Wear analysis of retrieved ceramic‐on‐ceramic articulations in total hip arthroplasty: Femoral head makes contact with the rim of the socket outside of the bearing surface

Abstract

We investigated articular bearing surfaces retrieved from three patients with ceramic-on-ceramic total hip arthroplasties using high-quality alumina. The duration of implantation was 3.5, 3.0, and 2.5 years, respectively. Dislocation of the hip joint after implantation did not occur in any patients. The retrieved prostheses were examined by stereomicroscopy and scanning electron microscopy (SEM). In the main load-bearing area, no wear marks were seen in any sockets. However, in all three cases, stripe scars were observed at the rim of the alumina inlay under stereomicroscopy, despite the lack of indentation in the socket and the stem, which suggests impingement. Such scars were not observed on the load-bearing surface. Under SEM, the scars showed excessive wear, including material excavation, that has not been observed in conventional hip simulator experiments. These findings are similar to those of experiments in which a simulator was programmed to distract the femoral head from the socket. The present results suggest that the femoral head can separate from the socket without neck-socket impingement in vivo.

Characterization of worn alumina hip replacement prostheses

“…The characteristics of the stripe wear region were similar to the observations from in vivo samples, for example, by Nevelos et al. [8][9][10] However, the studies of Nevelos et al and Yamamoto et al [11][12][13] used surface topographic information from the SEM to interpret the wear mechanism, and they focused on the final state of the prosthesis, rather than the time dependent progression of the wear. In this work, we present a detailed analysis of surface and subsurface damage taken from extensive broad test programme of in vitro tested alumina on alumina prostheses, which included microseparation, in order to simulate, as closely as possible, the tribological conditions found in the body.…”

“…However, the wear transition zone is proposed in the present work due to its distinct microstructural characteristics. Yamamoto et al [11][12][13] classified this region as Grade III (mild wear).…”

“…[8][9][10] It was proposed that low level wear began on initial surface contact, progressing to stripe wear in contact areas of the component associated with high stresses and hence poorer lubrication. Yamamoto et al [11][12][13] classified in vivo worn surface into five regimes, namely, the original surface, low wear, mild wear, progressive wear, and disruptive wear. They suggested that the initial wear process was mainly relief polishing whereby the original machine-tracks were gradually erased, occasional small pits were revealed, and the grain outline began to appear.…”

High Incidence of Squeaking in THAs with Alumina Ceramic-on-ceramic Bearings

“…For instance, increased microseparation makes squeaking as a result of the stickand-slip mechanism more likely [21]. Microseparation is also a known risk factor for the formation of stripe wear and metal deposits on the ceramic femoral head [15,18,26], which in turn led to increased surface roughness, and could be a cause of squeaking.…”

Fatigue Life Prediction of Biomedical Titanium Alloys under Tensile/Torsional Stress

“…1) A hip-joint simulator that simulates the motion of an artificial hip joint in a pseudo-physiological environment is one example. 2) From the mechanical viewpoint, the human body is under complex stresses, including tensile and torsional. Biomedical materials must have sufficient torsional and tensile strength.…”