Week 1 Flashcards
Name some congenital bone disorders
- Chondrodysplasias
- Osteopetrosis
- Osteogenesis imperfecta
- Congenital hyperostosis
- Osteochondromatosis
What is Chondrodysplasias and what types of animals does it affect?
- 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
What is Osteopetrosis?
- Defect in bone resorption by osteoclasts
- Although bone mineral density is increased, bones can
be more fragile
What are the three main metabolic bone diseases?
- Osteoporosis
- Rickets/Osteomalacia
- Fibrous osteodystrophy
What is the pathology associated with Osteoporosis?
Reduced bone mass (normal bone quality, well mineralized)
What are some of the causes of Osteoporosis?
- malnutrition
- physical inactivity
- dietary calcium deficiency
What are the consequences of Osteoporosis?
- Brittle bones
- fractures
What is Rickets/Osteomalacia?
Failure of mineralization in growing skeleton (rickets) and adults (osteomalacia)
What are some of the causes of Rickets/Osteomalacia?
- calcium/vitamin D deficiencies
- phosphorus deficiency
- chronic renal disease
What are the consequences of Rickets/Osteomalacia?
- Bone deformities
- Thickening of growth plates and fractures
What is the pathology associated with Fibrous osteodystrophy?
Increased widespread osteoclastic resorption of bone and replacement by fibrous tissue
What are some of the causes of Fibrous osteodystrophy?
- Primary hyperparathyroidism
- Secondary hyperparathyroidism (renal or nutritional)
- Pseudohyperparathyroidism (certain neoplasia)
- Lack of UV in reptiles (the disease is usually referred as metabolic bone disease)
What are the consequences of Fibrous osteodystrophy?
- Lameness,
- fractures,
- deformities
What are the typical causes of Hypervitaminosis D?
- Ingestion of plants calcinogenic plants (e.g. Solanum
sp. , Trisetum flavescens) (herbivores) - Feed overdoses (pigs and horses)
- Ingestion of certain drugs (e.g. rodenticide)
What is the pathology associated with Hypervitaminosis D?
- Produce hypercalcemia and/or hyperphosphatemia
and consequently metastatic mineralization
What are the typical sites of mineralization in Hypervitaminosis D?
- vessels,
- lung,
- kidney
- stomach
What is the cause of scurvy?
- Vitamin C is required for collagen synthesis
- Guinea pigs, some primates, and some bats cannot
synthetize vitamin C
What are the consequences of scurvy?
- Osteopenia: bone fragility, fractures
- Metaphyseal, articular, muscular and subcutaneous
haemorrhages
What is osteitis?
Inflammation of bone
What is Periostitis?
Inflammation of bone with involvement of periosteum
What is Osteomyelitis?
Inflammation of bone with bone marrow involvement
What are the routes of infection in inflammatory bone disease?
- Haematogenous
- Trauma
- Inflammation of adjacent tissues (e.g. periodontitis –
maxilla/jaw, otitis – tympanic bulla)
What is the signalment of Metaphyseal osteopathy?
- Young dogs (2-6 months)
- Usually large breeds
What is the presentation of Metaphyseal osteopathy?
- 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
What is Hypertrophic Osteopathy and what is it associated with?
- Dogs
- Progressive, bilateral periosteal new bone formation in the diaphyses of distal limbs
- Usually associated to intrathoracic neoplasms or
inflammation
What is the signalment and presentation of Craniomandibular Osteopathy (“lion jaw”)?
- Hereditary condition
- West Highland white terrier (WHWT)
- Thickening of mandibles, occipital and temporal bones
What is the cell of origin of osteosarcomas?
Osteoblast
What is the primary site of osteosarcomas?
Predominantly metaphyses of larger appendicular bones
What is the behaviour of osteosarcomas?
Highly malignant with early metastasis
What is sclerosis?
- Localised area of increased bone opacity
- Response of bone to wall-off ‘pathology’ e.g. infection,
cyst - Response to increased or abnormal loading: Wolff’s
Law
What artefacts can appear on a radiograph that look like new bone?
- Superimposition of structures (bone or soft tissue)
- Adjacent bone loss – can see increased opacity on
other bone due to this - Foreign material e.g. on coat
What artefacts can appear on a radiograph that look like bone loss?
- Gas, or defect in soft tissues
- Mach lines – where 2 bones overlap (mimics hairline
fractures) – increased opacity
What is the appearance of an aggressive lesion on a radiograph?
rapid bony change = minimal time for bone to remodel
What is the appearance of a non-aggressive lesion on a radiograph?
slow-growing, benign more chronic process – remodelling possible – organised looking change
How can you assess whether a lesion is aggressive or non-aggressive on a radiograph?
- Bone destruction (lysis)
- Periosteal reaction
- Lytic edge character
- Cortical disruption
- Transition from normal to abnormal bone
- Rate of change (10-14 days)
Give examples of Radiographic signs of degenerative joint disease?
- Soft tissue swelling / joint effusion – certainly in the
acute phase - Changes in subchondral bone opacity – may see
sclerosis - Changes in joint space – difficult to assess unless
animal is weight bearing- Initially widens due to effusion, then narrows due to
cartilage erosion
- Initially widens due to effusion, then narrows due to
- Osteophyte formation – new bone
- Form at chrondrosynovial junction, on non-weight-
bearing surfaces
- Form at chrondrosynovial junction, on non-weight-
- Joint mice or osteochondral fragments within the joint
cavity - Joint subluxation (hip joint)
- Cyst formation (rare)
Where are the typical locations of osteophytes in the stifle?
- Proximal/distal patella
- proximal trochlear ridge (femur)
- both femoral epicondyles
- fabellae
- proximal tibia
Where are the typical locations of osteophytes in the elbow?
