Approach to Bone and Joint Diseases in the Horse

Question 1

What is periosteal new-bone formation?

Answer 1

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

Question 2

What is Sclerosis?

Answer 2

• Densification
• Localised formation of new bone within bone
• Stress
• Protection of a weakened area
• Walling off infection

Question 3

What is bone lysis?

Answer 3

• Destruction of an area of bone
• Infection
• Neoplasia
• Keratoma

Question 4

What is osteophyte formation?

Answer 4

Spur of bone on a joint margin
* Joint instability
* Intra-articular disease (eg Osteoarthritis)

Question 5

What is enthesophyte formation?

Answer 5

• New bone formation at attachment of tendon/ligament/joint capsule to bone
• Bone’s response to stress applied through these structures
• Soft tissue injury

Question 6

What are the three characteristics of aggressive bone disease?

Answer 6

• Destruction of the cortex
• Character of the perisoteal lesion
• Lack of distinctness of boundary between the bone lesion and normal bone (transition zone)

Question 7

What can ultrasonography be useful for?

Answer 7

assess the bone surface
* should appear smooth
* useful to image areas which are difficult to radiograph

Question 8

What would show the presence of a fracture on a radiograph?

Answer 8

Non-displaced break in normal hyperechoic bone
surface
* Displaced fragment
– visualisation of hyperechogenic bony structure distracted from
underlying bone

Question 9

How does nuclear scintigraphy work?

Answer 9

• Radioisotope is injected intravenously
• increased IRU in areas where there is increased osteoblastic activity
• High sensitivity but low specificity imaging modality

Question 10

What is computed tomography?

Answer 10

A 3D image is generated from a large series of 2D radiographic images taken
around a single axis of rotation

Question 11

What is the advantage of computed tomography?

Answer 11

• 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

Question 12

What is the benefit of magnetic resonance imaging?

Answer 12

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

Question 13

What is the difference between Epiphyseal/Physeal dysplasia and ligamentous laxity?

Answer 13

Ligamentous laxity can be corrected manually

Question 14

What is physitis?

Answer 14

• Inflammation of the growth plate
• irregularly thickened growth plate
• metaphyseal sclerosis
• Periosteal new bone formation

Question 15

What is the meaning of osteitis?

Answer 15

Bone is involved

Question 16

What is the meaning of osteomyelitis?

Answer 16

Bone marrow and bone is involved

Question 17

What are the clinical signs of osteitis/ osteomyelitis?

Answer 17

• Increased lameness
• Local swelling
• paiful response on palpation
• discharge from the wound/ incision site

Question 18

What is the meaning of sequestrum?

Answer 18

Piece of dead radiopaque bone

Question 19

What is an involucrum?

Answer 19

surrounded by an area of lucent granulation
tissue- Area of sclerosis may be surrounding (to wall off the
infection)

Question 20

What is a sinus?

Answer 20

radiolucent tract between infected bone and skin

Question 21

How might you treat osteomyelitis/ osteitis?

Answer 21

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)

Question 22

When might a hairline fracture become visible?

Answer 22

Hairline fracture may not become visible for 10-14
days
* Osteoclastic activity breaks down bone
* The fracture line then becomes visible

Question 23

What is osteoarthritis?

Answer 23

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

Question 24

What is septic arthritis?

Answer 24

• Any age
• Wound near a joint
• Acutely and severely lame
• +/- pyrexia

Question 25

What is osteochondrosis?

Answer 25

* Young animal * Joint effusion * Often do not present with lameness

Question 26

What is magnetic resonance imaging?

Answer 26

* Useful to assess concurrent soft tissue damage which may be resulting in joint instability

Question 27

What is synoviocentesis?

Answer 27

* 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

Question 28

What is a contrast study?

Answer 28

* Contrast agent injected into joint and radiographs taken * Contrast agent will be visible leaking out of wound on radiographs if both communicate

Question 29

What is a pressure test?

Answer 29

* Distend joint with sterile saline * Saline will exit through the wound if joint and wound communicate

Question 30

What is the normal appearance of synoviacentesis?

Answer 30

* Pale yellow/transparent, high viscosity * Low in white bloods cells and total protein

Question 31

What is an abnormal appearance of synoviocentesis?

Answer 31

Serosanguinous/turbid/reduced viscosity * High white blood cells and total protein * >90 % Neutrophils

Question 32

What is arthroscopy?

Answer 32

* Allows direct visualisation of joint * Diagnostic and therapeutic

Question 33

What are the aims of osteoarthritis management?

Answer 33

1. Provide analgesia 2. Control articular inflammation 3. Limit damage to articular tissues 4. Promote healing of damaged cartilage

Question 34

What does a displaced fragment look like?

Answer 34

visualisation of hyperechogenic bony structure distracted from underlying bone

Question 35

What is the issue with MRI's in horses?

Answer 35

Only possible to view the distal limb

Question 36

What is the benefit of the dynamic imaging modality in horse MRI's?

Answer 36

Identifies intra-osseous fluid

Question 37

What does 'valgus' mean?

Answer 37

lateral deviation of the limb

Question 38

What does 'varus' mean?

Answer 38

Medial deviation of the limb 'windswept foals'

Question 39

What is curattege and what is it used for?

Answer 39

Debridement of bone and soft tissue to remove necrotic debris, purulent material and avascular bone * used in cases of osteitis/ osteoarthritis

Question 40

What is IVRP?

Answer 40

Intravenous regional perfusion delivers high concentrations of antibiotics to an area to relieve infection

Question 41

How would you collect the fluid for synoviocentesis?

Answer 41

NOT through the contaminated skin/ wound

Question 42

What is synoviocentesis most likely going to be used for?

Answer 42

Septic arthritis

Question 43

Name two intra-articular corticosteroids?

Answer 43

1. MPA 2. TA

Question 44

What are corticosteroid useful for?

Answer 44

* Reduction in inflammation within the joint * Should be avoided in laminitis prone individuals

Question 45

What is Hyaluronic acid used for?

Answer 45

* adjunctive treatment * injected intra-articularly * important component of synovial fluid * lubricant, anti-inflammatory, chondroprotective

Question 46

What is Pentosan polysulphate sodium (Cartrophen) - IM used for?

Answer 46

Reduction in articular cartilage fibrillation * Once weekly for 4 weeks

Question 47

What are bisphosphates used for?

Answer 47

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

Question 48

Name 4 more adjunctive treatments (e.g not the hyaluronic acid slide)

Answer 48

* **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

Question 49

What four things may cause septic arthritis?

Answer 49

* Trauma * Iatrogenic * Haematogenous * Extension

Question 50

What is the pathogenesis of septic arthritis?

Answer 50

* Inflammatory response- vasodilation and influx of neutrophils * Fibrin clot traps bacteria (reduction in synovial nutrient exchange)

Question 51

What is the gold standard for septic arthritis?

Answer 51

Arthroscopic debridement and lavage

Question 52

What is Osteochondritis Dissecans?

Answer 52

Fragment separates from adjacent subchondral bone

Question 53

What is Osseus cyst -like lesions (OCLLs)?

Answer 53

Retention of a focal area of degenerate cartilage within the subchondral bone (subchondral bone cyst)