Bone and Soft Tissue Infections Flashcards
(29 cards)
Acute Osteomyelitis:
What is it?
Epidemiology?
Acute inflammation of the bones
Usually occurs to young children (boys)
Acute Osteomyelitis:
Risk Factors (7)
1) Diabetes
Poor blood circulation can lead to formation of ulcers that can allow bacteria to enter + higher risk of infection due to high glucose content in blood
2) Immunocompromise
Lower immunity = higher risk of bacterial infection
3) Long-term steroid treatment
Steroid leads to immunocompromise
4) Trauma
Creation of entry points for bacteria
5) UTI
Infection can spread to the bones
6) Sickle Cell Anaemia
Occlusion of gut with sickle-cells can lead to gut ischaemia, creating an entry point for salmonella to enter the blood, causing septicaemia that can cause bone infection
7) Rheumatoid Arthritis
RA, during flare ups, can trigger the formation of a pannus that can erode the cartilage and bone + spread the inflammation
Acute Osteomyelitis:
Source of infection?
Haematogenous (Blood)
1) Remote seeding - Bacteria from another point of the body, travelling to the bone via blood vessels (e.g. UTI infections)
Contiguous (Local Spread)
1) Trauma - Bacteria can enter through entry points in broken bone
2) Cellulitis - Infection can spread from the overlying soft tissue (dermis and subcutaneous fat)
3) Ulcers - Openings to the skin can form from vascular insufficiency, leading to exposure of bone to bacteria
Acute Osteomyelitis:
Bacteria Infecting….
A. Infants (3)
B. Children (3)
C. Adults (7)
A. Infants
1) Staph A
2) Group B Streptococci
3) E. Coli
B. Children
1) Staph A
2) Group A Streptococci
3) Haemophilus Influenzae
C. Adults
1) Staph A
2) Coagulase -ve Staph - e.g. Staph Epidermidis, Staph saprophyticus (UTI infection)
3) Proprionibacterium spp. - Axillae commensal
4) Pseudomonas - From rusty nails
5) Salmonella (in sickle cell disease)
6) Fungal infections (e.g. Candida) in immunocompromised
7) Mycobacterium Tuberculosis
Acute Osteomyelitis
Entry points?
Infants
Children
Adults
Infants - Infected umbilicus
Children - Boils (furuncles), tonsilitis, skin abrasion
Adults - IV lines, UTI, contaminated needles
Acute Osteomyelitis
Where do this infection usually occur in children/infants and adults?
Why?
In infants and children:
Extra-articular long bones metaphysis (e.g. Distal femur, proximal tibial, proximal humerus)
Intra-articular long bones metaphysis (e.g. Proximal femur, radial head of elbow)
In adults:
Vertebrae (thoracolumbar spine)
Why?
Large vascular supply
Microfractures
Acute Osteomyelitis:
Pathogenesis Process
Bacteria infect metaphysis of bone and proliferate
Neutrophils, macrophages and lymphocytes enter
Enzymes WBC use to kill bacteria lyses bone -> formation of pus
If infection not contained, pus continues to form and spread out throughout the bone -> cuts off blood supply to it
No blood supply = area of necrotic bone due to infarction (sequestrum)
- This also makes it difficult to treat the infection as antibiotics and blood antibodies cannot penetrate into the bacteria seeding (need to treat with surgery)
- Upon forming the sequestrum, it is chronic osteomyelitis
- To reach this point, it must be due to diagnosis delays or inadequate antibiotics to contain the bacteria
Surviving osteoblasts create a “sleeve” of weak bone surround the pus (involucrum)
- Eventually the pus can burst through the periosteum and damage local tissue around
Acute Osteomyelitis:
Presentation in Infants
Infants
1) Decreased ROM
2) Tenderness and swelling
- Around metaphysis (between diaphysis (most of shaft) and epiphysis (the part beyond the epiphyseal growth plate, which is growing)
3) Not growing properly (failure to thrive)
***Signs of suppurative septic arthritis
- Sepsis and infection signs
Acute Osteomyelitis:
Presentation in Children
1) Reluctance to weight bear
- Pain upon weightbearing (standing or crawling)
2) Swinging pyrexia
- Due to pus formation
3) Severe pain
4) General malaise
Acute Osteomyelitis:
Presentation in Adults
Primary acute OM usually affects the thoracolumbar spine (vertebrae)
1) Back pain - Pus formation can cause collapse and impingement of nerves
2) History of UTI/urological procedure (S.saprophyticus)
** Secondary acute OM more common (Open fractures, post-surgery)
Acute Osteomyelitis:
History and Examination
History in Children and Infants:
HPC:
- Reduced ROM
- Pain on weight bearing
- Metaphyseal swelling and tenderness
- Swinging fever
- Malaise (unwellness)
PMH:
- Infected umbilicus
- Sickle cell anaemia
Adults:
HPC:
- Back pains, fever
PMH:
- UTI/Urological procedure
- Trauma/surgery/skin infection
- IV lines/
- Prolonged steroid use
- Immunocompromise
Examination:
Infants/children:
- Swollen tender joints (erythema and warmth)
- Painful immobile limb (exacerbated by movement)
Adults:
- ???
