bone and joint infection

Question 1

What is osteomyelitis

Answer 1

Bone infection

Question 2

What is septic arthritis

Answer 2

joint infection

Question 3

Who is most at risk of acute osteomyelitis

Answer 3

Children
Males
History of trauma
Adults with other diseases such as diabetes which cause immunosuppression
People who have had sickle cell disease

Question 4

How does the infection begin in acute osteomyelitis

Answer 4

Most commonly the infection is somewhere in the body and haematogenously spreads to the bone

There can be local spread from a continuous site of infection e.g open fracture

People with poor vasculation are prone to infections of the bone

Question 5

In infants what is the source of infection for osteomyelitis

Answer 5

Infected umbilical cord

Question 6

In children what is the most common sources of infection in osteomyelitis

Answer 6

Boils
Tonsilitis
Skin abrasions
Chicken pox

Question 7

In adults what is the most common source of infection for osteomyelitis

Answer 7

UTI, arterial line, chest infection, gall bladder infection

Question 8

What is the most common organism which causes the osteomyelitis

Answer 8

Staphylococcus aureus

Question 9

What are the common organisms which cause osteomyelitis in infants

Answer 9

Staph aureus
Group B strep
E.coli

Question 10

What are the common organisms which cause osteomyelitis older children

Answer 10

Staph aureus
Strep pyogenes
Haemophilus influenza

Question 11

What are the common organisms which cause osteomyelitis in adults

Answer 11

Staph aureus
coagulase negative staphylococci

Question 12

What bones is acute osteomyelitis most common in and why

Answer 12

Long bones, specifically the metaphysis e.g distal femur, proximal tibia and proximal humerus
This is because they have a larger blood supply since they are larger

Question 13

Describe how osteomyelitis occurs - infection moving through blood to bone

Answer 13

The infection clumps and then travels in the circulation - it gets stuck like an arterial thrombus - causes the build up of back pressure - lymphocytes are sent there but this causes pus which causes more pressure - the pressure needs released so infection enters the bone

Question 14

What causes pain in bone when there is increase in pressure

Answer 14

Pressure receptors in the bone

Question 15

What are the 3 sites where infection can infiltrate the bone

Answer 15

medulla, sub-periosteal or into joint resolution

Question 16

What is a sequestrum

Answer 16

isolated piece of bone which has undergone necrosis due to no blood supply

Question 17

What is involucrum

Answer 17

Formation of new bone

Question 18

What are the clinical features of acute osteomyelitis in infants

Answer 18

May be minimal or very ill
Drowsy or irritable and not feeding
Pseudoparalysis - not moving a limb
Tendon at the bone with swelling
reduction of movement
Commonest at the knee

Question 19

What are the clinical features of acute osteomyelitis in children

Answer 19

Severe pain
Reluctant to move
Pyrexia and tachycardia
Malaise
Toxaemia

Question 20

What are the clinical features of acute osteomyelitis in adults

Answer 20

Backache - unremitting and at rest
History of UTI or urological procedure
Usually immunocompromised

Question 21

What is the most common osteomyelitis location in adults

Answer 21

Thoracolumbar spine

Question 22

How is osteomyelitis diagnosed (what are the investigations done)

Answer 22

History and clinical examination
FBC +WBC
ESR +CRP - inflammation markers
Blood cultures
U&Es
X-ray
US
bone biopsy
MRI

Question 23

What is the differential diagnosis of osteomyelitis (other diagnosis options)

Answer 23

Soft tissue infection - cellulitis
Acute septic arthritis
Trauma
acute inflammatory arthritis
transient synovitis

Question 24

What is the treatment of acute osteomyelitis

Answer 24

Antibiotics are the main treatment - IV because the bone isolates the infected blood supply
Analgesia and fluids for pain and dehydration (supportive treatment)
Surgery - not common

Question 25

What is the indication for surgery in acute osteomyelitis

Answer 25

Aspiration of pus and abscess draining from bone via drilling into bone if pyrexia is prolonged after antibiotic treatment

Question 26

What are the complications of acute osteomyelitis

Answer 26

Metastatic infection - infection spreads to different areas of the body Pathological fracture Septic arthritis Septicemia Altered bone growth through damaged epiphyseal growth plate Chronic osteomyelitis

Question 27

What organisms cause chronic osteomyelitis

Answer 27

Usually mixed but mainly staph aureus Other common are E.coli, strep pyogenes and proteus

Question 28

What is the treatment of chronic osteomyelitis

Answer 28

Local antibiotics - gentamicin cement Systemic antibiotics - orally/IV To try to cure - surgical eradication of the dead bone which is infected

Question 29

What are the complications of osteomyelitis

Answer 29

Chronically discharging sinus Metastatic infection pathological fracture growth disturbance and deformities Squamos cell carcinoma

Question 30

What is the route of infection of septic arthritis

Answer 30

Haematogenous eruption of bone abscess Direct invasion - penetrating wound

Question 31

What are the common organisms that cause septic arthritis

Answer 31

Mainly Staph aureus Haemophilus influenzae Strep pyogenes E.coli

Question 32

What happens in acute septic arthritis

Answer 32

Acute synovitis and purulent joint effusion Articular cartilage attacked by bacterial toxin and cellular enzymes Complete destruction of articular cartilage

Question 33

How does septic arthritis present in neonates

Answer 33

Irritabile Resistance to joint movement

Question 34

How does septic arthritis present in children and adults

Answer 34

Severe acute pain in a single large joint Reluctancy to move the joint swelling erythema in the later stage pyrexia and tachycardia tenderness

Question 35

What is the differential diagnosis for septic arthritis

Answer 35

Acute osteomyelitis trauma irritable joint hameophilia rheumatic fever gout Gaucher's disease

Question 36

What is one of the most common causes of acute septic arthritis in adults

Answer 36

Infected joint replacement

Question 37

What is the treatment for acute septic arthritis

Answer 37

Antibiotics for 3-4 weeks supportive measure - analgesia and fluids Surgical drainage to let pus out the joint

Question 38

Why is TB a great mimic

Answer 38

Presents in different forms and can present in the joint and as osteomyelitis

Question 39

What are the clinical features of TB

Answer 39

insidious onset & general ill health contact with TB pain (esp. at night), swelling, loss of weight low grade pyrexia joint swelling decrease ROM ankylosis Progressive deformity

Question 40

What is ankylosis

Answer 40

stiffness of the joint

Question 41

describe how TB spreads in the body

Answer 41

Starts in the gut or the lungs usually - then spreads elsewhere and commonly lodges into the vertebral joint and infects it

Question 42

What are the signs seen in TB for diagnosis

Answer 42

Long history Single joint involvement Thickened synovium Marked muscle wasting Periarticular osteoporosis

Question 43

What is periarticular osteoporosis

Answer 43

Low bone mass around a joint

Question 44

What are the investigations done for TB

Answer 44

FBC,ESR - elevated Mantoux test - tuberculin is put in the skin and causes red colour around it Sputum/urine culture Increased white cell count X-ray Joint aspiration and biopsy

Question 45

What is the treatment of TB

Answer 45

Mainly antibiotics Initially - rifampicin, isoniazid, ethambutol and then rifampicin and isoniazid for 8 weeks Then prolonged treatment of rifampicin and isoniazid for 6-12 months