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Exam #1: Bone Pathology

Terms in this set (45)

• two types of joints:
• nonsynovial joints
• synovial joints
NONSYNOVIAL JOINTS
• mainly for structure
• permit only minimal movement
• also known as solid joints or synarthroses
• fibrous tissue can bridge between
the skeletal elements
SYNOVIAL JOINTS
• joint space permits wide range of motion
• also known as cavitated joints
• lubricated by synovial fluid
• joint space bounded by synovial membrane
HYALINE CARTILAGE
• forms articular surfaces, glide on one another
• serves as elastic shock absorber

• wear-resistant interface
• chondrocytes make surrounding matrix
MATRIX OF HYLINE CARTILAGE
• proteoglycans for elasticity, reduce friction

• type II collagen for tensile strength
(resist tearing/deformation)

• water for normal distension, reducing friction
FEATURES OF HYLINE CARTILAGE
• avascular

• no innervation

• zones 1-4 (superficial to deep)

• chondrocytes make enzymes and
enzyme inhibitors involved in
matrix molecule turnover
SYNOVIUM
• forms boundary of joint space

• lined by synoviocytes
• connective tissue cells
• no basement membrane
• fast exchange with blood
Synovium Cells:
1) type B synoviocytes
2) type A synoviocytes
type B synoviocytes (fibroblast-like) make:
• hyaluronic acid, a glycosaminoglycan
giving viscosity and lubricant properties to synovial fluid
• can make enzymes that degrade
cartilage matrix
type A synoviocytes
phagocytic
SYNOVIAL FLUID
• formed in part as a filtrate of plasma
• contains hyaluronic acid, a glycosaminoglycan giving viscosity and lubricant properties to synovial fluid
• contains nutrients for articular cartilage
• normally is clear and viscous
viscosity of synovial fluid
• viscosity can be assessed in laboratory:
mucin clot test
• normal synovial fluid rich in mucin,
a normal hyaluronic acid-protein complex
-viscosity is decreased in inflammatory
arthritis, both infectious and noninfectious
Tests for synovial fluid
-viscosity
-sample for microbial cultures
-contains detectable crystals in some disease states
DENSE FIBROUS CAPSULE
• surrounds the joint
• synovial membrane anchored to it
NAME DISORDER:
• deep pain, increases with use during day

• morning stiffness brief (under 30 minutes)

• usually one or a few joints affected

• can be asymmetric joint involvement

• crepitus (hear or feel grinding or grating)
• decreased range of motion

• spinal nerve root compression by osteophytes

• x-ray changes include joint space narrowing
(often asymmetric)
OSTEOARTHRITIS-degenerative joint disease
Rates of osteoarthritis in M vs. F
same
Primary osteoarthritis
idiopathic,
happens with aging,
symptoms starting in 50s
secondary osteoarthritis
due to trauma, obesity, limb deformity, etc.
may occur at younger age
osteoarthritis join involvement
• knee

• hip

• spine
(cervical, lumbar)

• hand DIP, PIP
• base of thumb
(1st CMC)
• foot 1st TMT
Early osteoarthritis pathology
• chondrocyte injury
(aging, biomechanical stress,
genetic and biochemical factors)
• chondrocyte proliferation ("cloning")
• release of inflammatory mediators, proteases
• cartilage proteoglycan and collagen degraded
• cartilage matrix altered, weakened
Late osteoarthritis pathology
• fibrillation (superficial clefting, softening)
• cracking of matrix, sloughing of fragments
(produces "loose bodies" in synovial fluid, also known as "joint mice")
• chondrocyte death
• subchondral bone exposure
• eburnation = smooth bone surfaces,
burnished from grinding against one another
• subchondral cyst formation, from fluid entry into small fractures
• osteophytes arise at margins of articular surfaces
OSTEOARTHRITIS PATHOLOGY
synovium develops:
- mild congestion

- inflammation

- fibrosis
RHEUMATOID ARTHRITIS
in general...
• chronic systemic autoimmune disease

• involves joints and many tissues and organs
NAME DISEASE:
• age of onset 3rd and 4th decade
• malaise, fatigue
• musculoskeletal pain
• hand joints symmetric swelling (metacarpophalangeals, PIPs)
-feet, wrists, ankles, elbows, knees
• extra-articular lesions in 25 percent of patients
• subcutaneous nodules
• tenosynovitis (inflammation of tendon sheath)

• other organs (eg vasculitis involving arteries)
Rheumatoid Arthritis
Rheumatoid arthritis: M vs. F
females to males 3 to 1
RHEUMATOID FACTOR (RF)
• antibody in patient to Fc portion of IgG

• detected in laboratory tests, eg serum

• high titre RF IgM often with severe RA disease
ACPA (anti-CCP)
• anti-cyclic citrullinated peptide IgG antibody

