Synovial Final2

7/28/2019 Synovial Final2

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I. Physiology & Composition Movable joints (diarthroses) composed of: Bones lined with articular cartilage

Separated by a cavity containing synovial fluid enclosed in asynovial membrane

Synovial membrane

synoviocytes: Phagocyticsynthesizes degradative enzymes

Synthesizes hyaluronate

Connective tissue Blood vessels, lymphatics & nerves

Fluid formation Ultrafiltrate of plasma across synovial membrane Non selective

Excludes proteins of high molecular weight

Synoviocytes Secrete mucopolysaccharite which contains:

Hyaluronic acid

protein


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Cartilage & fluid function: Reduce friction between bones Lubricates joints Fluid provides nutrients to cartilage

Lessens shock of walking and jogging impactSynovial Fluid Normal ValuesVolume


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Collection: arthrocentesisneedle aspiration ofsynovial fluid

Volume: Normal= 3.5 mL

Diseased / inflamed = up to 25 mL

Collect 2 tubes Heparin tube : microbiology

Plain top: chemistry and immunology EDTA (liquid) : hematology

*Avoid all powdered anticoagulantsinterfere with crystalanalysis

Fluid verification

Mucin clot test- Add fluid to dilute acetic acid turbidity (clot formation) due

to hyaluronate

Metachromatic staining Place fluid on filter paper + few drops of toluidine blue

metachromatic staining


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Color: Normalclear, pale yellow

Red to brown: indicates trauma of procedure ordisorder Turbidity: associated with presence of WBCs Milky: may indicate presence of crystals

Viscosity:

Measured at bedside by ability to form a string from tipof syringeNormal: 4-6 cm

Ropes test (mucin clot test)measurement ofhyaluronate polymerizationFluid forms a clot surrounded by clear fluid when added to

acetic acidClot quality is reported:Good = solid clot

Fair = soft clot

Poor = friable clot

Very poor = no clot

Test is of questionable precision and seldom used


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Cell CountWBCs Method

Use Neubauer counting chamber May pretreat viscous fluids with hyaluronidase & incubate

at 37oC for 5 min. Dilution with hypotonic saline is used to lyse any RBCs OR Dilute with normal saline/methylene blue mixture to

differentiate WBCs from RBCs

Normal =


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Other cell abnormalities: Increased eosinophilsrheumatic fever, parasitic

infections, metastatic carcinoma, post radiationtherapy or arthrography

LE cellspatients with lupus erythematosus

Reiter cellsmacrophages with ingested neutrophils

RA cells (ragocytes)precipitated rheumatoid factor

appearing as cytoplasmic granules in neutrophils

Hemosiderin granulesdue to hemorrhagic process

or cases of pigmented villonodular synovitis

Cartilaginous cellsobserved in cases of osteoarthritis

Rice bodiesfound in septic and rheumatoid arthritisand Tuberculosis

Fat dropletsindicate traumatic injury


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Synovial lining cell


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Neutrophils in synovial fluid


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Lymphs in synovial fluid


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LE cell in synovial fluid


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Crystals Crystal formation may be due to: Metabolic disorders Decreased renal excretion

Cartilage and bone degeneration Medicinal injection (ex: corticosteroids)

Fluid is examined using the wet preparation technique ASAP examination as pH and temperature affect observation Ideally examined prior to WBC disintegration Examine under both direct and compensated polarizing light

*may also be observed in Wright stain preparations Under polarizing light (Direct polarization) Birefringent substances appear as bright objects on a black

background Intensity varies between substances

Under compensated polarizing light

A red compensator plate is placed between the crystal and slide Crystals aligned parallel to the compensator appear yellow

(negative birefringence) Crystals aligned perpendicular to the compensator appear blue

(positive birefringence)

M di U t C t l (MSU)


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Monosodium Urate Crystals (MSU)

Indicate gouty arthritis due to: Increased serum uric acid

Decreased renal excretion of uric acid

Impaired metabolism of nucleic acid

Exhibit negative birefringence Intracellular (acute stages) & extracellular location

Polarized lightstrongly birefringent

Compensated polarized lightyellow when parallel

blue when perpendicular

Needle shaped Calcium pyrophosphate (CCPD) Indicates pseudogout due to: Degenerative arthritis

Endocrine disorders with increased serum calcium

Calcification of cartilage

Exhibit positive birefringence Seen intracellular- and extracellularly

Polarized lightweakly birefringent

Compensated polarized lightblue when parallel (yellow whenperpendicular)

Blunt rods or rhombic shapes


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Acute gout (uric acid crystals)


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Uric acid crystals


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Cholesterol

Nonspecific indications Associated with chronic inflammation

Exhibit negative birefringence (compensated polarized light)

Usually seen extracellularly Polarized lightstrongly birefringence

Rhombic plates

Hydroxyapatite (HA) (Calcium phosphate)

Associated with calcific deposition conditions

May produce an acute inflammatory reaction

Intracellular

Not birefringent

Require an electron microscope to examine

Small, needle shaped

Corticosteroid Associated with intra-articular injections; NO clinical significance

Primarily intracellular

Exhibit positive and negative birefringence Can closely resemble MSU and CCPD

Flat, variable shaped plates


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Calcium Oxalate

Following renal dialysis

Birefringent Artifacts:

Anticoagulant crystals (calcium oxalate, lithiumheparin)

Starch granules

Prosthesis fragments

Collagen fibers

Fibrin

Dust particles


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Glucose Done simultaneously with blood sample (prefer 8 hour

fast)

Difference between blood and synovial glucose valuesis evaluated Normal = < 10 mg/dL Inflammatory conditions = > 25mg/dL Sepsis = >40 mg/dL Considered low if < serum plasma glucose value

Should be run within 1 hour of collection Draw in sodium fluorideprevents glycolysis

Total protein Not routinely performed Normal = < 1/3 of serum value (~3g/dL)

Large molecule, not easily filtered by membrane Increased protein Changes in membrane permeability Increased joint synthesis Indicates an inflammatory process


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Uric Acid

Alone, not diagnostic

May determine gout in conjunction with plasma uric

acid, esp. when crystals are undetectable Normal = serum level

Lactate

May differentiate between inflammatory and septicarthritis

Septic arthritis = >250 mg/dL

Gonococcal arthritis = normal to low levels

Production results from :

Increased demand for energy

Tissue hypoxia Severe inflammatory conditions


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Gram stain

Performed on all specimens Most infections are bacterial:

Staphylococcus

Streptococcus

S. pyogenes

S. pneumoniae Hemophilus

Neisseria gonorrhea

Fungal, viral and tubercular agents may also beobserved

Culture Routine culture

Enrichment medium (chocolate agar

Specialty media depending on clinician orders and

indications


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Autoantibody detection (same as

found in serum)

Rheumatoid arthritis (RA)

Lupus erythematosus (LE)

Antibody detection in patients serum

Borrelia burgdorferi

Causative agent of Lyme disease Cause of arthritis


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Group Classification SignificanceI. Noninflammatory Degenerative joint disorders

II. Inflammatory Immunologic problems (RA,LE)Gout&pseudogout(crystal induced)

I. Septic Microbial infectionII. Hemorrhagic Traumatic injury

Coagulation deficiency

Note:

* categories overlap* multiple conditions can occur simultaneously* disease stage can vary laboratory results

*see text for details of associated abnormal laboratoryfindings

Synovial Final2

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