Orthopaedics Flashcards
what cells are found in bone?
osteoclasts
osteocytes
osteoclasts
what is the bone matrix made of?
collagen
hydroxyapatite crystals
what is the function of bone?
skeletal support protection haematopoesis regulation of mineral homeostasis fat storage
what is the precursor to bone in utero?
cartilage
what are the two types of bone?
cortical cancellous bone (trabecular bone)
where is cancellous bone found?
metaphysis
flat bone
cuboidal bone
what is the function of cancellous bone?
dissipation of load
what process increased bone length?
endochondral ossification
what process is responsible for cuboidal bone development?
endochondral ossification
what is appositional growth?
increases length
what is longitudinal growth?
increase longitudinally
what is modelling?
alteration in the shape of the bone
what happens to the trabecular bone when load/exercise is increased?
increased thickness
increased bridging between trabeculae
(modelling by microfractures)
what is bone remodelling?
replacement of damaged bone
define anisotropic
describes how a substance responds to load depending on the speed it is loaded
what determines the mechanical properties of bone?
size/shape
magnitude of load
direction of load
rate of loading
what are the two responses to load?
elastic deformation
plastic deformation
what is elastic deformation?
with loading/unloading the bone deforms and returns to its original shape
what is plastic deformation?
with loading/unloading the bone deforms but doesn’t return to its original shape (microcracks, incomplete fractures…)
what does plastic deformation trigger?
bone remodelling
what is the consequences of repeated plastic deformation?
weakening of normal bone
complete failure of bone
what are three metabolic bone diseases?
parathyroid hormone abnormality
vitamin D deficiency
paraneoplastic
what is developmental orthopaedic disease?
group of diseases of multifactorial aetiology resulting in musculoskeletal problems
where does endochondral ossification occur?
metaphysical growth plate
articular-epiphyseal cartilage complex
what are the stages seen at the growth plate?
resting cartilage proliferative cartilage hypertrophic cartilage calcifying cartilage secondary spongiosa
what is required for cartilage to mineralise?
blood supply
what ways can endochondral ossification malfunction at the physical growth plate?
abnormal deposition of matrix
abnormal mineralisation
poor conversion of bone
retention of cartilage
what is the results of endochondral ossification malfunction at the physical growth plate?
slow growth
uneven growth
what ways can endochondral ossification malfunction at the articular-epiphyseal cartilage complex?
abnormal deposition of matrix
abnormal mineralisation
retention of cartilage
what is the results of endochondral ossification malfunction at the articular-epiphyseal cartilage complex?
slow growth
uneven growth
cartilage flaps
what is chondrodysplasia?
dwarfism
what is osteochondrosis?
general term to describe abnormalities of cartilage within a joint
what is osteochondritis?
inflammation of the cartilage within a joint
what is osteochondrosis/osterochondritis dissecans?
the formation of cartilaginous or osteochondral flaps and undulations
what is OCD?
osteochondritis dissecans
when can abnormalities occur to cause osteochondritis dissecans?
disruption of blood supply
abnormal chondrocyte maturation
defective matrix production
persistence of hypertrophic chondrocytes
what does OCD lead to?
thickened retained hypertrophic cartilage
disruption to the subchondral bone plate
how can disrupted blood supply lead to OCD?
affects the mineralisation of the bone altering the biochemical and biomechanical properties of bone
what is the first clinical sign of OCD?
effusions (swelling of the joint)
what are some risk factors for OCD?
rapid growth (cattle/pigs)
genetics
nutrition
trauma
what nutritional influence effect OCD?
excess energy/protein
imbalances in calcium and phosphate
what can untreated OCD result in?
osteoarthritis
how does OCD appear on radiographs?
irregular subchondral bone osseous densities (fragments in joint)
what are some developmental orthopaedic diseases of horses?
osteochondrosis
physitis
angular limb deformities
flexural deformities
what are some developmental orthopaedic diseases of dogs?
osteochondrosis
hypertrophic osteodystrophy
legg calve perthes
hip dysplasia
what are some developmental orthopaedic diseases of cows?
osteochondrosis
flexural deformities
what are some developmental orthopaedic diseases of pigs?
osteochondrosis
what can cause subchondral cyst like lesions?
abnormal endochondral ossification (collapse)
trauma of articular cartilage and SC bone
what is physitis?
enlargement of the physis through inflammation and disrupted endochondral ossification
what are the clinical signs of physics?
lameness
stiff gait
what aged dogs does hypertrophic osteodystrophy occur in?
