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

Articular vs periarticular?

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

Olecranon bursitis

Septic arthritis

• 15-30 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?

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.

• 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

THANK-YOU