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MSK > Bone Infections > Flashcards

Bone Infections Flashcards

1
Q

What is osteomyelitis

A

Infection of the bone

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2
Q

What is the pathology of osteomyelitis

A

Acute inflammation
Suppuration (pus)
Release of pressure if discharges
Sequestrum (necrosis) due to interrupted blood supply
Involcrum (new bone formation) over necrotic
Resolution or chronic

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3
Q

Where can infection discharge into

A

Joint spaces

Skin via sinuses

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4
Q

When should you always suspect OM

A

Diabetic feet
Deep pressure sores
Non-healing ulcers

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5
Q

How does OM spread

A

Haematogenous
Local spread from trauma / surgery / ulcer
2 to local infection with or without vascular insufficiency

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6
Q

What local infections can OM spread from

A 
Infected umbilical cord
Abscess 
Pneumonia
UTI
Arterial line
Urological procedure
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7
Q

What are common organisms in children

A

S.Aureus
E.coli
Strep pyogenes
H. influenza

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8
Q

What are common organisms in adults

A

S.aureus = most common
Strep pyogenes
Pseudomonas

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9
Q

What organisms is common in sickle cell

A

Salmonella

May think sickle crisis so always X-ray

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10
Q

What organism in Butcher

A

Brucella

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11
Q

What organisms in immunocompromised (HIV / malignancy / surgery)

A

Candida
Mycobacterium TB
Propionibacterium

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12
Q

What STI can cause

A

Gonococcus

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13
Q

Where is OM common in children

A

Metaphysis of long bone

Femur / tibia

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14
Q

What are signs of OM in children

A 
Severe pain 
Decreased ROM 
FTT
Drowsy 
Swelling 
Fever
Tachycardia
N+V
Malaise
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15
Q

Where is OM common in adults

A

Thoracolumbar - IVDA
Feet - DM
Epiphysis of bone

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16
Q

What are signs of OM in adults

A 
Backache
Gradual onset
Limited ROM
Local tenderness / warmth / erythema
Signs less marked in adults
Signs of systemic infection
Hx UTI / ORIF / surgery
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17
Q

What are RF for OM

A 
Children
M>F
Trauma - open fracture 
DM 
RA
Immunocompromised 
Chronic disease
IVDA
Alcohol use
Sickle cell
Vascular insufficiency
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18
Q

What investigations for OM

A

Bloods - FBC, U+E, CRP
Blood culture x3
Bone biopsy - rarely required
MRI = best imaging for diagnosis

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19
Q

What is gold standard for Dx

A

Bone biopsy + blood culture

Needed to exclude cancer as look similar on imaging

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20
Q

What are other options

A

Aspiration of material near bone
X-ray - commonly used 1st
Isotope bone scan
USS

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21
Q

When would isotope bone scan be used

A

Prosthesis

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22
Q

What does X=ray show

A

Destructive changes after 10-14 days
Destruction of bone
Gas bubbles
Hazy

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23
Q

How do you treat OM

A

Treat pain and dehydration (analgesia + fluiD)
Rest + splint
Ax for 6 weeks
Surgery

