Shoulder Joint Aspiration

Shoulder anatomy

Indications

General arthrocentesis indications

• Suspicion of septic arthritis
• Suspicion of crystal arthropathy
• Evaluation of therapeutic response for septic arthritis
• Unexplained arthritis with synovial effusion
• Evaluation of joint capsule integrity if overlying laceration
• Relative: therapeutic (decrease intra-articular pressure, injection of anaesthetics/steroids)

Contraindications

General arthrocentesis contraindications

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

Equipment Needed

General arthrocentesis equipment

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

Procedure

General Setup

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

Anterior approach

• Sit patient upright facing you
• Insert needle just lateral to coracoid process (between coracoid process and humeral head)
• Direct needle posteriorly

Posterior Approach

• Sit patient upright with back facing you
• Palpate scapular spine to its lateral limit (the acromion)
• Identify the posterolateral corner of the acromion
• Insert 1.5-in needle 1 cm inferior and 1 cm medial to this corner
• Direct needle anterior and medial toward presumed position of coracoid process
• Glenohumeral joint is located at a depth of approximately 1-1.5in

Evaluation

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

Complications

General arthrocentesis complications

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

See Also

• Arthrocentesis

External Links

• https://www.nuemblog.com/blog/joint-aspiration?rq=arthrocentesis