Septic arthritis is defined as the infection of 1 or more joints caused by pathogenic inoculation of microbes. It occurs either by direct inoculation or via haematogenous spread.

It is an emergancy condition as the joint can be destroyed by the infection

Pathophysiology

• most common organism overall is Staphylococcus aureus
  • in young adults who are sexually active, Neisseria gonorrhoeae is the most common organism (disseminated gonococcal infection)
• the most common cause is hematogenous spread
  • this may be from distant bacterial infections e.g. abscesses
• in adults, the most common location is the knee

Risk factors:

• Underlying joint disease - OA/RA
• Joint prosthesis
• IV drug user
• Alcohol abuse
• Diabetes
• Previous intra-articular corticosteroid injection
• Cutaneous ulcers

PC

• acute, swollen, painful joint
  • restricted movement in 80% of patients
  • examination findings: warm to touch/fluctuant
• fever: present in the majority of patients