Routine synovial fluid culture: is it necessary? Lessons from an audit

Joint aspiration and injection and synovial fluid analysis

Joint aspiration/injection and synovial fluid (SF) analysis are both invaluable procedures for the diagnosis and treatment of joint disease. This chapter addresses (1) the indications, technical principles, expected benefits and risks of aspiration and injection of intra-articular corticosteroid and (2) practical aspects relating to SF analysis, especially in relation to crystal identification. Intra-articular injection of long-acting insoluble corticosteroids is a well-established procedure that produces rapid pain relief and resolution of inflammation in most injected joints. The knee is the most common site to require aspiration although any non-axial joint is accessible for obtaining SF. The technique involves only knowledge of basic anatomy and should not be unduly painful for the patient. Provided sterile equipment and a sensible, aseptic approach are used, it is very safe. Analysis of aspirated SF is helpful in the differential diagnosis of arthritis and is the definitive method for diagnosis of septic arthritis and crystal arthritis. The gross appearance of SF can provide useful diagnostic information in terms of the degree of joint inflammation and presence of haemarthrosis. Microbiological studies of SF are the key to the confirmation of infectious conditions. Increasing joint inflammation associates with increased SF volume, reduced viscosity, increasing turbidity and cell count and increasing ratio of polymorphonuclear:mononuclear cells, but such changes are non-specific and must be interpreted in the clinical setting. However, detection of SF monosodium urate and calcium pyrophosphate dihydrate crystals, even from un-inflamed joints during intercritical periods, allows a precise diagnosis of gout and calcium pyrophosphate crystal-related arthritis.

Use and cost-effectiveness of intraoperative acid-fast bacilli and fungal cultures in assessing infection of joint arthroplasties

The objective of this study is to determine a protocol for collecting acid-fast bacilli (AFB) and fungal intraoperative cultures during orthopedic procedures. An observational study was undertaken. Four hundred forty-six AFB cultures and 486 fungal cultures were processed over a 2-year period. The number of positive cultures was determined. A protocol specific to handling these types of specimens was developed. Cost analysis was completed to determine both the time and money saved if the new protocol was implemented. The infrequency of positive AFB and fungal cultures in this study suggests that it is only necessary to routinely request AFB and fungal cultures on 1 of 5 samples. Implementation of this protocol has potential to lead to substantial cost reduction and resource savings without diminishing patient outcomes.

Joint aspiration and injection and synovial fluid analysis

Joint aspiration/injection and synovial fluid (SF) analysis are both invaluable procedures for the diagnosis and treatment of joint disease. This chapter addresses: (1) the indications, the technical principles and the expected benefits and risks of aspiration and injection of intra-articular corticosteroid; and (2) practical aspects relating to SF analysis, especially in relation to crystal identification. Intra-articular injection of long-acting insoluble corticosteroids is a well-established procedure that produces rapid pain relief and resolution of inflammation in most injected joints. The knee is the most common site to require aspiration, although any non-axial joint is accessible for obtaining SF. The technique requires a knowledge of basic anatomy and should not be unduly painful for the patient. Provided sterile equipment and a sensible, aseptic approach are used, it is very safe. Analysis of aspirated SF is helpful in the differential diagnosis of arthritis and is the definitive method for diagnosis of septic arthritis and crystal arthritis. The gross appearance of SF can provide useful diagnostic information in terms of the degree of joint inflammation and presence of haemarthrosis. Microbiological studies of SF are the key to the confirmation of infectious conditions. Increasing joint inflammation is associated with increased SF volume, reduced viscosity, increasing turbidity and cell count, and increasing ratio of polymorphonuclear: mononuclear cells, but such changes are non-specific and must be interpreted in the clinical setting. However, detection of SF monosodium urate and calcium pyrophosphate dihydrate crystals, even from un-inflamed joints during intercritical periods, allow a precise diagnosis of gout and of calcium pyrophosphate crystal-related arthritis.

