Low Risk of Cup Fixation Failure at 10 Years Using Constrained Liners at the Same Time of Acetabular Component Revision.

Background: There remains concern regarding simultaneous constrained liner (CL) implantation during acetabular component revision in revision total hip arthroplasty due to potential fixation loss at the bone-implant interface. There are scarce long-term data on this technique. This study aimed to determine the survivorship free from aseptic cup loosening (fixation failure) and all-cause re-revision when CLs were implanted concurrently with acetabular cup revision.

Methods: We retrospectively identified all revision total hip arthroplasties where CLs were implanted simultaneously with acetabular cup revision at our institution between 2001 and 2021. We included 174 revisions with a mean follow-up of 8.7 years (range, 2 to 21.7). The mean age was 70 years, and 60.9% were women. There were 10% that had Paprosky type I bone loss, 68.4% had type IIA-C, and 21.3% had type IIIA-B. The main indications for index acetabular revision were instability (35%), second-stage reimplantation (26.4%), and loosening (17.2%). Only 25% of revisions used modern, highly porous revision shells. There were two-thirds of the CLs manufactured by one implant company and one-third by another. There were 23 (13%) cemented CLs. Screw fixation was evaluated. Kaplan-Meier survival was determined with revision for cup aseptic loosening and all-cause re-revision as endpoints.

Results: There were 32 (18.3%) patients who underwent re-revision at a mean of 2.9 years (range, 0.1 to 14.1). The most common reason for re-revision was instability (14). There were three (1.7%) that required re-revision for acetabular component fixation failure. Acetabular component survival free from re-revision due to fixation failure was 98.9% at 5 years and 98.1% at 10 years. The all-cause re-revision-free survival was 84.9% at 5 years and 79.9% at 10 years.

Conclusions: Implanting CLs during acetabular component revision with stable fixation is safe with a very low risk of cup fixation failure. There were no cup fixation failures in highly porous shells.