The Selective Use of Acetabular Screws in Routine Primary Total Hip Arthroplasty is Non-Inferior to Habitual Screw Use.

Abstract

Introduction: The aim of this study was to assess if selective screw insertion can achieve low rates of acetabular component loosening and whether this approach to screw usage is non-inferior to habitual screw insertion.

Methods: This was a retrospective international multi-center cohort study assessing 4,707 acetabular components for primary total hip arthroplasties (THAs) at mean follow-up of 6.5 years. There were 3,855 acetabular components in the selective no-screw (SNS) group, 734 in the selective with-screw (SWS) group, and 118 in the habitual (H) group. The primary outcome was all-cause aseptic revision. Secondary outcomes were all-cause revision and revision for aseptic acetabular loosening.

Results: The rate of aseptic revision in the selective user group was 0.89% (41 of 4,589) and 1.7% (two of 118) in the habitual user group (P = 0.467). The aseptic revision rate for SNS, SWS, and H groups was 0.7, 1.5, and 1.6%, respectively (P = 0.71). The all-cause revision rate for SNS, SWS, and H groups was 0.7, 1.5, and 4.2%, respectively (P = 0.001). The revision rate for cup loosening was 0.02% (one of 3,855) in the SNS group, 0.2% (two of 734) in the SWS group, and 0.8% (one of 118) in the H group (P = 0.002). The cumulative screw length (CSL) had no effect on the aseptic revision rate (P = 0.52).

Conclusion: Acetabular components with no screws (SNS) had the lowest rate of all-cause revision, aseptic revision, and revision for acetabular loosening. If screws are inserted, there is no significant difference in results depending on the number of screws inserted or the cumulative screw length. A selective approach to screw insertion is non-inferior to habitual screw insertion and may achieve superior rates of aseptic revision and acetabular loosening.