Inflamatory Arthritis Flashcards
(38 cards)
What is often seen with inflammatory OA? ECHOOOO
PUO
How can immune mediated v. septic processes be differentiated?
> arthrocentesis
- neutrophils degenerate if septic
- poportion of nucleated/mononuclear/neutrophils different
changes on radiography with both
- subacute/chronic : eroision of cartilage and sunchondral bone
Causes of septic arthritis
> haematogenous - foal umbilicus - intestine > traumatic - esp. horses > Iatrogenic (often "aseptic") IA injections, surgery etc.
What bacteria is the most common cause of eptic arthritis iatrogenicaly?
Staph aureus
- forms a glycocalyx on implants especially. (titanium more resistant)
Tx SA inflammatory arthitis?
- ABx (amoxy-clav 20mg/kg IV)
- no differnece between medical and sx tx
- 95% infections will resolve
- may need to remove implants
- 6 week Abx based on culture
Tx equine septic arthritis? Px?
- acute infection = emergency
- eliminate organisms from joint
- eliminate enzymes and mediators causing cartilage destruction
- Abx/through and thorugh lavage
- Arthoscopy/arthrotomy
- IA Abx, IV Abx (pen and gent)
- resample joint fluid q48hrs
- oral Abx
> C+S but IV to start with amoxyclav - can deliver locally (gentamicin impregnated sponges, intrasynovial catheters)
> early stages : rest - Px excellent if tx rpadily but only 50% return to racing
- Physio/ hydrtherapy to reduce adhesions and pevent periarticular fibrosis
Aetiology of IMPA?
- Ag/Ab complex -> formationi of inflammatory products
- Host IgG and M bind to altered autlogous IgG
- Ag/Ab complexes deposited on synovium -> neutrophil/macrophage chemotaxis
[Erosive] - cellular or humoral immunopathogenic factors - release of chondrodestructive collagenases/proteases
- failure of self-tolerance
- production of immunogenic immunoglobulins
Outline path of Rheumatoid arthritis
- Plasma cells/B lymphocytes -> RF factor
- Synoviocytes in the synovium are activated
- IL1, collagenases produced
- Osteoclasts -> bone resorption and subchondral bone cyts
- Pannus formation
- > fibroblast proliferation leads to contracture and limb deformation
Outline autoimmune pathophysiolgy
> mistake 1
- immune systems fails to recognise self
- clones of potentially autoaggressive cells originally inactivated in thymus proliferate
mistake 2
- inappropriate reaction doesn’t know when to stop
= hypersensitivity
Risk factors for autoimmune dz?
- hereditary (eg. beagles)
- certain infections (GpA strep pharyngitis -> acute rheumatic factor)
- bacterial endocarditis (full PE!!)
- discospondylitis
- immune mediated bowel disease
- neoplsia
- chronic hepatitis
What are the 4 types of hypersensitivity reactions? Which type causes IMPA?
> 1: immedite/anaphylactic
- IgE, mast cells and basophils
2: Ab dependent cytotoxic
- IgG, IgM against a cell surface component
3: immune complex mediated
- Large amonts of IgG or M + Ag -> microprecipitates
- cause of IMPA (precipitates lodge in joint or are created in joint)
4: cell-mediated, delayed type
- INtra-cellular organisms
Typical presentation of immune-mediated arthritis?
- Polyarticular disease (>6 joints) usually
- occasionally pauciarticular (2-5)
- rarely mono-articular
> if single joint affected but culure negative try empirical Abx tx - chronic dz
Outline immune-mediated arthritis process
- continual or recurrent presence of inciting antigens
- failure of normal down-regulation when incititing antigens gone
- initial dmagae to host resulting in exposire of altered self Ag
Causes of a palmigrade stance?
> traumatic hyper-extension injuries
palmigade likley to be more severely afected (erosive dz)
systemic disease (eg. Addisons??) all 4 limbs
palmar fibrocartilage damage
autoimmune disease
What may be fond on clinicla exam with immune mediated joint disease?
- multisystem pyrexia
- depression
- anorexia
- ligament slackening
4 types of non-erosive polyarthritis? Most common? LOOK UP
> 1: uncomplicated idiopathic
- most common
- early RA?
- severe signs
2: reactive arthritis (assoc with remote infections)
- endocarditis/urogenital
- severe signs
3: reactive arthritis (assoc with GI/hepatic dz)
- less severe signs
4: reactive arthritis (assoc with remote neoplasia)
- less severe signs
Invstigation of polyarthritis
> polyarthropathy - arthrocentesis - joint ads - synovial biopsy > underlying dz hunt - haem, biochem, urinalysis - thoracic rads - abdo ultrasound - other tests (CSF? Serology? PCR?)
Radiographic signs of immune mediated arthitis?
- joint effusion with cranial displacement of the fat pad
- not very excited
Egs. of other Non-Erosive polyarthritis?
- SLE
- Lyme dz
- Drug-associated (eg. Dobies, sulphonamides, penicillin, phenobarb)
- Vax induced (seen within 30d of vax)
- Calicivirus kittens
- Steroid-responsive meningitis-arteritis in adolescent dogs
- IBD
Why are rads important when they are rarely exctiing for immne mediated arthritis?
- r/o erosive disease
> much poorer prognosis (but rare!)
Outline pathophysiology of erosive disease. How common is erosive dz?
- chronic synovitis -> production proliferative granulation tissue (PANNUS)
- pannus invades articular cartilage and can erode subchondral bone
- pannus and inflamed synovium produce enzymes (proteases, collagenases) -> destruction
- similar changes in septic arthritis
> 1% of PA
Types of erosive joint disease?
- rheumatoid arthritis
- periosteal proliferative polyarthritis in cats
- polyarthritis of greyhounds (Felty’s syndrome in humans: RA
Is classic RA diagnosis applicable to animals? What shold be looked for?
> rarely applicable to animals (dont have nodules, rarely abnormal synovial fluid) - stiffness after rest - pain - swelling of one joint + another within 3mo - symmetrical joint swelling - subcut nodules - rad signs of eroision - RF + serology - abnormal synovial fluid - synovial histology - nodule histology > theoretically should have 7 of these inclusing 2/3 of erosion, RF+ and synovial histology
Radiogrpahic changes seen with erosive joint disease?
- subchondral bone erosion
- destructive symmetric multi-joint arthropathy
- early may be only soft tissue changes
- chronic: collapse of joint spaces, joint deformity or sub-luxation, peri-articular new bone formation, calcification of peri-articular soft tissues
