Musculoskeletal Pathology

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Musculoskeletal Pathology
2010-12-01 18:13:46

Musculoskeletal pathology
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  1. What are two hereditary diseases of the bone?
    • Osteogenesis imperfecta (OI): aka brittile bone disease
    • Osteopetrosis: (marble bone disease)
    • There are a number of hereditary disorders of the bone that interfer with the bone growth by affecting maintenance of a normal osteoid matrix.
  2. What is Osteogenesis Imperfecta?
    Most severe problem with OI?
    Clinical manifestations?
    • Group of hereditary bone disorders with abnormal synthesis/development of type I collagen. This causes SKELETAL FRAGILITY and "brittle bone disease"
    • Most are autosomal dominant (4 variants)
    • In most severe forms, death results from passage through birth canal.
    • Blue sclera and opalescent teeth (dentinogensis imperfecta) are components.
    • Prognosis depends on type of OI and expression of the gene.
  3. Osteopetrosis: What is it?
    affect on bone structure?
    • aka "marble bone disease"
    • Group of rare hereditary bone disorders with defective bone remodeling (osteoclast dysfunction)
    • Affected bone is dense, but structurally unsound and weak.
    • Prone to fracture, cranial nerve compression and infections.
    • Bone marrow transplantation may re-populate functional osteoclasts (derived from monocyte precursors)
  4. Osteopetrosis:
    Density of bone causes what?
    Predisposed to what?
    Compression of marrow area causes what?
    • Increased unorganized bone matrix density causes them to be more brittle.
    • Predisposed to infections.
    • Compression on nerve roots creates nerve palsies.
  5. What are some acquired diseases of bone development?
    • Osteoporosis
    • Paget disease (osteitis deformans)
    • Hyperparathyroidism
    • Osteomyelitis
    • Fibrous Dysplasia
  6. Osteoporosis:
    What is it?
    Who is affected? hormonal affects?
    Most common sites of osteoporotic problems?
    • Increased porosity of the skeleton resulting from REDUCED bone mass: increased bone FRAGILITY
    • Postmenopausal females, associated with reduced estrogen. (most affected)
    • Older men because of lower androgen levels w/ age
    • Older people bc of reduced physical activity.
    • Most common sites include vertebral bodies, pelvis, femoral neck and other WEIGHT bearing bones.
  7. What are the causes of primary vs secondary Osteoporosis?
    • Primary: (most common) associated with aging, decrease in hormones/activity.
    • Secondary: (Generalized) dude to a wide variety of pathoses. Endocrine disorders, neoplasia, gastrointestinal issues, rheumatologic disease, drugs, miscellaneous things.
  8. Osteoporosis:
    Time of peak bone mass.
    Factors influencing peak bone mass
    • Peak bone mass 25-30. Decreases from there
    • Physical activity, genetics and nutrition affect peak bone mass.
    • Menopause and aging influence development of osteoporosis.
  9. Osteoporosis:
    • TX: Diet and exercise, disphosphonates, estrogen replacement or SERMS, Calcitonin, Parathyroid hormone, dietary intake of calcium and vitamin D.
    • Prognosis: "Gaurded" questionable.
  10. Paget disease of Bone (aka?)
    What is it?
    overview of progression:
    net effect?
    • Paget disease (Osteitis deformans) Abnormal dense bone formation which is structurally weak and prone to fracture.
    • Repetitive episodes of increased regional osteoclastic activity and bone resorption, followed by osteoblastic activity and bone formation, and finally by exhaustion of cellular activity.
    • Net effect = gain in bone mass, but newly formed bone is disorded an lacks strength.
    • Skeletal deformation caused by accumulation of excessive amounts of abnormal, unstable bone!
  11. Paget disease (osteitis deformans)
    Monostotic vs. polyostotic?
    • Affects adults over 40
    • Monostotic 15% and Polystotic 85% Usually affects multiple bones. Rarely affects entire skeleton.
    • Bone enlargement, pain, deformity, cranial nerve compression, bowing of bones and fractures.
  12. Histopathologic features of Pagets Disease (Osteitis deformans)
    Mosaic pattern of bone. Radiographically, mixture of adiolucent/radiopaque areas referred to as the cotton wool pattern.
