14. Arthritis Flashcards
What is Arthritis?
Defined as “inflammation of a joint”, though often “arthritis” describes a disease or group of diseases associated with single or multi joint inflammation.
A 25 year old female presents to A&E with a 2 day history of pain in right knee. She is an intravenous drug user, with no other significant past medical history.
On examination: Red, hot and swollen right knee with a reduced range of movement. The patient is febrile (38.5 ͦ C).
Blood tests have been sent and the patient is stable.
What is the next most appropriate course of action?
A. Request review by orthopaedic surgeon
B. MRI knee
C. X-ray of the knee
D. Start broad-spectrum IV antibiotics
E. Aspirate the joint effusion
E. Aspirate the joint effusion
Important to aspirate the joint before giving antibiotics in septic arthritis if patient stable to improve ability to grow and thus detect causative pathogen.
Ortho r/v should occur prior to aspiration in a patient with a prosthetic joint, as arthrocentesis should not occur outside of sterile environment.
MRI may show associated osteomyelitis, but not appropriate at this stage.
Joint aspirate colours and meaning
Green/yellow pus – white blood cells (predominantly neutrophils and will contain causative bacteria)
Sterile - Reactive Arthritis
Septic arthritis Definition, Aetiology and RF
Definition: Infection of one or more joints caused by pathogenic bacteria.
Aetiology:
Direct bacterial inoculation
Haematogenous spread
- Staphylococcus aureus (60%) - Neisseria gonorrhoea (in young sexually active)
Risk factors:
- Pre-existing joint disease (e.g. RA)
- Immunosuppression (e.g. DM, iatrogenic)
- Prosthetic joints
- IVDU
Symptoms & signs of Septic arthritis
- Acutely inflamed tender, swollen joint
- ↓Range of movement
- Systemically unwell (e.g. fever)
- Knee most commonly affected
History usually <2 weeks duration.
Septic arthritis Investigations
Urgent joint aspiration:
- Gram stain & culture
- White blood cell count
Bloods:
- ESR/CRP, WCC, Blood cultures
Imaging to identify underlying pathology (e.g. osteomyelitis, chondrocalcinosis)
- X-ray, MRI
Ortho to do aspiration in theatre for joint prothesis.
Septic arthritis Mx
IV antibiotics (after aspiration) Analgesia Consider joint washout under GA
A 54 year old man presents to A&E with severe pain in his left foot. The pain started suddenly 45 minutes ago. He denies any trauma, and has only recently been discharged following treatment for pneumonia.
On examination: Red, hot and swollen metatarsophalangeal joint. His basic observations are normal.
Bloods: ↑WCC, ↑CRP, uric acid normal
Joint aspiration: Needle-shaped negatively birefringent crystals
What is the most likely diagnosis?
- Gout
- Pseudogout
- Septic arthritis
- Reactive arthritis
- Osteomyelitis
Gout
“Worst pain I’ve ever had doctor”
Most likely to be gout, given the severity & rapid-onset of the pain, and the joint involvement pattern (MTP). Dehydration often predisposes to gout – in this case the recent pneumonia likely contributed to this.
Gout Definition, Aetiology, RF
Definition: Acute monoarthropathy with severe joint inflammation, secondary to deposition of monosodium urate crystals.
Aetiology:
↑Uric acid (Purine metabolite)
- Under excretion
- Over-production
Gout Risk factors:
Male gender
- High cell turnover state (e.g. tumour lysis syndrome, lymphoma, psoriasis) = high endogenous purine metabolism
- Drugs (e.g. diuretics, aspirin, cytotoxics)
- Alcohol excess
- Purine rich diet (e.g. meat, seafood)
- Renal impairment (decreased excretion)
Gout Symptoms
Symptoms:
- Rapid-onset severe pain – “worst pain ever”
↓Range of movement
- Most commonly affects joints in feet
- First metatarsophalangeal joint (podagra)
Symptoms:
- Acutely – swollen joint
Long term:
- Tophi can deposit over extensor joint surfaces (particularly elbows and knees) and may be evident in helix of ears.
- Uric acid stones can cause renal tract obstruction & interstitial nephritis.
