The importance of accurate identification and reporting of surgical
site infection (SSI) is well recognised but poorly defined. Public
Health England (PHE) mandated collection of orthopaedic SSI data
in 2004. Data submission is required in one of four categories (hip
prosthesis, knee prosthesis, repair of neck of femur, reduction
of long bone fracture) for one quarter per year. Trusts are encouraged
to carry out post-discharge surveillance but this is not mandatory.
Recent papers in the orthopaedic literature have highlighted the
importance of SSI surveillance and the heterogeneity of surveillance
methods. However, details of current orthopaedic SSI surveillance
practice has not been described or quantified. All 147 NHS trusts in England were audited using a structured
questionnaire. Data was collected in the following categories: data
collection; data submission to PHE; definitions used; resource constraints;
post-discharge surveillance and SSI rates in the four PHE categories.
The response rate was 87.7%.Aims
Patients and 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:
Lately, concerns have arisen following the use of large metal-on-metal bearings in hip replacements owing to reports of catastrophic soft-tissue reactions resulting in implant failure and associated complications. This review examines the literature and contemporary presentations on current clinical dilemmas in metal-on-metal hip replacement.
Metal-on-metal total hip replacement has been targeted at younger patients with anticipated long-term survival, but the effect of the production of metal ions is a concern because of their possible toxicity to cells. We have reviewed the results of the use of the Ultima hybrid metal-on-metal total hip replacement, with a cemented polished tapered femoral component with a 28 mm diameter and a cobalt-chrome (CoCr) modular head, articulating with a 28 mm CoCr acetabular bearing surface secured in a titanium alloy uncemented shell. Between 1997 and 2004, 545 patients with 652 affected hips underwent replacement using this system. Up to 31 January 2008, 90 (13.8%) hips in 82 patients had been revised. Pain was the sole reason for revision in 44 hips (48.9%) of which 35 had normal plain radiographs. Peri-prosthetic fractures occurred in 17 hips (18.9%) with early dislocation in three (3.3%) and late dislocation in 16 (17.8%). Infection was found in nine hips (10.0%). At operation, a range of changes was noted including cavities containing cloudy fluid under pressure, necrotic soft tissues with avulsed tendons and denuded osteonecrotic upper femora. Corrosion was frequently observed on the retrieved cemented part of the femoral component. Typically, the peri-operative findings confirmed those found on pre-operative metal artefact reduction sequence MRI and histological examination showed severe necrosis. Metal artefact reduction sequence MRI proved to be useful when investigating these patients with pain in the absence of adverse plain radiological features.
60 out of total series of 643 metal-on-metal hip replacements, carried out over the last nine years, have so far required revision, 13 for peri-prosthetic fracture and 47 for extensive, symptomatic, peri-articular soft-tissue changes. Dramatic corrosion of generally solidly fixed, cemented stems has been observed and is believed to have resulted in the release of high levels of cobalt chrome ions from the stem surface. The contribution of the metal-to-metal articulation is, as yet, unclear. Not including the fracture cases, plain films have demonstrated little or no abnormality to account for patients’ progressive symptoms. MRI scanning, on the other hand, utilising a technique designed to minimise implant artefact, has correlated very closely with findings at the time of revision surgery. The histological changes, typified by extensive lymphocytic infiltration and a severe vasculitis leading to, in some cases, extensive tissue necrosis are demonstrated and discussed. The failure of any of the existing protective mechanisms or regulatory restrictions to identify and limit the exposure of large numbers of patients to unsatisfactory implants has again been demonstrated.
