Causative organisms in revision total hip & knee arthroplasty for infection: Increasing multi-antibiotic resistance in coagulase-negative Staphylococcus and the implications for antibiotic prophylaxis.

BACKGROUND AND PURPOSE: Increasing resistance among post-operative Coagulase-negative Staphylococci (CNS) infections have been reported. We present our experience changing resistance patterns. METHODS: We examined microbiological results from hip and knee revisions from 2001 to 2010 and compared resistance to all Staphylococcus aureus (SA) and CNS cultured from regional pan-speciality sources, in order to examine the patterns of antibiotic resistance. MAIN FINDINGS: 72 revisions in 67 patients were included. The most common organisms were SA (36%) and CNS (35%). Resistance to methicillin was 72% for CNS versus 20% for SA and resistance to gentamicin was 40% for CNS versus 4% for SA. Among all regional (background pan-speciality) cultures SA resistance to methicillin fell from 32% to 16% from 2006 to 10 with no change in gentamicin resistance at 3%. During the same period resistance of CNS to methicillin and gentamicin increased from 63% to 70% and 32%-47% respectively. CONCLUSIONS: Resistance of CNS to both methicillin and gentamicin is higher than with SA and appears to be increasing. At least 32% of CNS and 4% of SA from infected TKRs/THRs were resistant to our current prophylaxis regime. These changing patterns of resistance may have implications for future antibiotic prophylaxis regimes.

Diagnosis and management of osteomyelitis. Decision analytic and pharmacoeconomic considerations.

Osteomyelitis, or bone infection, is becoming more common, largely because of increases in the use of implanted prosthetic devices in the management of arthritis or fractures. The clinical management of osteomyelitis requires accurate microbiological diagnosis that will identify appropriate antibacterials to which the pathogenic organisms are sensitive. Therapy will largely depend on the type of bacteria, the route by which the bacteria reach the bone, the presence of any orthopaedic devices and the patient's ability to mount an immune response. Consequently, therapy often requires a combination of medical and surgical management. The aim of this review is primarily to assess the impact of different drug regimens on the total cost and to clarify the implications of various treatment options for patients with osteomyelitis. Thus, the review examines the link between the main categories of osteomyelitis and common pathogens, and provides additional comments on the aetiology and epidemiology of the condition. At present, there is a real shortage of high quality evidence to guide the decision-maker through the range of available options. One way to deal with the complexity and uncertainty surrounding the management of osteomyelitis is to develop treatment protocols leading to decision trees which will in turn systematically analyse the options available for treating patients with osteomyelitis. Consequently, we have developed a number of decision trees to show the range of options available and have applied these to the relatively simple problem of route of administration of antibacterials. However, even here the available data allow only relatively crude estimations of the costs and consequences of alternative regimens. Thus, the aim has been to provide structures that may help to set priorities for research based on the expected value of new information. In the absence of evidence, there are broadly 2 alternatives. One is based on selection of the least expensive regimen in the absence of evidence to prove that more expensive options are more effective; patients with multiply resistant staphylococci, for which no effective oral regimen is available, should be treated with intravenous therapy. This is consistent with the UK legal system, which is founded on the so-called Bolam test. The alternative is providing the maximum available treatment; in the US, it is more likely that a doctor will be held negligent for not providing the maximum available treatment, and most standard texts recommend routine use of intravenous therapy for osteomyelitis.

Acute compartment syndrome of the thigh after joint replacement with anticoagulation.

We describe three patients with a compartment syndrome of the thigh, two after total hip replacement and one after total knee replacement. Two of the patients were fully anticoagulated. A compartment syndrome of the thigh is a rare, but important complication of joint replacement surgery if patients are receiving anticoagulants. Close observation is needed and when indicated monitoring of the intracompartmental pressure should be done. Early recognition of the signs and symptoms of an acute compartment syndrome and knowledge of the anatomy of the compartments of the thigh will help in the diagnosis and treatment of this potentially devastating complication.

Hip replacement surgery.

This review describes the current status of hip arthroplasty, hip mechanics, the materials used and the designs of the implants. The aims of and indications for surgery are outlined. Various complications and their prophylaxis are discussed, with particular stress on infection and thromboembolic problems. Results from published series and likely future developments are outlined.