Increasing Liner Anteversion Decreases the Interfacial Strength of Polyethylene Liners Cemented Into Titanium-Alloy Acetabular Shells.

BACKGROUND:Acetabular component positioning during revision total hip arthroplasty can be suboptimal. Cementation of an acetabular liner into a well-fixed acetabular shell can allow surgeons to correct component version and inclination without the need for extensive revision surgery and progressive pelvic bone loss. However, to date, it is unknown what degree of version can be corrected without sacrificing fixation strength of the construct. In this study, cemented liners were biomechanically evaluated at increasing degrees of liner anteversion. METHODS:Twenty-five commercially available liners were cemented into acetabular shells at 0°, 10°, 20°, 30°, and 40° of liner anteversion, relative to the acetabular shell (n = 5 per group). Components were then fixed to a materials testing frame and evaluated via an established lever-out testing protocol. Test data were collected via test frame software for calculation of yield and maximum moments during biomechanical testing. RESULTS:When liners were cemented at 20°, 30°, and 40° of liner anteversion, a significant decrease in maximum fixation moment was found when compared liners cemented at both 0° and 10° (P < .05). A significant negative correlation was noted for both yield and maximum moments and increasing liner angle (r = -0.566; P = .011 and r = -0.604; P = .006, respectively). CONCLUSION:Biomechanical data from our study suggest that a threshold of acceptable anteversion during revision total hip arthroplasty is <20°. However, further studies are warranted to continue evaluation of the potential clinical impact and long-term device performance in this setting.