Arthrocentesis (synovial fluid aspiration) can be performed diagnostically (for identification of the etiology of acute arthritis) or therapeutically (for pain relief, drainage of effusion, or injection of medications). ^[1, 2] The clinician performing the procedure should be familiar with the anatomy of the specific joint in order to avoid puncture of tendons, blood vessels, and nerves. ^[3] Using the extensor surface of the joint for needle insertion, while keeping the joint in minimal flexion, minimizes the risk of such injuries.

The ankle joint is a hinged synovial joint with primarily up-and-down movement (plantarflexion and dorsiflexion). However, when the ranges of motion (ROMs) of the ankle and subtalar joints (talocalcaneal and talocalcaneonavicular) are taken together, the complex functions as a universal joint. For more information about the relevant anatomy, see Ankle Joint Anatomy.

Diagnostic indications for ankle arthrocentesis include the following:

• Evaluation of monoarticular arthritis ^[4]
• Evaluation of suspected septic arthritis ^[5]
• Evaluation of joint effusion
• Identification of intra-articular fracture
• Identification of crystal arthropathy ^[6]

Therapeutic indications include the following:

• Relief of pain by aspirating effusion (including hemarthrosis)
• Injection of medications ^[7] (eg, corticosteroids, antibiotics, anesthetics)
• Drainage of septic effusion