Sandbox:septic arthritis pathogenesis
Pathophysiology
Presence of extreme vasularity and absence of limiting of basement membrane, promotes the easy access of infections into the synovial space.[1]
Hematogenous spread: Septic arthritis most commonly develop as a result of hematogenous spreading bacteria into the vascular synovial membrane.[2] Hematogenous spread is commonly associate with injection drug use, presence of indwelling catheters, and an underlying immunocompromised state such as HIV infection.
Direct inoculation: Direct inoculation of microorganisms may occur during deep penetrating injuries, intra-articular steroid injection, arthroscopy or prosthetic joint surgery, particularly in association with knee and hip arthroplasties and contiguous osteomyelitis rupturing into the joint.[3][4]
Bone infection such as osteomyelitis can spread by breaking through its outer cortex and then into the intracapsular region that lead to joint infection. This kind of spread is more common in children as the small capillaries can cross the epiphyseal growth plate and permit extension of infection into the epiphysis and joint space.[5][6]
Pathogenesis of septic arthritis depends on multiple factors and it mainly depends on the balance between virulence of the microbial pathogen and the host immune response against the pathogen.
Non-gonococcal arthritis
Staph. aureus is the most common pathogen non gonococcal pathogen that causes septic arthritis. The pathogenesis of septic arthritis by staphylococcus can be a better representation for pathogenesis of most non gonococcal arthritis.
Bacterial colonization and adherence into the synovium
Mechanism of infection transmission
Hematogenous spread: Septic arthritis most commonly develop as a result of hematogenous spreading bacteria into the vascular synovial membrane.[2] Hematogenous spread is commonly associate with injection drug use, presence of indwelling catheters, and an underlying immunocompromised state such as HIV infection.
Determinants of hematognous seeding:[2]
- Well vascularized synovium
- Absence of limiting basement membrne
- Recent joint surgery, induces the production of host-derived extracellular matrix proteins( e.g. collagen) that aids in post surgical healing process, can assist bacterial attachment and progression to infection
- Virulence of microorganism
- Susceptibility of synovial membrane for microorganism
Direct inoculation: Direct inoculation of microorganisms may occur during deep penetrating injuries, intra-articular steroid injection, arthroscopy or prosthetic joint surgery, particularly in association with knee and hip arthroplasties.[3][4]
Contiguous spread: Bone infection such as osteomyelitis can spread by breaking through its outer cortex and then into the intracapsular region that lead to joint infection.
Role of bacterial products in pathogenesis
| Bacterial colonization and adherence into the synovium 🢃 |
|---|
| Mechanism of transmission |
| Hematogenous spread: Septic arthritis most commonly develop as a result of hematogenous spreading bacteria into the vascular synovial membrane.[2] Hematogenous spread is commonly associate with injection drug use, presence of indwelling catheters, and an underlying immunocompromised state such as HIV infection.
Determinants of hematognous seeding:[2]
Direct inoculation: Direct inoculation of microorganisms may occur during deep penetrating injuries, intra-articular steroid injection, arthroscopy or prosthetic joint surgery, particularly in association with knee and hip arthroplasties.[3][4] Contiguous spread: Bone infection such as osteomyelitis can spread by breaking through its outer cortex and then into the intracapsular region that lead to joint infection. |
| Role of bacterial products in pathogenesis |
| Bacterial attachment proteins promote colonization and initiate the infectious process, a number of bacterial products activate the host immune response and increase tissue damage in cases of septic arthritis. |
- ↑ Goldenberg DL, Reed JI (1985) Bacterial arthritis. N Engl J Med 312 (12):764-71. DOI:10.1056/NEJM198503213121206 PMID: 3883171
- ↑ 2.0 2.1 2.2 2.3 2.4 Klein RS (1988) Joint infection, with consideration of underlying disease and sources of bacteremia in hematogenous infection. Clin Geriatr Med 4 (2):375-94. PMID: 3288326
- ↑ 3.0 3.1 3.2 Atcheson SG, Ward JR (1978) Acute hematogenous osteomyelitis progressing to septic synovitis and eventual pyarthrosis. The vascular pathway. Arthritis Rheum 21 (8):968-71. PMID: 737020
- ↑ 4.0 4.1 4.2 Gray RG, Tenenbaum J, Gottlieb NL (1981) Local corticosteroid injection treatment in rheumatic disorders. Semin Arthritis Rheum 10 (4):231-54. PMID: 6787706
- ↑ Barton LL, Dunkle LM, Habib FH (1987) Septic arthritis in childhood. A 13-year review. Am J Dis Child 141 (8):898-900. PMID: 3498362
- ↑ Buckholz JM (1987) The surgical management of osteomyelitis: with special reference to a surgical classification. J Foot Surg 26 (1 Suppl):S17-24. PMID: 3559051