- dorsal anconeal process (ulna)
- cranial joint aspect
- lateral epicondylar crest (humerus)
- Medial epicondyle (humerus)
- Medial coronoid process (ulna)
- Trochlear notch (ulna)
What is Metabolic Bone disease?
- Generalised bone disease
- Usually a decrease in opacity = osteopenia
What are the causes of metabolic bone disease in reptiles?
- Inappropriate feeding and/or husbandry
- Imbalance of Ca, P, or Vit D in body
- Usually too low dietary Ca or Vit D or excess P
What is the presentation of metabolic bone disease in reptiles?
- Lethargy, reluctance to move
- Osteopenia
- Pathological fractures
What is the signalment of Metaphyseal osteopathy?
Usually young, medium-large breed dogs
What is the radiographic presentation of Metaphyseal osteopathy?
- Localised lesion, but affects multiple long bones (esp
R+U) - Early changes: radiolucent line adjacent to metaphyses
- Later: periosteal new bone formation and sclerosis
What is the presentation of Hypertrophic osteopathy?
- Periosteal new bone formation
- Soft tissue swelling
- No joint involvement or bone destruction – just affects
long bones - Metacarpal / metatarsal bones affected first, but then
spreads to other bones
What is Hypertrophic osteopathy secondary to?
Secondary to space-occupying lesion in thorax or abdomen (image thorax/abdomen)
What is the radiographic presentation of Craniomandibular osteopathy?
- Reactive periosteal new bone formation on mandible
and ventral skull bones - Increased bone density
What is the clinical presentation of Panosteitis?
- Shifting lameness in young growing dogs esp. GSD
- May be polyostotic
- Affects fore legs more commonly than hind legs
- Self-limiting - full recovery
What is the radiographic presentation of Panosteitis?
- Increased opacity of medullary canal – irregular, heterogenous
- ‘Thumb prints’
- Thickening of cortical bone
- Often centered around nutrient foramina
What is the clinical presentation of Immune-mediated polyarthritis?
Painful, stiff, depressed animal often with swollen joints and ligamentous laxity
What is the radiographic presentation of Immune-mediated polyarthritis?
- Bony changes in erosive form only
- Multiple lytic lesions, around and ‘crossing’ joints
- Affects all joints, but changes most common / initially seen in carpi and hocks
What is the radiographic appearance of Bone cysts?
- Usually oval/circular, and well marginated +/- sclerotic
rim - Usually near joints
What are the Predilection sites of bone cysts?
equine stifle and fetlock
How do you Evaluate bones related to their radiographic (or Roentgen) signs?
- Number
- Location
- Size
- Shape
- Margination
- Radiopacity (including internal architecture)
How can Aggressive versus non-aggressive bone lesions be assessed?
- Bone destruction (lysis)
- Periosteal reaction
- Lytic edge character
- Cortical disruption
- Transition from normal to abnormal bone
- Rate of change (10-14 days)
What is a simple fracture?
only 1 fracture line i.e. bone split into 2 pieces
What is a transverse fracture?
- Fracture ≤ 30 degrees perpendicular to long axis of
bone - Inter-digitating i.e. fracture surface irregular with spikes
and depressions on both ends of fractured bone that
“interdigitate” with each other
What is an oblique fracture?
Fracture line > 30 perpendicular to long axis of bone
What is a spiral fracture?
- Spiral = oblique fracture
- curves / spirals around the bone
What is a Comminuted fracture?
- more than one fracture line that connect
- may be multiple joining fractures
- end result = 3 or more pieces of bone
What is a Segmental fracture?
- Special type of comminuted fracture
- RARE
- 2 or more fracture lines that do not connect
- Each bone is a complete piece of cortex
- Result = 3 or more pieces of bone
- Wedge / Butterfly
What is an avulsion fracture?
- Apophyseal bone avulsed
- insertion point of tendon or ligament
When do Physeal fractures usually occur?
Physeal fractures usually only happen in young (skeletally immature) animals
What are the FIVE primary physiologic
forces acting on a normal bone?
- Axial Compression - Main force of weight-bearing
- Bending - compressive force eccentrically loading of bone
- Shear - sideways bone displacement
- Torsion - axial rotation / twisting
- Tension - only applies at point of insertion of ligaments
(apophysis) NOT diaphyseal bone
When does TENSION AVULSION – EXTERNAL occur?
occurs when ligaments or tendons apply
a distractive force
Give examples of external tension avulsion (don’t worry about knowing all of them)?
- gluteal muscles, greater trochanter
- patella tendon on the tibial tuberosity
- triceps, olecranon of ulna
- common calcaneal tendon, calcaneous
What is axial compression? How does it work on different fractures?
- Produces a compressive force
- Compression is good if fracture is
transverse or fragment ends interdigitate - On an oblique fracture produces a shear
force over-riding and collapse of fracture e.g. if oblique
or comminuted
Which forces are plates strong and weak to?
Strong: to tension (stretching)
Weak: To Bending
Which fractures are unstable to all forces?
Comminuted or non-reconstructed
What is strain theory?
- Measurement of the strain (% movement) at the fracture
- Strain is a measure of the distance moved by the fracture ends as the animal weight bears
- Different healing tissue types can cope with different degrees of deformation
- An indication of the degree of stability required of the implants
What is strain reduced by?
- increasing the distance between the fracture ends, i.e.
big fracture - gap or resorbing some of the bone as occurs early in
fracture - reducing movement = fracture repair and stabilising
- reducing movement = as callus develops
What is primary healing of bone?
Bone apposition & reduction = stability
ideally compression
What is secondary healing of bone?
- Bone not apposed reconstructed
- Relative movement instability
- Callus formation
What force does axial compression cause in bone?
‘axial’ compression creates a bending
force within bone
Which forces are plates weak to?
weak to bending
