Acetabular Liner Dissociation: A Comparative Study of Two Contemporary Uncemented Acetabular Components

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Medical Device Engineering

Background:

• Reports indicate polyethylene liner dissociation in third-generation modular acetabular components.
• This study evaluates two contemporary systems to determine if dissociation is implant- or class-specific.

Purpose of the Study:

• To compare the revision rates of Pinnacle and R3 acetabular components.
• To investigate the incidence and potential causes of polyethylene liner dissociation in these systems.

Main Methods:

• A single-center retrospective study of 961 primary total hip arthroplasties.
• Comparison of Pinnacle (535) and R3 (426) cementless acetabular shells with polyethylene liners.
• Kaplan-Meier survival analysis for all-cause revision, acetabular reoperation, and liner dissociation.

Main Results:

• The Pinnacle group had significantly higher rates of all-cause revision, acetabular reoperation, and liner dissociation compared to the R3 group (P = .024 to 0.038).
• Seven-year survival for all-cause revision was 96.1% for Pinnacle vs. 99.0% for R3 (P = .022).
• Seven-year survival for acetabular reoperation was 96.9% for Pinnacle vs. 99.3% for R3 (P = .035).

Conclusions:

• The Pinnacle acetabular component demonstrated a higher revision rate at 7 years compared to the R3 component.
• Polyethylene liner dissociation was the primary driver for the increased revisions in the Pinnacle group.
• The findings suggest the dissociation issue is specific to the Pinnacle cup design.