Arthrocentesis and soft tissue aspiration and injection.

Accessing a joint with a needle (arthrocentesis) to extract synovial fluid is a skill intrinsic to the rheumatologist's praxis. Joint aspirations are essential for diagnosing or excluding septic joints, are the gold standard for diagnosing acute crystal arthritis, and can provide valuable information about the nature of other forms of arthritis. In appropriate settings, injecting medications into joints can provide rapid, temporary, or even prolonged relief of pain and swelling and can provide a window of relief until other treatment modalities (anti-inflammatories, immunomodulators, and physical therapy) can enforce durable responses. Soft tissue aspirations (e.g., of bursae) and soft tissue injections (of bursae, tendons, trigger points, and areas of nerve compression) can provide similar relief, earning the practitioner the gratitude of the patient. Here, we provide a primary on joint and soft tissue aspiration and injection, including indications for and against procedures, preparing for procedures, and approaches to specific musculoskeletal structures.