Acute Osteomyelitis:
Investigations
Imaging:
1) X-ray
- Pus can be seen on X-ray, and areas of weakness and destruction
- Limited use in seeing soft tissue infections
XRAYS MAY SEEM NORMAL IN THE FIRST 10-14 days
2) Ultrasound
- Similar to X-ray, locating areas of weakness or damage to bone
3) Aspiration
- Aspiration of the swelling to culture for example or to find pus
4) Isotope bone scan
- Isotope taken up by areas of infection
5) MRI (acute)
- To check for soft tissue injury and swellings (e.g. Vertebral pus/collapse)
Tests:
1) FBC + WBC count
- Elevated neutrophils indicate bacterial infection
2) Culture
- To confirm the organism so can use targeted antibiotics
- Taken 3 times for haematogenous osteomyelitis and septic arthritis
3) Biopsy
- Drill biopsy
Acute Osteomyelitis:
Management (non-surgical and surgical)
Non-Surgical:
Supportive (Analgesia and rehydration) - To cope with pain so that they can continue to weight bear
Splinting and Rest - To prevent movement of the joint as it heals (prevents pathological fracture)
IV Antibiotics - flucloxacillin and benzylpenicillin (or clindamycin if allergic to penicillin)
Surgical:
Pus drainage and aspiration- To prevent it from getting worse and eroding bone and articular cartilage - Can be sent for culture to see which organism for targetted antibiotics
Debridement - Might need to remove the dead bone or tissue affected by the spread of inflammation
Joint replacement (?)
Acute Osteomyelitis:
Complications
Chronic Osteomyelitis
Pathological Fracture
Spread of infection - To surrounding soft tissue, joints, and blood
- Cellulitis
- Septic arthritis
- Septicaemia
Altered bone growth
Chronic Osteomyelitis:
What is it?
Chronic inflammation of the bone
Followed from acute osteomyelitis when the body is unable to clear the infection, or can be de novo (new)
Chronic Osteomyelitis:
Risk Factors for contributing to chronic infection?
Diabetes
Elderly
Immunocompromised
Post-op
Open fractures
Chronic Osteomyelitis:
Bacteria
Staph A
E.Coli
(Strep) Pyogenes
Proteus spp,
Chronic Osteomyelitis:
Management
Long-term antibiotics
- Gentamicin (Local; incorporated in cement/beads, Systemic; oral/IV)
Surgery
- Eradication of infection by cleaning out bone
Treat soft tissue problems
- e.g. Cellulitis or other inflammation
Amputation? Recon? Deformity correction???
Chronic Osteomyelitis:
Complications
Pathological Fracture
Ongoing chronic abscesses + pus discharge - Causes local inflammation
Growth disturbance
Squamous cell carcinoma
Acute Septic Arthritis:
Route of Infection
1) Haematogenous
2) Bone Abscess - Eruption of abscess in bone from acute/chronic osteomyelitis
3) Direct spread - Due to invasive procedures such as injections, penetrating wound, arthroscopy etc.
Acute Septic Arthritis:
What is it?
Acute Synovitis
- Joint effusion w pus (purulent)
- Destruction of articular cartilage (arthritis)
- Swollen, warm, and tender
Can either…
- Pus clears and the inflammation settles
- Partial damage to articular cartilage
- Full loss of articular cartilage + ankylosis (fusion of the bones due to fibrosis and inflammation
Acute Septic Arthritis:
Presentation?
Infant
- Resistant to movement due to pain
- Irritability (due to pain)
- Malaise
Child
- Resistant to movement due to pain
- Fever (pyrexia), and high HR
- Increased joint tenderness
Adult
- Joint pain and resistant to movement and weight bearing
- Most common cause is from joint replacements (Staph infection)
Acute Septic Arthritis:
Investigations
Aspiration
- To check for pus and also check the effusion (culture to find bacteria)
Ultrasound
- Check joint to find any reason for inflammation
Bloods
- Inflammatory markers and neutrophils
Culture
- Culture bacteria for targetted antibiotics
Acute Septic Arthritis:
Management
Supportive - e.g. Analgesia
Antibiotics - 3-4weeks
Surgical drainage and lavage (washing out of joint) - Drain pus from joint and preventing it from further eroding the articular cartilage
