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Acute monoarthropathy. Jaya Ravindran Rheumatologist. Aims. an approach to the investigation and differential diagnosis of acute monoarticular pain focus on septic and crystal arthritis. Acute Monoarthritis - differential diagnosis. Septic arthritis Crystal arthritis Gout (uric acid)
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Acute monoarthropathy Jaya Ravindran Rheumatologist
Aims • an approach to the investigation and differential diagnosis of acute monoarticular pain • focus on septic and crystal arthritis
Acute Monoarthritis - differential diagnosis • Septic arthritis • Crystal arthritis • Gout (uric acid) • Pseudogout/calcium pyrophosphate deposition disease (CPPD)
What are other differentials for acute monoarticular pain?
Monoarthritis - differential diagnosis Psoriatic arthritis • Onycholysis • Subungual hyperkeratosis • Pitting • Extensor surfaces, scalp, natal cleft, umbilicus • Other associated features eg uveitis, inflammatory bowel disease, enthesitis, Ankylosing spondylitis
Monoarthritis - differential diagnosis Reactive arthritis • Prodromal GI /GU Infection eg campylobacter, salmonella, shigella, Yersinia,chlamydia • Pustular psoriasis and circinate balanitis
Monoarthritis - differential diagnosis • Trauma - # and haemarthroses (warfarin, bleeding disorders) • Palindromic rheumatism – 24-48 hours inflammatory monoarthritis, can evolve into polyarthritis eg RA
Others to think about • Osteonecrosis/AVN (steroids/alcohol) • Severe pain but good ROM • Monoarticular RA • Monoarticular OA • Prosthetic joint - loosening, # or infection • Periarticular pathology
Is it an articular or extra-articular problem? • ARTICULAR PERI-ARTICULAR • pain all planes pain in plane of tendon • active = passive active > passive • capsular swelling/effusion linear swelling • joint line tenderness localised tenderness • diffuse erythema/heat localised erythema/heat
Septic arthritis • 15-30 per 100,000 population • Fatal in 11% of cases in UK • Delayed or inadequate treatment leads to irreversible joint damage
common organisms Staphylococci or Streptococcus young adults, significant incidence gonococcal arthritis Elderly & immunocompromised gram -ve organisms Anaerobes more common with penetrating trauma Who gets septic arthritis?
Who gets septic arthritis? • pre-existing joint disease • prosthetic joints • low SE status, IV drug abuse, alcoholism • diabetes, steroids, immunosuppression • previous intra-articular steroid injection
Who gets septic arthritis? • Skin lesions e.g. ulcers, particularly in context RA often source of infection • poor prognostic features: older, pre-existing joint disease & presence of synthetic material within joint
What are the signs and symptoms of septic arthritis?
Symptoms & signs of septic arthritis • Typically hot, swollen, red tender joint with reduced range of movement, difficulty weight bearing • Systemic upset • Night and rest pain • Symptoms usually present for < 2/52 • Large joints more commonly affected than small • majority of joint sepsis in hip or knee
Symptoms & signs of septic arthritis • In pre-existing inflammatory joint disease symptoms in affected joint(s), out of proportion to disease activity in other joints. • 10-15% of cases, > one joint - so polyarticular presentation does not exclude sepsis • presence of fever not reliable indicator- if clinical suspicion high - treat
What investigations are useful in septic arthritis?
Investigations • Synovial fluid aspiration • volume/viscosity/cellularity/appearance • gram stain/culture • Absence of organism does not exclude septic arthritis • polarised light microscopy (crystals) • NB suspected prosthetic joint sepsis should ALWAYS be referred to orthopaedics
Investigations • Always blood cultures • significant proportion blood cultures + ve in absence of + ve synovial fluid cultures • FBC ESR & CRP • BUT absence of raised WBC, ESR or CRP not exclude diagnosis of sepsis - if clinical suspicion high always treat
Other investigations • CRP useful for monitoring response to treatment • Urate may be normal in acute gout and of no diagnostic value in acute gout or sepsis • Measure urea, electrolytes & liver function for end organ damage (poor prognostic feature) • Renal function may influence antibiotic choice
Other tests? • If skin pustule is present, suggestive of gonococcal infection, then skin swab should be taken • If history suggests possibility of genitourinary or respiratory tract infection then culture sputum (and CXR) & urine & take anogenital & throat swabs where appropriate • If periarticular sepsis – appropriate swabs and cultures
Imaging • Plain X rays no benefit in diagnosis but form baseline for any future joint damage. May show chondrocalcinosis. • MRI useful in distinguishing sepsis from OA but less good between sepsis & inflammation • MRI sensitive for osteomyelitis
Imaging • Ultrasound useful in guiding needle aspiration eg hip • White cell scanning helpful in diagnosing prosthetic sepsis
Antibiotic treatment of septic arthritis • Local and national guidelines • Liaise with micro. guided by gram stain • Conventionally given iv for 2 weeks or until signs improve, then orally for around 4 weeks
Joint drainage & surgical options • medical aspiration, surgical aspiration via arthroscopy or open arthrotomy • Suspected hip sepsis – early orthopaedic referral – may need urgent open debridement
Recommendations specific to 1o care & emergency department • commonest hot joint to present in 1o care is 1st MTP gout • usually diagnosed on clinical grounds without needle aspiration or referral to hospital. (Make referral if inadequate recovery) • Some GPs aspirate & inject joints for inflammatory arthritis or osteoarthritis. If withdraw pus/unexpected cloudy fluid should send sample with patient to local emergency department
Recommendations specific to 1o care & emergency department • GPs & doctors in EAU should refer patients with suspected septic arthritis to specialist with expertise to aspirate joint. May be orthopaedic surgeon or rheumatologist • Admit if sepsis is suspected or confirmed.
Summary • with a short history of a hot, swollen, tender joint (or joints) plus restriction of movement; septic arthritis until proven otherwise • If clinical suspicion high investigate & treat as septic arthritis even in absence of fever