What Is Ankle Arthrocentesis?

Ankle arthrocentesis is the drainage by needle of fluid inside the ankle joint.

Arthrocentesis (joint aspiration) is a diagnostic procedure where the body’s synovial joint lubrication fluid is drained using a sterile needle and syringe. Ankle arthrocentesis is an important procedure used for diagnosing arthritis and differential diagnosis of inflammatory and noninflammatory arthritis. Arthrocentesis can also be performed therapeutically for pain relief, drainage of fluid or injection of medications.

Any joint in the body can be aspirated. Joint aspiration is a relatively quick and inexpensive procedure to perform. It can be done in a clinic or hospital. Any trained physician, physician’s assistant or nurse can perform the procedure.

Ankle arthrocentesis is indicated for any patient with inflamed ankle joints or who does not have an established diagnosis. Inflamed joints are recognized by being red, warm, tender, swollen, and painful during movement. Ankle arthrocentesis is indicated for diagnosis of the following conditions: 

• Monoarticular arthritis (inflammation of the joint)
• Septic arthritis (infection of the joint)
• Joint effusion (swelling due to fluid accumulation in the body)
• Intra-articular fracture (fractures which involve the joint space) 
• Crystal arthropathy (accumulation of calcium crystals in the joint and surrounding areas)

Joint aspiration may be performed as a treatment in certain conditions, such as:

• Septic joint or hemarthrosis (bleeding into the joints): Repeated aspirations are performed to relieve discomfort and prevent joint damage.
• Hemarthrosis (blood in the joints): Aspiration is performed to prevent adhesions. 

Aspiration can be performed while injecting intra-articular medications such as corticosteroids or hyaluronic acid to improve efficacy. 

• Steroid injections help reduce joint inflammation, reduce pain, preserve joint structure and function. 
• Hyaluronic acid lubricates the joint, decreases impact, delays joint aging, reduces pain and stiffness. 

Ankle arthrocentesis should be performed with caution in patients with a bleeding disorder or those on anticoagulant drugs (blood thinners). Patients taking anticoagulant drugs may be advised to pause the medications from a few days before to a few after the procedure.

Procedure

• Ankle arthrocentesis is a relatively quick procedure and only in some cases may be performed under local anesthesia to avoid pain. 
• A sterile needle of appropriate size and length is introduced into the joint and the synovial fluid is collected in syringes. 
• The fluid collected is then analyzed microscopically. 
• Apart from microscopic analysis, the appearance of the aspirated synovial fluid can indicate certain features. 
• Normal fluid is clear or light yellow and viscous. 
• Inflammatory fluid appears darker yellow to cloudy and loses its viscosity. 
• Purulent fluid (pus in the fluid) is brownish to whitish and opaque.
• Occasionally, ankle arthrocentesis can be performed using radiological imaging, as it may be required to confirm the presence of fluid before aspirating. 
• Radiological imaging can help aspirate other deep and technically difficult joints like the hip joint or spine. 

After the procedure

• After the procedure, the patient is asked to rest for a few minutes, after that they can resume normal activities. 
• Some patients may experience pain and bruise which resolves in a few days. 
• Ice packs and pain killers can help reduce pain and bruising.

Ankle arthrocentesis is a relatively safe procedure, and complications are rare. The common complications patients usually face are localized bleeding, pain and swelling and sometimes reaction to local anesthesia. In rare cases, infection of the joint may occur, which is called septic arthritis. 

If medications like steroids are simultaneously injected during the procedure, it may rarely cause localized shrinkage or hypopigmentation of the skin. Long-term use of steroid injections may cause systemic side effects like weight gain, puffy face, stretch marks and easy bruising.