2-8 month old (large breeds)
what is the pathogenesis of hypertrophic osteodystrophy?
necrosis of the capillary loops of the cartilage of the metaphysical physis leads to a cuff of metaplastic cartilage
what are the clinical signs of hypertrophic osteodystrophy?
lameness, pain
fever
(bilateral and symmetrical)
what radiographic abnormalities are seen in dogs with hypertrophic osteodystrophy?
abnormal bone on diaphysial side of physis
decreased radio density parallel to physis
irregular widening of physis
what is done to treat hypertrophic osteodystrophy?
self limiting
what type of bones is effected by hypertrophic osteodystrophy?
long
what age dogs are effected by panosteitis?
5-18 months old (large breeds)
what type of dogs are most effected by panosteitis?
rapidly growing large breeds (males)
what is the pathogenesis of panosteitis?
increased osteoblastic and fibroblastic activity leads to fibrosis of bone tissue
what are the clinical signs of panosteitis?
acute shifting lameness and pain
what radiographic abnormalities are seen of dogs with panosteitis?
increased opacity of medullary cavity
indistinct trabecular pattern
increased endosteal opacity
what is done to treat panosteitis?
self limiting
what aged dog is legg calve perthes disease seen in?
4-11 months (toy breeds)
what is the pathogenesis of legg calve perthes disease?
avascular necrosis of the femoral head leads to collapse of the of the articular surface
what are the clinical signs of legg calve perthes disease?
acute onset lameness
what are the radiographic abnormalities seen with legg calve perthes disease?
osteolysis of femoral head
collapse and thickened femoral neck
fractures
what are the two dysplasia seen in dogs?
hip and elbow
what causes hip dysplasia in dogs?
abnormal anatomy of femoral head and acetabulum
what are the two types of angular limb deformities?
valgus (lateral)
varus (medial)
what are the potential locations of angular limb deformities in horses?
metaphysical growth plate
epiphysis
cuboidal bones
metaphysis
what dog breeds are predisposed to angular limb deformities?
small breeds (ShihTzu)
what causes angular limb deformities in dogs?
differential growth between bones - radius and ulna - (generally due to damage/trauma to toroth plates)
what causes flexural deformities of horses and cows?
disproportionate growth of tendons and its associated skeletal muscles
in horses, what fractures result in immediate euthanasia?
complete femur fracture
complete humorous fracture
complete tibia fracture
open, unstable fractures
how should horses with forelimb injuries be transported?
facing backwards
how should horses with hindlimb injuries be transported?
facing forwards
what rule must be followed when splitting a fracture?
stabilise joint above and below
what are compound fractures?
open (breaks the skin)
what are the three types of compound fracture?
1 - bone punctures through skin (treat as closed)
2 - open but minimal soft tissue damage and bone loss
3 - significant tissue damage and bone loss
what is a fracture?
disruption in the cortical continuity of bone (complete/incomplete)
what are the 4 As?
alignment
apposition
apparatus
activity
what does alignment mean regarding fracture repair?
joints need to be in line
what must be done when correcting a fracture surgically?
appose the forces acting on the fracture
what fractures are transverse?
any up to 30 degrees
what needs to be included when describing a fracture?
open/closed bone position fracture line degree of displacement
what ways can the position of a fracture be described?
articular
epiphyseal
growth plate
diaphyseal
how can fracture lines be described?
transverse oblique spiral comminuted segmental
what are avulsion fractures?
small pieces of bone pulled off at the point of tendon attachment
what classification system is used for growth plate (physeal) fractures?
salter-harris (I-VI) - lower the number the better the prognosis
what is a type I salter-harris fracture?
straight across the physis
what is a type II salter-harris fracture?
across physis and out through metaphysis
what is a type III salter-harris fracture?
across physis and out through articular surface
what is a type IV salter-harris fracture?
from articular surface through the growth plate to metaphysis
what are the two types of bone healing?
primary (direct)
secondary (indirect)
what are the stages of secondary fracture healing?
haematoma granulation tissue connective tissue fibrocartilage bone formation (callus) callus remodelling
what has to be done for direct bone healing to take place?
bone compressed against each other
what factors influence the healing on fractures in a positive way?
young patient (<8 months) healthy closed fracture low energy single injury closed reduction non-articular
what are the only fractures suitable for casting?
transverse fracture on the distal limb
what is the only force IM pins oppose?
bending
what are the disadvantages of IM pins?
poor at resting rotation or shear (shouldn’t be used on their own)
interfere with medullary blood supply
what is the aim of cerclage wire?
give tight compression to bone
what fractures should cerclage wire be used for?
long oblique fractures
what are the uses of positional screws?
maintain relative position of two bone fragments
fasten plate to bone
anchor wire/suture to bone
lock an interlocking nail
what are lag screws used for?
