Bone (Ex3) Flashcards
What is woven bone?
- immature bone present during fetal development, and in the early stages of bone repair
- collagen fibers randomly arranged, have a criss-cross pattern microscopically
What is lamellar bone?
- mature bone
- collagen fibers are arranged in a parallel pattern
Intramembranous ossification
- occurs within membranes of condensed primitive mesenchymal tissue
- flat bones of the skull
Endochondral ossification
- occurs in majority of bones of the skeleton
- bone develops from cartilaginous model, that is replaced by osseous tissue present in ossification centers
- in ossification centers of mature bone, and growth plates of developing bone
Describe chondrodysplasia
- membranous apositional growth is normal, but intersititial growth of cartilage is abnormal
- results in premature close of growth plates and decreased length of long bones
- breed associated, usually hereditary
What is “Dexter Bulldog”?
- congenital lethal chondrodysplasia
- common in beef cattle breeds
- affected calves are often aborted, and exhibit disproportionate dwarfism, short vertebral column, large head with short muzzle, protruding tongue, and large abdominal hernia
What is Wobbler’s Syndrome?
- cervico-vertebral stenotic myelopathy
- localized skeletal dysplasia, most common in horses and large dogs
- results in dynamic or static compression of cervical spinal cord by abnormal cervical vertebrae
What is osteopetrosis?
- metaphyseal dysplasia
- inherited disease caused by osteoclast failure to reabsorb the primary spongiosa
- results in increased bone density, and lack of medullary spaces
- animals often present aplastic anemia
- bones more susceptible to fracture
What is congenital cortical hyperostosis?
- autosomal recessive inherited condition in pigs
- limbs appear swollen due to excessive deposition of radiating trabeculae on periosteal surface, and blockage of local lymphatic circulation
- most born dead, or die quickly
What is amelia?
absence of a limb
What is hemimelia?
absence of the distal half of a limb
What is polymelia?
supernumerary limbs
What is phocomelia?
absence of proximal portion of a limb
What is micromelia?
abnormally small or short limbs
What is syndactylia?
fusion of the digits
What is lordosis?
ventral deviation of vertebral column
What is kyphosis?
dorsal deviation of vertebral column
What is scoliosis?
lateral deviation of vertebral column
Describe a valgus deformity
- lateral deviation (outward)
- knock kneed
Describe a varus deformity
- medial deviation (inward)
- bow legged
What are the possible etiologies of metabolic bone diseases?
- nutritional
- hormonal
- disuse
- toxic
Describe osteoporosis
- metabolic bone disease
- characterized by osteopenia (decreased amount of bone tissue)
- the bone that is present is normal
- reduction in thickness of cortical bone, and decreased number of trabeculae in cancellous bone
What are the etiologies of osteoporosis?
- nutritional: starvation, Cu or Vitamin C deficiency
- aging: reabsorption outpaces bone formation
- disuse
What is Rickets?
- metabolic bone disease affecting young, growing animals
- defective calcification of osteoid, and defective endochondral ossification
- etiology typically involves vitamin D or phosphorus deficiency
Explain the gross lesions of Rickets
- irregular thickening of growth plates with tongues of uncalcified cartilage extending into the metaphysis
- widening of growth plates, enlarged ends of long bones
- enlargement of costochondral junctions (rachitic rosary)
- weight-bearing bones become bowed
- hemorrhages beneath cartilage or in growth plates
Describe osteomalacia
- a disease of grown animals
- failure in mineralization of osteoid, primarily due to vitamin D or P deficiency
- unmineralized osteoid is resistant to osteoclast resorption, accumulates in bone
Describe Fibrous osteodystrophy
- metabolic bone disease characterized by extensive bone resorption and replacement by fibrous connective tissue and poorly mineralized immature bone
- caused by hyperparathyroidism
- decreased calcium and increased phosphorus, resulting in increased PTH
Describe primary hyperparathyroidism
- associated with functional parathyroid adenomas in dogs
- exhibit hypercalcemia and hypophosphatemia
- lesions include FO, thyroid C-cell hyperplasia, hypercalcemic nephropathy, and metastatic mineralization of soft tissues
Describe secondary hyperparathyroidism
nutritional: dietary deficiency of Ca, excess P, or deficiency of vitamin D
- affects young, growing animals
renal: P retention due to loss of glomerular function, and inadequate synthesis of calcitriol by the kidney
- bones swollen and firm, rubber jaw
What happens in lead poisoning?
- lead interferes with osteoclastic acitivity
- subtle bone lesions > increased bone density in metaphysis > lead line
What happens in fluoride toxicosis?
- affects normal metabolism of bone and teeth
- soft dark-brown discolored teeth that wear down easily
- bones exhibit periosteal hyperostosis
- in herbivores
What causes hypervitaminosis A?
What happens?
- cats consume high amounts of bovine livers for a long period of time
- deforming cervial spondylosis
- develop osteophyte formation around joints of cervical vertebrae, shoulder, and elbow
What is a sequestrum?
a piece of necrotic bone isolated from the remaining viable bone
What is an involucrum?
- a layer of granulation tissue and reactive bone
- formed when there is an attempt to wall off the sequestrum
What is a comminuted fracture?
fragmented fracture
What does it mean when a fracture is avulsed?
caused by the pull of a ligament/tendon at its insertion into the bone
What is a microfracture/infraction?
- fracturing of trabeculae without external deformation of cortical bone
What are possible complications with bone fractures?
- bone necrosis and formation of a sequestrum
- non-union fracture: pseudoarthrosis formation (false joint)
- osteomyelitis
- cachexia
