used more frequently as a treatment rather than prophylaxis of instability. Constrained liners bear a higher risk of dislocations when implanted into retained acetabular components and when used with heads of lesser diameter.