create compression between bones (larger hole in near cortex so its pulled together)
what are the indications for external fixators (ESFs)?
long bone fractures highly comminuted fractures adjacent to other fractures open/infected fractures immobilising joints for soft tissue repair corrective osteotomies
what are the advantages of external fixators?
inexpensive
can adjust fracture after surgery
what is required for articular fracture healing?
rigid fixation
early return to function (range of motion, avoid atrophy)
why is lameness in cattle important?
welfare (pain) public perception milk loss reproductive loss increased culling nutrition (reduce DMI) costs
what is the first step of managing lameness in cattle?
being able to measure it (mobility scoring and lesion recording)
what can hock scoring be used for?
determining how comfortable the environment is - predisposes to lameness
what is the proximal phalanx also known as?
fetlock bone
what is the middle phalanx also known as?
pastern bone
what is the distal phalanx also known as?
pedal bone
what is the lamellae of the cows foot?
leaflets of horn lining the inside of the wall
what is the laminae of the cows foot?
leaflets of connective tissue, collagen fibres, blood vessels and nerves that fit between the lamellae
what is the suspensory apparatus of the cows foot?
collagen fibres keeping the pedal bone and dermal lamellae attached
which claw of the hindlimb of cattle outgrows the other?
lateral outgrows the medial
what are the two methods of foot trimming in cows?
5 step dutch method
dairyland method
how long should the dorsal wall length be trimmed to in cattle feet?
8cm (depending on size)
what should the sole depth at the toe be when trimming cattle feet by the dutch method?
7mm
what are arthritides?
conditions causing pain/dysfunction to joints
what is arthritis?
inflammation/degeneration of a joint
what is a diarthrodial joint?
specialised joint consisting of a synovial cavity allowing articulation of two or more bones
what is osteoarthritis?
degenerative condition ultimately leading to cartilage breakdown and loss of function
what is the function of a diarthrodial joint?
allow frictionless pain free motion
what makes synovial fluid?
ultrafiltration of plasma plus protein (hyaluronic acid)
what covers articular bones at joints?
hyaline cartilage
what makes up the fibrous joint capsule?
synovial membrane
nerves/blood vessels
supportive ligaments/tendons
what is articular cartilage made of?
extracellular matrix with some articular chondrocytes
what is responsible for the maintenance of the matrix of articular cartilage?
chondrocytes
what is osteoarthritis a disease of?
articular cartilage (other tissue also contributes)
what are some predisposing factors for osteoarthritis?
exercise/trauma developmental orthopaedic disease obesity genetics sepsis repeated medication ageing
what are the radiographic signs of osteoarthritis?
soft tissue swelling osteophytosis enthesiophytosis subchondral bone sclerosis intra-articular mineralisation fragmentation joint space collapse subchondral bone cyst
what is osteophytosis?
new bone formation around the joint margin
what is enthesiophytosis?
new bone formation within soft tissue around the joint
what are the aims of osteoarthritis therapy?
analgesia
control articular inflammation
limit damage to articular tissue
promote healing
what is conservative therapy of osteoarthritis?
rest/restrict activity
weight loss
exercise (care)
what can be used to treat osteoarthritis medically?
NSAIDs
corticosteroids
hyaluronic acid
bisphosphonates
what are the three effects of NSAIDs?
anti-inflammatory
anti-pyretic
analgesic
how do NSAIDs work?
by COX inhibition
how do corticosteroids work?
bind to cytoplasmic and nuclear receptors - inhibit cytokines and alter signalling pathways
what effects does hyaluronic acid have on joints?
replaces synovial fluid
anti-inflammatory
analgesia
what effect do bisphosphonates have on joints?
inhibits bone resorption by inhibiting osteoclasts
what surgical treatments can be used for osteoarthritis?
arthroscopy (decried/flush)
joint replacement
arthrodesis
how does immune-mediated joint disease present?
polyarthritis (erosive/non-erosive)
what are most immune mediated joint diseases due to?
abnormal/inapproriate activity of immune cells and antigen presentation
what is the main part of the joint effected by immune mediated joint diseases?
synovium
what are the clinical signs of immune mediated joint diseases?
multiple limb joint pain/swelling, stiffness, lameness, pyrexia of unknown origin
what is the predominant cell seen following synoviocentesis of immune mediated joint diseases?
high neutrophil count
what changes to the blood could suggest an immune mediated joint disease?
anaemia leucopenia thrombocytopenia raised globulins low albumin
what drugs can be used to treat immune mediated joint diseases?
corticosteroids
what are some causes of infective arthritis?
bacteria - haematogenous, trauma/wound, iatrogenic
what is the response to infective arthritis?
marked inflammation - vasodilation and neutrophil influx with inflammatory cytokine/enzyme release
how does normal synovial fluid appear?
pale yellow and viscous
how does septic synovial fluid appear?
serosanguineous, turbid and reduced viscosity, increased volume
what is done to treat septic arthritis?
treat un darling cause
systemic/local antimicrobials
remove inflammatory mediators (lavage)
what causes Lyme disease?
