Aspiration and Injection Techniques of the Lower Extremity :

To analyse the clinical features and outcomes of gouty patients with concomitant septic arthritis in a medical centre. From the hospital database, we collected 30 hospitalized cases with concomitant septic arthritis and gouty arthritis from 1987 to 2001. All patients had positive bacterial culture and monosodium urate crystals in the affected joints. Medical records of the patients were analysed in detail. The mean age of patients was 52.8+/-12.5 yr. One-third of patients were afebrile at presentation, 30% had a normal blood leucocyte count and 10% had a synovial fluid leucocyte count less than 6000/mm3. The knee joint was the most common site of involvement, followed by the ankle, shoulder and wrist joints. Most patients had long-standing disease and subcutaneous tophi. Subcutaneous tophi rupture with secondary wound infection is the most common route of infection. Causative micro-organisms were Staphylococcus aureus (16 cases, 7 of whom were oxacillin-resistant), Streptococcus sp. (5 cases), Pediococcus sp. (1 case), and Gram-negative bacilli (9 cases). Fourteen patients received surgical debridement, among them two patients had an arthrodesis owing to severe joint destruction and one received above-knee amputation. Two patients died. One died of septic complications and the other died of acute myocardial infarction. Septic arthritis coexistent with gout presented a diagnostic difficulty. An early diagnosis requires a high level of suspicion. Prompt aspiration and analysis of the synovial fluid is imperative, regardless of the absence of fever or leucocytosis. Culture of the aspirated synovial fluid is warranted in gouty attack, even when it has a low white cell count or the Gram stain reveals no organisms.

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.