Ankle Arthrocentesis 

Updated: Feb 28, 2019
Author: Gil Z Shlamovitz, MD, FACEP; Chief Editor: Erik D Schraga, MD 

Overview

Background

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.

Indications

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

Contraindications

There are no absolute contraindications for ankle arthrocentesis.

Relative contraindications include the following:

  • Suspected septic joint - In this case, no contraindications exist
  • Cellulitis overlying the joint
  • Skin lesion or dermatitis overlying the joint
  • Known bacteremia
  • Adjacent osteomyelitis
  • Uncontrolled coagulopathy
  • Joint prosthesis
 

Periprocedural Care

Equipment

Equipment used for ankle arthrocentesis includes the following:

  • Sterile gloves and drapes
  • Gauze pads (5), 4 × 4 in.
  • Skin preparatory solution
  • Lidocaine 1%
  • Syringe, 5 mL
  • Needles, 18 gauge and 25 or 27 gauge
  • Syringes, 20 mL, 30 mL, 60 mL
  • Needle, 18 gauge or 20 gauge (a patient who is morbidly obese might require a 21-gauge spinal needle for arthrocentesis)
  • Hemostat
  • Specimen tubes
  • Bandage

Patient Preparation

Anesthesia

Patients who are anxious, in severe pain, or unable to cooperate with the procedure might require procedural sedation and/or analgesia. For more information, see Procedural Sedation.

Local anesthesia is warranted. After skin preparation, draping, and identification of the needle insertion site, use a 25- or 27-gauge needle to inject 2-5 mL of local anesthetic (eg, lidocaine 1%) into the subcutaneous tissue. (See the image below.) For more information, see Local Anesthetic Agents, Infiltrative Administration.

Infiltration of local anesthetic. Infiltration of local anesthetic.

Deep injections that might enter the joint space are not recommended, because they may alter the synovial fluid analysis results.

Positioning

The patient should be placed either sitting or supine on a stretcher, with the knee flexed at 90º and the leg either hanging from the side of the stretcher or bent with the heel resting against the stretcher.

Plantarflexion of the ankle against minimal ankle dorsiflexion by the patient helps define the anatomy.

 

Technique

Aspiration of Synovial Fluid From Ankle

Prepare the skin with sterile solution, allow drying, and then drape.

Using a sterile technique, attach the 18- or 20-gauge needle to the 20-mL syringe, and pull the plunger to break resistance.

While stretching the skin over the insertion site (see below for choices of insertion site), insert the needle into the joint space while gently aspirating until synovial fluid enters the syringe (usually 1-2 cm in an adult of average size). If a bone is encountered, pull the needle back, verify the anatomic landmarks (see the images below), and readvance the needle in a corrected direction.

Right ankle. Right ankle.
Anatomic landmarks for ankle arthrocentesis. EDL = Anatomic landmarks for ankle arthrocentesis. EDL = extensor digitorum longus; EHL = extensor hallucis longus; TA = tibialis anterior.

If removal of more fluid is desired, a hemostat flush to the skin can be used to secure the needle in place while the syringe is replaced with a new one.

Remove the needle and apply a bandage.

Divide the aspirated synovial fluid into the different specimen containers.

Anterolateral approach (preferred)

This is the preferred approach for ankle joint aspiration because it avoids potential injury to the dorsalis pedis and posterior tibial vessels or the deep peroneal nerve, which course through the medial aspect of the ankle and foot.

Identify the ankle joint line, the lateral malleolus, and the lateral border of the extensor digitorum longus (EDL).

Extension of the foot against the patient’s resistance or active flexion/extension movement by the patient helps the practitioner identify the space between the base of the lateral malleolus and the lateral border of the EDL.

Insert a needle (18-20 gauge) at the joint line midway between the base of the lateral malleolus and the lateral border of the EDL, advancing the needle perpendicular to the fibular shaft.

Anteromedial approach

Exercise care with this approach to avoid injury to both the dorsalis pedis vessels and the deep peroneal nerves that are immediately below and lateral to the extensor hallucis longus (EHL) tendon.

Identify the ankle joint line, the medial malleolus, and the tendons of the EHL and the tibialis anterior.

Extension of the foot against the patient’s resistance or active flexion/extension movement by the patient helps the practitioner identify the space between the medial border of the EHL and the lateral border of the tibialis anterior or between the base of the medial malleolus and the medial border of the tibialis anterior. (See the image below.)

Identification of space between medial malleolus a Identification of space between medial malleolus and medial border of tibialis anterior tendon.

