Monoarthritis Flashcards
Describe the pathologies that may present as monoarthritis.
INFECTION
Gout = crystal arthritis
Trauma/haemoarthrosis (bleeding into joint space)
Osteoarthritis
Other sero-negative arthritis (psoriatic/IBD)
Reactive arthritis
Sarcoid
RA (unlikely)
Questions to ask with regards to monoarthritis?
Pain (SOCRATES + sleep affected) Fever/rigors/systemic upset Previous episodes Trauma Peceding illness - GI/GU Sexual history Family history Psoriasis/IBD/Eye disease/other PMH Other joint pains Medication/alcohol Systems review
Key questions when asking about monoarthritis?
Onset Trauma Previous episodes Systemic upset Associated conditions
What is septic arthritis?
Acute inflammation of joint caused by direct infection
What are the common pathogens associated with septic arthritis?
Bacterial
- Staphylococcus aureus (majority)
- Gonococcus (younger adults)
- Streptococcus
- E.coli /others (salmonella, proteus)
Mycobacterial
Fungal/viral (rarely)
Typical presentation of septic arthritis?
Suddent / subacute onset with:
- Pain = difficulty weight-baring and moving at all
- Swelling
- Erythema
What are pre-disposing factors of Septic Arthritis?
Prosthetic joint
Immunosuppressed/elderly
RA
Existing joint damage
IV drug abuse
Source of infection: haematogenous (majority), direct infection, adjacent bone
What would the outcome be if septic arthritis was left untreated?
Rapid joint destruction
Sinus (cavity within bone)/abcess formation
Septicaemia
Multi-organ failure
What is the likely outcome if treated?
High morbidity (50%)
Mortality up to 50% (10%)
What can septic arthritis look like on radiograph?
Narrowing of joint space
Irregularity of subchondral bone
- subchondral erosions
- osteonecrosis
Investigations and results for septic arthritis?
Sepsis? => Bloods - FBC => raised WCC and neutrophilia - U+E, LFT - CRP usually elevated - Blood cultures - Urate, etc. X-ray Joint fluid aspiration - look at it (NOT prosthetic joints) - normal => cooking oil - infection => cloudy
What tests do we use for joint fluid aspiration?
Gram stain (urgent)
MC+S (multiple chemical sensitivity)
Crystals
TB (AFBs)
Fungal culture
How to treat suspected septic arthritis?
IV antibiotics (2 wks IV, 4 weeks PO) - choice depends on resistance patterns - e.g. Ceftriaxone for Gonococcus - empirical = Flucloxacillin + fusidic acid - eyrthromycin if penicillin allergy - MRSA = teicoplannin instead of flucloxacillin Monitor closely Look for infection source
What is better surgery or drainage?
Similar outcome
Surgery will improve health faster
Repeated washouts / drainage may be needed
What is gout?
A clinical syndrome caused by an inflammatory response to:
- monosodium urate monohydrate crystals
May form in people with hyperuricaemia
Acute and chronic forms are recognised
What is a possible reason for increased monosodium urate monohydrate crystals?
Hyperuricaemia due to:
- increased production of urate
- decreased clearance of urate (90%)
What is uric acid (urate) produced from?
Metabolic product of purines
Theories for uric acid?
1) Adjuvant (enhance body’s own immune system)
2) Antioxidant
3) BP control
4) Intelligence
What is the purine metabolic pathway for uric acid formation?
Adenosine –> Inosine –> Hypoxanthine –> Xanthine –> Urate
Guanine –> Xantine –> Urate
What causes underexcretion of urate?
Can be down to renal impairment
What causes overproduction of urate?
Purine rich diet
Increased synthesis of purines
Which age is gout at its peak?
Male: 40 - 50
Female: >60
Which gender is it most prevalent in?
Males
M:F = 2-7 :1
What is the prevalence of gout?
M: 0.5 - 2.8%
F: 0.1 - 0.6%
What is the annual incidence of gout?
M: 0.1 -0.3%
F: 0.02%
Are there any genetic associations with gout?
Inherited enzyme abnormalities
Inherited urate underexcretion
Are there any environmental associations with gout?
Diet
Drugs
Toxins
What are modifiable risk factors for gout?
Hyperuricaemia High-purine diet Alcohol consumption Obesity Certain medications, e.g. diuretics
Which drugs increase the excretion of urate?
High dose Aspirin
Oral anti coagulants
Adrenal corticosteroids
Which drugs decrease excretion or urate?
Low dose Aspirin Thiazide diuretics Frusemide Ethambutol Pyrizinamide Nicotinic acid
What is the chronic form of gout associated with?
Tophus (crystaline urate deposit) formation
Bone/joint destruction
Which joint is most commonly affected by gout initially?
1st Metatarsophalangeal joint
How long do attacks of acute gout last?
Mild: 1-2 days
Severe: 7-10 days
What investigations are done for Gout?
Joint fluid aspiration (best examined fresh)
- confirm urate crystals presence
- exclude septic arthritis
What biochem/haematology investigations should be done for investigation of gout?
Urate, urea, creatinine, BM, Fasting lipids
LFT
Urinalysis: blood and protein
Acute attack: CRP
How should gout be treated?
Treat acute attacks early and effectively
Correct hyperuricaemiea either by determining a correctable cause or by using drugs
Which drugs can be used to treat Gout?
NSAIDs
- ibuprofen, naproxen
Cochicine
Steroid
- oral
- intra-articular
When should urate lowering drugs be used?
First atack: comorbidities, risk-benefit balance, patients wishes
Start ULT if second attack within a year or renal impairment or urate stones or Tophi or tissue damage
What are the urate lowering drugs used to treat gout?
Xanthine oxidase inhibitors (reduce urate production)
- Allopurinol (interacts with warfarin, azathioprine)
- Febuxostat (not in CV disease)
Urcosuric agents (increase urate excretion)
- Sulphinpyrazone
- Probenecid
- Benzbromarone (risk of liver toxicity)
What do xanthine oxidase inhibitors do?
Reduce uric acid production
What do urcosuric agents do?
Increase uric acid excretion
What are the clinical objectives of urate lowering therapy?
Prevent acute gout attacks
Resolve tophi and prevent further tophi formation
Prevent joint damage
What is pseudogout?
Similar to gout but down to Ca2+ pyrophosphate crystals
What are the clinical features of pseudogout?
Elderly women
Knee/wrists most commonly affected
Attacks can last much longer
No specific treatment
How do you diagnose pseudogout?
Aspiration shows brick shaped crystals
Chances increased in chondrocalcinosis on x-ray
Associated with hyperparathyroidism, osteoarthritis, haemochromatosis, diabetes, acromegaly
How do you treat pseudogout?
Analgesia
Steroid injection
Joint replacement