Joint aspiration and injection

Joint aspiration/injection is an invaluable procedure for the diagnosis and treatment of joint disease. The knee is the commonest site to require aspiration although any non-axial joint is accessible for obtaining synovial fluid. Septic arthritis and crystal arthritis can be readily diagnosed by aspirating synovial fluid. Intra-articular injection of long-acting insoluble corticosteroids produces rapid resolution of inflammation in most injected joints and is a well established procedure in rheumatological practice. The technique involves only a knowledge of basic anatomy and should not be unduly painful for the patient. Provided sterile equipment and a sensible, aseptic approach are used it is a safe procedure. This chapter addresses the indications, technical principals, expected benefits and risks of intra-articular corticosteroid injection. The use of other intra-articular injections including osmic acid, radioisotopes and hyaluronic acid, which are less universally utilised than intra-articular corticosteroid, will also be addressed.

The value of synovial fluid assays in the diagnosis of joint disease: a literature survey

OBJECTIVE

To carry out a critical appraisal of the literature in an attempt to assess the current value of synovial fluid (SF) analysis in the diagnosis of joint disease.

METHODS

A literature search was undertaken using the Medline, Biomed, Bids, Pubmed, and Embase electronic databases using the keywords: synovial fluid (SF) analysis, SF crystals, joint sepsis, acute arthritis, and SF cell counts, cytology, biomarkers, and microbiology.

RESULTS

Publications fell into three main categories. Firstly, reports assessing the value of the three traditional assays (microbiology, white blood cell counts, and microscopy for pathogenic crystals). For these quality control evidence was found to be sparse, and tests for sensitivity, specificity, and reliability showed worrying variations. These poor standards in SF analysis may be due to lack of inclusion of some tests within routine pathology services. Secondly, claims for the usefulness of "new" assays (cytology and biochemical markers). For cytology, the supporting evidence was mainly anecdotal and there were no reports on specificity, sensitivity, and reliability. Interpretation difficulties are a major hindrance to the clinical use of biochemical assays, which remain primarily research tools. Finally, work on the diagnostic value of SF analysis in general. The appraisal confirmed that SF analysis remains of major diagnostic value in acute arthritis, where septic arthritis or crystal arthropathy is suspected, and in intercritical gout.

CONCLUSIONS

Given the importance of SF tests, rationalisation of their use, together with improved quality control, should be immediate priorities. Further investigation is recommended into the contribution of SF inspection and white cell counts to diagnosis, as well as of the specificity and sensitivity of SF microbiological assays, crystal identification, and cytology.

A risk-benefit assessment of intra-articular corticosteroids in rheumatic disorders

The appeal of intra-articular corticosteroid therapy has increased with the growing emphasis on early disease control in rheumatoid disease. The impact on the patient's pain and stiffness is impressive and prompt. This may encourage patient compliance with longer term therapies given to slow the course of the disease. The release of corticosteroid into the circulation also provides some generalised improvement. This can prove helpful during the management of flares of inflammatory disease. There is less evidence to support the use of intra-articular corticosteroids in other inflammatory arthritides, but experience suggests that the benefits are similar. In osteoarthritis the benefits are less certain, but intra-articular therapy may prove important in patients who cannot undergo salvage operative procedures because of intercurrent illness. The benefits of intra-articular corticosteroids may be enhanced by rest after the injection, or by the additional administration of agents such as radio-colloids, rifampicin (rifampin), or osmic acid. Most controlled trial data have been published on knee injections, but other joints can be useful targets for local therapy. The risks are mainly related to the discomfort of the procedure, localised pain post-injection and flushing, but most feared is septic arthritis which probably occurs in about 1 in 10000 injections. Careful aseptic technique is the best protection. Tissue atrophy at the injection site, abnormal uterine bleeding, hypertension and hyperglycaemia rarely cause problems. Osteonecrosis might be as much a problem with uncontrolled painful arthritis as with a joint rendered less symptomatic by corticosteroid injections. Intra-articular corticosteroids form an important part of the management of inflammatory joint disease and might be considered where an inflammatory element occurs in osteoarthritis. They may be used at any stage in the arthritic process, but should be seen as an adjunct to other forms of symptom relief. In patients needing multiple joint injections, systemic therapy should be reviewed to see if better disease control could reduce the need for invasive therapy.