Traditionally, surgical waiting lists have served to prioritize care, with the worst cases addressed first, along, in some instances, with those who have shouted the loudest. Patients with less severe symptoms have usually waited for much longer periods. This is now politically unacceptable. Setting priorities in waiting lists would be far simpler and much less relevant were it not for the major discrepancies between demand and supply. These discrepancies, which have for so long been the norm in the NHS, lead to the creation of long waiting times.
1Department of Orthopaedics, Norfolk and Norwich University Hospital, Colney Lane, Norwich, Norfolk NR4 7UY, United Kingdom. E-mail address for A. Viswanath: [email protected]. E-mail address for J.F. Nolan: [email protected]
The aim of this review is to describe the clinical, histopathologic, and MRI features of aseptic lymphocytic vasculitis-associated lesions in total hip replacements.The introduction of modern metal-on-metal hip arthroplasty has been accompanied by a newly described disease, aseptic lymphocytic vasculitis-associated lesions, which is characterized histologically by bland necrosis and dense perivascular lymphocytic infiltrates. Conventional radiographic findings are often normal, but the typical MRI findings include periprosthetic fluid collections, soft-tissue masses, gluteal tendon avulsion, bone loss, periosteal stripping, neurovascular involvement, and periprosthetic fractures. The severity of the histologic and MRI appearances can be graded according to defined published criteria.
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.
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.
While Clinical Decision Support Systems (CDSS) can be developed as a large group of rules- based advice occasionally, cases of preventable adverse drug events come to the attention from various pathways, both through clinical and policy activities. At Partners HealthCare Systems, there is a centralized knowledge management structure that allows for clinicians to present information to a Medical Knowledge Committee (MKC) in a structured way so that any information can be properly vetted. A case of a fatality due to the administration of 2 medications concurrently and the understanding that key decision support components were not available to the prescribing clinicians, drove us to implement this advice in both our acute care and ambulatory clinical systems.
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: Bone Joint J 2013;95-B:1035–9.
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