• arginine to citrulline post translational change

• ACPA present in patient, eg serum

• highly specific marker for RA

• Some alleles of the HLA-DRB1 gene have been implicated (in studies often found present in those rheumatoid arthritis populations having high levels of ACPA)
PATHOLOGICAL CHANGES
IN RHEUMATOID ARTHRITIS
• synovium becomes edematous, thickened

• villi develop (frond-like protrusions)

• proliferation of synoviocytes

• inflammatory cells, initially perivascular infiltrate
• vascular proliferation
• hemosiderin, fibrin deposition

• neutrophils (synovial surface, synovial fluid)
• activation of osteoclasts in bone

• allows synovium to penetrate bone

• contributes to juxta-articular erosion

• contributes to osteoporosis there

• contributes to subchondral cysts
• pannus formation
(mass of inflamed, abnormal synovium,
drapes over and causes degradation of
cartilage surface)

• pannus may bridge joint surfaces

• can lead to tight union (ankylosis)
late deformities in RA such as
• ulnar deviation
• juxta-articular bone loss
• contractures
NAME DISORDER
• all forms of arthritis that begin before
age 16 years and persist for a minimum
of 6 weeks
• females to males 2:1
• systemic onset is frequent (fever, rash, etc.)
• oligoarthritis
• large joints more often affected than small
• often symmetric knees, wrists,
elbows, ankles
• rheumatoid factor and nodules absent
(usually)
• ANA (antinuclear antibody)
lab test is commonly positive
JUVENILE IDIOPATHIC ARTHRITIS (V)
• oligoarthritis more common in ___ than ___
(1 to 4 joints in 1st six months of disease)
JIA than in RA
NAME DISORDER
• develop in genetically predisposed
individuals

• many associated with HLA-B27 allele

• absence of autoantibodies (eg RF -ve)

• triggered by T cell response, often
initiated by infection
SERONEGATIVE
SPONDYLOARTHROPATHIES (VI)
• aka rheumatoid spondylitis
• aka Mari Strumpell Disease

• 90% HLA-B27+, often male teenager

• sacroiliac and intervertebral joint
involvement with pannus formation
preceding ankylosis
ankylosing spondylitis
• arthritis, urethritis, conjunctivitis

• 80% HLA-B27, mostly men in 20s, 30s

• autoimmune reaction post infection
eg GU chlamydia, GI shigella,
salmonella, campylobacter
• often symmetric ankles, knees, feet
Reiter syndrome
• affects 7% of psoriatic population

• commonly aged
30-50

• DIP joints,
axial joints
and entheses
psoriatic arthritis
• most patients HLA-B27 +
• pathology similar to RA
• in ulcerative colitis, bowel resection
relieves the arthritis
arthritis associated with inflammatory
bowel disease
Usually hematogenous; joint pain, sudden swelling, fever.

Most common organisms: gonococcus, staph., strep, H. influenza,
E. coli, Pseudomonas, Salmonella (SS disease).

Predisposing factors: chronic arthritis (RA, gout), SS, hemophilia,
AIDS, IV drug use.

TB arthritis usually secondary to pulmonary TB. Monostotic large
joint in children, polyostotic, small joints in adult and
spine (Pott disease).

Other : Viruses ( Parvo B19, Rubella, Hepatitis B/C); and
spirochete bacteria (syphilis and Lyme disease).
INFECTIOUS ARTHRITIS
Onset is acute with swelling and redness in the affected joint

Pathogenesis: inflammatory condition caused by precipitation of urate crystals in hyperuricemic patients

long, slender crystals on synovial fluid analysis, negatively birefringent

accumulation of aggregates of urate crystals in soft tissue and joint can cause tophi formation

tophi are aggregates of urate crystals surrounded by inflammation

in chronic tophaceous gout, see synovial hyperplasia, inflamed, with pannus formation (get erosions, ankylosis)
gout
primary gout
(common) metabolic defect
Most primary gout patients have
hyperuricemia as a result of
decreased excretion.
secondary gout
(less common)
eg drugs, leukemia
Accumulation of calcium pyrophosphate crystals
Crystals are weakly birefringent
Other joint changes can be similar to gout
CALCIUM PYROPHOSPHATE CRYSTAL
DEPOSITION DISEASE (PSEUDOGOUT)
small cyst, can be at joint capsule, arises from degeneration of connective tissue there
ganglion cyst
from herniation of synovium through joint capsule (or enlargement of bursa), example Baker Cyst of knee
synovial cyst
tenosynovial giant cell tumor
benign, treated by surgical excision
synovial sarcoma
malignant, 30% 10 year survival, looks like synovium, but located in thigh or calf
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