DJD (bolt) Flashcards
Terminology used for DJD?
OA
DJD
Osteoarthrosis
Arthrosis
What is the purpose of the menisci?
Compensate for incongruency of joint (stifle)
2 types of synoviocytes?
A (modified epithelial cells)
B (metabolically active, produce hyaluronic acid)
What is the ECM of hyaline cartilage mainly composed of?
Secreted by chondrocytes
- type 2 collagen
- GAGs(aggrecan)
- water
- very small amount of elastic and reticular fibres and chondrocytes
Are immune mediated joint disease seen in endorse?
Nooo
What is DJD?
- multi factorial disorder of joints
- degeneration of articular cartilage
- bone changes (OA)
- lysis and new bone formation
Common conditions causing DJD?
> trauma - acute - repetitive > infectious inflam - septic > non-infectious inflam (VERY COMMON HORSES) > developmental dz - dysplasia - angular /flexural limb deformity - OCD
What is bone spavin?
DJD of the TMT/DIT
Outline the pathophysiology of DJD LOOOK UP
> failure of homeostasis of articular cartilage
- cartilage breakdown products
- matrix metalloproteinases (MMP2,3,4… Etc)
- catabolic cytokines
synovial membrane
- PGs, LTs
- neuropeptides and cytokines
subchondral bone
- altered load absorption: cartilage damage
- inflammatory mediators (IL-1, TNFa)
How is pain caused with DJD?
No pain fibres in the articular cartilage
- pain fibres in synovium (joint capsule)
- pain fibres in subchondral bone (exposure bad)
How do soft tissues affect pathophysiology of DJD?
> synoviocytes release mediators and enzymes (PGs, cytokines, MMPs)
Do radiographic signs correlate well with clinical signs?
No
Is intra-articular medication cheap?
No!
What should be looked at in PE for DJD?
> weight BCS > lameness exam - identify and loacalise - scoring - palap and manipulatio nof joint - pain, heat, swelling, crepitus - reduced ROM - joint effusion > muscular atrophy
Further Dxx for joint dz?
> imaging - rads - ultrasound - MRI/CT > nerve blocks > synovial fluid analysis (rare in horses, usually normal, unless suspect iatrogenic sepsis) > arthroscopy (rarely for 1* DJD investigation, only to debride etc) - synovial biopsy possible
Why may intra-articular analgesia be more specific? Why are there limitations to intra-articular analgesia in the distal limb?
Close proximity of DIP joint, navicular bursa and distal recess of digital synovial sheath
- more specific than peripheral nerve blocks otherwise
Osteophytes
- see rads
Soft tissues
eg. meniscal tear and protrusions, can become 2* mineralised, effusions
Subchondral bone sclerosis
thickened radiodensity
Tx goals for DJD?
- pain
- stop inflammatory process (all DJD comes from inflam)
- V production inflam mediators
- chondroprotection (“disease modification” arrest or slow down cartilage degeneration, usually not drugs, (called Neutroceuticals but NOT as no nutritional value) supplement type things)
- OA can not be cured, just managed *
Tx strategies LOOK UP
>maintenance
- weight loss
- excercise mod/physio
- stratgetic analgesia
> control flare ups
- initial analgesia (5-10d)
- gradual resume excercise
- swimming/hydrotherapy
- joint supplements ("neutraceuticals" / for disease modificiation)
> salvage/new tx optionsPotential medical Tx of DJD in large animals?
- NSAIDs
- intraarticular steroids
- analgesia
- GAGs
- sodium hyaluronate
- supplemetns
> chondroitin sulphate
> glucosamine - IL1 receptor antagonist protein
- Tiludronate “Tildren” (bisphospohate)
Most common medication for orthopeadic problems? Side effects?
>NSAIDs - inexpensive - efficient - mechanism = inhibition of COX, prevent PG > side effects - GI ulceration - nephritis - PLE - negative influence of bone and cartilage metabolism?!!
Look at lecture for table of NSAIDs
-
Why is ketoprofen good? Bad?
- good for foals, COX specific
- $$$$$
Most potent anti inflam Tx?
Intra articular corticosteroids
- inflam cells and humoral mediators
> mechanism
- inhibits PG synthessis by blocking PLA and COX pathways
- inhibit synthesis of cartilage degrading cytokines (IL1, TNFa)
- inhibit cartilage degrading enzymes themselves (MMP, aggrecanase)
Potential side effects of coritcosteroids ?
