12 - Bones, Joints, Muscle and Endocrine System Flashcards
Describe achondroplasia in terms of inheritance and what causes the disease
Autosomal dominant defect of long bone formation, caused by mutation in fibroblast growth factor 3 (FGFR3) which is expressed in cartilage and bone
Describe osteogenesis imperfecta in terms of inheritance and what causes the disease
autosomal recessive or dominant inheritance, caused by defective collagen type I and results in production of weak osteopenic bone
Describe osteopetrosis in terms of inheritance and what causes it.
Aka marble bone disease, it’s an autosomal or x-linked inherited disease resulting from defective osteoclast function. This results in bones growing but not remodeled, therefore resulting in thick but brittle bones
For DEXA, identify the ranges that indicate osteoporosis, osteopenia, and normal
Osteoporosis (< -2.5)
Osteopenia (-1 to -2.5)
Normal (-1 to +2)
Describe the two types of primary osteoporosis
Type I: postmenopausal osteoporosis
- loss of cancellous bone
- loss of estrogen
Type II: senile osteoporosis
- affects both men and women
- loss of cortical bone predominates
Describe secondary osteoporosis
Caused by hormonal imbalance, diet, immobilization, drugs, tumors
How is osteoporosis diagnosed?
- X-ray
- bone density studies
- no biochemical abnormalities
What are 7 risk factors for osteoporosis?
age, genetics, sex, hormones, nutrition, physical activity, environment
What are osteomalacia and rickets? What are the two major causes + pathogenesis?
Osteomalacia: inadequate mineralization resulting in softening of the bone
Rickets: osteomalacia in growing bones
Causes: vitamin D deficiency and hypophosphatemia (lack of phosphate)
Pathogenesis:
1. vit D def and hypophosphatemia leads to decreased absorption
2. causes increase in PTH which causes bone resorption
3. compensatory bone formation occurs to try and make up for lack of mineralization
What are 3 consequences of osteomalacia and rickets?
- bowlegs
- nodular and palpable costochondral junction -> rachitic rosary
- growth development problems
What is renal osteodystrophy and what does it result in?
Complex bone changes that occur in patients with chronic renal failure (CRF)
CRF results in decreased phosphate excretion -> secondary hyperphosphatemia -> secondary hyperparathyroidism -> increased osteoclast activity
What are three signs of renal osteodystrophy?
- osteomalacia
- osteofibrosis
- activation of osteoclast activity -> cystic changes
Describe the characteristics of Paget’s Bone Disease. What are the three phases?
- chronic disease of unknown etiology
- irregular restructuring results in thick and deformed bones (mosaic pattern in histology)
Three phases:
- osteolytic destructive phase
- mixed osteoclastic-osteoblastic phase
- burnt-out osteosclerotic phase
What are the 4 clinical features of Paget’s disease of bone
- pain of affected bone
- thickened cranial bones -> compression of cranial nerves -> dizziness, headache
- bowlegs
- may develope into osteosarcoma
What is osteomyelitis caused by? Treatment? Complications?
Inflammation of bone caused by hematogenous spread of bacteria (S. aureus, MB tuberculosis, T. pallidum)
Treatment: antibiotics +/- surgical drainage
Complications: bone deformities, fractures, squamous caricnoma, amyloidosis
Describe aseptic necrosis and give an example. What are 5 important causes?
AKA avascular necrosis or osteonecrosis, involves interruption of blood flow causing death to part of the bone
Example: Legge-Calve-Perthe disease
Important causes:
- trauma
- corticosteroids
- radiation therapy
- systemic disease
- emboli
Define the following types of #: simple, comminuted, complete, incomplete, closed, open/compound, pathological/spontaneous
Simple: single fracture line
Comminuted: multiple fracture lines/fragments
Complete: separated bone fragments
Incomplete: not complete discontinuity of bone
Closed: has intact overlying skin and soft tissue
Open/compound: communicawtes with external environment
Pathological/spontaneous: occurs in weakened bones without external trauma (e.g. Paget’s bone disease)
Describe the 4 stages of bone # healing
- Hematoma: fills # gap and creates framework for new vessels
- Granulation tissue: inflammatory mediators stimulate osteoblast and osteoclasts
- Bony callus: soft callus mineralizes to bony callus
- Remodelling: spongy/trabecular bone
Half of primary bone tumors and the other half are…?
Half are blood-forming cells of BM (multiple myeloma, leukemia)
Other half are…
benign: osteoma, chondroma, fibroma
Malignant: osteosarcoma, chondrosarcoma, Ewing’s sarcoma
what is the most common primary malignant bone tumor? Where does it normally start and what does it affect?How is it treated?
Osteosarcoma
Starts in the bone matrix, affects metaphysis of long bone
Treated with combined chemotherapy and surgery
what is the second most common primary malignant bone tumor? Where does it normally start and what does it affect?
Chondrosarcoma
- malignant neoplams that produces cartilage
- affects the axial skeleton (vertebrae, pelvis, femur, shoulder)
Describe Ewing’s sarcoma
- malignant neoplasm consisting of undifferentiated cells
- diaphysis of long bone, may arise in soft tissue
- metastases common
What is the name of the most common joint disease? What is it characterized by? Most common symptom? Diagnosis?
Osteoarthritis
characterized by asymmetric chronic degenerative disease of articular joints with loss of cartilage, sclerosis, eburnation, cysts, and osteophytes
most common symptom is pain
Diagnosis is based on clinical/radiology
Characteriziation of rheumatoid arthritis? What are the 4 extra-articular features?
- chronic system autoimmune disease of unknown etiology characterized by symmetric inflammation of joints
Extra-articular features:
- rheumatoid nodules
- lung disease
- eye disease
- vasculitis