The biological pathways responsible for adverse reactions to metal debris (ARMD) are unknown. Necrotic and inflammatory changes in response to Co-Cr nanoparticles in periprosthetic tissues may involve both a cytotoxic response and a type IV delayed hypersensitivity response. Our aim was to establish whether differences in biological cascade activation exists in tissues of patients with end-stage OA compared to those with aseptic loosening of a metal on polyethylene (MoP) THR and those with ARMD from metal-on-metal (MoM) THR. A microarray experiment (Illumina HT12-v4) was performed to identify the range of differential gene expression between 24 patients across 3 phenotypes: Primary OA (n=8), revision for aseptic loosening of MoP THR (n=8) and ARMD associated with MoM THR (n=8). Results were validated using Taqman Low Density Array (TLDA) selecting the top 36 genes in terms of fold-change (FC)>2 and a significant difference (p<0.05) on ANOVA. Pathways of cellular interaction were explored using Ingenuity IPA software.Introduction
Patients & Methods
Metal artefact reduction (MAR) MRI is now widely
considered to be the standard for imaging metal-on-metal (MoM) hip
implants. The Medicines and Healthcare Products Regulatory Agency
(MHRA) has recommended cross-sectional imaging for all patients
with symptomatic MoM bearings. This paper describes the natural
history of MoM disease in a 28 mm MoM total hip replacement (THR)
using MAR MRI. Inclusion criteria were patients with MoM THRs who had
not been revised and had at least two serial MAR MRI scans. All
examinations were reported by an experienced observer and classified
as A (normal), B (infection) or C1–C3 (mild, moderate, severe MoM-related
abnormalities). Between 2002 and 2011 a total of 239 MRIs were performed
on 80 patients (two to four scans per THR); 63 initial MRIs (61%)
were normal. On subsequent MRIs, six initially normal scans (9.5%)
showed progression to a disease state; 15 (15%) of 103 THRs with
sequential scans demonstrated worsening disease on subsequent imaging. Most patients with a MoM THR who do not undergo early revision
have normal MRI scans. Late progression (from normal to abnormal,
or from mild to more severe MoM disease) is not common and takes
place over several years. Cite this article:
