Synovial fluid L-lactic acid in acute arthritis of the adult knee joint

Performance of a new rapid diagnostic test the lactate/glucose ratio of synovial fluid for the diagnosis of septic arthritis

OBJECTIVE

To evaluate the diagnostic performance of the synovial lactate, glucose and lactate/glucose ratio assay for the diagnosis of septic arthritis.

METHODS

In this monocentric cross-sectional study, synovial fluids were prospectively obtained from patients with acute joint effusion (<30 days) on native joint. Septic arthritis was defined using Newman's criteria. To evaluate diagnostic performance, Receiver Operating Characteristic (ROC) curves with Area under the curve (AUC), Sensitivities (Se), Specificities (Sp), LR+ their 95% confidence intervals were calculated. Synovial fluid cultures with gram staining, crystal analyses, synovial fluid white blood cell counts (WBC), lactate and glucose assays were performed.

RESULTS

A total of 233 synovial fluids were included. 25 patients had septic arthritis and 208 had non-septic arthritis (104 crystal-induced arthritis, 15 RA, 8 SpA, 6 reactive arthritis, and 75 acute arthritis of undifferentiated origin). Synovial lactate/glucose ratio performed higher than the synovial lactate or glucose assay separately (AUC: 0.859 [0.772-0.945]). Best synovial lactate/glucose ratio threshold to differentiate septic arthritis from non-septic arthritis was 5 Se 52% [0.34-0.7], Sp 98.1% [0.95-0.99], LR+ 27.0[9.50-76.00]).

CONCLUSION

The diagnostic performance of synovial lactate/glucose allows septic arthritis to be effectively and very quickly distinguished from other types of arthritis.

Metabolic disturbances in synovial fluid are involved in the onset of synovitis in heifers with acute ruminal acidosis

Acute ruminal acidosis (ARA) is the result of increased intake of highly fermentable carbohydrates, which frequently occurs in dairy cattle and is associated with aseptic polysynovitis. To characterise the metabolic changes in the joints of animals with ARA, we performed an untargeted gas chromatography-mass spectrometry (GC-MS)-based metabolomic analysis of synovial fluid. Seven heifers were challenged with an intraruminal oligofructose overload (13 g/kg of body weight [BW]) dissolved in water. Synovial fluid samples were collected at 0, 9 and 24 h post-overload. Metabolome analysis revealed the presence of 67 metabolites. At 9 h post-overload, glyceric acid, cellobiose, fructose and lactic acid were all increased, whereas at 24 h, sorbitol, lactic acid and fructose levels were all increased >10-fold. At 24 h, citric acid and threonine levels were significantly reduced. We detected increased L- and D-lactate, and the presence of interleukin-6 (IL-6) in synovial fluid. Furthermore, using bovine fibroblast-like synoviocytes, we observed that D-lactate induces IL-6 synthesis. Our results suggest that ARA produces severe metabolomic changes in synovial fluid, including disturbances in starch and sucrose metabolism, and increased lactate levels. These changes were observed prior to the appearance of synovitis, suggesting a potential role in the onset of polysynovitis.

Clinical use of plasma lactate concentration. Part 2: Prognostic and diagnostic utility and the clinical management of hyperlactatemia

OBJECTIVE

To review the current literature pertaining to the use of lactate as a prognostic indicator and therapeutic guide, the utility of measuring lactate concentrations in body fluids other than blood or plasma, and the clinical management of hyperlactatemia in dogs, cats, and horses.

DATA SOURCES

Articles were retrieved without date restrictions primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Increased plasma lactate concentrations are associated with increased morbidity and mortality. In populations with high mortality, hyperlactatemia is moderately predictive in identifying nonsurvivors. Importantly, eulactatemia predicts survival better than hyperlactatemia predicts death. Consecutive lactate measurements and calculated relative measures appear to outperform single measurements. The use of lactate as a therapeutic guide has shown promising results in people but is relatively uninvestigated in veterinary species. Increased lactate concentrations in body fluids other than blood should raise the index of suspicion for septic or malignant processes. Management of hyperlactatemia should target the underlying cause.

CONCLUSION

Lactate is a valuable triage and risk stratification tool that can be used to separate patients into higher and lower risk categories. The utility of lactate concentration as a therapeutic target and the measurement of lactate in body fluids shows promise but requires further research.

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.

Septic arthritis with negative bacteriological findings in adult native joints: a retrospective study of 74 cases

BACKGROUND

No microorganism is identified in 7-35% of cases of septic arthritis. The diagnosis is, therefore, only presumptive. We reviewed our cases of septic arthritis in adult native joints to determine the frequency of negative cultures, disease characteristics and the frequency of misdiagnosis of septic arthritis.

METHODS

This retrospective study included all patients admitted to our department from 1979-2005 with arthritis, diagnosed and treated as septic.

RESULTS

No microorganism was isolated from synovial fluid or blood samples from 74 out of 398 (19%) patients with presumed septic arthritis. Patients without microorganisms were younger (54 vs 62 years), less likely to have risk factors for septic arthritis (31% vs 41%) and had lower mortality (0 vs 5%) than patients with positive cultures. Long-term outcome was known for 48 patients. A retrospective analysis of all data and long-term outcome concluded that septic arthritis was probable in 18 patients and improbable in 13. Ten of the latter developed rheumatic disease after a mean time of 6 months: rheumatoid arthritis (n=3), spondyloarthropathies (n=3), unclassified rheumatic disease (n=2), Wegener granulomatosis (n=1) and cytosteatonecrosis (n=1). Fever and signs of inflammation were more frequent and synovial fluid cell counts were higher in patients with improbable septic arthritis. Conversely, radiological signs were more common in patients with probable septic arthritis.

