Septic arthritis is a joint infection caused by bacteria or other microbes entering the joint space. It leads to inflammation of the synovial membrane and purulent effusion. Common symptoms include pain, swelling, warmth and limited movement of the infected joint. Diagnosis involves synovial fluid analysis showing purulence and leukocytosis, along with supportive blood tests. Treatment is with antibiotics and surgical drainage may be needed. Complications can include bone and cartilage destruction, joint deformity, and secondary osteoarthritis.

1. Septic Arthritis
Prepared by Tan Soo Siang

2.  Introduction
 Pathogenesis
 Clinical Features
 Investigations
 Treatment

3. Introduction
• Septic arthritis is inflammation of a synovial
membrane with purulent effusion into the
joint capsule, due to infection.
Synovial membrane
Membrane surrounding joint
cavity
Produce synovial fluid
Contain rich capillary network
for phagocytic and hyaluronate-
producing function

4. • Bacterial, but sometimes viral,mycobacterial,
and fungal.
• Usually caused by Staphylococcus aureus .
Other organisms are : E.coli , Proteus ,
Streptococcus
Predisposing Factor :
 Rheumatoid arthritis  Immunosuppressive drug therapy
 Chronic disorder  AIDS
 Intravenous drug abuse

5. Pathogenesis
• Bacteria can gain entrance to a joint via 3 routes:
Haematogenous Direct spread from
adjacent focal infection
Direct inoculation

6. Most common form of spread
Usually affect people with underlying medical problem
May result from penetrating trauma
Introduction of organisms during diagnostic and surgical
procedures. For eg arthroscopy and intra-articular injection
More common in children.
Osteomyelitis usually begin in the metaphyseal region,
from which it breaks through the periosteum into the
joint.

7. Synovial membrane is highly vascularised.
↓
Bacteria can easily enter synovial joint via blood stream.
↓
There will be inflammatory reaction with seropurulent exudate and increase in
synovial fluid.
↓
As pus appear in the joint, the articular cartilage is eroded and destroyed.
Partly by the bacterial enzyme, and partly by the enzyme released from
synovium, inflammatory cell and pus
Infant Adult
Children
Destroy the epiphysis, Effect confined on
Vascular occlusion lead
which is still largely articular cartilage
to necrosis of
cartilaginous. Extensive erosion can
epiphyseal bone
occur due to synovial
proliferation and
ingrowth

8. 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) Healing then leads to ankylosis

9. If left untreated, it will spread to the underlying bone
and out of joint to form abscess and sinus.
Healing with:
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

10. Clinical Features
Differ according to age
In new born infants In children In adults
o acute pain in single
 More on septicaemia
large joint(esp hip)  Often in the superficial
Rather than joint pain
joint(knee, wrist or ankle )
o Pseudoparesis
 Baby is irritable &
 Joints painful, swollen
refuse to feed
o Child is ill,rapid pulse & inflamed.
and swingingfever
 Tachycardia with fever
 Warmth and marked
o Overlying skin looks red local tenderness &
 Joints are warmth,
& superficial joint swelling movement restricted.
tenderness, resistance
may be obvious
to movement
 look for gonococcal
o Local warmth and infection or drug abuse.
 Umbilical cord and
marked tenderness
inflamed IV site should be
 Patient with
suspicious of source of
o All movements are rheumatoid arthritis and
infection
restricted by pain or spasm. especially those on
corticosteroid may
o Look for source of develop “silent” joint
infection from septic toe or infection.
discharge ear

11. Physical examination:
• Lower limb  antalgic limp / cannot walk
• Upper limb  affected part is closedly 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.

12. Investigations
Investigations Explaination
Full blood count Elevated white blood cell count
ESR > 40 mm/hr
CRP > 20 mg/dL
Blood culture May be positive

13. Synovial fluid analysis
Aseptic technique is used during aspiration of synovial fluid.
Avoid taken from infected site of skin.
The fluid is then analyzed by gross and microscopic
examination and culture.
Gross examinations include appearance, volume,
viscosity, mucin clotting (amount of proteoglycans).
Microscopic examinations include leucocyte count,
staining of smears, serum glucose ratio, protein.
Finally, culture and sensitivity for definitive diagnosis
and treatment.

14. Suspected Appearanc Viscosity White Crystals Biochemistry Bacteriology
condition e cells
Normal Clear High Few - As for plasma -
yellow
Septic Purulent Low + - Glucose low +
arthritis
Tuberculous Turbid Low + - Glucose low +
arthritis
Rheumatoid Cloudy Low ++ - - -
arthritis
Gout Cloudy Normal ++ Urate - -
Pseudogout Cloudy Normal + Pyropho - -
sphate
Osteoarthrit Clear High few Often + - -
is yellow

15. Imaging
X ray
 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
 Plain film findings of superimposed osteomyelitis may
develop (periosteal reaction, bone destruction, sequestrum
formation).

16. Narrowing of joint space and irregularity of
subchondral bone.
subchondral erosions and osteonecrosis and
Joint space loss sclerosis of the femoral complete collapse of
head the femoral head

17. Ultrasonography
• 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

18. Treatment
General supportive care
-Analgesics
-IV fluids
Splintage
- The joint must be rested either on a splint or in a widely split
plaster
-In neonates and infants, with hip infection the joint is held
abducted and 30 degree flexed, on traction to prevent dislocation.
Antibiotics
Treatment is started once the blood and samples are obtained
without waiting for the detail results.
Choice of antibiotic depends on the most likely pathogen

19. Surgical Management
 Surgical Drainage
 Arthroscopic debridement and copious irrigation with normal
saline – more frequently in knee joint septic arthritis

20. Complications
• Bone destruction and dislocation of the joint (esp
Hip)
•Cartilage destruction
-may lead to either fibrosis or bony ankylosis
- in adult partial destruction of the joint will result in
secondary osteoarthritis
•Growth disturbance
- presenting as either localised deformity or shortening
of the bone