Bone & Joint Infections

Question 1

Define Osteomyelitis

Answer 1

Infection of bones

Question 2

Define Septic arthritis

Answer 2

Infection of joints

Question 3

What is the biggest causes of bone infections?

What are the other causes of bone infections?

(Bacterial)

Answer 3

Staphylococcus aureus

Steptococci (Beta-haemolytic & Strep. Pneumonaie)

Enteric Bacteria (E.Coli, Salmonella species)

Coagulase Negative Staphlococci (Staph. Epidermidis)

Myobacterium Tuberculosis

Question 4

What is sequestrum?

Answer 4

Infected bone becomes necrotic

Question 5

Infected bone becomes necrotic- what is this called?

Answer 5

Sequestrum

Question 6

What is biofilm? Where do they occur?

Answer 6

Bacteria in an organic matrix on an inert surface. Can form on prosthetic joints

Question 7

What is involucrum?

Answer 7

New bone formation outside sequestrum

Question 8

What is Cloacae?

Answer 8

Pus from sequestrum escapes through involucrum via holes

Question 9

What is discharging sinuses?

Answer 9

Infection & pus from cloacae causes skin necrosis

Question 10

What are the risk factors for a bone & joint infection?

Answer 10

Direct innoculation (Trauma, Medical procedure, Skin Ulcer)

Contigous Spread (eg: nearby SSTI)

Haematogenous Dissemination (IV drug abuse or IV device)

Immunosuppresion (DM, Renal failure, Sickle cell disease)

Question 11

What are the Microbial Pathology Factors?

Answer 11

Access

Adherance

Invasion

Multiplication

Evasion

Resistance

Damage

Transmission

Question 12

What is the pathology- Host Response for Osteomyolitis?

Answer 12

Initial abscess starts in cortex progresses into subperiosteal space

Sequestrum

Involucrum

Question 13

What would you expect to see as a host response in chronic osteomyelitis?

Answer 13

New brittle bone

Pus

Decreased medullary cavity

Dying bone marrow

Question 14

What are the general clincal features of inflammation?

Answer 14

Pain

Loss of function

Erythema

Warmth

Swelling

Question 15

What is the presentation of osteomyelitis?

Answer 15

Pain, Swelling, Loss of function, Erythma, Warmth

Fever, pathological fractures, discharging sinuses

Question 16

What are common forms of osteomyelitis?

(think more causes)

Answer 16

Traumatic infection, Operative infections, Predisposing factors (eg: DM foot), Infected Haematoma, Pressure sores etc..

Question 17

What are the Inx you would conduct?

(5 key groups)

Answer 17

Bloods:

• FBC & CRP
• Blood tests to look for sepsis- eg: Lactate
• Blood cultures

Skin samples:

• Swabs

Imaging:

• X-Ray: Late changes not early changes visible (periosteal reaction = earliest visible sign)
• CT scans: Show bone changes
• MRI: Good for soft tissue changes

Joints Aspiration:

• MC&S (may show bacteria, crystals, WBCs)
• Synovial fluids may be: Non viscous, Turbid, Purulent, Blood stained

Bone Bx:

• Sample for culture, PCR test & Histopathology

Question 18

What is the treatment?

Answer 18

• Manage sepsis
• Empirical Abx = IV Fluclox & IV Benpen
  
  • (2-6 weeks IV then 4-6 weeks PO)
  • Take samples before Abx if possible

Question 19

What should you do if there is septic arthritis

Answer 19

Joint washout

Question 20

When might surgery for osteomyelitis be needed?

Answer 20

If chronic changes have occured

Question 21

How would you deal with a prosthetic joint infection?

Answer 21

Removal & replace with abx continues in between ops

Question 22

How can you prevent Bone & Joint infections?

Answer 22

Promt Dx & Tx of predisposing conditions

Aspectic conditions for joint replacements

Antibiotic embedded into cement for prosthetic joints

Question 23

What is the clinical features of spetic arthritis?

Answer 23

Pain, Loss of function, Erythema, Swelling, Warmth

Fever, Damage to Articular Surface (tends to be more acute presentation as in an enclose space)