Introduction
Septic arthritis is infection of one or more joints by microorganisms. Any joint may be involved but usually large joint such as knee or ankle.
It is mostly due to bacteria, but can also be due to fungal, viral, or protozoan agent, rickettsia.
Staphylococcus aureus is the commonest organism.
Other organisms are
- Klebsiella pneumonia (in the alcoholics)
- pseudomonas aeruginosa (among intravenous drug abusers)
- Gram negative bacteria (malignancy use of immunosuppressive drugs);
- salmonellae
- Neisseria meningitides;
- streptococcus pneumonia (SLE)
Joint infection is mostly as a result of haematogenous seeding during a bacteriaenic episode.
Joint Infection may also occur secondary to penetrating cutaneous trauma.
Rarely iatrogenic from local corticosteroid joint injection
Risk Factors
- Extremes of life – very young and persons above 80yrs
- Immunosuppressive/ cytotoxic agents
- Immunosuppression – HIV, chronic renal, failure, hypogammaglobulinaemia
- Diabetes mellitus
- Previous intra-articular steroid
- Osteoarthritis.
- Alcoholism
- Haemoglobinopathies
- Cutaneous ulcers.
- Prosthetic joint
Clinical Features
Septic arthritis is usually monoarticular.
Its clinical features include
- Acutely swollen joint
- Joint hot to touch, extremely painful
- Tenderness on palpation
- High fever
- Rigors, diaphoresis
Differential Diagnosis
- Gout
- Pseudogout
- Reactive arthritis
- Haemarthrosis – possibly from aspirin
- Osteoarthritis
- Intra articular injury
- Osteonecrosis
- Metastic carcinoma
Complications:
- Septicaemia
- Joint ankylosis
- Degenerative joint disease
- Osteomyelitis
- Soft tissue injury
- Irreversible joint destruction
Investigations
- Haematocrit, white blood cell count and differentials
- Joint aspirate microscopy, culture and sensitivity
- Blood culture
- ESR, CRP
- X-ray of affected joints
- CT, MRI
Treatment
Antibiotic treatment
This should depend on bacteria isolated
- Cloxacillin or Flucloxacillin
- Vancomycin for MRSA resistant
staphylococcus - Ceftriaxone- 1-2gm once daily (IM or IV) for suspected gonococcus or meningococcus
- Intravenous therapy for 10-14 days and then a switch to oral antibiotics for up to 6 weeks
NSAIDs
Surgical measure
- Daily needle aspiration
- Open drainage
- Arthroscopic debridement with lavage
Prevention
- Effective treatment of the primary infective agents and other predisposing disease state e.g. sickle cell disease, complicated fracture
- Attention to asepsis in joint manipulation procedures and during intra-articular diagnostic/therapeutic intervention.