Give examples of radiodense (opaque), intermediate lucency and radiolucent stones
- Radiodense (radiopaque) stones: Calcium Oxalate & Struvite
- Intermediate lucency: Cystine
- Radiolucent stones: Uric Acid
Gout Investigations:
Blood:
- Serum uric acid (can be normal in acute attack, can be falsely low or normal during); NB: can also be normal or low serum acid
Synovial fluid:
- Polarised light microscopy
- Negatively birefringent needle-shaped crystals
X-ray:
- Early – soft tissue swelling and joint effusion
- Late – juxta-articular ‘punched-out’ erosions (also called rat-bite erosions)
Gout Management
- Acute: NSAIDs/colchicine
- Chronic: Conservative & allopurinol
Pseudogout definition, EF and Symptom/Signs
- Definition: Inflammation of a joint, secondary to deposition of calcium pyrophosphate crystals
- Risk factors: Elderly Hyperparathyroidism Hemochromatosis Osteoarthritis
- Symptoms & signs:
Very similar to gout
Commonly wrist or knee
Pseudogout Invx and Mx
Synovial fluid (Polarized light microscopy) - Positively birefringent rhomboid-shaped crystals
X-ray:
- Chondrocalcinosis (e.g. ca deposition in knee cartilage)
Mx: same as gout
DDx Septic Arthritis, Gout and Pseudogout
Septic arthritis
- Bacterial infection
- White cells and bacterial growth
Gout
- Monosodium urate
- NeGative birefringence
Pseudogout
- Calcium pyrophosphate
Positive birefringence
Joint aspiration is essential in the assessment of an acutely inflamed joint.
A 21 year old man presents with a 3 week history of a painful, hot, swollen right knee. He denies trauma or fever. He also complains of pain in his left heel. He was treated for a chlamydia infection 6 weeks ago.
What is the most likely diagnosis?
A. Gout B. Pseudogout C. Septic arthritis D. Reactive arthritis E. Rheumatoid arthritis
D. Reactive arthritis
Reactive arthritis definition, aetiology, RF
Definition:
- A sterile arthritis (one of HLA-B27 associated seronegative spondyloarthropathies), typically affecting the lower limb ~1-4 weeks after urethritis or dysentery.
Aetiology:
- Post-infection joint inflammation
(Chlamydia,Salmonella,Campylobacter,Shigella, Yersinia)
Risk factors:
- Male gender (9:1) for chlamydia-induced reactive arthritis
- HLA-B27 genotype (30-50%)
- Preceding infection
Symptoms of Reactive Arthritis
- Asymmetrical oligoarthritis
(Worse in morning) - Knee most commonly affected
Around 25% of patients have recurrent episodes whilst 10% of patients develop chronic disease
Reactive arthritis Signs
- Enthesitis (e.g. Achilles’ tendonitis)
- Keratoderma blenorrhagica (Brown raised plaques on soles and palms)
- Mouth ulcers
- Conjunctivitis
- Circinate balanitis (Painless and plaque-like lesion on the shaft or glans of the penis)
What syndrome is RA associated with?
Reiter’s syndrome - ‘Can’t see, pee or climb a tree’
- Arthritis
- Urethritis
- Conjunctivitis
A 56 year old woman presents with pain and stiffness of her hands. This pain is particularly bad at the end of the day. She has occasionally dropped things, and thinks her grip has become worse. She is taking regular over the counter analgesia. Heberden’s (Distal interphalangeal joints) and Bouchard’s nodes (proximal interphalangeal joints).
What is the most likely
diagnosis?
Rheumatoid arthritis Osteoarthritis Reactive arthritis Psoriatic arthritis Systemic sclerosis
Osteoarthritis
History of pain and stiffness in hands at the end of the day is classic for OA.
A 67 year old woman presents with pain, swelling and stiffness of her left knee. This pain is particularly bad after walking the dog.
On examination there is swelling of the left knee and a reduced range of movement. She has an antalgic gait.
What is the most likely
diagnosis?
Rheumatoid arthritis Osteoarthritis Reactive arthritis Psoriatic arthritis Systemic sclerosis
Osteoarthritis
Antalgic gait develops as a way to avoid pain while walking (A shortened stance phase in painful limb)
Image is a weight bearing AP plain radiograph of knees. This shows a right-sided total knee replacement and features of osteoarthritis in the left knee.
These can be remembered as LOSS:
Loss of joint space
Osteophytes
Subchondral sclerosis
Subchondral cysts
