Makindo Medical Notes.com

Related Subjects: |Monoarticular arthritis |Polyarticular arthritis |Rheumatoid arthritis |Gout |Pseudogout |Septic Arthritis |Osteomyelitis |Systemic Lupus Erythematosus (SLE) |Enteropathic Spondyloarthritis |Reactive Arthritis

Most commonly, infectious arthritis affects a single joint, but occasionally more joints are involved and refer to a bacterial infection in a joint, and can include other causative agents such as fungal and mycobacterial. For those with suspected infected prosthetic joints, this should only be managed by orthopaedic surgeons

About

• Septic arthritis is a medical/orthopaedic emergency
• Delayed diagnosis can lead to significant joint damage at any age
• The diagnosis must be considered whenever painful joint dysfunction is present

Infectious agents

• Staphylococcus aureus including MRSA
• Streptococci, Pseudomonas, Pneumococci
• Neisseria gonorrhoea in sexually active adults
• Haemophilus Influenzae type b has fallen with vaccination
• E. coli and Pseudomonas spp. in IVDU and the elderly
• Candida albicans

Aetiology

• Important risk factor for septic arthritis is abnormal joint architecture
• Infection is introduced haematogenously or by direct inoculation.
• Relatively common in infancy and childhood and must not be missed

Risk factors in adults

• Age greater than 80 years, Skin infection
• Immunosuppression, Diabetes mellitus
• Rheumatoid arthritis
• Sickle cell disease, IVDU
• Prosthetic joint, Recent joint surgery

Clinical

• Symptoms come on over 1-2-week history of erythematous, painful
• Swollen, and hot joint(s) with a decreased range of motion.
• Large joint involvement. The knee is involved in about 50% of cases.
• Also hip, shoulder, ankle, elbow, and wrist.
• Multiple joints are involved in 15% of patients,
• Symptoms less pronounced in the elderly, the immunocompromised, and IVDU.
• Fever, joint pain, swelling, redness, stiffness, and warmth.
• Joint pain held protected in the position where maximal space is allowed (ie, in extension for the knee joint)

Investigations

• FBC, U&E, Raised CRP and WCC and ESR
• If septic arthritis is suspected, arthrocentesis should be performed on presentation. Gram stain, culture, leukocyte count and differential, and crystal analysis should be done. - Grey/white pus, joint WBC count > 50,000 / ml with 80% neutrophils and Positive gram stain.
• X-Ray - exclude a fracture
• CT, MRI, Radionuclide scan, USS (except to show effusion) are entirely unhelpful
• If a haemarthrosis is found, always consider a bleeding disorder - haemophilia

Joint Aspiration and testing

Differential in a child

• Transient synovitis - viral less raised inflammatory markers
• Still's disease
• Rheumatic fever- flitting
• Lyme disease
• Perthes disease

Differential in adult

• Gout - crystals of monosodium urate
• Pseudogout - crystals of calcium pyrophosphate dihydrate
• Rheumatoid arthritis - erythema unusual
• Reactive arthritis

Management (Take microbiology advice)

• For those with prosthetic joint sepsis this should be managed by orthopaedic surgeons
• Rest joint in an appropriate position. Give analgesia. VTE prophylaxis
• Treat for 6 weeks - 1st 2 weeks IV. The first line is Flucloxacillin 2 g 6 hourly iv +/- Fusidic acid 500 mg 8 hourly
• Alternatives: Cephalosporins e.g. Ceftazidime (1-2 g IV 8 hours)
• If Gram-negative is considered then add Ciprofloxacin 500 mg BD
• Other Microbiological causes
  • Gonococcal arthritis: STD or (often asymptomatic). Seen in previously fit young adults. Skin : maculopapular pustules. Can be cultured from the bloodstream and from the joints. Culture is usually positive from the genital tract, even if the joint fluid is sterile. Treatment is with penicillin, ciprofloxacin or doxycycline for 2 weeks, and joint rest.
  • Meningococcal arthritis: may complicate meningococcal septicaemia and presents as a migratory polyarthritis. It results from the deposition of circulating immune complexes containing meningococcal antigens. Treatment is with penicillin.
  • TB arthritis: Hip, knee, bone involvement. The hip, knee and spine (intervertebral disc) are most commonly affected. Progressive pain, swelling and dysfunction. Febrile, night sweats and loses weight.
  • Culture of synovial fluid, synovial biopsy or intervertebral disc biopsy (under CT guidance) is necessary to make the diagnosis. Treatment is as for TB elsewhere but extended to 9 months, together with initial joint rest and immobilization.
• Orthopaedic involvement - needle aspiration, joint washout
• Immobilise acutely and then mobilise early

References

• Septic Arthritis Review