Approach to Bone and Joint Diseases in the Horse Flashcards
What is periosteal new-bone formation?
Blunt trauma can lead to sub-periosteal haemorrhage
* Lifting of periosteum away from bone
* Stimulates production of periosteal new bone
* Initially less dense and irregular outline
* Becomes more radiopaque with smooth outline
* Splint bone exostoses, healing fractures, infection,
inflammation, neoplasia, osteoarthritis
What is Sclerosis?
- Densification
- Localised formation of new bone within bone
- Stress
- Protection of a weakened area
- Walling off infection
What is bone lysis?
- Destruction of an area of bone
- Infection
- Neoplasia
- Keratoma
What is osteophyte formation?
Spur of bone on a joint margin
* Joint instability
* Intra-articular disease (eg Osteoarthritis)
What is enthesophyte formation?
- New bone formation at attachment of tendon/ligament/joint capsule to bone
- Bone’s response to stress applied through these structures
- Soft tissue injury
What are the three characteristics of aggressive bone disease?
- Destruction of the cortex
- Character of the perisoteal lesion
- Lack of distinctness of boundary between the bone lesion and normal bone (transition zone)
What can ultrasonography be useful for?
assess the bone surface
* should appear smooth
* useful to image areas which are difficult to radiograph
What would show the presence of a fracture on a radiograph?
Non-displaced break in normal hyperechoic bone
surface
* Displaced fragment
– visualisation of hyperechogenic bony structure distracted from
underlying bone
How does nuclear scintigraphy work?
- Radioisotope is injected intravenously
- increased IRU in areas where there is increased osteoblastic activity
- High sensitivity but low specificity imaging modality
What is computed tomography?
A 3D image is generated from a large series of 2D radiographic images taken
around a single axis of rotation
What is the advantage of computed tomography?
- Structures are not superimposed on top of each other
- Facilitates examination of complex structures e.g skull
- Viewing image in several planes helps to better delineate fracture orientation- useful for planning
fracture repair
What is the benefit of magnetic resonance imaging?
Allows better imaging of soft tissue structures (less detailed examination of bony structures – lower
resolution compared to radiography, CT, U/S)
» Dynamic imaging modality; identifies intra-osseus fluid
» Only distal limb possible in horses
What is the difference between Epiphyseal/Physeal dysplasia and ligamentous laxity?
Ligamentous laxity can be corrected manually
What is physitis?
- Inflammation of the growth plate
- irregularly thickened growth plate
- metaphyseal sclerosis
- Periosteal new bone formation
What is the meaning of osteitis?
Bone is involved
What is the meaning of osteomyelitis?
Bone marrow and bone is involved
What are the clinical signs of osteitis/ osteomyelitis?
- Increased lameness
- Local swelling
- paiful response on palpation
- discharge from the wound/ incision site
What is the meaning of sequestrum?
Piece of dead radiopaque bone
What is an involucrum?
surrounded by an area of lucent granulation
tissue- Area of sclerosis may be surrounding (to wall off the
infection)
What is a sinus?
radiolucent tract between infected bone and skin
How might you treat osteomyelitis/ osteitis?
Systemic antimicrobial therapy
* Must have good bone penetration, broad spectrum
* Long course required
» Analgesia
» Wound care: debridement and lavage
» Curettage
* Debridement of bone and soft tissue to remove necrotic debris,
purulent material and avascular bone
» Implant removal if relevant
» Bone graft?
» Intravenous regional perfusion (IVRP) (Amikacin)
When might a hairline fracture become visible?
Hairline fracture may not become visible for 10-14
days
* Osteoclastic activity breaks down bone
* The fracture line then becomes visible
What is osteoarthritis?
Older animal
* Gradual onset
* Lameness mild to moderate to severe depending on stage of disease
* Lameness may improve with exercise
* Reduced ROM and bony changes may be palpable in advanced cases
What is septic arthritis?
