Risk factors for joint infections include previous arthritis, trauma, diabetes mellitus, immunosuppression, bacteremia, sickle cell anemia, and prosthetic joints. The most common pathogens causing joint infections vary by age and risk factors, with Staphylococcus aureus being most common overall except in neonates, who most commonly experience group B streptococcus infections. Joint infections can occur via seeding from a contiguous infection, hematogenous spread, or direct inoculation from surgery, trauma, or joint aspiration.

1. joint
infections

2. Objectives
be able to define septic arthritis
know what factors predispose to development of joint
infection, what bacteria commonly cause joint infections
be able to list most common pathogens causing septic
arthritis by age and risk factor.
be able to distinguish gonococcal arthritis from other forms
of bacterial septic arthritis.
know the common characteristics of viral arthritis and how
these differ from bacterial septic arthritis.

3. JOINTS
A site where two or more bones come together, whether
or
not movement occurs between them, is called ajoint
1-Fibrous Joint
The articulating surfaces of the bones are joined by fibrous tissue
very little movement is possible
e.g : - sutures
- inferior tibiofibular joints
2-Cartilaginous Joint
A primary cartilaginous joint is one in
which the bones are united by a plate or bar of hyaline cartilage.
No movement is possible.
e,g : between the first rib and the manubrium sterni
A secondary cartilaginous joint is one in which the
bones are united by a plate of fibrocartilage and the articular surfaces of the
bones are covered by a thin layer of hyaline
cartilage. Examples are the joints between the vertebral bodies the symphysis pubis. A
small amou nt of movement is possible.

4. 2-Synovial Joints
The articular surfaces of the bones are covered by a thin
.laye r of hyaline cartilage separated by a joint cavity
Synovial (diarthrodial) joints are found at the ends of two adjacent
bones that articulate.
Articular cartilage • Extremely smooth (nearly frictionless)
covering of the bone ends that glide on each other
It can be injured leading to pain, degeneration, or dysfunction
Subchondral bone • Dense bone that supports and is found
directly beneath the articular cartilage
Appears radiodense on plain fi lm x-rays and has low signal
(black) on MR
Synovium • Inner membrane lines the joint capsule
“Makes” (fi lters plasma to produce) synovial fl uid
Synovial folds (plica) form normally but occasionally can be
pathologic
Capsule • Outer layer, surrounds and supports the ends of two
bones in proper orientation
Thickenings of the capsule (capsular ligaments) maintain stability
of the joint

5. Synovial fluid •
- Ultrafiltrate of plasma (synovium fi lters it)
- Composed of hyaluronic acid, lubricin, proteinase, and collagenases.
Viscosupplementation therapy aims to replace hyaluronic acid in the
joint
-Function: 1. Lubrication of joint. 2. Nutrition to articular cartilage (and
menisci, etc)
-Laboratory evaluation is important part of workup of intraarticular
processes
Other
• Joints often have additional structures within them, including ligaments
(e.g., ACL, PCL), tendons
(e.g., biceps, popliteus), supporting structures (e.g., meniscus, articular
discs)

6. Bone
Fibrous capsule
Joint space
filled with
synovial fluid Articular
cartilage
Synovial
membran
e
Synovial Joints

8. Risk factors for joint infections:
• Previous arthritis
• Trauma
• Diabetes Mellitus
• Immunosupression
• Bacteremia
• Sickle cell anemia
• Prosthetic joint

9. Frequency of Joints
• Knee-48%
• Hip-24%
• Ankle-7%
• Elbow-11%
• Wrist-7%
• Shoulder-15%
• Sternoclavicular-8%

10. Joint Infections Mechanism :
Seeding from a contiguous source of
infection
Hematogenous seeding most common
Direct inoculation from surgery, trauma or
joint aspiration.

12. The word arthritis literally means
joint inflammation; but it is often
used to refer to group of more than
100 rheumatic diseases that can
cause pain, stiffness ,and swelling in
the joints.
Arthritis

14. Microbes & Arthritis
Overview and Classification
Class Infection
Live organism
present ?
Microbial
structures
present?
Example
Infection Yes Yes Yes Septic Arthritis
Reactive Yes No Yes
Chlamydia, Yersinia,
Salmonella, Shigella,
Campylobacter
Inflammatory No No No Rheumatoid Arthritis