CONCLUSION

At least 14% of patients diagnosed with septic arthritis with negative bacteriological results subsequently develop rheumatic disease. This pseudoseptic arthritis is indistinguishable from true septic arthritis. When no microorganism is identified, the diagnosis remains presumptive and follow-up is necessary to screen for other diseases, especially rheumatic diseases.

Can L(+)-lactate be used as a marker of experimentally induced inflammation in rats?

OBJECTIVE

The purpose of this study was to investigate if L(+)-lactate (lactate) can be used as a marker of progression of joint inflammation in comparison with a reference marker, prostaglandin E2 (PGE(2)), and to analyse implications for drug treatments.

MATERIALS AND METHODS

The assessment of the inflammation time course and the treatment efficacy studies were performed on two occasions. At specific time points, synovial fluid was extracted from Sprague-Dawley rats (n = 87) challenged with either carrageenan (Cg) or Freund's complete adjuvant (FCA) or from six non-inflamed rats. Naproxen (7.5 or 30 micromol/kg) or rofecoxib (30 micromol/kg) was administered per os 2 h post Cg or at 48 h post FCA. Levels of PGE(2) and lactate were assessed either by immuno-assay or by colorimetric assay.

RESULTS

Increased levels of both markers were detected following Cg or FCA injection. Pharmacological treatments resulted in lower concentrations of PGE(2) whereas levels of lactate remained unaffected compared to the vehicle-treated group.

CONCLUSION

Our results suggest that lactate may be useful as an additional biomarker of inflammatory processes, especially for monitoring the non-cox-inhibitor sensitive cascade.

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.

Management of septic arthritis: a systematic review

OBJECTIVE

To evaluate the existing evidence on the diagnosis and management of septic arthritis in native joints.

DESIGN

Systematic review.

DATA SOURCES

Cochrane Library, Medline, Embase, National Electronic Library for Health, reference lists, national experts.

REVIEW METHODS

Systematic review of the literature with evaluation of the methodological quality of the selected papers using defined criteria set out by the Clinical Effectiveness and Evaluation Unit of the Royal College of Physicians.

RESULTS

3291 citations were initially identified. Of these, 189 full text articles were identified for potential selection. Following review of these full text articles, 80 articles were found to fulfil the inclusion criteria and were included in the final list.

CONCLUSIONS

were drawn on the diagnosis, investigation and management of septic arthritis.

DISCUSSION

Little good quality evidence exists to guide the diagnosis and management of septic arthritis. Overall, no investigation is more reliable in the diagnosis of septic arthritis than the opinion of an experienced doctor. Aspiration and culture of synovial fluid is crucial to the diagnosis, but measurement of cell count is unhelpful. Antibiotics are clearly required for a prolonged period, but there are no data to indicate by which route or for how long. Key unanswered questions remain surrounding the medical and surgical management of the infected joint.

Synovial fluid analysis

AsA prompt and accurate diagnosis of a painful, swollen joint is imperative, primarily in the case of a septic joint, as delayed therapy may result in progression of disease or permanent loss of function. Procurement and analysis of synovial fluid (SF) are paramount in helping the clinician to determine a patient's clinical condition and further course of treatment. Measurement of white blood cell (WBC) counts, crystal analysis by polarized microscopy, and microbiologic studies including Gram stain and culture are the SF parameters that are collectively most important in the ultimate determination by a clinician of the presence or absence of an infectious or inflammatory joint. It is important for the clinician to understand and recognize the limitations of various SF parameters to minimize under-treating patients with potentially serious joint pathology.

Synovial fluid analysis

Synovial fluid (SF) accumulates in the joint cavity in different conditions; this review outlines the data from those analyses that help in their differential and definitive diagnosis. The gross appearance of the fluid can provide a quick bedside orientation with regard to the amount of inflammation present in the joint: totally transparent SF originates in non-inflammatory conditions--of which osteoarthritis is the most common--and the amount of turbidity grossly relates to the amount of inflammation. Most turbid to purulent fluids usually come from infected joints, but exceptions are not uncommon. The white cell count offers quantitative information, but the boundaries between non-inflammatory and inflammatory SF and between this and septic fluid are very hazy and figures have to be interpreted in the clinical setting. Detection and identification of monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals allow a precise diagnosis of gout and CPPD crystal-related arthropathy. Only one in five CPPD crystals have sufficient birefringence for easy detection and they are easily missed if searched for only using a polarised microscope. Instructions for beginners are given. Proper microbiological studies of the SF is the key to the diagnosis of infectious conditions.

Bacterial arthritis in the elderly: an overview

The key to successful treatment of acute bacterial arthritis is early diagnosis and initiation of empirical antibacterial therapy. Treatment includes antimicrobial therapy, debridement of the infected joint and treatment of pain. Empirical antibacterial treatment should be re-evaluated as soon as the causative pathogen is identified from joint fluid and other cultures. Mobilisation with partial weight bearing is encouraged early during treatment. The outcome of properly treated bacterial arthritis in the elderly is generally favourable and at least 50% of patients may recover without developing secondary osteoarthritis.

Septic arthritis

Septic arthritis is a medical emergency that can lead to significant morbidity and mortality. Prompt recognition and treatment are critical to ensuring a good prognosis. Thus, this article reviews the clinical presentation, microbiology, diagnostic workup, and outcome of nonprosthetic joint infections.