Hip Replacement & Hip Reconstruction Journal Scan

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Short-term Wear Evaluation of Thin Acetabular Liners on 36-mm Femoral Heads.

Clin Orthop Relat Res. 2013 Jul 17;

Authors: Johnson AJ, Loving L, Herrera L, Delanois RE, Wang A, Mont MA

Abstract
BACKGROUND: Dislocation remains the leading cause of revision THA. One approach to decreasing prosthetic dislocation risk has been the use of larger femoral head component sizes. The upper limit of head size in metal-on-polyethylene hip arthroplasty has historically been limited because of concerns about increased wear on thin polyethylene components. It is not known to what degree this concern should apply to more wear-resistant polyethylene components.
QUESTIONS/PURPOSES: We therefore determined (1) in vitro wear rates of polyethylene liners of varying thicknesses, (2) whether there were differences in the microscopic wear characteristics as a function of polyethylene thickness, and (3) whether thin polyethylene components resulted in early catastrophic failures.
METHODS: We used a hip wear simulator to compare the wear performance of 12 highly crosslinked polyethylene acetabular inserts. The internal diameter of all components was 36 mm, and there were three samples tested of each thickness (1.9, 3.9, 5.9, or 7.9 mm). Testing was conducted for 2.4 million cycles. Gravimetric mass loss was converted to volumetric loss, which was subsequently converted to theoretical linear penetration rates.