Infection of Locomotor Tissues Flashcards
What is septic arthritis?
Surgical emergency where there is infection of a joint + bacteraemia
-mortality 10%
What is the typical form of spread in septic arthritis?
Haematogenous
-typically from skin/resp tract
What are the risk factors for septic arthritis?
Extremes of age Pre-existing joint disease (RA) IVDU DM/immunosuppression Recent op/injective procedure
What are the most likely causative organisms of septic arthritis?
Staph. aureus (most common)
Disseminated gonococcal (young adults)
Strep pneumonia/haem influenzae (children)
What is Osteomyelitis?
Infection of bone
-carries same risk factors/organisms as SA
What are the common sites for acute Osteomyelitis?
Metaphyseal plates of long bones (in children)
Spine (in immunosupressed adults)
What are the risk factors for chronic Osteomyelitis?
Open fractures
Operative procedures
How do SA/Osteomyelitis present?
Acute/subacute monoarthritis
-hot/swollen/erythematous joint
Joint held in ‘loose pack’ position
What are the signs on examination of SA/Osteomyelitis?
Fever & systemic sx
Demonstrable effusion
Loss of movement of the joint
Extreme pain w/ even passive movement
Which joints are most commonly affected in SA/Osteomyelitis?
Knee
Hip
What is the differential diagnosis for SA/Osteomyelitis?
Crystal arthritis
Reactive arthritis
Overlying cellulitis
Monoarticular presentation of RA/CTD/seroneg arthritis
How does acute Osteomyelitis present?
In a child w/ -continuous pain -throbbing -worse at night Fever Malaise Local swelling Erythema Warmth/oedema
What investigations may be appropriate in suspected SA/Osteomyelitis?
Joint aspiration (gram stain, synovial fluid culture)
-aspirate in theatre if prosthetic/not readily accessible
Blood cultures
FBC, ESR, CRP, uric acid, clotting
What is the management of SA/Osteomyelitis?
A-E resus Admission under orthopaedics IV a/b, after joint aspiration (2g Fluclox 6hrly) -continue for 2wks -6wks of oral treatment Analgesia Early source control (in theatre washout) Early active rehabilitation
What is the underlying pathophysiology of locomotor sepsis?
Joint invaded
-haematological spread OR
-eruption of bone abscess
-directly through penetrating wound
Infection spreads through joint, destroys cartilage
Pus forms abscesses & sinuses
Raw articular surfaces adhere –> ankylosis
What are the X-ray changes in Septic Arthritis?
Soft tissue swelling in first 2wks -widening of joint space due to effusion Cartilage later destroyed -narrowed joint space -bone destruction & ankylosis
What is the underlying pathophysiology of Osteomyelitis?
Inflammation
-acute inflam response, inc intraosseous pressure, intense pain
Supparation
-pus appears in medulla (2/7), forms subperiosteal abscess
Necrosis
-compromised blood supply, necrosis by (7/7)
New bone formation
Resolution
What are the imaging abnormalities of Osteomyelitis?
No abnormality on XR for 10/7
Inc bone activity on radioisotope scans
Reduced bone density & new bone formation by 2wks
Sclerosis/thickening of cortex
What causes viral arthralgia?
Any viral infection
-occurs during prodromal phase, along w/ viral rash
How does viral arthralgia present?
Symmetrical, non-destructive
Occurs along w/ viral rash
What investigations may be appropriate in suspected viral arthralgia?
Viral titres/antigens
RF
