MSK - arthritis Flashcards
Outline osteoarthritis
Chronic
Cartilage deterioration → bones rub together → stiffness, pain, less mobility
Main risk factors of OA?
Age Weight Intense sport or forces Hereditary Female gender and menopause
Explain the cycle of obesity and OA
Obesity increases pressure on knee joints This leads to joint pain/arthritis Limited mobility Lack of physical activity Obesity
Where are the main sites of OA?
Spine
Knees
Fingers
Hips
Signs and symptoms of OA?
Pain gets worse throughout day as use increases
Little morning stiffness
Joint instability, bony enlargement, less mobility, crepitus, some swelling
What abnormalities can be seen on an OA radiograph?
Osteophytes
Subchondral cysts
Sclerosis
Small space between bones
What are the 3 main types of OA management + examples?
Conservative - weight loss, analgesics, physio
Injections - steroids, lubrications gel, platelet plasma
Operative - replace, realign, excise
What are the names of DIP and PIP nodes?
Bouchard’s - proximal
Heberdens - distal
What are the 3 functional classifications of joints?
Synarthoses - no movement
Amphiarthoses - limited movement
Diarthosese - free movement
What makes up the synovium?
Type A synoviocyte - phagocytic
Type B synoviocyte - hyaluronic acid
Type 1 collagen
What are the main components of articulation cartilage?
Chondrocytes
ECM:
Type 2 collagen
Proteoglycan, aggrecan
Water
What is a function of aggrecan?
Interacts with hyaluronic acid to from proteoglycan aggregates
Why does cartilage heal poorly?
It is avascular
What are the two types of arthritis?
Osteo, degenerative
Inflammatory
5 manifestations of inflammation?
Redness Pain Heat Swelling Loss of function
Pathophysiology of inflammation?
Increased blood flow
Leucocytes to tissues
Activation of these
Cytokine produced
What are the 3 main causes of joint inflammation?
Infection
Crystals
Autoimmunity
What causes septic arthritis?
Infection usually from blood
Septic arthritis risk (3)
Intravenous drug use
Immunosuppressed
Pre existing joint damage
What is the usual presentation of SA?
Mono arthritis
Acute pain, redness, heat, swelling, fever
How is SA diagnosed and treated?
Joint aspiration sent for gram stain and culture
Treatment of surgical lavage and IV antibiotics
What organisms can cause SA?
Staphylococcus aureus
Stretococci
Gonococcus
How does gonococcal SA present differently?
Usually polyarthritis
Less likely to cause joint destruction
2 types of Crystal arthritis?
Gout
Pseudogout
What is gout caused by?
Deposition of urate crystals
This caused by high uric acid levels
What causes hyperuricaemia?
Genetics
Increased consumption of purine rich foods
Kidney failure- reduced excretion
What causes pseudogout?
Deposition of calcium pyrophosphate dihydrate crystals
What are 3 risk factors for pseudogout?
Osteoarthritis
Elderly
Inter current infection
What are the clinical features of gout?
Acute rapid onset monoarthritis
Can be in foot, ankle, knee, wrist, finger, elbow
Tophi can also be seen
What is the most commonly affected joint on gout?
First metatarsophalangeal joint - podagra
How can crystal arthritis present on radiography?
Rat bite erosions
What is the difference between gout and pseudogout aspirations? And how is it analysed?
Under microscope using polarised light
G - needle crystals, negative birefringence
PG - rhomboid crystals , positive birefringence
How can rheumatoid arthritis be classified?
Chronic
Auto immune
Inflammatory
What are 3 main signs of RA?
Polyarthritis - often hands and wrists
Symmetrical
Early morning joint stiffness
What can be detected in the blood of RA patients?
Rheumatoid factor - an autoantibody against IgG
What is the main site of pathology in RA?
Synovium- synovitis, tenosynovitis, bursitis
What are some extra articular features of RA?
Fever, weight loss, subcutaneous nodules
Vasuculitis Episcleritis Neuropathies Feltys syndrome Lung disease Amyloidosis
What is Felty’s syndrome?
Triad of splenomegaly, leukopenia, RA
What are the subcutaneous nodules in RA?
Centre of fibrinogen necrosis surrounded by histiocytes and connective tissue
Approx 30% patients
Explain the pathogenesis of RA in regards to the synovium
Synovium becomes a mass of tissue (pannus) due to :
Neovascularisation
Lymohangiogenesis
Imflammatiry cells excess due to an excess of pro inflammatory cytokines
What is the dominant pro inflammatory cytokine in RA and what is it produced from?
TNF-a produced by activated macrophages
Name a treatment for RA
TNFa inhibitors
What are the 2 antibodies in RA?
Rheumatoid factor (IgM antibody against IgG)
Antibodies to citrullinated protein antigens (ACPA) - highly specific to RA
What is the citrulliantion of peptides and what enzyme is involved?
Arginine → citrulline
Peptidyl arginine deaminases (PADs)
What are the treatment options for RA?
DMARDs
1st: methotrexate with hydroxychloroquine/salfasalazine
2nd: biological therapies, Janus Kinase inhibitors
Glucocorticoids (prednisolone)
Give 4 examples of biological therapies for RA?
Anti TNFa
B cell depletion, rituximab
Modulation of T cell co stimulation
Inhibition of IL6 signalling , tocilizumab
Outline some of the differences in presentation between OA and RA
RA : 30-50yrs, rapid onset, bilateral symmetric, better with movement, morning stiffness, PIP & MCP joints, wrist ankle elbow, systemic symptoms, red warm joint swelling, serum positive, high CRP & ESR
OA : >50yrs, slow onset, assymetric, worse with movement, no morning stiffness, DIP & CMC joints, bony joint swelling , serum negative
Radiological differences between OA and RA?
RA : osteopenia, bony erosions
OA : subchondral sclerosis, osteophytes
Both have joint space narrowing
What is one difference between RA and psoriatic arthritis?
PA is seronegative , no rheumatoid factors
How can psoriatic arthritis present?
Asymmetrical arthritis in IPJs
Symmetrical involve,ent of some small joints (rheumatoid pattern)
Spinal and sacroiliac joint inflammation (spondyloarthritis)
Oligoarthritis of large joints
Arthritis mutilans
What is reactive arthritis and when does it normally occur?
Sterile inflammation of joints
Follows urogenital or gastrointestinal infections , 1-4 weeks after
What 2 conditions can reactive arthritis present in?
HIV and hepatitis C
What are 3 extra articular manifestations of reactive arthritis?
Skin inflammation
Eye inflammation
Enthesitis
What is a risk factor for reactive arthritis?
Young adults with genetic predisposition with environmental trigger
Differences between septic and reactive arthritis?
SA : positive synovial fluid culture, antibiotic therapy, joint lavage
RA : negative culture, no ab therapy, no joint lavage
What is systemic lupus erythematous?
Autoimmune disease affecting multiple organs
What do the autoantibodies in SLE attack?
Nucleus - nucleic acids and proteins
What are the 2 autoantibodies in SLE and their differences?
Antinuclear antibodies - high SLE sensitivity but not specific
Anti-double stranded DNA antibodies - high specificity for SLE