- Any age
- Wound near a joint
- Acutely and severely lame
- +/- pyrexia
What is osteochondrosis?
- Young animal
- Joint effusion
- Often do not present with lameness
What is magnetic resonance imaging?
- Useful to assess concurrent soft tissue damage which
may be resulting in joint instability
What is synoviocentesis?
- Essential in diagnosis of septic arthritis
- Also useful to detect inflammation within the joint (synovitis)
- Aseptic collection
- NOT through contaminated skin/wound
- Test
- Cytology
- Culture & Sensitivity
What is a contrast study?
- Contrast agent injected into joint and radiographs taken
- Contrast agent will be visible leaking out of wound on radiographs if
both communicate
What is a pressure test?
- Distend joint with sterile saline
- Saline will exit through the wound if joint and wound communicate
What is the normal appearance of synoviacentesis?
- Pale yellow/transparent, high viscosity
- Low in white bloods cells and total protein
What is an abnormal appearance of synoviocentesis?
Serosanguinous/turbid/reduced viscosity
* High white blood cells and total protein
* >90 % Neutrophils
What is arthroscopy?
- Allows direct visualisation of joint
- Diagnostic and therapeutic
What are the aims of osteoarthritis management?
- Provide analgesia
- Control articular inflammation
- Limit damage to articular tissues
- Promote healing of damaged cartilage
What does a displaced fragment look like?
visualisation of
hyperechogenic bony structure distracted from
underlying bone
What is the issue with MRI’s in horses?
Only possible to view the distal limb
What is the benefit of the dynamic imaging modality in horse MRI’s?
Identifies intra-osseous fluid
What does ‘valgus’ mean?
lateral deviation of the limb
What does ‘varus’ mean?
Medial deviation of the limb ‘windswept foals’
What is curattege and what is it used for?
Debridement of bone and soft tissue to remove necrotic debris,
purulent material and avascular bone
- used in cases of osteitis/ osteoarthritis
What is IVRP?
Intravenous regional perfusion
delivers high concentrations of antibiotics to an area to relieve infection
How would you collect the fluid for synoviocentesis?
NOT through the contaminated skin/ wound
What is synoviocentesis most likely going to be used for?
Septic arthritis
Name two intra-articular corticosteroids?
- MPA
- TA
What are corticosteroid useful for?
- Reduction in inflammation within the joint
- Should be avoided in laminitis prone individuals
What is Hyaluronic acid used for?
- adjunctive treatment
- injected intra-articularly
- important component of synovial fluid
- lubricant, anti-inflammatory, chondroprotective
What is Pentosan polysulphate sodium (Cartrophen) - IM used for?
Reduction in articular cartilage fibrillation
* Once weekly for 4 weeks
What are bisphosphates used for?
Bisphosphonates - IV or IM (Tildren or Osphos)
o Inhibitor of bone resorption (osteoclasts)
o Slow down progression of OA
o Licensed for OA of the small tarsal joints & Navicular disease
Name 4 more adjunctive treatments (e.g not the hyaluronic acid slide)
- Autologous conditioned serum- Counteracts inflammatory protein IL-1 produced in joint synovitis
- Platelet rich plasma- Enrichment of platelets and degranulation to release growth factors
- Bone marrow derived mesenchymal stem cells- Promotes repair and regeneration
- Polyacrylamide hydrogel- Integrates into the joint capsule
What four things may cause septic arthritis?
- Trauma
- Iatrogenic
- Haematogenous
- Extension
What is the pathogenesis of septic arthritis?
- Inflammatory response- vasodilation and influx of neutrophils
- Fibrin clot traps bacteria (reduction in synovial nutrient exchange)
What is the gold standard for septic arthritis?
Arthroscopic debridement and lavage
What is Osteochondritis Dissecans?
Fragment separates from adjacent subchondral
bone
What is Osseus cyst
-like lesions (OCLLs)?
Retention of a focal area of degenerate cartilage
within the subchondral bone (subchondral bone
cyst)
