Block 2 PATH Exam -- Bone and Joint Disease Lecture
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- Degenerative Joint Disease
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A.K.A. osteoarthritis
Most common form of arthritis
Characterized by progressive erosion of articular cartilage
Bony outgrowths, osteophytes, may occur
Hip, knees, and vertebrae are the major sites of involvement - Rheumatoid Arthritis
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Chronic, systemic inflammatory disorder
Sustained by auto-immune reaction
The mass that is produced is the PANNUS
Ultimately, obliteration of the joint space and FUSION
Rheumatoid nodules occur in 25% (esp. children) - Crystal Induced Joint Disease
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Most commonly is gout (monosodium urate)
Can be pseudogout (calcium pyrophosphate dihydrate)
Provoked by precipitated crystals in the synovium - Osteopenia
- Decreased bone mass to below normal
- Osteomalacia
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Condition of defective matrix mineralization
Associated with nutritional deficit or Vit. D problems
Undermineralized bone is formed
Known as Rickets in children - Osteoporosis
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Reduction in the mass of bone per unit volume (SO, decr. density)
Micro-architectural deterioration of bone (porosity)
Bone resorption exceeds bone formation
MINERALIZATION IS NORMAL
The most common metabolic bone disease - Type I Osteoporosis
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Occurs primarily in post-menopausal women
Related to loss of estrogen --> Inc. recruitments of osteoclasts
Fractures typically occur in trabecular bone
Distal forearm, vertebral bodies - Type II Osteoporosis
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Associated with aging, in BOTH men and women
Associated with progressively fewer osteoblasts
Loss of bone on BOTH trabecular and cortical sites
Fractures common in the femur, femoral neck, proximal tibia, pelvis - Idiopathic Osteoporosis
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Seen in the young
UNCOMMON - Vertebral regions most prone to osteoporosis
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Mid-lower thoracic
Lumbar
Fracture of vertebrae is most prominent in anterior portion
Produces flattening and wedging
Shortening and kyphosis of the spine - Paget Disease
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Osteolytic --> Osteoclastic/blastic --> Osteosclerotic
Appears to involve both environmental and genetic factors
Begins to appear at 40 years
Slight male preponderance
Pelvis > skull > femur > spine > tibia
Haphazard mosaic pattern in bone
Cortex is thickened but NOT strengthened - Osteopetrosis
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A.K.A. Marble Bone Disease
Rare hereditary disease
Osteoclast function is defective - Osteonecrosis
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Usually involves the head of the femur
Subchondral pain and fracture
40-80% have bilateral disease in 10 yrs
Necrosis of bone marrow results in collapse of cartilage
Attempts at repair never restore normal contour - Osteomyelitis
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Inflammation of the bone and marrow
Due to Staph or Mycobacteria - Different types of fractures
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Complete vs. Incomplete
Closed vs. Compound
Comminuted vs. Displaced
Stress
Pathologic - Fibrous Cortical Defect
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NOT a neoplasm
20 - 50% of normal kids
Gradually disappears by the end of teens
Only important because if they grow large, they weaken bone - Osteosarcoma
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Most common malignant neoplasm of bone
Tumor cells capable of making osteoid
Most common in young men
Responds to chemo
5-yr of > 60% using chemo and limb salvage - Ewing's Sarcoma
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A.K.A. PNET
Nearly all show TRANSLOCATION t(11;22)
Most common in the young (2/3 < 20 yo)
More common in boys than girls (2:1)
5-yr. of 60 - 75% with chemo, radio, and surgery