Joint disease Flashcards
Define arthritis
Inflammation of the joint
Label the joint parts
What are the categories of joint disease and examples of each?
- Congenital
- e.g. Incomplete ossification of cuboidal bones - Developmental
- e.g. Osteochondritis Dissecans (OCD)
- e.g. Subchondral bone cyst - Degenerative
- e.g. Osteoarthritis
- e.g. Osteochondral fragmentation (OCF) - Immune mediated
- e.g. Canine immune mediated polyarthritis (IMP) - Infectious
- e.g. Septic arthritis
Interpret this radiograph of a foal’s carpus taken soon after birth. What condition is present?
Congenital joint disease - Incomplete Ossification of Cuboidal Bones
Findings: Cuboidal bones appear small & under-mineralised with radiolucent (black) areas
Cause: Failure of cartilage to fully mineralise into bone
Thick cartilage around unossified areas prone to collapse, leading to joint instability & deformities
Interpret this lateromedial radiograph of a horse’s stifle. What condition is present?
Developmental joint disease - Osteochondritis Dissecans (OCD)
Findings: Multiple small, round, radiodense fragments in femoropatellar joint
Cause: Failure of endochondral ossification leads to retained necrotic cartilage & bone fragments
(Treatment: Arthroscopic removal of fragments (good prognosis))
Interpret this caudocranial radiograph of a horse’s stifle. What condition is present?
Developmental joint disease - Subchondral Bone Cyst
Findings: Radiolucent zone in medial femoral condyle
Cause: Developmental defect leading to fluid-filled cavity within bone
Very painful, causes significant lameness
Prognosis: Poor, often difficult to manage
Interpret these radiographs of an equine hock (left: lateromedial, right: dorsoplantar). What condition is present?
Degenerative joint disease - Osteoarthritis of the Hock
Findings:
- Joint space collapse in distal intertarsal joint due to cartilage destruction
- Periarticular bone lysis (multiple small radiolucent lesions)
- Sclerosis (increased bone density in central & third tarsal bones)
Causes pain & reduced mobility
Interpret this lateromedial radiograph of a horse’s foot. What condition is present?
Degenerative joint disease - Osteochondral Fragmentation (OCF) (Bone Chip)
Findings: Small, irregular radiodense fragment in dorsal aspect of distal interphalangeal joint
Cause: Degenerative joint disease leading to cartilage & bone breakdown, causing fragment to separate
Interpret these images of a dog’s carpus (left: clinical image, right: dorsopalmar radiograph). What condition is present?
Immune mediated joint disease - Canine Immune-Mediated Polyarthritis (IMP)
Findings:
- Joint swelling & soft tissue thickening
- Bone destruction in carpus
- Multiple joints affected (polyarthritis)
Common in: Sight hounds, especially Whippets
What causes septic arthritis (infectious joint disease)?
Bacteria enter joint & set up infection
How is joint disease investigated?
History
Clinical exam
Radiography – predominantly bones
Ultrasonography – predominantly soft tissues
Advanced imaging – MRI, CT, Nuclear Scintigraphy
Synovial fluid analysis
How is joint disease treated?
Disease specific
Multifaceted
Medical & surgical
Systemic & local
Short or long term
Anti-inflammatory & analgesic
Disease modifying agents
Lifestyle changes
What are common causes of joint sepsis?
Traumatic wound
- Joint capsule open to outside world, allow bacteria to enter
Iatrogenic
- Any time you put needle into joint, there is risk of taking bacteria into it (esp. corticosteroids as they reduce body’s immune response)
Haematogenous
- Bacteria from septicaemia/ bacteraemia enter joint
- Travel via slow-flowing capillaries in joint membrane, allowing adhesion & infiltration
- Usually in neonates, with umbilicus as infection source
Why are neonates at most risk for joint sepsis?
Lack of natural immunity
Failure of passive transfer
What is the incidence of joint sepsis in different species?
Horses – common
- wounds!/haematogenous/ iatrogenic
Farm animals – common
- haematogenous
Small animals / exotics - rare
How is joint sepsis diagnosed?
History
- Have they got a wound?
- Are they systemically ill?
Clinical exam
- Examine wound
- Degree of lameness
- Swelling/heat
Synovial fluid analysis
- appearance (cloudy +- bloody)
- nucleated cell count, % neutrophils, TP (all elevated in infected joint)
- C&S (to know which antibiotic to use)
How is joint sepsis treated?
Life-threatening
Early treatment = better outcome
- Lavage
- 2 methods (picture) - Antibiotics
- Local & systemic
- Based on C&S - Remove underlying tissue
What are the 2 methods of administering local antibiotics for joint sepsis?
Intra-articular injection:
- Antibiotics injected directly into joint, delivering high concentration to infection site
Intravenous regional perfusion:
- Tourniquet placed above infected joint to restrict circulation
- High volume of antibiotics injected into vein below tourniquet, ensuring high local antibiotic concentration
- IVRP allows antibiotics to penetrate surrounding tissues while minimising systemic exposure
What factors should be considered when treating joint disease?
Cascade
Competition withdrawal (equine)
Efficacy
What are the systemic treatment options for osteoarthritis?
NSAIDs (all species)
Paracetamol
Bisphosphonates (equine)
Glycosaminoglycan derivatives
What are the intra-articular treatment options for osteoarthritis?
Corticosteroids
Glycosaminoglycan derivatives (Hyaluronic acid)
Synthetic hydrogels
Biological products (Stem cells, IRAP, PRP)
What are the systemic treatment options for immune-mediated joint disease?
Corticosteroids
Immunomodulators
Why can’t bisphosphonates be used in this case?
Not permitted in horses under 3.5 years in UK racing
Using them in younger horses removes them from racing permanently
Has a 30-day withdrawal period, which is too long
Why are biologic treatments (e.g., glycosaminoglycans) not suitable for this horse?
Limited evidence for rapid efficacy
Unlikely to provide enough anti-inflammatory effect before race
What is the preferred treatment for this racehorse’s joint disease?
Intra-articular corticosteroids
Triamcinolone is best choice due to shorter withdrawal time
Why is joint sepsis unlikely in this dog?
No massive neutrophilia in synovial fluid
Moderate protein increase, not as high as expected in sepsis
Chronic shifting lameness, rather than acute severe pain
What is the most likely diagnosis?
Immune-Mediated Polyarthritis (IMP)
Multiple joints affected at different times
Symptoms vary in severity
Autoimmune nature rather than infection
Why is local joint treatment (e.g., intra-articular steroids) not effective for IMP?
Different joints are affected at different times
Local injections only treat one joint, not systemic disease
Condition requires systemic immunosuppression
Withdrawal times
Damage-associated molecular patterns and pathogen-associated molecular patterns
Pattern recognition receptors (PRRs)
SIRS (Systemic Inflammatory Response Syndrome)
DIC (Disseminated Intravascular Coagulation)
Traumatic wounds
Failure of passive transfer of immunity
Arthroscopy (keyhole surgery)
Analysing the synovial fluid for nucleated cell count and protein levels
Osteoarthritis
Limited availability of licensed products
Corticosteroids
No true regenerative products exist on the market
Interleukin-1 receptor antagonist protein used to modulate the immune response
It allows for higher local concentrations of antibiotics
