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My knee hurts
MSU Emergency Medicine
Lansing, MI
Dr. Patricia Manhire
What are the Indications
for Arthrocentesis?
Indications for Arthrocentesis
Crystal-induced arthropathy
 Hemarthrosis
 Symptomatic relief of a large effusion
 Unexplained joint effusion
 Unexplained monarthritis
 Suspect interarticular infection
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What are the
Contraindications to Joint
Needle Aspiration?
Contraindications to Joint
Needle Aspiration
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Absolute
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Overlying infection in the soft tissues*
 abscess & cellulitis
Severe coagulopathy
Severe overlying dermatitis
Relative contraindication
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Bacteremia
Hemophilia
On Warfarin
Uncooperative patient
*** Often Acutely arthritic joint symptoms may mimic a
soft tissue infection
Review of Procedure
Knee Arthrocentesis
Ultrasound
Ultrasound-assisted arthrocentesis can
be used as an adjunct to assist in
localization and aspiration of joint fluid.
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Using a linear 5-10 MHz probe
Anterior transverse scan
A (top)= prior to aspiration
B (bottom) = following aspiration
> = tip of the needle,
f = femur.
Filippucci E, Iagnocco A, Meenagh G, Riente L,
Delle Sedie A, Valesini G, Grassi W.
Position & Prep
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Knee extended or slightly bent
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Can use medial or lateral approach
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Controversial: Studies show bent has a
lower yield of fluid in small effusions but is
more comfortable.
Suggest lateral with smaller effusions
Prep skin povidone-iodine or Choroprep
Identify Landmark
Lateral Approach
Insert needle 1 cm
above and 1 cm
lateral to the superior
lateral aspect of the
patella. The needle is
tilted beneath the
patella at a 45-degree
angle.
Aspiration
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Inserted needle through stretched skin. Stretching
the skin can reduce discomfort
Some administer lidocaine into the skin.
The needle is directed at a 45-degree angle
distally and 45 degrees into the knee, tilted below
the patella
Compression applied over the joint space or
"milking" of the bursae, on the patellar side
opposite the needle insertion site, may facilitate
aspiration.
Roberts & Hedges. Clinical Procedures in Emergency Med. 4th Ed Saunders 2004
You now have the Fluid
Sample.
What labs do you Order?
Examination of Synovial Fluid
Normal
Noninflammatory Inflammatory
Septic
Clarity
Transparent Transparent
Cloudy
Cloudy
Color
Clear
Yellow
Yellow
Yellow
WBC/L
<200
<200–2000
200–50,000
>50,000
PMN % <25
<25
>50
>50
Culture
Negative
Negative
>50%
positive
Crystals None
None
Multiple or
none
None
Associated
conditions
Osteoarthritis, trauma, Gout, pseudogout,
spondyloarthropathies,
rheumatic fever
Negative
RA, Lyme disease,
SLE
RA = rheumatoid arthritis; SLE = systemic lupus erythematosus
Nongonococcal or
gonococcal
septic arthritis
What is your interpretation
of the fluid?
•Normal
•Noninflammatory
•Inflammatory
•Septic
So, you have determined your
patient has Inflammatory Arthritis
What information would help you decide
which Inflammatory Arthritis your pt has:
Gout?
 Pseudogout?
 Spondyloarthropathies?
 RA?
 Lyme disease?
 SLE?
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Number of joints involved
Crystals or no crystals
Classification of Arthritis by Number of Affected Joints
Number of Joints
Differential Considerations
Monoarthritis
Trauma-induced arthritis
Infection/septic arthritis
Crystal-induced (gout, pseudogout)
Osteoarthritis (acute)
Lyme disease
Avascular necrosis
Tumor
2–3 = Oligoarthritis
Lyme disease
Reiter syndrome
Ankylosing spondylitis
Gonococcal arthritis
Rheumatic fever
>3 = Polyarthritis
Rheumatoid arthritis
Systemic lupus erythematosus
Viral arthritis
Osteoarthritis
EMERGENCY MEDICINE: A Comprehensive Study Guide, 6th ed, The McGraw-Hill Companies, Inc.
Lyme Disease
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The arthritic manifestations occur in the weeks, months, or
years following the primary, stage I infection
Typically, a monarticular or migratory oligoarticular
Large joints are most often affected
Arthrocentesis
 inflammatory synovial fluid, usually with negative cultures
History of
 endemic area exposure
 history of tick bite or erythema chronicum migrans (ECM)
rash is helpful but often absent
 Show characteristic stage II and stage III findings—such
as fatigue, neurologic abnormalities, and/or cardiac
conduction disturbances
 May require laboratory confirmation
Treatment is administered for 3 to 4 weeks. Rx: doxycycline,
penicillin G, amoxicillin, or ceftriaxone.
Rheumatoid Arthritis
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Symmetric, polyarticular involvement.
 Sparing of the distal interphalangeal (DIP) joints.
 Stiffness of the joints after inactivity (morning stiffness).
Multisystem involvement is characteristic
 depression, fatigue, and generalized myalgias.
 pericarditis, myocarditis, pleural effusion, pneumonitis,
Arthrocentesis of synovial fluid - inflammatory profile.
Treatment:
 Salicylates or other NSAIDs
 Immobilization providing added relief from joint
movement pain.
 Corticosteroids may be utilized for brief periods
 Long-term therapy using agents such as antimalarials,
gold, and methotrexate.
Ankylosing Spondylitis
Seronegative spondyloarthropathies
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Ankylosing Spondylitis
Similar to RA
 morning stiffness and multisystem
involvement with constitutional symptoms
such as malaise, weakness, and fatigue.
Usually younger than age 40
Treatment consists of pain control with shortterm and long-term management with NSAIDs.
Crystal-Induced Synovitis: Gout & Pseudogout
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Gout & Pseudogout
 Middle-aged and elderly adults.
 Both often follows trauma, surgery, a significant illness, or
change in medications affecting uric acid levels.
Pseudogout
 Positive birefingence crystals: Calcium pyrophosphate -rhomboid shape
 Acute treatment: same as Gout.
Gout
 Negative birefringence: Uric acid crystals -- needle-shaped
and blue
 30 % have normal uric acid levels during an acute gout
attack
 Treatment: nonsteroidal anti-inflammatory drugs (NSAIDs)
or Colchicine or indomethacin
 Once the symptoms of an acute resolved, elimination of
gout-inducing agents (diuretics, aspirin, or cyclosporine) and
treatment with allopurinol or probenecid
Your Diagnosis?
Acute Rheumatoid
Arthritis
What is your Treatment Plan