> negative effects on cartilage healing? (Not seen clinically, very effective!) > ^ risk of iatrogenic joint infection - immunosuppressive > laminitis - check max doses
Which 2 drugs are used most commonly for Tx DJD in horses?
- Triamcinolone acetinonide
- methylprednisolone acetate
When is the term OA used?
Only when radiographic signs of underlying bone involvement
What GAG products are available for horses? What is it’s mechanism and recommedned dose?
> “Adequan” Polysulfated GAG
- extract from bovine lung and trachea $$$
- mechanism: MMP inhibition, HA production stimulator, matrix synthesis stimulator
- IA injection
- ^ risk of sepsis or non septic inflam (flare)
- licensing?
- Dose: 500mg IM q4d for 28d
“Cartrophen” Pentosan Polysulphate
- extract from beechwood hemicellulose
- mechanism: stimulates cartilage matrix and HA synth, MMP and inflam inhibition, mobilises thrombi and fibrin in synovium, lipids and cholesterol in vessels, inhibits platelet aggregation and clotting, ^ plasma lipase levels
- Dose: 3mg/kg SC 4x q5-7d
What is sodium hyaluronate and how can it be administered? What effects do supplements have?
- major structural componenet (articular cartilage matrix synthesis by chondrocytes, synovium synthesis by btype B synoviocytes)
-> viscoelasticity, concentration, polymerisation, boundary lubrication
-> anti-inflammatory function (steric hinderance, chemotactic response)
> IA/IV/PO - may supplement depeleted HA or stimulate endogenous HA synthesis (unknown)
What is the difference between cheap and expensive HA supplements?
Molecular weight in kDa - bigger the better
What effects can supplements have on DJD?
= neutraceuticals (feed additives)
- dz modification
- mechanism: stim cartilage matrix synthesis, MMP inhibition, reduce inflam mediators
- often administered without vet prescription
Egs. of matrix GAGs? Are these commonly used?
> glucosamine
- bioavailability variable
chondroitin sulphate
- molecular weight: SMALLER the better!!
- degradation in GI mucosa
glucosamine/chondroitin sulphate combo may be better?
most horses will be on some kind of supplement!!
WHere is chondroitin sulphate found naturally?
- Green-lipped mussell extract!!!
- Perna canaliculus (edible shellfish in NZ)
+ anti-inflam via leukotriene pathway
+ fatty amino acids
+ minerals
+ vitamins
What is MSM?
Methylsulphonylmethane > sulphur source - collagen - matrix metabolism > derived from DMSO > Mechanism (no convincing efficacy data, no effect on inflam) - analgesic (human studies)
What is Devil’s claw?
- harpagophytum Procumbens (Iridoid Glycosides)
- decreses inflam mediators in people but no science in horses
- used in traditional african medicine (arthritis, fever, skin conditions, GI dz)
- not cheap but good alternative if allergic to bute
What is IRAP? How is it used?
= IL1-R antagonist protein
- IL1 key inflam mediator in OA
- stimultes cartilage degrading enzymes (MMPs, aggrecanases)
> IRAP diectly blocks IL1, v inflam but no controlled large scale studie sin horses
- therapeutic sucess in cases refractory to steroids
> autologous conditioned serum (ACS) used byu culturing patient blood in special syringe with chromium sulphate soaked glass beads
-> upregulation of IRAP and other anti-inflam mediators
- IA administration
- serum can be stored frozen
What is Tildren? What drug is similar?
Tiludronate (Non-nitrogenous Biphosphonate) - inhibits bone resorption by osteoclast apoptosis - anti-inflam > Europe LIC for horses - distal tarsal OA - navicular dz - ?clinical efficacy - side effects.. colic? > DOse: 1mg/kg IV CRI over 30 mins - may require NSAID premed ?? > ~=Osphos (IM version)
What surgical tx are possible for DJD?
> Excision arthroplasty (SA)
Arthrodesis
- horse pastern, distal tarsus, fetlock, carpus (often slavage procedure)
Total joint replacement (SA)
What is high ring bone?
DJD of the pastern (DIP)
Tx high ring bone? Prog?
Arthrodesis (40% return to work in FL, 70% HL)
Which steroids are best for high motion joints? Which for low motion?
> TMA high motion (fetlock)
Methylprednisolone low motion or 2nd line
- can cause reaction @ injection site (hock/back)
