Clinical and simulator wear study of alumina ceramic THR to 17 years and beyond

Abstract

Three THAs with cementless monolithic alumina ceramic sockets and cementless Co-alloy stems were retrieved because of aseptic loosening after 17 and 24 years. At revision heads and cups were marked for orientation. Maps were drawn of wear patterns with the use of light microscopy and surveyed by SEM. In a simulator experiment 28-mm-diameter alumina heads and liners were used. The cups were mounted inverted in a hip simulator and run with calf serum as the lubricant. The hip loads were 2 kN maximum and a 1-Hz frequency for 20 million cycles. Wear severity was classified into five grades. In retrieved implants, SEM analysis showed that the main wear zones (MWZ) had Grade 4 wear. The peripheral wear zones (PWZ) showed grain pull-out regions (Grade 5 wear). These corresponded to necksocket impingement and head-acetabular cup separation. Gray was due to transferred CoCr particles from the stem. In the simulator study, the MWZ had only localized areas of grain pull out surrounded by polished surface regions (Grade 4 wear) at 20 million cycles; stripe wear was not seen. The alumina ceramic bearings proved excellent up to 22 years in simulator studies and clinical studies. However, microseparation kinematics would be necessary in the simulator to duplicate the more peripheral wear zones.

Risk of Impingement and Third-body Abrasion With 28-mm Metal-on-metal Bearings

“…There were also frequent reports of ''stripe'' wear across heads and around cup rims [15,54,62,71,77]. Our MoM retrieval studies noted similar stripe damage in retrieved MoM [6,9,10], although other groups disavowed their existence [34].…”

“…Retrieval studies of ceramic-on-ceramic (CoC) THA in particular have revealed ''normal'' wear mode produced by everyday activities as a circular wear pattern on the head and inside the cup [71,75]. There were also frequent reports of ''stripe'' wear across heads and around cup rims [15,54,62,71,77].…”

Stripe wear rates in alumina THR—Comparison of microseparation simulator study with retrieved implants

“…8 Simulators were programmed to provide a vertical distraction as well as a horizontal distraction during the swing phase, providing a simulation of the superior stripe wear created during walking ( Figure 1) and of the inferior stripe wear produced by other activities such as rising from a flexed position.…”

Evaluation of Two Total Hip Bearing Materials for Resistance to Wear Using a Hip Simulator

“…It has been suggested that the nature of the femoral head might affect the wear of the polyethylene so a change to ceramic heads [15][16][17][18][19][20][21][22][23][24] was tested and has been instituted in many marketed devices. The use of ceramic-on-ceramic, in which both component materials are replaced by ceramic has also been tested and utilized in surgery [25][26][27][28] for several years. Metal-on-metal articulations initially had been used in the 1960s and 1970s [29,30] and have recently become attractive again as a possible solution to wear problems [22,[31][32][33][34][35][36][37][38].…”