Flashcards in Bone pathology Deck (99)
What is the bone matrix composed of?
- Organic component: osteoid (90% type 1 collagen, 10% water, non-collagenous proteins, lipids, proteoglycas)
- Inorganic component of mineralised tissue (hydroxyapatite = hydroxylated calcium phosphate)
What is the consequence of the loss of inorganic matrix of the bone?
What is the consequence of the loss of organic matrix of the bone?
Describe the appearance and role of osteoclasts
Multinucleate, remove calcium from bone
Describe the histological appearance of osteocytes
Sit in lacunae, surrounded by matrix
Compare the ossification of long and flat bones
- Long: endochondral ossification at the metaphyseal growth plates (physes)
- Flat: intramembranous ossification, bone formed directly from he periosteum
Briefly describe the histological appearance of the physes of long bones
- Growth starts at hyaline cartilage (dark purple)
- Moves down into medullary cavity
- Then mineralises and ossifies, becomes pink
- Medullar cavity and spongy bone
What is the most common response of injured periosteum?
Formation of new bone e.g. around a fracture site
What is meant by brachygnathia?
Abnormally short jaw
What is meant by prognathia?
Abnormal projection of jaw
What is meant by kyphosis?
Dorsal curvature of the spinal column
What is meant by lordosis?
Ventral curvature of the spinal column
What is meant by scoliosis?
Lateral deviation of the spinal column
What is amelia?
Absence of limbs
What is hemimelia?
Absence of distal limb part
What is polydactyly and which animals are predisposed?
Presence of supranumerary digits, most common in cats, esp. Hemignway cats
What is adactyly?
Absence of a digit
What is syndactyly?
Fusion of digits
What causes chondrodysplasias?
Hereditary disorder of bone growth as a result of primary lesions in the growth cartilage
Which bones are affected by chondrodysplasias and why?
Long bones only, as only endochondral ossification is affected
Describe the appearance of an animal with chondrodysplasia
- Short legs and normal sized heads (dogs)
- Sheep usually normal length of legs but abnormal appearance of these (aka spider lamb syndrome)
- Also seen in cattle (bulldog cattle)
What causes osteopetrosis?
Defect in bone resorption by osteoclasts - plenty of osteoclasts but are not functioning correctly
Describe the consequences of osteopetrosis
- Bone mineral density increased, but bones are more fragile
- Not enough collagen
Which species are most commonly affected by osteopetrosis?
Cattle, sometimes horses
Give examples of congenital bone disorders
- Osteogenesis imperfecta
- Congenital hyperostosis
Give the main metabolic bone diseases
- Fibrous osteodystrophy
What are common causes of metabolic bone diseases?
Nutritional, toxic or endocrine
Describe the structure of bone affected by osteoporosis
Reduced bone mass, normal bone quality, well mineralised
List the main causes of osteoporosis
- Dietary calcium deficiency
- Advanced age
- Glucocorticoid excess (e.g. long term steroid administration)
- Oestrogen or androgen deficiency