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 – 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

Articular vs periarticular?

Is it an articular or extra-articular problem? ARTICULARPERI-ARTICULAR pain all planespain in plane of tendon active = passiveactive > passive capsular swelling/effusion linear swelling joint line tenderness localised tenderness diffuse erythema/heatlocalised erythema/heat

Olecranon bursitis

Septic arthritis per 100,000 population Fatal in 11% of cases in UK Delayed or inadequate treatment leads to irreversible joint damage

How do you get septic arthritis?

Pathogenesis

Who gets septic arthritis?

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? 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 % 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 1 o care & emergency department commonest hot joint to present in 1 o care is 1 st 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 1 o 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

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