16. Septic arthritis

17. Definition
Inflammation of a synovial membrane with
purulent effusion into the joint capsule, often
due to bacterial infection
Incidence:
. Commonest in middle age. (Liable to trauma).
. 0.2%-0.7% of hospital admissions
. Peak incidence in the first years of 1st decade
and >50 years
. Males>Females

18. Usually hematogenous but may also result
from contiguous spread or direct inoculation
Occurs in all age groups
Most common in children
Usually monoarticular
Polyarticular in less than 10% of pediatric
cases and less than 20% of adult cases
Hip and knee are most frequently affected

19. - Etiology: Staph., strept. "direct, blood"
- C/P: as inf. + night / rest pain + complete
loss of all movements
- Comp.: destruction, Dislocation, Disturbed
growth, Deformity (ankylosis)
- lnvest.: as inf. + imaging "X-ray*"
-TTT: AAA a urgent arthorotomy
Septic arthritis

20. Bacteria are most common
Viruses, fungi and parasites are possible
Staph aureus most common in all ages except
neonates
GBS most common in neonates
H. influenzae b has essentially disappeared as
a pathogen in vaccinated children
Pathogens:

21. Pathogens:
Gonococcal arthritis is the most common
type of septic arthritis in individuals under
30 years old
In the elderly, gram-negative bacteria
account for a higher percentage of cases of
bone and joint infections than in younger
people
MRSA, and VRE have emerged as a
significant microbiologic problem in the
past decade

22. Pathogens
Usually unimicrobial
Polymicrobial (36 to 50%) more likely in
diabetic foot osteomyelitis, posttraumatic
osteomyelitis, chronic osteomyelitis, and
chronic septic arthritis
In children between 1 and 4 years
usually Staphylococcus aureus

24. PATHOLOGY
Pathologic sequence:
In the early stage (a)
there is an acute synovitis with a purulent jointeffusion. (b)
Soon the articular cartilage is attacked by bacterial and cellular enzymes.
If the infection is not arrested,thecartilage may be completely destroyed (c).
Healing then leads to bony ankylosis (d).
(a) (b) (c) (d)

25. . Pathological types:
- Serous:
o Hot, red, tender, swollen joint.
o Fluid is clear.
- Serofibrinous:
o More inflammation,{r manifestations.
o Fluid is turbid.
- Purulent:
o Pure pus in joint.
o Throbbing pain, hectic fever.
o Edema & ulceration of the synovial membrane.
o Erosion then complete separation of
articular cartilage.

26. Clinical features
Symptoms
. General: F A H M.
. Local:
-pain: severe, sudden,
throbbing (later).
- Swelling at the joint area.
- lnability to move the joint

28. Signs
. General: Fever & tachycardia.
. Local:
o lnspection:
- Redness, swelling and discharging sinus
(if neglected).
- Deformity (late)
o Palpation:
- Hotness and tenderness.
o Movement:
- complete loss of all movements
(active & passive

31. Bone destruction..
. Pathological dislocation.
. Growth disturbance.
. Bony ankylosis.
. Toxemia, septicemia & pyemia.
COMPLICATION

32. Diagnosis

33. Laboratory
Increase ESR and CRP +ve.
CBC
Blood culture
Histopathology:
Joint aspiration +/-
U/S guidance :
o Diagnostic:
- Confirm the diagnosis.
- Culture & sensitivity.
o Therapeutic.
After aspiration, the joint should be splinted

35. Radiology
. X-ray
- Early: soft tissue shadow.
- Later: decreased joint space then
complete obliteration bony ankylosis
U⁄S
accurate for detection of effusion

41. 1-Trauma. .
2-Acute osteomyelitis
(passive movement is preserved) .
3-Rheumatic fever
4-Gout.
D/D

43.  General supportive measures
 Antibiotics
 Surgical drainage

44. General supportive measures
Analgesics are given for pain and intravenous
fluids for dehydration.
SPLINTAGE
The joint should be rested, and for neonates
and
infants this may mean light splintage; with hip
infection,
the joint should be held abducted and 30
degrees
flexed, on traction to prevent dislocation.

