Bones Flashcards
What is the matrix of bone called? And what is it made of?
Osteoid
Glycoproteins and collagen fibers
What is the main component of mineralization ?
Calcium hydroapatite (CHAP) crystals
What are the cellular elements of bone?
Osteoblasts
Osteocytes
Lining cells (inactive osteoblasts)
Osteoclasts
What are the two types of bone?
Wooooven bone - immature and randomly arranged
Lamellar bone- mature with collagen fibers arragned in a parallel pattern
What are the two ways of bone formation?
Intramembranous ossification - within “membranes” of condensed primitive mesenchymal tissue-> flat bones of the skull
Endochondral ossification -develops from hyaline cartilage that is replaced by osseous tissue present in the ossification centers
Where does endocondrial ossification occur?
Epiphyseal plate of developing bone
What is the condition of decreased length of long bones?
Chondrodysplasia
How does chondrodysplasia occur?
Membranous appositional growing is normal but interstitial growth of cartilage is abnormal resulting in premature closure of growth plate.
What are the most common cattle breeds that get chondrodysplasia?
Dexter cattle
Also angus and Hereford
What lethal form of chondrodysplasia is seen in dexter cattle?
“Dexter bulldog”
Inherited condition - affected cattle are often aborted and exhibit disproportionate dwarfism
Moo cow with …
shortened vertebral column, marked micromelia, large head with short muzzle, protruding tongue, and large abdominal hernia.
What is this?
Dexter bulldog
Chondrodysplasia
What is Wobblers syndrome?
AKA cervical-vertebral stenosis myelopathy
Localized skeletal dysplasia -> degenerative joint disease of the axial skeleton -> compression of spinal cord -> ataxia
What are the two types of cervical-vertebral stenosis myelopathy
Static - constant compression no matte the position of the neck
Dynamic - occurs when the neck is flexed
What is an inherited disease caused by osteoclast failure to reabsorb the primary spongiosia?
Osteopetrosis
AKA metaphyseal dysplasia
What is the pathogenesis of osteppetrosis ?
Decreased osteoclasts-> increase bone density and lack of medullary spaces –> aplastic anemia and bones susceptible to fracture (loss of flexibility)
Pig
Limbs (mostly forelimb) appear to be swollen due to excessive disposition of radiating trabecule on the periostal surface
What is this?
Congenital cortical hyperososis of pig
Amelia is ???
Absence of limb
Hemimelia is????
Absence of distal half of limb
Polymelia is ???
Supranumerary limbs
Micromelia is?
Abnormally small or short limbs
Syndactylia is??
Fusion of the digits
Polydactylia is ??
Supernumerary digits
___________ is a ventral deviation of the vertebral column
Lordosis
__________ is a dorsal deviation of the vertebral column
Kyphosis
____________ is a lateral deviation of the vertebral column
Scoliosis
____________ is a dorsal-lateral deviation of the vertebral column
Kyphoscoliosis
___________ is due to asymmetric lesion of the growth plate, occurring in young animals
Angular limb deformities
Lateral deviation of the joint is called _________ and medial deviation is called ___________
Valgus deformity (knocked kneed) Varus deformity (bow legged)
Angular deformities can be caused by ???
Malposition in utero Joint laxity Hypothyroidism (congenital goiter) Trauma Malnutrition Impaired endochondrial ossification
Metabolic bone diseases are also called ________
Osteodystrophies
Metabolic bone diseases are a result of disturbed bone growth or remodeling due to __________ or __________ imbalances
Nutritional; hormonal
What nutritional imbalances can result in metabolic bone disease
Vitamin C, D, Ca, P, or protein
What hormonal imbalances can lead to metabolic bone disease?
Parathyroid (PTH), thyroid (calcitonin), gonad (estrogen), and adrenal (corticosteroids) problems
What toxicities can lead to metabolic bone diseases?
Learn and fluoride poisoning, hypervitaminosis A
Metabolic bone disease are classified into what 4 conditions?
