Paediatric septic arthritis is an infection of the joint space, most commonly caused by bacteria entering through the bloodstream. It can lead to destruction of joint components if not treated promptly. The diagnosis involves examining the affected joint for swelling, warmth and limited range of motion, as well as blood tests and imaging. Treatment consists of intravenous antibiotics for 6-8 weeks alongside surgical drainage and physiotherapy, with the aim of preventing long-term joint damage. Proper follow-up is important to monitor a child's development.
2. Contents
• Introduction
• Pathophysiology
• Microbiology
• Diagnosis
• History
• PE
• Investigations
• Treatment Options
3. What is it?
• An infection of the joint space
• Monoarticular-90%, Polyarticular, Suppurative and non-suppurative
4. 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
5. 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
6. 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.
7. 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
8. 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
9.
10. Clinical Features
Infants
• 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(esp
hip)
• 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
11. 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
12.
13.
14.
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
16. 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.
17.
18. Investigations
Bloods Imaging Synovial
Fluid
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
19. Imaging
2. 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
20. Narrowing of joint space and
irregularity of subchondral bone.
Joint space loss
subchondral erosions and
sclerosis of the femoral
head
osteonecrosis and
complete collapse of
the femoral head
21. Synovial Fluid Analysis
Arthritis 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 Urate
NBF
- -
Pseudogout Cloudy Normal >2000 Pyrophos
phate
PBF
- -
Osteoarthritis Clear yellow High <2000 Often + - -
24. 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
26. 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
Editor's Notes
Risk Factors
Neonates at greater risk since their vessesl
Umbilical vessel catheterisation
Central venous catheters
Femoral vessel blood sampling
Osteomyelitis
Immunodeficiency
Joint surgery
Thalassemias
Diabetes
Most common due to effective blood flow and lack of basement membrane in synovium
The bacteria may invade other sites too such as meninges, pericardium, soft tissue) esp if H. influenza is involved
Could be from trauma, kneeling, crawling on sharp objects. Cats claws or from surgery like arthroscopy. Polymicrobial should be suspected if this is the case. Could occur AFTER external wound heals
Osteomyelitis in infants:
Metaphyseal capillaries perforate epiphyseal growth plate so infection can easily spread to epiphysis and cartillage
Joint capsule extends distal to epiphyseal plate
Inflamed synovium:
Vasodilatation, increased permeability oedema and neutrophilic infiltration
Increased proteins due to permeability and decreased glucose due to bactireal and synovial consumption and reduced circulation
Neutrophil damage:
Reactive oxygen species (H peroxide, superoxide radicals)
Depolymerises hyaluronic acid (Dec. viscosity to 15)
Breaksdown cartillage matrix molecules
Destroys protease inhibitors
Proteolytic enzymes released
Stimulates arachidonic acid metabolism
Prostaglandins released which contribute to bone resorption
Joint components damaged are articular cartillage, and synovium.
Sequlae:
We’ll see avascular necrosis due to ischaemia due to increased pressure
Laxity of joint capsule due to distension. Causes subluxation and dislocation
Joint restriction
Limb length problem if growth plate involved
Enlargement of femoral head in hip SA
Pathological fractures
Sequlae:
We’ll see avascular necrosis due to ischaemia due to increased pressure
Laxity of joint capsule due to distension. Causes subluxation and dislocation
Joint restriction
Limb length problem if growth plate involved
Enlargement of femoral head in hip SA
Pathological fractures
Strep species include GABHemolytic (GAS, Strep. Pyogenes, S pneumoniae, Group B strep (s. agalactiae)
Gnegative: Most common Kingella kingae
Infants present with gen., non-specific s&s
Cellulitis
Discomfort on being handled
Postural changes
Unilateral swelling of extremity, buttocks or genitalia
History
Progression: Worsens with time, does not wax or wane. May awaken at night
As we saw before, the inflammation causes increased pressure within the joint space. Certain positions help.
Septic arthritis of hip. Held rigidly in flexion, external rotation, and abduction.
SA of wrist in 8 day old. Group B Strep drained.
E. coli arthritis of knee in neonate
Gonorrhoea: Dermatitis-SA
Has dermatitis, migratory polyarthralgia and tenosynovitis
Fever, skin lesions, bacteremia
In adolescent girls onset with mensus.
Inflammatory arthropathies like JIA are worse in the morning
Knee pain complaints may be referred from the hip
Unusual pathogens
Usually portal for s aureus and strep pyogenes leading to bactiremia. Very common in Fiji.
UTRI can lead to bacterimia or viral synovitis. Concurrent varicella zoster virus can facilitate entry of s. aureus or GAS.
Disseminated gonococcal infection usu in 7 days of mensus.
Hib
Psoriatic arthritis
Don’t forget
eyes: conjunctivitis in Kawasaki disease and reactive arthritis
Liver: Hepatomegaly in brucella arthritis
Musculoskeletal exam: Look, feel move all joints and affected one last. 90% cases are in ONE joint.
There may be severe swelling due to extensive infection or venous thrombosis.
ESR and CRP are better negative than positive predictors of SA. Good for monitering progress.
ESR normal is newborns: 0-2 mm.hr and older: 3-20mm/hr
May rise 3-5 days after therapy. Can stay elevated for a month.
CRP usually <10mg/L
Peaks within 30- 48 hours of infection and falls to normal within a week of treatment
Other tests are PCR for K. kingae
Cultures from genitals if gonococcal suspected
GAS ASOT to be done
Radiographic signs of hip arthritis may include [8,12,31,68-71]:
●Swelling of the capsule
●Obliteration or lateral displacement of the gluteal fat lines (image 1)
●Elevation of the femoral portion of Shenton line, with widening of the arc
●The obturator sign (the margins of the obturator internus are displaced medially into the pelvis as its tendon passes over the capsule of the hip joint)
●Lateral and superior displacement of the femoral head with relatively normal acetabular development (in contrast to developmental dysplasia of the hip, in which the acetabulum is abnormal)
●Concomitant osteomyelitis of the femur (this is a late sign, since bone destruction takes a minimum of a week to become apparent on routine radiographs)
Usually higher than this. WBC can also >50,000 in JIA or reactive arthritis
Gram stain very important as synovial fluid has bacteriostatic properties which may render culture negative
Ctrl fever, pain and hydration and splinting affected limb in position of least pressure possibly with traction to prevent dislocation. NSAID will also stop PG production thereby reducing cartillage destruction
Empirical stat and then based on culture results
Open drainage indications:
Hip SA
Long duration
Exclusion of foreign body
Large amounts of fibrin
Debridement in those with osteomyelitis
Lack of clinical improvement after 48 hours of antibiotic therapy
Criteria for oral meds:
Clinical and lab improvements
Dec. or absent fever
Appropriate oral agent available for proper duration
Adherence is assured
1. Antistaph and antistrep:
Clindamycin
Vancomycin
Cefazolin
2. Hib: cefotaxime or ceftriaxone or cefuroxime
3. Gonococcal: 3rd gen cephalosporin
Salmonella: in sickle celled anemia- 3rd gen cephalosporin
4. Strep. Pneumonia: ceftriaxone, clindamycin, cefotaxime
5. Enteric gram neg: Cefotaxime, ceftri PLUS any aminoglycoside