45. Antibiotics

47. Septic Arthritis: Adults
Septic Arthritis Pathogen Antibiotics
Adults (native joint
+/- penetrating
trauma)
S. aureus, P.
aeruginosa
Cloxacillin or
cefazolin +/-
gentamicin
Gonococcal N. gonorrhoeae Cefotaxime
Rheumatoid arthritis S. aureus, Strep sp,
Enterobacteriaceae
Cefazolin +/-
gentamicin
Prosthetic joint S. aureus, S.
epidermidis, others
Vancomycin +
gentamicin
IVDU S. aureus, P.
aeruginosa
Cloxacillin or
cefazolin +/-
gentamicin

48. Septic Arthritis: Kids
Septic Arthritis Pathogen Antibiotics
Neonates GBS, S.
aureus,
Enterbacteriac
eae
Cloxacillin +
Cefotaxime
Children S. aureus,
Strep sp.,
rarely H. flu
<5yrs:
cefuroxime
>5yrs:Cloxacilli
n or cefazolin
Sexually active N.
gonorrhoeae
Cefotaxime

49. . Washout of the infected ioint:
- ln knee, ankle and shoulder joints
arthroscopic washout or open arthrotomy + washout
- ln hip joint sepsis
only open arthrotomy.
. lf eroded cartilage
arthrotomy then traction for weeks.
. lf completely separated cartilage
arthrodesis.
Surgical drainage

50. Indications for Surgery
• Aspiration vs. debridement
• Joint does not respond to serial aspirations
• No improvement in 48hrs of ttt
• Frank pus is aspirated
• Loculations noted on MRI or U/S
• Documented Hip and SI septic arthritis
should be debrided surgically
• No change in morbidity between
arthroscopic vs. arthrotomy of knee

51. Gonococcal Arthritis
• Typically seen in young adults
• The most common cause of septic arthritis in
sexually active populations
• More common in females (asymptomatic
carrier state)

52. Gonococcal Arthritis
Tenosynovitis, dermatitis, polyarthralgia syndrome
• Acute illness with fever,
chills, malaise.
• Tenosynovitis
• Generalized arthralgia
• Dermatitis: pustular or
vesicopustular

53. Gonococcal Arthritis
Purulent (septic) arthritis
• Monoarticular or Pauciarticular
•Large joint involvement (knees, wrists, ankles)
• Most patients are afebrile
• Signs of disseminated infection are rare

54. Gonococcal vs. non gc Arthritis
• Gc-sexually active adults, migratory
polyarthralgias, tenosynovitis, dermatitis
common, >50% polyarthritis and joint fluid
positive 25%
• Non GC-very young or elderly,
polyarthralgias, tenosynovitis rare,
dermatitis rare, >85% monoarthritis
joint fluid positive 85-90%

55. Viral Arthritis
• Inflammatory polyarthritis, similar to early RA
• Duration usually < 1 month, self limited illness
• Not destructive to joint
• Prodromal symptoms
• Fever
• Rash
• Supportive Treatment (NSAIDs, Analgesics)

56. VIRAL ARTHRITIS
VIRUSES THAT CAUSE ARTHRITIS
Definite Possible
Hepatitis (B & C)
Rubella
Parvovirus
Mumps
Arbovirus
Variola
Vaccinia
Varicella
Rubeola
Echo
EBV
Adenovirus

57. VIRAL ARTHRITIS
PARVOVIRUS B19
Erythema Infectiosum (fifth disease)
Children
10% Arthralgia
5% oligoarticular arthritis
Adults
Up to 80% with joint symptoms
Chronic Recurrent Arthritis

58. Viral Arthritis
Parvovirus B19
• Diagnosis
• Usually seronegative for RF
• RFand anti-Lymphocyte antibodies can be
seen
• anti-B19 IgM antibodies may be elevated for up
to 2 months after acute infection.

59. Viral Arthritis
Hepatitis B
• Sudden onset
• Symmetric polyarthritis, (hands and knees are
most common)
• Urticarial rash
• Arthritis usually goes away before onset of
jaundice

60. Viral Arthritis
Rubella Arthritis
• Post-pubertal females
• Sudden onset
• Symmetric polyarthritis
• Tenosynovitis (carpal tunnel syndrome)
• May occur with some live attenuated virus
vaccines.

61. Clinical impression
septic arthritis
Patient Presents With Acute Increase In Pain +/- Swelling In One Or More Joints
G.P
Refer for urgent A&E
or specialist
assessment
Definite
alternative
diagnosis
Inflammatory
arthritis
Crystal arthritis
Haemarthrosis
Trauma
Bursitis/Cellulitis
Treat as
appropriate
No definite
alternative
diagnosis but
could be septic
Self referral to
A&E
MUST ASPIRATE
and other
investigations
History
Examination
History
Examination
Diagnosis SEPTIC ARTHRITIS
Empirical antibiotic treatment (as per local protocol)
Alter if necessary once results available
NOT
SEPTIC

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