Osteoporosis
Rickets
Osteomalacia
Fibrous osteodystrophy
What is osteoporosis ?
Osteopenia (decreased amount of bone) - reduced thickness of cortical bone and decreased number of trabeculae in the cancellous bone
What are etiologies of osteoporosis ?
Nutritional - starvation, Cu deficiency, Vit C deficiency
Aging
Disuse
What is rickets?
Metabolic bone disease of young growing animals
-defective calcification of osteoid and defective endochondrial ossification
What is the etiology of rickets?
Vitamin D or phosphorus deficiency
Lack of sunlight (decrease vitD)
What are the gross lesion of rickets?
Irregular thickening of growth plates with tongues of uncalcified cartilage extending into the metaphysics
Widening of growth plates ->.enlarged ends of long bones; enlargement of costocondrial junctions
Weight bearing long bones become bowed
Hemorrhage of articular cartilage or in growth plate
Pathological fracture
What disease of adult animals is due to unmineralized osteoid that is resistant to osteoclastic reabsorption and accumulation in the bone?
Osteomalacia
What is the etiology of osteomalacia?
Failure of mineralization due to vit D or P deficiency
Mature animals with…
Shifting lameness (bone pain)
Pathological fractures
Deformities like kyphosis, lordosis, or scoliosis?
Osteomalacia
What bone disease is characterized by extensive bone reabsorption and replacement by fibrous CT and poorly mineralized immature bone ?
Fibrous osteodystrophy
What is the etiology of fibrous osteodystrophy?
Hormonal
Hyperparathyroidism (primary or secondary)
What is primary hyperparathyroidism ?
Associated with parathyroid adenoma in dog
-> increased PTH = hypercalcemia and hypophsphatemia
What is secondary hyperparathyroidism ?
Nutritional -> dietary deficiency of Ca/ vitD, or excess P => increase PTH
Renal -> P retention due to loss of glomerular function and inadequate synthesis of calcitriol => increase PTH
What is the pathogenesis of lead poisoning leading to bone disease?
Lead interferes with osteoclastic activity -> subtle bone lesions -> increase bone density in the metaphysics -> “lead line”
What is the pathogenesis of fluoride toxic osteodystrophy ?
Herbivores (mainly cattle and sheep) -> affect normal metabolism of bone and teeth -> ameoloblast and odontoblasts are markedly sensitive to excess Fourier and result in dark-brown discoloured teeth that wear down easily
Bones exhibit periosteal hyperostosis
Cats that eat a high amount of bovine livers for a long period of time have what toxic osteodystrophies?
Hypervitaminosis A
What is hypervitaminosis A toxic osteodystrophies ?
Deforming cervical spondylitis
Develop ostophyte formation around the joints of the cervical vertebrae, shoulder, and elbow
What is the reaction of bone to ischemia ?
Necrosis -> bone ischemia associated with trauma/ inflammation/neoplastic bone disease
Cell death with loss of osteocytes for their lacunae
What is the outcome of osteonecrosis?
Complete resorption and replace the of necrotic bone
“sequestrum” -> piece of necrotic bone isolated from remaining viable bone -> formation of granulation tissue and reactive bone called “involucrum”
What type of bone fracture is due to normal bone broken by excessive force
Traumatic
What type of bone fracture is due to abnormal bone broken by minimal trauma or normal weight bearing
Pathological
What type of bone fracture is caused by the pull of a ligament or muscle tendon at its insertion?
Avulsed
What is fracturing of trabeculae without external deformation of cortical bone called?
Micro-fracture/infraction
How is a fracture repaired?
Blood clot in fracture site
Fibroblasts enter site
Blood vessels through the periosteum
Formation of cartilage and woven bone
Osteoclasts clean up debris
What complications can be associated with bone fractures?
Bone necrosis and formation of sequestrum
Nonunion fracture-> pseudoarthrosis (false joint) formation
Osteomyelitis (compound fractures)
Cachexia
