Bone pathology Flashcards
Bone tissue is formed by?
Cells
Osteoblasts makes
Osteocytes
Osteoclasts break
What is the organic and inorganci components of osteoid?
Organic component: Osteoid
- 90% type I collagen
- 10% water, non-collagenous proteins, lipids, proteoglycans…
Inorganic component: mineralized tissue (called hydroxyapatite)
- Hydroxylated calcium phosphate
What does loss of inorganic matrix and organic matrix mean?
Loss of organic matrix: Brittle bone
Loss of inorganic component: Flexible bone
Label osteoblasts, osteoclasts and osteocytes on a histological image?
Where does Endochondral ossification of long bones occur?
Metaphyseal growth paltes (physes)
Where does Intramembronous ossification of flat bones occur?
Bone formed directly from the periosteum
Describe bone remodelling?
Bone (re)modelling: Bone is deposited where needed and resorbed where not (dynamic)
What causes alteration in bone mass?
Alterations in bone mass:
Systemic diseases and abnormal use may affect bone mass:
- Increase: hypervitaminosisA
- Decrease: Osteoporosis, disuse
Injured periosteum often responds by forming bone (see picture)
Define brachycephalic?
shortening of the head
Define Brachygnathia
abnormally short jaw
Define Prognathia?
abnormal projection of the jaw
Define Kyphosis?
dorsal curvature of the spinal column
Define Lordosis?
ventral curvature of the spinal column
Define Scoliosis?
lateral deviation of the spinal column
Define Amelia?
absence of limb/s
Define Hemimelia?
absence of distal limb part
Define Polydactyly?
presence of supranumerary digits
Define Adactyly?
absence of a digit
Define Syndactyly?
fusion of digits
Name congenital bone disorders?
- Chondrodysplasias
- Osteopetrosis
- Osteogenesis imperfecta
- Congenital hyperostosis
- Osteochondromatosis
Describe chondrodysplasias?
Dysplasia: Disordered development
- Hereditary disorders of bone growth result of primary lesions in growth cartilage
- Defect in bones having endochondral ossification (long bones) but not in bones with intramembranous ossification (flat bones)
- Short-legged and normal-sized heads e.g Basset hound Dachshund
- Spider lamb syndrome
What is the congenital disorder osteopetrosis?
- Defect in bone resorption by osteoclasts
- Although bone mineral density is increased, bones can be more fragile
Describe metabolic bone diseases?
Usually systemic diseases
Common causes: nutritional, toxic or endocrine
The three main diseases are:
- Osteoporosis
- Rickets/Osteomalacia
- Fibrous osteodystrophy
Describe osteoporosis?
- Reduced bone mass (normal bone quality, well mineralized)
- Not commonly diagnosed in veterinary species, but can happen
- Causes: malnutrition, physical inactivity, dietary calcium deficiency, advanced age, glucocorticoid excess, oestrogen or androgen deficiency
- Consequences: Brittle bones, fractures
Describe Rickets/osteomalacia?
- Failure of mineralization in growing skeleton (rickets) and adults (osteomalacia)
- Causes: calcium/vitamin D deficiencies, phosphorus deficiency, chronic renal disease
- Consequences: Bone deformities, thickening of growth plates and fractures
Describe fibrous osteodystrophy?
Increased widespread osteoclastic resorption of bone and replacement by fibrous tissue
Causes:
- Primary hyperparathyroidism
- Secondary hyperparathyroidism (renal or nutritional)
- Pseudohyperparathyroidism (certain neoplasia)
- Lack of UV in reptiles (the disease is usually referred as metabolic bone disease)
Consequences: Lameness, fractures, deformities
What can be seen here?
Fibrous osteodystrophy
What can be seen here?
Normal bone, normal mass, Normal bone mineralisation
What can be seen here?
Osteoporosis
- Decreased bone mass
- Normal mineralisation
What can be seen here?
Rickets/Osteomalacia
Reduce bone mineralisation
What can be seen here?
Fibrous osteodystrophy
- Decreased bone mass
- Fibrous replacement
Compare normal, osteoporitic, rickets/osteomalacic and fibrous dystrophic bone?
Compare normal, osteoporitic, rickets/osteomalacic and fibrous osteodystrophic bone?
Discuss hypervitaminosis D?
Typical causes:
- Ingestion of plants calcinogenic plants (e.g. Solanum sp., Trisetum flavescens ) (herbivores)
- Feed overdoses (pigs and horses)
- Ingestion of certain drugs (e.g. rodenticide)
- Produce hypercalcemia and/or hyperphosphatemia and consequently metastatic mineralization
- Typical places of mineralization: vessels, lung, kidney and stomach
Define Periostitis?
Inflammation of bone with involvement of periosteum
Discuss scurvy?
Vitamin C is required for collagen synthesis
Guinea pigs, some primates, and some bats cannot synthetize vitamin C
Consequences:
Osteopenia: bone fragility, fractures Metaphyseal, articular, muscular and subcutaneous haemorrhages
Define osteitis?
Inflammation of bone
Define Osteomyelitis?
Inflammation of bone with bone marrow involvement can be infectious or non-infectious in origin
What are the routes of infection for Infectious inflammatory diseases?
Routes of infection:
- Haematogenous
- Trauma
- Inflammation of adjacent tissues (e.g. periodontitis – maxilla/jaw, otitis –tympanic bulla)
What are common infectious causes of inflammatory bone disease?
Infectious causes:
Bacteria.
- Most common. Pyogenic bacteria ( Trueperella pyogenes , Streptococcus spp., Staphylococcus spp., Escherichia coli , Salmonella spp..)
Fungi
- Coccidioidesimmitis , Blastomycesdermatitidis
Virus
- (Canine distemper virus (CDV) , Bovine viral diarrhea virus (BVDv)
Haematogenous bacterial osteomyelitis is common in young farm animals and foals
What is this?
Chronic pyogranulomatous osteomyelitis, Actinomyces bovis “lumpy jaw”
What can be seen here?
Radius, dog, Canine distemper Growth retardation lattice
Describe the non-infectious inflammatory disease metaphyseal osteopathy?
- Young dogs (2-6 months)
- Usually large breeds
Presentation:
- Lameness
- fever
- swollen
- painful metaphyses in multiple long bones
- Suppurative and fibrinous osteomyelitis of the trabecular bone of the metaphysis
Most cases resolve completely
Unknown aetiology
Describe the non-neoplastic proliferative lesion Hypertrophic Osteopathy?
- Dogs
- Progressive, bilateral periosteal new bone formation in the diaphyses of distal limbs
- Usually associated to intrathoracic neoplasms or inflammation
Describe the non-neoplastic proliferative lesions Craniomandibular Osteopathy (“lion jaw”)?
- Hereditary condition
- West Highland white terrier (WHWT)
- Thickening of mandibles, occipital and temporal bones
Discuss bone neoplasia?
- Malignant neoplasia more common
- Imaging is highly important for diagnosis, since bone biopsies often contain reactive periosteum
- Secondary (metastatic) bone tumours are rare. Mainly carcinomas. e.g. pulmonary carcinomas in cats can metastasise to digits (to the 3rd phalanx, sloughing claws)
Create a table for primary bone neoplasms?
Discuss osteosarcomas?
- Most common primary bone neoplasia in dogs and cats, rare in other species
- Malignant neoplasm in which neoplastic cells form bone and/or osteoid
- More common in medium and large breed dogs
- Most commonly: arises from metaphysis and is close to the knee, away from the elbow
- Do not affect joint
- Haematogenous pulmonary metastasis is common
What can be seen here?