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24
Q

What Ax

A

Vanc + cefotaxime till sensitivities known

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25
What surgery do you do
Aspiration of pus Abscess drainage Debridmeent of necrotic bone Replace infected joint
26
What are complications of OM
``` Septicaemia Metastatic infection Pathological fracture Septic arthritis Altered bone growth / deformity Chronic OM ```
27
Differentials of OM
``` Malignancy Acute septic arthritis Inflammatory arthritis Trauma Transient synovitis Soft tissue infection TB ```
28
What is pathology of chronic OM
Retained sequestra and involcrum
29
What organisms in chronic OM
S.aureus E.coli Strep pyogenes Proteus
30
When do you suspect chronic
Vascular insufficiency Non healing tissue over bone Bone felt on probing ulcer
31
How does chronic oM present
``` Repeated breakdown of healed wounds Chronically discharging sinus Flare ups Pain Fever ```
32
Who is at risk of chronic
Immunosuppressed DM = very high risk Elderly IVDA
33
How do you Dx
X-ray shows thick irregular bone
34
How do you Rx
``` Long term Ax >12 weeks Excision of sequestra Amputation Correct deformity Treat soft tissue ```
35
What are complications of chronic OM
Pathological fracture Growth disturbance SCC
36
What causes subacute OM
Impaired resistnace Lowered bacterial virulence Antibiotic use
37
What are signs
Long history of pain, limp, swelling and warmth
38
What is Brodie's abscess
Subacute OM in older children | Present with painful limp but no systemic fears
39
How do you Dx
X-ray - lucency Biopsy Bone scn
40
How do you treat
Ax | Curettage surgery
41
What is Ddx of Brodies'
Ewing's sarcoma Osteoid osteoma TB
42
What is septic arthritis
Acute synovitis with joint effusion
43
What is pathology
Articular cartilage attacked Complete destruction Replaced with fibrocartilage
44
When should you consider SA
Any acutely inflammed joint as can destroy in under 24 hours | May not present typically if obese etc.
45
How does SA spread
Direct / local from wound / injury / arthroscopy Eruption of abscess Haematogenous
46
What are common orgnaism
``` S.aureus = most common H.influenza S.pyogenes E.coli - if elderly + UTI Gonococcus - think in young patient with acute swollen joint ```
47
What should you think
How did organism get there - cellulitis / IV line / pneumonia / immunosuppressed Source of infection can go to joint before it causes fever
48
How does SA present
``` Very unwell - more than OM Extreme pain Reluctant to move Decreased ROM Acute pain Swollen joint Fever - only in 50% Tachycardia Irritable ```
49
Where does it affect
Knee >50% | Anywhere where source
50
RF for SA
``` Infected prosthetic = most common Recent joint surgery Immunosuppressed - DM Chronic renal Joint disease - RA / OA IVDA Age ```
51
Who might not find it painful
On steroids Immunocompromsied DM
52
What is 1st line investigation
Joint aspiration for gram stain and culture + microscopy to look for crystals
53
What else do you do
Bloods - FBC, U+E, LFT, urate Blood cultures X-ray / USS but may be normal of joint
54
What criteria for DX
Kocher - Fever >38.5 - Non-weight bearing - Raised ESR - Raised WCC
55
What should you never do
NEVER ASPIRATE PROSTHETIC as may put infection in
56
How do you treat
``` BROAD SPEC AX SEPSIS 6 IV van + cefotaxime till sensitivities known Splint Fluid and analgesia Surgical drainage ```
57
What do you do if complex / immunosuppressed
Microbiology
58
When do you always refer to ortho
If prosthetic joint
59
What do you do when infection resolves
Physio
60
Complications
Partial loss of cartilage OA Fibrous or bony ankyloses
61
What are differentials of SA
``` OM Trauma - haemarthrosis (if anti-coagulant / bleeding disorder) Haemophilia Gout Fracture Reactive arthritis - think GI / GU Sx OA Acute exacerbation RA Gauchers Malignancy ```
62
What is acute infection of a prosthetic joint
Within 3 months | Infection of hospital origin
63
What is deep late infection
3 months - 2 years | Nosocomial origin e.g. staph epidermis during procedure
64
What is late haematogenous
>2 years | Community origin
65
How does joint get infection
Direct implantation Haematogenous Reactivation of latent
66
What organism
S.Aureus | S.epididermis (less pathogenic)
67
Why is it harder for Ax to work
Biofilm forms over metal work so can't penetrate
68
Symptoms
Pain | May not have typical infectious
69
What are RF
``` Obesity Age Bilateral Post-op AF MI UTI ASA ```
70
How do you Dx
NEVER ASPIRATE Ortho review X-ray to look for destruction
71
How do you Rx
Long term Ax if not fit for surgery DAIR One or two stage revision Amputation
72
What Ax do you add if metal work
Rifampicin
73
What is DAIR
Debridmeent Ax Implant retention
74
What is most effective
One stage revision | Take out metal work and put back in with Ax
75
What is two stage
Take metal work out Put Ax in with cement Replace joint later in 3 months
76
When do you give Ax before culture
If life or death but want to know organism
77
Where can TB affect
Extra-articular Intra-articular Vertebral body = Pott's
78
How do you get TB in bone
Primary complex in lung | Spread via haematogenous or nodal
79
What are the Sx
``` Insidious onset Long Hx Pain worse at night Marked muscle wasting Swelling Weight loss Pyrexia Decreased ROM Ankylosis Deformity Peri-articular osteoporosis Thickened synovium ```
80
How does Pott's present
``` Gradual onset back pain Stiffness Abscess Kyphosis Cord compression ```
81
RF
Previous TB infection Immunocompromised HIV
82
How do you Dx
``` Bloods- FBC, ESR Mantoux test Sputum / urine PCR Joint aspiration and culture - AAFB on ZN Biopsy / X-ray MRI for spine ```
83
What does X-ray show
Swelling | Articular space narrowing
84
How do you Rx
Standard TB Rx Immobilise large joint Drain abscess Surgical for severe deformity / abscess / paraplegia
85
What is TB Rx
``` Rifampicin Isoniazid Ethambutol Pyrezamide May be needed >6 months ```
86
What is prognosis for TB
Good if no neuro involvement
87
Complications of long term Ax / not fit for surgery
If need another replacement won't get as will just become infected as infection throughout blood
88
What causes red / hot / swollen joint
IL 1+6 in inflammatory process

MSK (21 decks)

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