soft tiss 1 Flashcards
(21 cards)
Bone undergoes constant remodeling Via
RANK/RANKL signaling and circulating levels of PTH, vit D
Dysostosis
Aberrant localization/migration of bone precursor (mesenchymal) cells
Results in absence, addition, fusion of bones
Dysplasia
Refers to abnormal bone/cartilage growth, but does not lead to neoplastic dysplasia
Inappropriate bone and/or cartilage formation, maintenance, remodeling
Osteodysplasia & chondrodysplasia
most common type of dwarfism
Achondroplasia
Achondroplasia
Mutations in the fibroblast growth factor receptor 3 gene prevent tyrosine kinase activity & endochondral ossification
Most frequently inherited as autosomal dominant
Osteogenesis imperfecta results from abnormalities in
α1 or α2 chains of type I collagen
Osteogenesis imperfecta
Various subtypes with broad range of clinical manifestations, but most are inherited in autosomal dominant fashion
-Often referred to as brittle bone disease
Osteopetrosis is caused by
aberrations (reductions) in osteoclast function or osteoclast differentiation
Osteopetrosis
- Bone is made, but not remodeled or resorbed
- Most frequent subtypes are autosomal dominant with mild clinical features or autosomal recessive with infantile lethality
- Clinically manifests as frequent bone fractures as well as nerve palsies, recurrent infection, hepatosplenomegaly
Metabolic Acquired Bone Disease
- Metabolic bone disease includes abnormalities in the endocrine function of the bone in calcium homeostasis as well as abnormalities of mineral deposition.
- Common metabolic bone diseases include osteomalacia, osteoporosis, osteitis deformans, and hyperparathyroidism.
- Osteomalacia means defective mineralization of newly formed osteoid.
- Osteomalacia can also result from abnormal serum concentrations of calcium and phosphorus in patients with osteodystrophy.
Osteoporosis
extremely common disease, most severe in postmenopausal women
-Compression fractures of the vertebrae are very common in osteoporosis.
Paget’s Disease (osteitis deformans)
- Abnormality of bony remodeling which results in overall gain of (abnormal) bone.
- Characterized by phases of pronounced resorption (osteolytic stage), then pronounced bone formation (osteoclastic-osteoblastic stage), then loss of cellular activity (osteosclerotic stage)
- Can present as monostotic or polyostotic
Hyperparathyroidism
- PTH normally maintains Ca++ homeostasis (increased -bone resorption, increased Ca++ resorption in kidney, increased urinary excretion of P, increased Vit D synthesis)
- Hyperparathyroidism is primary or secondary in nature, promoting osteoclast activity
- Dissecting osteitis
- Severe, prolonged hyperparathyroidism can result in the formation of brown tumors.
complete bone fracture
clean break
open bone fracture
bone breaks through muscle and CT
-increased risk of infection
comminuted bone fracture
shattered
displaced bone fracture
have to be pushed back into place
pathologic bone fracture
loss of bone material
-underlying bone disease
stress bone fracture
microscopic fractures that occur in a bone over time
- ex: runners
- not severe
Fractures of normal bone rupture blood vessels & promote clots so that fractures heal with the formation of the _______.
callus
Osetomyelitis
Most common forms are: pyogenic osteomyelitis (Staphylococcus aureus) & tuberculous osteomyelitis (Mycobacterium tuberculosis)
Presence of necrotic bone (sequestrum) at infected site
Reactive woven or lamellar bone can be deposited around the sequestrum called involucrum
-Osteomyelitis is often difficult to cure because of limited blood supply to bone
