Infectious Arthritis

• Micro-organisms can lodge in joints due to;
  • Haematogenous dissemination
  • Direct inoculation from a soft tissue abscess of focus of osteomyelitis
• Is potentially very serious as it can rapid joint destruction and permanent deformity

 

Suppurative Arthritis

 

• Bacteria usually seed the joint during an episode of bacteraemia
• The most common organisms are;
  • Gonococcus (prevalent during late adolescence and early adulthood)
  • Staphlococcus (main causative agent in older children and adults)
  • Streptococus
  • Haemophilus influenzae (predominately in children under the age of 2)
  • And gram negative bacteria;
  • E.coli
  • Salmonella (prone in individuals with Sickle cell disease)
  • Pseudomonas
• Predisposing conditions include;
  • Immune deficiencies – congenital and acquired
  • Debilitating illness
  • Joint trauma
  • Chronic arthritis of any cause
  • Intravenous drug abuse

 

• Classic presentation is a hot, swollen, painful joint with restricted range of movement
• Systemic findings of fever, leukocytosis and elevated ESR are common
• In 90% are non-gonococcal cases the infection involves a single joint
• Usually the knee of, followed by frequency, the hip, shoulder, elbow, wrist and sternoclavicular joint
• Axial articulations are more common in drug addicts

 

 

Tuberculosis arthritis

 

• Chronic progressive monoarticular disease
• Develops as a complication of adjoining osteomyelitis or after haematogenous dissemination from a visceral (usually pulmonary) site of infection
• Onset is insidious and causes gradual progressive pain
• Systemic symptoms may or may not be present
• Mycobacterial seeding may result in granuloma formation and caseous necrosis
• The affected synovium may grow as a pannus over the articular cartilage and erode into bone along the joint margins
• Chronic disease results in fibrous ankylosis and obliteration of the joint space
• Weight bearing joints are generally affected especially hips, knees and ankles

 

Lyme Arthritis

 

• Initial infection of the skin is followed within days and weeks by dissemination of the organism to other sites including the joints
• Arthritis is the dominant feature of late disease and it relapsing and migratory involving large joints particularly the knees, shoulders, elbows and ankles
• Infected synovium takes the form of a chronic papillary synovitis with synoviocyte hyperplasia, fibrin deposition, mononuclear cell infiltrate (especially CD4 T cells) and onion skin thickening of the arterial walls
• Arthritis may be caused by immune responses against borrelia antigens (such as OspA) which cross react with joint proteins

 

Viral Arthritis

 

• Can occur in the setting of a variety of viral infections;
  • Parvovirus B19
  • Rubella
  • Hep C
• Clinical manifestations are variable and range from acute to sub-acute
• Unclear whether symptoms are due to direct infection of the joint or a cross reactivity generating an autoimmune reaction