Constrained acetabular liners in total hip arthroplasty: analysis of 265 primary and revision cases from the Dutch Arthroplasty Register (2007-2022).

Introduction: Constrained acetabular liners (CALs) are predominantly used as a salvage procedure in patients with a severe risk for dislocation after total hip arthroplasty (THA). However, the constrained design of CALs bears the risk of impingement with subsequent loosening or failure of the integrity of the implant. We investigated the use and survival of CALs in primary and revision THA in the Dutch Arthroplasty Register (LROI).

Methods: Use of CAL in THAs was extracted from the LROI in the period 2007-2022. 423,773 primary THAs and 52,706 revision THAs have been registered, of which 29 CALs were implanted in primary THA and 236 CALs in revision THA. Patient characteristics and survival of the CAL placed in primary and revision THA were separately analysed.

Results: Of the CALs placed in primary THA, no revisions of the implant occurred during a median follow-up of 5.4 years (interquartile range [IQR] 4.0-12.4). The CALs in revision THA were most frequently used for cases with recurrent dislocation (183/236). Median follow-up was 4.8 (IQR 2.3-8.2) years. The re-revision rate was 10% (95% CI, 6.6-14) at 5-year follow-up and 12% (CI, 8.1-17) at 9-year follow-up. The most frequently registered reason for re-revision was dislocation (n = 19, 70%).

Conclusions: In the Netherlands there is a relatively low use of CALs in primary as well as revision THA. The survival rate of CALs is acceptable, with recurrent dislocation as the main reason for re-revision. The use of CALs should be reserved for specific cases with high risk for dislocation.