Borrelia burgdorferi
how do dogs with Lyme disease present?
inflammatory non-erosive arthropathy
shifting lameness
swollen joints
what is used to treat Lyme disease?
doxycycline
what are the functions of tendons?
transfer force from muscle to bone (movement)
supports joint
store energy
what are the functions of ligaments?
attach/stabilise joints
protect tendons
proprioception
what is responsible for the maintenance and degradation of tendon/ligament extracellular matrix?
tenocytes/ligamentocytes
what are the two types of injury to tendons/ligament?
extrinsic (trauma)
intrinsic (overload/degeneration)
what should be assessed when ultra sounding tendons/ligaments?
change in cross-sectional area fibre echogenicity margination position focal lesions vs generalised acute vs chronic blood flow (doppler)
define anechoic
no echogenicity (black)
define hypoechoic
reduced echogenecity
what are the three phases of tendon/ligament injury repair?
inflammatory
proliferative
remodelling
what are the clinical signs of the acute inflammatory phase of tendon/ligament injury?
lameness
pain
heat
swelling
what pathological changes are seen during the acute inflammatory of tendon/ligament injury?
haemorrhage
inflammation (neutrophils, macrophage, oedema, increased blood flow)
what treatment can be used for the acute inflammatory phase of tendon/ligament injury?
cold therapy/NSAIDs (limit inflammation) supporting bandage (limit further damage)
what clinical signs are associated with proliferative phase of tendon/ligament injury?
reduced lameness
resolution inflammation
tendon enlarged
what pathological changes are seen during the proliferative phase of tendon/ligament injury?
angiogenesis
fibroplasia (fibroblasts and collage)
what treatment can be given during the proliferative phase of tendon/ligament injury?
splinting and stem cells (promote angiogenesis)
stem cells and physiotherapy (minimise scar formation)
exercise
what can be done if a tendon/ligament has been lacerated?
repair ends if feasible
what can be done if a tendon/ligament is part of an avulsion fracture?
reattach and cast
what are the clinical signs of chronic muscle injury?
stiffness, cramping, pain, atrophy, fibrosis/calcification
what biochemistry can be used in the diagnosis of muscle conditions?
serum muscle enzymes (CK/AST)
urine (myoglobin)
what is CK in relation to serum muscle enzymes?
creatinine kinase
what diagnostic tools can be used for muscle conditions?
biochemistry
ultrasound
muscle biopsy
what is atrophy?
reduction in size
what can cause muscle atrophy?
disuse
denervation
cachexia
what are some causes muscle denervation?
trauma (laryngeal hemiplasia) Myasthenia gravis (neuromuscular junction defect)
what must stay intact for a nerve to be able to reinnervate?
nerve sheath
what is muscular hypertrophy?
increased muscle bulk due to larger fibres (increased workload)
what are the three main types of muscular degeneration?
cellular swelling
hyaline degeneration
granular degeneration
what can cause cellular swelling of muscles?
minor chemical imbalances within the muscle (Na/K)
what does hyaline degeneration of muscles effect?
sarcoplasm
what myopathy often causes hyaline degeneration?
nutritional myopathy
what happens if there is irreversible damage to muscle tissue?
calcification
how is circulatory disturbances to muscle compensated?
collateral circulation
what causes white muscle disease?
selenium/vitamin E deficiency
what are the clinical signs of white muscle disease?
muscle weakness/stiffness
recumbency
arrhythmia/murmur if myocardial effected
what species is white muscle disease seen in?
cattle (calves)
what causes stiff lamb disease?
selenium/vitamin E deficiency
what is exertional rhabdomyolysis due to?
unfit horses (not been excised over the weekend)
what are the clinical signs of acute exertional rhabdomyolysis?
stiffness to severe pain
what muscles is acute exertional rhabdomyolysis seen in most commonly?
gluteal
semitendinosus
semimembranosus
what dog breeds is eosinophilic myositis seen in?
large breeds (German shepherds)
what muscles are effected by eosinophilic myositis?
temporal/masticatory muscles (enlarged)
what is used to treat eosinophilic myositis?
corticosteroids
what animals is atypical myoglobinuria seen in?
horses
what are the clinical signs of atypical myoglobinuria?
fatal
muscle weakness/recumbency
increased CK/AST
(widespread necrosis)