MSK: Part 7 Flashcards
How does meningococcal arthritis occur
- Deposition of circulating immune complexes containing meningococcal antigens
How is meningococcal arthritis treated
PENICILLIN
What causes tuberculous arthritis
MYCOBACTERIUM TUBERCULOSIS
What joints are commonly effected in tuberculous arthritis
Hip
Knee
Intervertebral discs
Pathophysiology of tuberculous arthritis
caveating granulomas
Rapid destruction of cartilage and adjacent bone
Clinical presentation of tuberculous arthritis
Fever
Night Sweats
Weight Loss
Pain, swelling and dysfunction
Diagnosis of tuberculous arthritis
- Culture synovial fluid
- Biopsy synovial fluid or intervertebral disc - CT guided
- X-ray may be normal but shows joint-space reduction and bone destruction
4
Treatment for tuberculous arthritis
9 months:
Rest joint and spine immobilised in cute phase
What is osteomyelitis
Bone marrow inflammation localised to one bone
What causes osteomyelitis
Haematogenous spread or due to local infection
What age group is effected by osteomyelitis
Children
How do adults get osteomyelitis
Secondary infection or direct trauma
Main causes of osteomyelitis
- Staph Aureus
- Coagulase negative staphylococci
- Haemophilus influenza
- Salmonella (SSA)
- Pseudomonas aeriguinosa and seratia marcesans in IVDU
Risk factors for osteomyelitis
- Diabetes mellitus
- Peripheral vascular disease
- Malnutrition
- Inflammatory arthritis
- Debilitating disease
- Decreased immunity
- Sickle cell disease
- Immunosuprresive drugs
- Trauma
Two ways bacteria can get into th bone
- Direct inoculation of infection into the bone via trauma
- Contigous spread of infection into the bone (not as easy):
Without breaking skin
Infection of adjacent soft tissue spreading into bone
Haematogenous seeding (hard to do)
What age group usually has osteomyelitis caused by spread of infection into th bone
Elderly: Diabetes mellitus Chronic ulcers Vascular disease Joint replacement Prostheses
What is haematogenous seeding
Infection from skin spreading to the blood then to the bone (Staphylococcus aureus from cannula on skin to blood then into bone)
EXAMPLE
What bones are usually effected in children in haematogenous seeding
Long bones - metaphysics (wide portion of a long bone between the epiphysis and the narrow diaphysis - contains growth plate) of the long bone
Why is the metaphysis most commonly effected in haematogenous seeding
- Here blood flow is slower, endothelial basement membrane is absent and the capillaries lack or have inactive phagocytic lining cells - all these factors predispose to bacteria migrating from blood into bone and the growth of bacteria in the bone
Where is haemotgenous seeding in adults
Vertebra
Why is the vertebra target for haematogenous seeding
With age, vertebra becomes more vascular thereby making bacterial seeding of the vertebral endplate more likely
What condition can cause risk for haematogenous seeding
- IVDU (in younger - clavicle and pelvis)
- Dialysis
- Sickle cell disease
- Urethral catheterisation and UTI
- Endocarditis
What bone does sickle cell disease cause bacteraemia in
Vascular necrosis of the hip
Acute changes to cells in osteomyelitis
- Inflammatory cells
- Oedema
- Vascular congestion
- Small vessel thrombosis