50 Questions
What is the main constituent of the inorganic mineral component of bone matrix?
Calcium hydroxyapatite
Which cells are responsible for bone formation?
Osteoblasts and osteocytes
What is the function of the periosteum?
Extremely rich in blood vessels and nerves
What is the composition of the organic component of bone matrix?
Osteoid
Which factor reflects exuberant bone turnover in Paget disease?
Elevated serum alkaline phosphatase
In which percentage of patients can Paget's disease lead to the development of osteogenic sarcoma?
1%
What can hypervascularity in extensive polyostotic Paget disease lead to?
High-output congestive heart failure
Which symptoms are associated with Paget disease?
Nerve impingement, back pain, and deformities in affected long bones
What is the process that involves the formation of an organizing hematoma and a pro-inflammatory state at the fracture site?
Fracture repair
What factors are released by platelets, inflammatory cells, and fibroblasts during fracture healing?
PDGF, TGF-β, and FGF
What is the transformation of the soft callus into during fracture healing?
Bony callus
What frequently results in deformity in fractures?
Displaced and comminuted fractures
What can inadequate immobilization lead to in fracture healing?
Delayed union and non-union
What delays healing and may never completely normalize in fracture cases?
Devitalized fragments of splintered bone
Which type of bone marrow begins to appear in the distal bones of the extremities around age 5-7?
Yellow bone marrow
In adult life, which of the following bones contain red bone marrow?
Skull, vertebrae, sternum, and pelvis
Which cells of bone include osteoblasts, osteoclasts, and osteocytes, each with specific functions?
Osteoprogenitor cells
Which process is involved in the development of long bones from a cartilage mold?
Endochondral ossification
What is involved in the growing process of bone radially?
Secondary ossification center
What is involved in the formation of epiphyseal plate?
Entrapping of cartilage between two expanding centers of ossification
What is involved in the tightly regulated process of adult skeleton remodeling?
RANK, RANKL, and OPG
At what stage is peak bone mass achieved?
Early adulthood
Which cells regulate osteoclast differentiation and bone resorption?
Osteoblasts
What is the process under the control of locally produced substances and hormonal effects?
Bone formation-destruction
In what two forms is the bone matrix synthesized?
Woven and lamellar bone
What process involves the resorption of bone exceeding formation, resulting in a decline in skeletal mass?
Bone remodeling
Which receptor triggers OPG production on osteoblasts?
LRP5
What is the cause of achondroplasia?
Activating FGFR3 mutation
Which condition is caused by FGFR3 mutations and is a lethal variant of dwarfism?
Thanatophoric dysplasia
What is the cause of osteogenesis imperfecta?
Defective type I collagen synthesis
What characterizes osteopetrosis?
Defective osteoclast-mediated bone resorption
What does osteopenia refer to?
Decreased bone mass
How is osteoporosis characterized?
Reduced bone mass, leading to fragility and fractures
What is primary osteoporosis commonly associated with?
Aging or postmenopausal state
What is the characteristic feature of dysostosis?
Abnormalities in mesenchyme migration and ossification
What are the consequences of osteopetrosis?
Cranial nerve palsies, recurrent infections, and hepatosplenomegaly
What do LRP5/6 receptors trigger on osteoblasts?
OPG production
What is the result of defective type I collagen synthesis?
Extreme skeletal fragility and extraskeletal manifestations
Which of the following factors contribute to osteoporosis pathogenesis?
Reduced physical activity
What is the impact of thoracic and lumbar vertebral fractures in osteoporosis?
Kyphoscoliosis and compromised respiratory function
Which specialized radiographic techniques are used to assess bone mineral density?
Dual-energy absorptiometry and quantitative computed tomography
What are the manifestations of vitamin D deficiency?
Rickets in children and osteoporosis in adults
What is the result of hyperparathyroidism?
Increased osteoclastic activity and bone resorption
Where is Paget disease of bone relatively common?