  13. Paget disease (Osteitis deformans)
    Symptoms? key symptom of the face?
    • 80-90% are asymptomatic, most are discoved on routine radiographs.
    • Symptoms variable: include enlargement, bone pain, deformity, CN compression, hearing loss and visual disturbances, bowing of bones/fractures.
    • Leontiasis ossea (lion face, overgrowth of factial/cranial bones).
    • Development of sarcomas (osteosarcomas).
  14. Paget Disease (Osteitis deformans)
    3 phases:
    • Osteolytic Phase: Initial increased osteoclastic activity/bone resorption.
    • Mixed Phase: osteoblastic activity and bone formation.
    • Osteosclerotic Phase: Finally an apparent exhaustion of cellular activity.
  15. Paget disease:
    Increased rik for development of what?
    • Diagnosis: initially radiographic, then check for elevated levels of urinary hydroxyproline (increased bone resorption) and serum alkaline phosphatase (increased bone apposition).
    • Tx: Calcitonin, bisphosphonates, analgesics for bone pain.
    • Increased risk for development of sarcomas (especially osteosarcoma).
  16. Hyperparathyroidism: what is it?
    What does PTH do?
    Net result?
    • Inappropriate secretion of PTH
    • PTH plays a central role in calcium homeostasis via it's effects on: Osteoclast activation, increased calcium resorption by the kidneys, and increased synthesis of vitamin D in the kidneys resulting in increased calcium absorption from the gut.
    • Net result: Elevation in serum calcium level.
  17. What's primary and secondary hyperparathyroidism?
    • Primary: due to parathyroid hyperplasia (95%), adenoma or carcinoma. Important cause of hypercalcemia.
    • Secondary: Due to renal failure (most common cause), leads to poor calcium retention and altered vitamin D metabolism. It's caused by any condition associated with a chronic depression in the serum calcium level. Low serum calcium level leads to compensatory over activity of the parathyroids.
  18. What clinical manifestations has been traditionally associated with primary hyperparathyroidism?
    painful bones, renal stones, abdominal groans and psychic moans.
  19. What is the treatment for primary and secondary hyperparathyroidism (they're different)
    • Primary: Remove affected gland/tumor
    • Secondary: Renal transplant, Vitamin D supplementation.
  20. Osteomyelitis
    What is it?
    what is it's main cause?
    What are it's three normal pathways of spreading?
    • Infection spreading through the medullary spaces of bone causing inflammation of the bone and marrow.
    • Usually a bacterial infection.
    • 1. Hematogenous spread (esp. Staph Aureus)
    • 2. Direct extension from soft tissues
    • 3. Direct traumatic introduction (implantation following compound fractures or surgery)
  21. Chronic Osteomyelitis:
    Radiographic findings?
    What's the treatment of osteomyelitis?
    • Ill-defined areas of radiolucency develop and may be intermixed with radiopaque sequestra.
    • Non-vital bone (sequestrum) surrounded by rim of new bone (involucrum).
    • Tx: drainage, antibiotics, surgical debridement.
  22. Fibrous dysplasia: what is it?
    who does it affect?
    Histopathologic appearance?
    • Replacement of normal bone by fibrous CT and abnormal bony trabeculae.
    • Affects adolescents and young adults.
    • "Chinese characters" mix of cellular fibrous CT intermixed with elongated trabeculae of immature woven bone. Looks like ground glass.
  23. Fibrous Dysplasia:
    Monostotic fibrous dysplasia?
    Polyostotic fibrous dysplasia without endocrine involvement?
    Polyostotic fibrous dysplasia in association with endocrinopathies?
    • Monostotic fibrous dysplasia: involves a single bone. 70% of cases. Childhood.
    • Polystotic fibrous dysplasia without endocrine involvement: (Jaffe Syndrome): multiple bones affected. Involvement is unilateral. craniofacial bones. Cafe-au-lait pigments.
    • Polyostotic fibrous dysplasia with endocrinopathies (McCune-Albright syndrome): least common 3%. Cafe-au-lait spots and endocrine abnormalities.