Insert a needle (18-20 gauge) at either insertion point, and advance the needle perpendicular to the tibial shaft. (See the image below.)

Ankle joint aspiration between medial malleolus an Ankle joint aspiration between medial malleolus and medial border of tibialis anterior tendon.

Analysis of Synovial Fluid

The aspirated synovial fluid is then analyzed (see Table 1 below).[8]

Table 1. Synovial Fluid Analysis in Different Diseases (Open Table in a new window)

 

Appearance

WBC, cells/μL

Polymorphonuclear (PMN) cells, %

Glucose concentration, mg/dL

Protein concentration, g/dL

Normal

Clear

< 150

< 0.25

Serum glucose

1.3-1.8

Noninflammatory

Clear

< 3000

< 0.25

Serum glucose

2-3.5

Inflammatory

Cloudy

>3000

< 0.75

< 25

>4

Purulent

Cloudy

>50,000

>0.9

< 25

>4

Hemorrhagic

Bloody

>2000

~0.3

Serum glucose

...

Operative characteristics of septic joint effusion findings include the following:

  • Total white blood cell (WBC) count >25,000/μL (sensitivity, 77%; specificity, 73%; positive likelihood ratio [LR +], 29; negative likelihood ratio [LR ], 0.71)
  • Total WBC count >50,000/μL (sensitivity, 62%; specificity, 92%; LR +, 7.7; LR , 0.42) [9]
  • Total WBC count >100,000/μL (sensitivity, 22%; specificity, 99%; LR +, 2.9; LR , 0.32)
  • PMN cells ≥90% (sensitivity, 73%; specificity, 79%; LR +, 3.4; LR , 0.34)
  • Synovial glucose or serum glucose concentration < 0.5 mg/dL (sensitivity, 51%; specificity, 85%; LR +, 3.4; LR , 0.58)
  • Protein concentration >3 g/dL (sensitivity, 48%; specificity, 46%; LR +, 0.9; LR , 1.1)
  • Lactic dehydrogenase (LDH) concentration >250 U/L (sensitivity, 100%; specificity, 51%; LR +, 1.9; LR , 0.1)

Although uncommon, crystal-induced arthritis and septic arthritis can coexist; therefore, the presence of crystals does not exclude bacterial arthritis.[10]

Complications

Improper needle placement, a small amount of effusion, mechanical obstruction of the needle against cartilage, or thickened synovium can result in a dry tap.

Potential damage to cartilage can be avoided by understanding the joint anatomy and avoiding further advancement of the needle into the joint space once synovial effusion enters the syringe.

Most hemarthroses are small and self-limited and only require observation. Hemarthrosis in coagulopathic patients may require correction of the coagulopathy after consideration of the relative risks of reversal. Proper skin cleansing and use of aseptic technique reduces the risk of introducing infection into a sterile joint to less than 1:10,000.

When performing arthrocentesis through infected skin for the diagnosis of a potentially septic joint, intravenous antibiotics should be given immediately following the procedure, and the patient should be admitted for continuation of the antibiotics.

 

Questions & Answers

Overview

When is ankle arthrocentesis performed, and how are complications prevented?

What is the anatomy of an ankle joint relevant to ankle arthrocentesis?

What are the diagnostic indications for ankle arthrocentesis?

What are the therapeutic indications for ankle arthrocentesis?

What are the contraindications for ankle arthrocentesis?

Periprocedural Care

What is the equipment needed to perform ankle arthrocentesis?

When is procedural sedation or analgesia indicated for ankle arthrocentesis?

What is the role of local anesthesia in ankle arthrocentesis?

How should the patient be positioned for ankle arthrocentesis?

Technique

How is synovial fluid aspirated during ankle arthrocentesis?

What is the anterolateral approach for ankle arthrocentesis?

How is anterolateral approach for ankle arthrocentesis performed?

What injuries can occur with the anteromedial approach for ankle arthrocentesis?

How is anteromedial approach for ankle arthrocentesis performed?

How are synovial fluid analysis results from ankle arthrocentesis interpreted?

What are the operative characteristics of septic joint effusion based on ankle arthrocentesis results?

What does the presence of crystals on the septic joint effusion from ankle arthrocentesis indicate?

What factors result in a dry tap when performing ankle arthrocentesis?

How can potential damage to cartilage be avoided when performing ankle arthrocentesis?

How are hemarthrosis caused by ankle arthrocentesis managed?

When are antibiotics indicated in ankle arthrocentesis?