We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases, retrieval analysis determined that these ion concentrations could not be explained simply by the wear rates of the components. We hypothesized that these effects may be associated with aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). We examined the influence of the ALVAL grade on synovial fluid Co and Cr concentrations following adjustment for patient and device variables, including volumetric wear rates. Initially restricting the analysis to include only patients with one MoM hip resurfacing device, we performed multiple regression analyses of prospectively collected data. We then repeated the same statistical approach using results from a larger cohort with different MoM designs, including total hip arthroplasties.Objectives
Patients and Methods
The high revision rates of the DePuy Articular Surface Replacement (ASR) and the DePuy ASR XL (the total hip arthroplasty (THA) version) have led to questions over the viability of metal-on-metal (MoM) hip joints. Some designs of MoM hip joint do, however, have reasonable mid-term performance when implanted in appropriate patients. Investigations into the reasons for implant failure are important to offer help with the choice of implants and direction for future implant designs. One way to assess the performance of explanted hip prostheses is to measure the wear (in terms of material loss) on the joint surfaces. In this study, a coordinate measuring machine (CMM) was used to measure the wear on five failed cementless Biomet Magnum/ReCap/ Taperloc large head MoM THAs, along with one Biomet ReCap resurfacing joint. Surface roughness measurements were also taken. The reason for revision of these implants was pain and/or adverse reaction to metal debris (ARMD) and/or elevated blood metal ion levels.Objectives
Methods
Wear debris released from bearing surfaces has been shown to
provoke negative immune responses in the recipient. Excessive wear
has been linked to early failure of prostheses. Analysis using coordinate
measuring machines (CMMs) can provide estimates of total volumetric
material loss of explanted prostheses and can help to understand
device failure. The accuracy of volumetric testing has been debated,
with some investigators stating that only protocols involving hundreds
of thousands of measurement points are sufficient. We looked to
examine this assumption and to apply the findings to the clinical
arena. We examined the effects on the calculated material loss from
a ceramic femoral head when different CMM scanning parameters were
used. Calculated wear volumes were compared with gold standard gravimetric
tests in a blinded study. Objectives
Methods
The aims of this piece of work were to: 1) record the background
concentrations of blood chromium (Cr) and cobalt (Co) concentrations
in a large group of subjects; 2) to compare blood/serum Cr and Co
concentrations with retrieved metal-on-metal (MoM) hip resurfacings;
3) to examine the distribution of Co and Cr in the serum and whole
blood of patients with MoM hip arthroplasties; and 4) to further
understand the partitioning of metal ions between the serum and
whole blood fractions. A total of 3042 blood samples donated to the local transfusion
centre were analysed to record Co and Cr concentrations. Also, 91
hip resurfacing devices from patients who had given pre-revision
blood/serum samples for metal ion analysis underwent volumetric
wear assessment using a coordinate measuring machine. Linear regression analysis
was carried out and receiver operating characteristic curves were
constructed to assess the reliability of metal ions to identify
abnormally wearing implants. The relationship between serum and
whole blood concentrations of Cr and Co in 1048 patients was analysed
using Bland-Altman charts. This relationship was further investigated
in an Objectives
Methods
An ongoing prospective study to investigate failing metal-on-metal
hip prostheses was commenced at our centre in 2008. We report on
the results of the analysis of the first consecutive 126 failed
mated total hip prostheses from a single manufacturer. Analysis was carried out using highly accurate coordinate measuring
to calculate volumetric and linear rates of the articular bearing
surfaces and also the surfaces of the taper junctions. The relationship
between taper wear rates and a number of variables, including bearing
diameter and orientation of the acetabular component, was investigated.Objectives
Methods
