Post on 02-Jul-2015
description
Paediatric Septic Arthritis
Contents
• Introduction
• Pathophysiology
• Microbiology
• Diagnosis
• History
• PE
• Investigations
• Treatment Options
What is it?
• An infection of the joint space
• Monoarticular-90%, Polyarticular, Suppurative and non-suppurative
Routes of Infection
1. Hematogenous
• Most common
• Bacteremia associated with URTI, Skin or GIT infections. Or invasive procedures.
2. Direct Inoculation
• Joint contamination by foreign object
3. Contiguous spread
• Osteomyelitis due to several factors in infants
Pathogenesis: Acute septic arthritis
Bacteria deposits in synovium producing inflamation
↓
Spreads to synovial fluid and multiplies
↓
Products of inflamation destroys joint components
(Swollen, painful joint)
↓
Sequlae
Infant
Destroy the epiphysis, which is still largely
cartilaginous.
Children
Vascular occlusion lead to necrosis of
epiphyseal bone
a) In the early stage, there is an acute synovitis with a purulent joint effusion
b) Soon the articular cartilage is attacked by bacterial and cellular enzyme.
c) If infection is not arrested , the cartilage may be completely destroyed
d) Sequlae include necrosis, sublaxation, dislocation and ankylosis.
Healing
May occur with/and/or
1.Complete resolution
2.Partial loss of articular cartilage and fibrosis of joint
3.Loss of articular cartilage and bony ankylosis
4.Bony destruction and permanent deformity
What causes it?
• Mostly bactireal. Also caused by mycobacteria, virus and fungi. (HiB vaccination status dependent)
• Gram positive 70-80% of which 40% is S. aureus
• Gram negative 9-20%
• Kingella kingae, N. gonorrhoeae
Clinical FeaturesInfants
• More septicaemia• Rather than joint pain
• Baby is irritable & refuses to feed
• Tachycardia with fever
• Joints are inflamed• Pseudoparalysis
• Check umbilical cord and IV site for infection
Children
• Acute pain in single large joint(esphip)
• Pseudoparesis
• Child is ill, rapid pulse and swinging fever
• Overlying skin looks red & superficial joint swelling may be obvious
• Local warmth and marked tenderness
• All movements are restricted by pain or spasm.
• Look for source of infection
Position of minimal intrasynovial pressure
Joint Degrees of flexion
Wrist 0
Elbow 40
Shoulder 0 40 abduction; 0 rotation
Hip 40 15 abduction; 15 external rotation
Knee 40
Ankle 15
History
1. Progression
• Worsens over time, does not wax or wane, and may awaken patient at night.
2. Joint trauma
• Falls, bites, cuts.
3. Skin lesions
4. Recurrent or concurrent illness
5. Recent onset of menses
6. MCH card (Immunization status)
7. Family history of rheumatologic disease
Physical Exam
• Lower limb antalgic limp / cannot walk• Upper limb affected part is closely guarded• Marked tenderness, active and passive range of
motion are limited• Examine for synovial effusion, erythema, heat and
tenderness.• Spasm of muscles around the joint may be
marked.• Patient may hold the joint in a position to reduce
the intra-articular pressure to minimize pain.
Investigations Explaination
Full blood count Elevated white blood cell count
ESR > 40 mm/hr
CRP > 20 mg/dL
Blood culture May be positive
Ultrasound
Xray
Synovial Fluid
Investigations
Bloods Imaging SynovialFluid
Imaging2. Xray: Frog-leg position for hip.
• Early Stage – Normal
• Look for soft tissue swelling, loss of tissue planes, widening of joint space and slight subluxation due to fluid in joint. Gas may be seen with E. coli infection
• Late stage – Narrowing and irregularity of joint space, erosion of epiphysis or metaphysis
• Plain film findings of superimposed osteomyelitis may develop (periosteal reaction, bone destruction, sequestrum formation).
1. USS
• More reliable in revealing a joint effusion in early cases.
• Widening of space between capsule and bone of > 2mm indicates effusion.
• Echo-free
transient synovitis
• Positively echogenic
septic arthritis
Narrowing of joint space and irregularity of subchondral bone.
Joint space losssubchondral erosions and
sclerosis of the femoral head
osteonecrosis and complete collapse of
the femoral head
Synovial Fluid AnalysisArthritis Type Appearance Viscosity White
cells/mm3
Crystals Biochemistry Culture
Normal Clear yellow High Few - As per plasma -
Septic arthritis
Purulent Low >>50,000 - Glucose low +
Tuberculous arthritis
Turbid Low <2000 - Glucose low +
Rheumatoid arthritis
Cloudy Low >2000 - - -
Gout Cloudy Normal >2000 UrateNBF
- -
Pseudogout Cloudy Normal >2000 Pyrophosphate PBF
- -
Osteoarthritis Clear yellow High <2000 Often + - -
DifferentialsInfectious Causes of arthritis in children
DifferentialsNon- Infectious Causes of arthritis in children
Management
• Medical
• General supportive (Fever, pain, hydration)
• Antibiotics: IV Antibiotics 6-8 weeks
• Cloxacillin, Flucloxicillin, gentamycin and rifampicin for mycobacterium and ceftriaxone for gonorrhoea
• Surgical
• Percutaneous arthrocentesis
• Arthroscopic of open surgical drainage
• Rehabilitation
• Physiotherapy: Rapid mobilizaton
Parenteral antibiotics
Take Home Points
• Prompt diagnosis and treatment is crucial to preventing bad bad sequlae. Esp. if the hip is involved
• Treatment goals are sterillisation and decompression of joint space and removal of debris
• Follow-up must be scheduled to ensure a growing child won’t be affected the rest of her/his life.
Veenaka