MSK Flashcards
Brief pathology of osteoarthritis
Degenerative progressive destruction of cartilage from repeated mechanical forces
Disruption of chondrocytes prevents rebuilding
Usually in synovial joints
Why is obesity considered a pro-inflammatory state?
Bc it releases IL1, TNF and adipokines
RF of osteoarthritis
Older age
High intensity labour
Joint hypermobility
Diabetes
F > M
Obesity
COL2A1 collagen type 2 gene plays a role
Why is age a risk factor for OA?
Cumulative effect of traumatic insult and ↓ of neuromuscular function
Main pathological features of OA
Loss of cartilage
Disordered bone repair
Key Presentation - OA
Painful joints, stiffness < 30 mins in morning
Worse throughout the day
Occurs at PIP (Bouchard) and DIP (Heberden)
What effects do oestrogen have on bone turnover?
And hence, what is a RF for MSK diseases e.g. osteoporosis, OA?
Oestrogen has restraining effect on bone turnover
∴ EARLY MENOPAUSE results in ↓ trab. Th, strength and bone connections
List 4 other signs/symptoms of OA
Joint pain on movement
Tenderness
Crepitus
Asymmetrical joint involvement
Ix Osteoarthritis
XRAY - LOSS
Loss of joint space
Osteophytes
Subchondral sclerosis (more white on XR)
Subchondral cysts
DDx OA
RA
Gout
Psoriatic arthritis
Tx OA
1. Px education & lifestyle changes
(weight loss if obese, physiotherapy, occupational therapy)
2. Analgesic ladder
a). Paracetamol, topical NSAIDs, topical capsaicin
b). Oral NSAIDs (+ PPI)
c). Opiates e.g. codeine, morphine
also, intra-articular steroid injections - hyaluronic acid
If extreme, joint replacement
(avoid steroids before surgery bc immunosuppressive)
What type of hypersensitivity reaction is RA?
Type III
RF RA
Female! (premenopausal women 3x more affected than men)
HLA-DR4 and HLA-DRB1 (more susceptible, associated w/ ↑ severity)
FHx
Stress
Infection
Smoking
What are the diagnostic criteria for RA?
Need 4/7 to be diagnostic
Rheumatoid nodules
Rh factor POS
Radiographic changes (XR LESS)
Arthritis of hand joints
Morning stiffness > 30 mins
Symmetrical
State and describe hand deformities found w/ RA
Ulnar deviation
Boutonniere deformity - PIP flexion, DIP hyperextension
Swan neck deformity - PIP hyperextension, DIP flexion
State 10 other signs/symptoms of RA
Digital infarcts along nail bed
Anaemia - normochromic/cytic
Palpable lymph nodes
Bursitis
Tenosynovitis
Warm, red, tender joints
Joint pain worse in mornings/cold
Loss of function
Popliteal cyst
Rheumatoid nodules at pressure points
Sicca
Carpal tunnel syndrome
Fatigue and malaise
Symmetrical
DIPs are usually spared!
Ix RA
FBC/Bloods
Rh factor POS (sensitive)
Anti-CCP POS (specific, not routine)
↑ ESR, ↑ CRP, ↑ Platelets
XR - LESS
Loss of joint space
bone Erosions
Soft tissue swelling
Soft bones (osteopenia)
Genetic testing
State some extra-pulmonary manifestations of RA
Caplan’s syndrome (esp in coal miners)
Felty’s syndrome
Anaemia of chronic disease
Lymphadenopathy
2° Sjogren’s syndrome
Amyloidosis
DDx RA
Psoriatic arthritis
OA
Symmetrical seronegative spondyloarthropathies
Tx RA
MDT treatment!
- NSAIDs (+PPI)
Steroids initially, for flare ups to settle - DMARDs e.g. methotrexate, leflunomide, sulfasalazine hydroxychloroquine (mildest DMARD ∴ preferential if disease isn’t too severe)
a) one of above
b) 2 of above
c) Methotrexate + TNF inhibitor
d) Methotrexate + biologic e.g. Rituximab
Remember :
OA less convincing response to NSAIDs than RA
RA - worse w rest, better w movement. OA is opposite
RA - symmetrical, OA - not
At what age, is the peak bone mass?
29 years
State 1° causes of osteoporosis
Post-menopause
Age
bc oestrogen protects bone!
State 2° causes of osteoporosis
SHATTERED
Steroid use
Hyperthyroidism/hyperparathyroidism
Alcohol/Smoking
Thin (low BMI < 22)
Testosterone low
Early menopause
Renal or liver failure
Erosive / inflammatory bone disease
Dietary calcium low
Key presentation of osteoporosis
Fractures!
