Rheumatology Flashcards
Which of the following is now a rare cause for joint infection in infants, due to the standard childhood immunisation schedule in the UK?
a. Staph aureus
b. Gp A (ß haemolytic) Strep
c. Varicella Zoster
d. Rubella
e. Haemophilus Influenzae
Haemophilus influenzae
HiB used to be commonest cause of septic arthritis in infants <2 (and 3rd cause in children >2) – but now rare
Staph a/ Strep are now leading 2 causes.
Varicella and rubella are immunised against, but don’t cause septic (pyogenic) arrhtirits (might get transient non-specific viral reactive arthritis)
Which of the following is the most frequent infecting organism after hip replacement?
a. Methicillin resistant Staph Aureus
b. Coagulase negative staph
c. Salmonella
d. Enterococcus faecalis
e. Propionibacterium acne
b. Coagulase negative staphylococcus
Describe the pathophysiology of osteoporosis
Changes in trabecular architecture with ageing
↓ in trabecular thickness, more pronounced for non load-bearing horizontal trabeculae
↓ in connections between horizontal trabeculae
↓ in trabecular strength and increased susceptibility to fracture
3 major characteristics seen in RA
Symmetrical arthopathy
Hands & feet > 80% cases
Early morning stiffness
What does SPINEACHE stand for
Sausage digit (dactylitis)
Psoriasis
Inflammatory back pain
NSAID good response
Enthesitis (heel)
Arthritis
Crohn’s/colitis
HLA B27
Eye (uveitis)
Pathogenesis of systemic sclerosis
Vasculopathy
Excessive collagen deposition
Inflammation
Auto-antibody production
How do you diagnose septic arthritis
Aspiration
- Turgid fluid
- Thick, discoloured fluid is suggestive of infection
Blood cultures
Radiological features of osteoarthritis
JOSSA:
Joint space narrowing
Osteophyte formation
Subchondral sclerosis
Subchondral cysts
Abnormalities of bone contour
Aetiology of osteoarthritis
The exact aetiology is unknown.
Age, hereditary predisposition, female sex, and obesity are associated with increased risk of OA.
Articular congenital deformities or trauma to the joint also increase the risk of developing OA.
Pathophysiology of osteoarthritis
In the affected joint, there is a failure in maintaining the homeostatic balance of the cartilage matrix synthesis and degradation, resulting from reduced formation or increased catabolism.
Give 3 differential diagnoses to osteoarthritis & how you can differentiate them from OA.
Bursitits
- Greater trochanteric bursitis in the hip and pes anserine bursitis in the knee present with pain over the lateral aspect of the hip and over the medial aspect of the knee, respectively. There is local tenderness in these areas that is usually absent in simple OA.
Gout
- The onset of arthritis in gout is usually more acute (over a period of a few hours),
RA
- RA usually causes a symmetrical small joint polyarthritis
- Typically, RA is associated with more prolonged morning stiffness than OA.
How are patients with osteoarthritis managed?
Patients are examined for declining range of motion in the affected joint, and for other signs reflecting advanced disease.
If the patient is taking an NSAID or a COX-2 inhibitor, tests for renal function and full blood count are obtained every 3 to 6 months.
Complications of osteoarthritis
Functional decline and inability to perform activities of daily living
NSAID-related GI bleeding
Risk factors for rheumatoid arthritis
Age
F>M
Family history
Smoking
Obesity
3 differential diagnoses to rheumatoid arthritis & how you can differentiate between them
Psoriatic arthritis (PsA)
Psoriasis is present in >90% of PsA patients, but is unusual in RA patients.
Gout
A small percentage of gout patients present with polyarticular gout, which can mimic RA. Tophi and high levels of uric acid are specific for gout, but are very rare in RA.
SLE
Systemic lupus erythematosus (SLE) can present with polyarthritis in the small joints of the hands and feet.
SLE arthritis is usually non-deforming.
How is a patient being treated for RA monitored
After starting DMARDs:
Laboratory monitoring for FBC and LFT abnormalities is done every 4 to 8 weeks at the start of treatment. When the patient is on a stable dose, they should be checked every 3 to 4 months.
Complications of RA
Work disability
Increased joint replacement surgery
Define gout
Gout is a syndrome characterised by: hyperuricaemia and deposition of urate crystals causing
- attacks of acute inflammatory arthritis
- tophi around the joints and possible joint destruction
- renal glomerular, tubular, and interstitial disease
- uric acid urolithiasis.
Aetiology of gout
There is a causal relationship between hyperuricaemia (high urate level) and gout.
(Urate is a metabolite of purines and the ionised form of uric acid (a weak acid at a physiological pH); hence, uric acid exists mostly as urate.)
Pathophysiology of gout
Humans and some other higher primates develop gout spontaneously.
Humans no longer express the gene for the enzyme uricase, which, in animals, degrades uric acid to a more soluble compound.
This, coupled with a high rate of renal re-absorption of urate, results in hyperuricaemia and gout
1st investigation to order if you suspect gout
Arthrocentesis with synovial fluid analysis
Provides definitive diagnosis
Differentials of gout & how you can rule them out
_Pseudogout (_calcium pyrophosphate deposition disease)
- Presentation may be identical to that of gout.
- Pseudogout is more likely to affect wrist and knee joints.
Trauma
- A positive history will be present
Septic arthritis
- Identical presentation
- RF for infection, eg IVDU, immunocompromised.
- Get blood cultures
Monitoring of gout patients
Patients should be monitored for adverse effects of NSAIDs and colchicine, especially if they are used for prolonged periods.
For NSAIDs, colchicine, and allopurinol, FBC, RFTs & LFTs should be obtained every 3 to 6 months.
Define calcium pyrophosphate arthritis
Acute CPP crystal arthritis is an acute inflammatory arthritis of one or more joints.
The chronic form of CPP arthritis mimics osteoarthritis or rheumatoid arthritis and is associated with variable degrees of inflammation
Risk factors for AS
HLA-B27
ERAP1 & IL23R gene
Positive family history
Male sex
Key diagnostic factors of calcium pyrophosphate arthritis
- Presence of risk factors
- Painful & tender joints
- OA-like involvement of joints (wrists, shoulders)
- Sudden worsening of osteoarthritis
Risk factors for pyrophosphate arthritis
- Advanced age
- Injury
- Hyperparathryoidism
- Haemochromatosis
Key diagnostic factor of osteoporosis
Presence of risk factors
- Female
- Prior fragility fracture
- White ancestry
- Older age >50 W, >65 M
Give 3 differentials for osteoporosis & how you can differentiate between them.
Multiple myeloma
- Bone pain & symptoms of anaemia & renal failure
- Serum electrophoresis reveals monoclonal gammopathy - in multiple myeloma
Osteomalacia
- PTH levels elevated; bone biopsy standard for confirmation of poor mineralisation.
CKD- bone and mineral disorder
- Serum creatinine & PTH will be elevated
Difference between osteomalacia & osteoporosis?
Osteomalacia - bones not hardening
Osteoporosis - bone thinning