Europe, Australia, New Zealand, and the United States
What is the primary treatment for osteoporosis prevention and management?
Dietary calcium intake and vitamin D supplementation
What is the characteristic feature of rickets?
Interfering with bone deposition in growth plates
What can result from fractures of the femoral neck, pelvis, or spine?
Pulmonary embolism and pneumonia
What is the impact of osteomalacia in adults?
Resulting in under-mineralized bone formed during remodeling
What is the impact of decreased calcium nutritional state on osteoporosis pathogenesis?
Contributes to osteoporosis pathogenesis
What is the result of Paget disease of bone?
Increased, disordered, and structurally unsound bone
Study Notes
Congenital Bone Diseases
- LRP5/ and 6 receptors on osteoblasts trigger OPG production
- Dysostosis includes abnormalities in mesenchyme migration and ossification
- Achondroplasia, caused by activating FGFR3 mutation, results in severe stunted long bones
- Thanatophoric dysplasia, a lethal variant of dwarfism, is caused by FGFR3 mutations
- Osteogenesis imperfecta is caused by defective type I collagen synthesis
- Osteogenesis imperfecta results in extreme skeletal fragility and extraskeletal manifestations
- Osteopetrosis is characterized by defective osteoclast-mediated bone resorption
- Osteopetrosis can lead to cranial nerve palsies, recurrent infections, and hepatosplenomegaly
- Nutritional, endocrine, and systemic disorders affect skeletal system development
- Osteopenia refers to decreased bone mass, while osteoporosis is severe osteopenia
- Osteoporosis is characterized by reduced bone mass, leading to fragility and fractures
- Primary osteoporosis is common and may be associated with aging or postmenopausal state
Osteoporosis: Pathogenesis and Clinical Course
- Osteoporosis leads to a significant increase in the risk of fractures in the vertebrae and hips.
- Age-related changes, reduced physical activity, genetic factors (e.g. LRP5 mutations), decreased calcium nutritional state, and hormonal influences contribute to osteoporosis pathogenesis.
- Thoracic and lumbar vertebral fractures are common in osteoporosis, leading to kyphoscoliosis and compromising respiratory function.
- Fractures of the femoral neck, pelvis, or spine can result in complications such as pulmonary embolism and pneumonia, leading to deaths.
- Osteoporosis is difficult to diagnose as it is asymptomatic until a fracture occurs and cannot be reliably detected in plain radiographs until 40% of bone mass is lost.
- Specialized radiographic techniques like dual-energy absorptiometry and quantitative computed tomography are used to assess bone mineral density.
- Osteoporosis prevention and treatment involve dietary calcium intake, vitamin D supplementation, regular exercise, and pharmacologic treatments including antiresorptive and osteoanabolic agents.
- Rickets and osteomalacia are manifestations of vitamin D deficiency, leading to impaired mineralization and unmineralized bone matrix accumulation.
- Rickets affects children, interfering with bone deposition in growth plates, while osteomalacia affects adults, resulting in under-mineralized bone formed during remodeling.
- Hyperparathyroidism results in increased osteoclastic activity, bone resorption, and osteopenia, affecting the entire skeleton.
- Excessive or inappropriate levels of parathyroid hormone can result from autonomous parathyroid secretion (primary hyperparathyroidism/parathyroid adenoma) or in the setting of underlying renal disease (secondary hyperparathyroidism).
- Paget disease of bone is a condition of increased, disordered, and structurally unsound bone, rare in Scandinavia, China, and Africa, but relatively common in much of Europe, Australia, New Zealand, and the United States, affecting up to 2.5% of the adult populations.
Test your knowledge of congenital bone diseases and osteoporosis with this quiz. Explore the pathogenesis, clinical course, and diagnostic and treatment strategies for these conditions affecting the skeletal system. Keywords: osteogenesis imperfecta, achondroplasia, osteopetrosis, osteoporosis, fractures, bone mineral density, osteoporosis prevention, rickets, hyperparathyroidism, Paget disease of bone.
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