  24. Fibrous dysplasia treatment
    Surgical reduction?
    • Observation: many will stabilize at puberty
    • Surgical reduction: Usually delayed until after skeletal maturity.
  25. Osteosarcoma:
    What is it?
    Mean age of onset?
    Symptoms? Characteristic feature?
    Most common site?
    • Mesenchymal malignancy that produces osteoid and bone.
    • Most common bone cancer in children, mean age 18
    • Pain and swelling of affected bone. Painful enlarging mass. Radiographic "sunburst" appearance.
    • Codman's triangle is a characteristic feature. The formation of an acute angle between the neoplastic bone and cortex.
    • Most common site is the knee 60%, hip 15%, shoulder 10%, face 8%
  26. Osteoarthritis: (aka?)
    what is it?
    Age related?
    Systemic affect?
    what does it develop from/fundamental feature?
    • aka "degenerative joint disease"
    • Most common joint disorder
    • Age related, usually people over 50
    • involvement of one or a few joints usually.
    • Fundamental feature: Stems from degeneration of articular cartilage (bone changes are secondary)
    • Mechanical stresses play a major role.
  27. What are two clinical findings of Osteoarthritic joints?
    • "joint mice" fragments of dislodged bone and cartilage that float free in the joint space.
    • At margins of the joint, small bony outgrowths termed osteophytes arise and help to further inflame the surrounding synovial membrane.
  28. Gout: what is it?
    Results in (3 things)
    what gender/body part is most affected?
    What is the second most affected organ?
    • Gout is a disease of uric acid accumulation.
    • Results in:
    • 1. Episodic, acute arthritis.
    • 2. tophus (tophi) formation (deposits of urate crystals in articular surface which penetrate joint surface and surrounding bone)
    • 3. kidney damage.
    • Adult males, great toe (90%)
    • Kidney is the second most affected organ (after joints): pyelonephritis, nephrosclerosis, uric acid renal stones)
  29. Treatment of Gout:
    • Diet modification
    • Colchicine, allopurinol,
    • NSAIDs for pain.
  30. Muscular dystrophy
    What is it?
    Heterogenous group of heritable disease with spontaneous, progressive degeneration of muscle fibers. Vary from mild motor weaknesses to sever life-threating alterations.
  31. What is Duchenne Muscular dystrophy?
    What is dystrophin?
    • Most common and devastating form of muscular dystrophy.
    • X-linked condition
    • Caused by the absence of DYSTROPHIN a key structural protein in skeletal and cardiac muscle.
    • Dystrophin: a protein that attaches muscle fibers to the cell membrane, plays an important role in the structure and function of the myocyte.
  32. Muscular dystrophy:
    when do symptoms begin, age of onset?
    • Signs usually begin by 3-5 years of age
    • Weakness of pelvic and shoulder areas, progressive atrophy and deterioration of muscle.
    • No treatment available, most patients in wheelchair by early teens and die before age 30 of disease related complications (pneumonia, cardiac or respiratory disease.
  33. Myasthenia Gravis:
    Type of disease?
    How is it caused?
    gender predominance?
    Symptoms/progression of disease?
    initial presentation/symptom?
    • Acquired, autoimmune disease.
    • Auto antibodies produced which results in a destruction of acetylcholine receptors in the neuromuscular junction.
    • manifested by weakness and prominent fatigability of voluntary muscles.
    • Problems with eye muscles and muscles of mastication may be initial presentation.
    • Weakness worsens with repeated contractions, symptoms worse in later days.
    • Female predominance, any age, insidious onset.
  34. Myasthenia gravis:
    Which muscles are most severly affected?
    eye muscle problems?
    • The most active muscles generally are the most severely affected, such as the muscles involved in eye movement, facial expression, chewing, swallowing and respiration.
    • Muscle weakness becomes evident with small, frequently utilized muscles:
    • eyelids (ptosis: drooping of eyelids)
    • eye movement muscles (diplopia: double vision).
  35. Myasthenia Gravis
    • Cholinesterase inhibitors (improves transmission by not destroying Ach), Imunosuppression, thymectomy may induce remission.
    • Spontaneous remission in some cases.