W09 - BONE AND SOFT TISSUE INFECTION; OSTEOARTHRITIS AND MGMT Flashcards
Outline the bacteriological and pathological basis of bone infection
- non-spec most common
- haematogenous spread (children & elderly)
- infants: infcd umbilical cord
- children: boils, tonsilitis, abrasions
adults: UTI, arterial line - 2º to vascular insufficiency
Compare acute and chronic osteomyelitis
ACUTE
children, M > F
trauma hx
adults: DM, R.Arth., imm compr., LT steroid, sickle cell
- start @ metaphysis, vasc. stasis, inflamm and suppuration and release
- bone necrosis
- INVOLUCRUM = resolution
CHRONIC
*nil resolution and continued infection
*DE NOVO d/t operation or open # = rpt breakdown of healed wounds
*risk groups: DM, elderly, drug abusers
Staph. Aureus, E. Coli, Strep. pyogenes, Proteus
Able to describe the clinical features, RF, and differential diagnosis of a patient with osteomyelitis
specific (e.g. TB) vs non-sepc. (most common)
*DM, imm suppr., xs alcohol, IVDU
severe pain in the affected region and associated low grade pyrexia. Pain is constant and can be worse at night
ACUTE SEPTIC ARTHRITIS
TRAUMA
ACUTE INFLAMM ARTHRITIS
TRANSIENT SYNOVITIS
SOFT TISS. INFECTION
Understand the investigations and expected results of patients with osteomyelitis, (and their interpretation)
temp FBC + diff. WBC = neutr. leucocytosis ESR, CRP Cultures x3 UEs, dehydration, systemic ill
- XR = 14d minimal change > periosteal changes > medullary lysis
- CULTURES*
- BONE BIOPSY*
Understanding of the principles of management of bone infections
> pain and dehydration support
> rest & splintage
> abx: empirical while waiting (Fluclox + BenzylPen)
- IV/oral 7-10d
- 4-6w depends on response
> Sx: abscess, debridement
- chronic
- acute refractory to abx
- infected prosthetic joint or foreign body
- post-trauma
Understand the possible complications of bone infections
- late osteonecrosis = sequestrum
- late peristeal new bone = involucrum
- METS infectioon
- fracture
- SEPTIC ARTHRITIS
- SEPTICAEMIA
- ALTERED BONE GROWTH
*CHRONIC DEVELOPMENT
=> hronic discharging sinus
=> abscess
=> SCC (0.07%)
Common organisms in acute osteomyel.
INFANTS:
s. aureus, group b strept., e. coli
OLDER CHILDREN
s. aureus, strep pyogenes, haemophilus influenza (imms!)
ADULTS
s. aureus, mycobact. tuberculosis, pseudomonas aeroginosa
coag neg. staph, propionibacterium spp (prostheses)
Special cases of organisms for acute osteomyel
DM: mixed infection
Vertebral osteo.: s. aureus, TB
Sickle cell: salmonella spp
Paediatric presentation of osteomyelitis
Children:
- minimal signs
- drowsy/irritable
- metaphyseal tenderness+swelling
- common around the knee + long bones+ mult. sites
Adult presentation of osteomyelitis
1º OM seen in thoracolumbar spine
backache
UTI hx or urological procedure
*elderly, diabetic, immunocompr.
2º OM more common d/t open fracture/sx
mix of pathogens
Differential Dx of OM: Soft Tissue Infection
CELLULITIS (gp A strep): deep infection of subcut.
ERYSIPELAS (gp a strep): superficial infection, red raised plaque
NECROTISING FASCIITIS (gp a strep, clostridia): aggy fascial infection
GAS GANGRENE (clostridium perf.)
TOXIC SHOCK SYNDROME (s. aureus): 2º wound colonisation
What is sequestrum
A bony sequestrum (pl. sequestra) is a piece of devascularised bone that becomes separated from the remainder of the bone in chronic osteomyelitis and acts as a nidus for ongoing infection
- d/t breaking off and losing vascular supply
- often is surrounded by new bone: INVOLUCRUM
Acute Septic Arthritis Aetiology
Sources:
- haematogenous
- bone abscess eruption
- direct invasion: wound; intra-articular injury; arthoscopy
*Staphylococus aureus
Haemophilus influenzae
Streptococcus pyogenes
E. coli
INFECTED JOINT REPLACEMENT
Able to describe the clinical features of a patient with septic arthritis
METAPHYSEAL SEPTIC FOCUS (septic arthritis or osteomyelitis)
*single swollen joint!
- acute synovitis w/ purulent joint effusion
- articular cartilage attacked (bact. toxin and cellular enzyme)
= destruction of articular cartilage
=> recovery / partial loss / subsequent OA / fibrous bony ankylosis
CHILDREN: septic; swelling superficial; not erythematous; febrile; tender
ADULT: superficial joint
Identify the investigations required for a diagnosis of septic arthritis and expected results
FBC, WBC, ESR, CRP, blood cultures X ray Ultrasound MRI aspiration
Understand the principles of management of septic arthritis
Supportive
Abx
Sx drainage & lavage
- open or arthroscopic lavage
Join repl = revisions or abx only
Differential Dx of Pt. w/ Septic Arth. Presentation
ACUTE OSTEOMYELITIS
TRAUMA
IRRITABLE JOINT
RHEUMATIC FEVER
GOUT
Understand the potential diagnosis of tuberculosis of bone and its clinical setting.
insidious onset w/ general illness
*NIGHT PAIN, SWELLING, WT LOSS
- spinal TB = abscess or kyphosis
- SINGLE JOINT w/ SYNOVIUM THICKENING + musc. wasting
*ESR, Mantoux, XR, aspiration and biopsy
DDx of Bone TB
- transient synovitis
- monoarticular RArth
- haemorrhagic arthritis
- pyogenic arthr.
TB Mgmt
RIFAMPICIN
ISONIAZID (8w)
Ethambutol
THEN rifampicin & isoniazid
REST & SPLINT
+op. drainage rare
Understanding of the definition and classification of OA into primary and secondary
Activity-related joint PAIN + nil morning stiffness or stiffness lasting no longer than 30 mins (30min+ = inflamm)
+rapid deterioration
+hot, swelling
1º - unknown cause
2º - caused by another disease, infection, injury, or deformity
OA Aetiologyy & Path
Persistent heavy activty; obesity in COMBO with musc wakness, ligmnt injury, abn anatomy
Degenerative joint condition, mainly affecting the knee
OA Clinical Features
45y/o+
Joint pain
Stiffness: typically, worse after activity and at the end of the day
Limitation in day-to-day activities
Investigating OA
Serum CRP/ESR NORMAL
XR: L oss of joint space O steophytes S ubchondral sclerosis S ubchondral cysts
