Patients presenting with joint pain or swelling should receive a thorough examination to rule out the presence of joint disease. Periarticular diseases such as tendinitis, bursitis, or cellulitis may mimic articular disease and therefore the clinician must first determine whether the patient’s constellation of signs and symptoms originate from the joint itself or from another contiguous structure. At times, such a distinction is difficult to make.¹ Arthrocentesis, the puncture and aspiration of a joint, can facilitate this evaluation as both a diagnostic and therapeutic tool in the assessment of musculoskeletal disease and trauma. This procedure can often be done at the bedside using local anesthesia, without radiographic guidance or significant risk to the patient.

The diagnostic indications for arthrocentesis include confirmation of nontraumatic joint disease and ligamentous or bony injury. The former includes the identification of infectious or immunologic markers in the synovial fluid. In contrast, the presence of blood in the joint space affirms traumatic injury; more specifically, the finding of blood and fat globules may be used to identify an intra-articular fracture.

The therapeutic indications for arthrocentesis include pain relief secondary to a tense effusion or hemarthrosis and the direct instillation of anti-inflammatory medications for the management of severe rheumatic arthritides. The physician should consider consultation with the primary specialist for patients with chronic hematologic or rheumatologic disease prior to performing this procedure.²

Although some authors argue that infection in the tissues overlying the puncture site (a skin abscess or cellulitis) is an absolute contraindication to arthrocentesis given the theoretical risk for spread of infection into the joint space, others state that this is a relative contraindication and the risk–benefit ratio must be discussed thoroughly prior to performing the procedure.^1-3 Additional relative contraindications to the procedure include bacteremia (because it may also facilitate the spread of infection to the joint space), active anticoagulation, fracture around the joint space (because aspiration may increase the chance of infection),⁴ and joint prostheses. Given the rarity of joint prostheses in the pediatric population and the high risk of infection, orthopedic consultation should be obtained if considering arthrocentesis.^2,4 In addition, bleeding diatheses should be corrected with appropriate clotting factors or blood product replacement before arthrocentesis to prevent a significant hemarthrosis.^1,2,4

Table 199-1 lists the equipment needed to perform arthrocentesis.