Arthrocentesis

Indications

  • Suspicion of septic arthritis
  • Suspicion of crystal induced arthritis
  • Evaluation of therapeutic response for septic arthritis
  • Unexplained arthritis with synovial effusion

Relative Indications

  • Therapeutic (decrease intra-articular pressure, injection of anesthetics/steroids)

Contraindications

  1. No absolute contraindications for diagnostic arthrocentesis
  2. Do not inject steroids into a joint that you suspect is already infected
  3. Relative Contraindications:
    1. Overlying cellulitis
    2. Coagulopathy
    3. Joint prosthesis (refer to ortho)

Equipment Needed

  1. Betadine or Chlorhexadine
  2. Sterile gloves/drape
  3. Sterile gauze
  4. Lidocaine
  5. Syringes
    1. Small syringe (6-12cc) for injection of local anesthetic
    2. Large syringe (one 60cc or two 30cc) for aspiration
  6. Needles
    1. 18 gauge: knee
    2. 20 guage: most other joints
    3. 25 guage: MTP joints
    4. 27 gauge for anesthetic injection
  7. Collection tubes (red top and purple for crystal analysis)
  8. Culture bottles
  9. Consider utilizing U/S to assess for effusion

Procedure

  1. Prep area w/ betadine or chlorhexadine using circular motion moving away from joint x 3
  2. Drape joint in sterile fashion
  3. Inject lidocaine w/ 25-30ga needle superficially and then into deeper tissues
  4. Insert 18ga needle (for larger joints) into joint space while pulling back on syringe
  5. Stop once you aspirate fluid; aspirate as much fluid as possible
    1. Send: cell count, culture, Gram Stain, crystal analysis

Approach

Shoulder

  1. Anterior approach
    1. Sit pt upright facing you
    2. Insert needle just lateral to coracoid process (between coracoid process and humeral head)
    3. Direct needle posteriorly
  2. Posterior Approach
    1. Sit pt upright w/ back facing you
    2. Palpate scapular spine to its lateral limit (the acromion)
    3. Identify the posterolateral corner of the acromion
    4. Insert 1.5-in needle 1 cm inferior and 1 cm medial to this corner
    5. Direct needle anterior and medial toward presumed position of coracoid process
    6. Glenohumeral joint is located at a depth of approximately 1-1.5in

Elbow

Shoulder arthrocentesis
  1. Place elbow in 90o flexion, resting on a table, w/ hand prone
  2. Locate radial head, lateral epicondyle , and lateral aspect of olecranon tip
    1. These landmarks form the anconeus triangle
  3. Palpate a sulcus just proximal to the radial head (in the middle of the triangle)
  4. Insert needle into sulcus directed medial and perpendicular to radius toward distal end of antecubital fossa


Wrist

Wrist arthrocentesis
  1. Palpate landmarks w/ wrist in neutral position:
    1. Radial tubercle of distal radius
    2. Anatomic snuffbox
    3. Extensor pollicis longus tendon
    4. Common extensor tendon of index finger
  2. Insert needle perpendicular to skin, ulnar to radial tubercle and anatomic snuffbox, between extensor pollicis longus and common extensor tendons


Knee

  1. Can be entered medially or laterally to the patella, superior or inferior to patella
  2. Fully extend knee and ensure quadriceps muscle is relaxed (optionally bump with 20 deg of flexion)
    1. Place your thumb on the patella and slide it over as you enter with needle
    2. For Suprapatellar Approach 1 cm lateral and 1 cm superior
  3. Identify midpoint of patella; insert needle either 1 cm lateral or medial
  4. Direct needle posterior to patella and horizontally toward the joint space
  5. Compression or "milking" applied to both sides of joint space may facilitate aspiration

Ankle

  1. Lateral approach (subtalar)
    1. Keep foot perpendicular to leg
    2. Enter subtalar joint just below tip of lateral malleolus
    3. Direct needle medially toward joint space
  2. Medial approach (tibiotalar)
    1. Have pt supine w/ foot perpendicular to leg
    2. Palpate sulcus lateral to medial malleolus and medial to TA and EHL tendons
    3. Then plantarflex foot w/ needle entering skin overlying the sulcus
    4. Angle needle slightly cephalad as it passes between medial malleolus and TA tendon

Hip[1]

  1. Should only be done under US guidance
  2. Orient your probe along the axis of the femoral neck (indicator towards abdomen)
  3. Identify Landmarks (Femoral V/A/N, Acetabular Labrum, Femoral Head/Neck)
  4. Effusion will be seen between femoral head/neck and the iliopsoas muscle
  5. Insert needle under probe, making sure that you know where pt's femoral V/A/N are

Metacarpophalangeal

  1. Have palm facing down and apply gentle traction to the affected digit
  2. Insert needle dorsally just medial or lateral to midline and proximal to the base of the proximal phalanx

Interphalangeal

  1. Have palm facing down and apply gentle traction to the affected digit
  2. Insert needle dorsally medial or lateral to midline and proximal to base of middle or distal phalanx

Metatarsophalangeal

  1. Patient supine with flexion of the MTP joint 15-20 degrees and apply gentle traction
  2. Insert needle dorsally just medial or lateral to midline between the metatarsal head and base of proximal phalanx

Interphalangeal

  1. Patient supine with joint flexed 15-20 degrees with gentle traction
  2. Insert needle dorsally, medial or lateral to midline between head of proximal phalanx and base of more distal phalanx

Complications

  • Pain
  • Infection
  • Re-accumulation of effusion
  • Damage to tendons, nerves, or blood vessels

Diagnosis

Arthrocentesis of synoval fluid

Synovium Normal Noninflammatory Inflammatory Septic
Clarity Transparent Transparent Cloudy Cloudy
Color Clear Yellow Yellow Yellow
WBC <200 <200-2000 200-50,000

>1,100 (prosthetic joint)

>25,000; LR=2.9

>50,000; LR=7.7

>100,000; LR=28

PMN <25% <25% >50%

>64% (prosthetic joint)

>90%

Culture Neg Neg Neg >50% positive
Lactate <5.6 mmol/L <5.6 mmol/L <5.6 mmol/L >5.6 mmol/L
LDH <250 <250 <250 >250
Crystals None None Multiple or none None
  • Viscosity of synovial fluid may actually be decreased in inflammatory or infectious etiologies, as hyaluronic acid concentrations decrease
  • The presence of crystals does not rule out septic arthritis; however, the diagnosis is highly unlikely with synovial WBC < 50,000[2]

See Also

External Links

Sources

  1. *Freeman, K., A. Dewitz, et al. (2007). "Ultrasound-guided hip arthrocentesis in the ED." Am J Emerg Med 25(1): 80-86.
  2. Shah K, Spear J, Nathanson LA, Mccauley J, Edlow JA. Does the presence of crystal arthritis rule out septic arthritis?. J Emerg Med. 2007;32(1):23-6.