Esp if happens when/where it shouldn’t happen
Ix Osteoporosis
DEXA Scan BMD measurement
T score (esp at hip)
(then compared against gender-matched YA average)
> -1 normal
Between -1 and -2.5 = Osteopenia
<-2.5 = Osteoporosis
ALSO : FRAX score - 10 year probability of major fracture
When ↓ seru Ca2+,
Parathyroid gland secretes PTH
∴ ↑ bone resorbtion and Ca2+ released into blood stream
When ↑ serum Ca2+,
Parathyroid gland produces calcitonin,
inhibits PTH secretions,
↑ bone formation and Ca2+ absorbed from bloodstream
What happens to trabecular architecture with age?
↓ Trab Th
↓ Connections between horizontal trabeculae
∴ ↓ Trab strength (∴ ↑ risk of fractures)
Why are horizontal trabeculae so important?
Makes bones a LOT stronger
Eular-Buckling theory
During bone turnover due to oestrogen deficiency, what type of bone is mostly lost?
Cancellous bone
What occurs if there’s too much mineralisation in bones?
Become stiff and shatter
What occurs if there’s too little mineralisation in bones?
Bones aren’t strong and break
What occurs if there’s too little mineralisation in bones?
Bones aren’t strong and break
What do bloods show in osteoporosis?
Ca2+, phosphate, alkaline phosphate are all normal
Tx Osteoporosis
Lifestyle changes - Avoid falls!!
Quit smoking, ↓ alcohol, healthy weight
Adcal D3 (Vit D + Calcium)
-
Oral bisphosphonate (↓ osteoclastic activity)
e.g. alendronate (10mg daily), risendronate (5mg daily) - Denosumab or Strontium ranelate or Teriparatide
ALSO : consider Hormone Replacement Therapy in young post-menopausal women
What does ESR stand for?
Erythrocyte Sedimentation Rate
Define ESR
Measure of how quickly erythrocytes will fall to bottom of tube
What does ESR measure?
Fibrinogen values
Rise w/ inflammation bc erythrocytes stick together and ∴ fall faster
How does ESR rise and fall?
Rises and falls SLOWLY (days to weeks)
What causes ESR to rise falsely? (False positives)
Female
Age
Obesity
SE Asian
Hypercholestrolaemia
High Immunoglobulin (myeloma)
Full form of CRP
C-Reactive Protein
Define CRP
Acute phase protein, released in inflammation
Where is CRP produced?
In liver in response to IL-6
How does CRP rise and fall?
QUICKLY - high at 6 hours, peaks at 48 hours
∴ if patient has infection in 24 hours, ESR won’t have risen but CRP will have
SPINEACHE go
Sausage digit (dactylitis)
Psoriasis
Inflammatory back pain
NSAID good response
Enthesitis (heel)
Arthritis
Crohn’s / Colitis / ↑CRP (but CRP can be normal)
HLA B27
Eye (uveitis)
What joint do Spondyloarthropathies typically affect?
Spinal and sacroiliac joints
Spondyloarthropathies are _____
seronegative (no RhF)
HLA-B27 encoded by
Major histocompatibility complex on chromosome 6
Why does HLA-B27 cause disease?
Causes autoimmune disease by molecular mimicry
Infection occurs and infection agents have peptides v similar to HLA-B27
∴ immune system launches attack on HLA-B27
Epidemiology of Ankylosing Spondylitis
*More common and severe in Males
*Presents in late teens/20s
↓ Incidence in African and Japenese people
Native NA ↑ incidence
Ix Ankylosing Spondylitis
Bloods -
HLA-B27 positive
↑ CRP, ↑ ESR
Normocytic anaemia
XR
MRI
Schober’s test!
Why can you perform an MRI for ankylosing spondylitis?
Bc before bamboo spine, bone marrow oedema occurs first - showed by MRI
What XR signs are there in Ankylosing spondylitis?
Sacroiliitis
Enthesitis
Dagger sign
Syndesmophytes
BAMBOO SPINE
Ankylosing Spondylitis, diagnose if :
Age at onset < 45 years
At least 3 months back pain
XR/MRI shows sacroiliitis + at least 1 SPINEACHE feature
State some other signs/symptoms of Ankylosing Spondylitis
Worse with rest
Slow onset morning stiffness > 30 mins
Fatigue
Buttock/thigh pain - sacroiliac joints
Rashes/skin changes