Septic Arthritis in Children

Hayan HamamehOrthopaedic surgery resident

Departmet of Orthopaedic Surgery

Teshreen Military Hospital

Suppervised by :

Hussam Aldin SulaimanChief of Spine and Orthopaedic surgery department

Overview

1-Backgraound

pyogenic A.suppurative A.purulent A.pyarthrosis

Joint infection

viruses

fungi

Bacteria+++

Overview

1-Backgraound

challenging clinical problem because:

 (1) signs and symptoms may be subtle and overlap with those found in other conditions.

(2) diagnosis methods are relatively insensitive.

 (3) optimal management, including duration of antibiotics and surgical approach, is not evidence based.

Overview2-Etiology

Normal joints synovial fluid

synovial membrane

highly vascular no basement membrane

EASY entry of bacteria

Overview2-Etiology

Bacteria deposition in S. membrane acute inflammatory cell response.

 no basement plate bacteria may access to the S. fluid.

bacterial endotoxin host cells cytokines stimulate the release of proteolytic enzymes and increase leukocyte migration

Overview2-Etiology

Proteolytic enzymes  damage joint cartilage + collagen matrix

 inflammatory mediators, bacteria, and pus  increase pressure within the joint  Pressure necrosis destroy synovium or cartilage

Distension of the joint capsule may cause laxity, with possible subluxation or dislocation as a sequela

Overview2-Etiology

hematogenous spread

direct inoculation

extension of a contiguous focus of infection (e.g., osteomyelitis).

Overview2-Etiology

neonates and young children often have coexisting septic arthritis and osteomyelitis.

capsule insertion allowing bone infection to invade the joint space.

Nutrient capillaries & physeal plate relationship

osteomyelitis  SA in 35%

SA secondary osteomyelitis  RARE

Overview2-Etiology-microbiology 

Gram positive

s.aureus

streptococciG

ram

n

eg

ati

ve

H. influenzae

N.meningitidis

N.gonorrheae

K.Kingae 

Salmonella

Overview2-Epidemiology

Children > adults < 3 years Boys to girls 1.2-2 to 1 Lower extremity 80% Hip & knee +++ upper extremity Elbow Neonates polyarticular SA.

Risk factors for SA in neonate (younger than one month)

#Umbilical vessel catheterization

#Presence of central venous catheters

#Femoral vessel blood sampling

#Osteomyelitis

Risk factors for SA in older infants and children Immunodeficiency

joint surgery

Hemoglobinopathies

underlying arthritis == JIA

Diabetes

Overview3-Prognosispoor outcome associated with : Time to diagnosis is the most important prognostic factor (>4-7 days)

Involvement of the hip

Involvement of the hip or shoulder with concomitant osteomyelitis

Young age (i.e., less than one year)

The causative organism (Enterobacteriaceae and S. aureus)

Presentation1-History

 The presentation age , site , organism.

Neonates and infants : = septicemia ( irritability, apprehension, poor feeding) or fever without a focus of infection .

lack of use of the involved extremity ("pseudoparalysis")

discomfort when handled or having the diaper changed.

extremity swelling.

Presentation1-History Older children and adolescents :

fever and constitutional symptoms (malaise, poor appetite, irritability, tachycardia)

Joint findings (e.g. swelling, tenderness) are generally present but may be subtle.

Pain with active or passive movement is a cardinal feature.

limp or refusal to walk or bear weight.

Referred pain :

SA of hip knee pain

SA of sacroiliac joint symptoms may mimic appendicitis, pelvic neoplasm, or urinary tract infection

Presentation2-Physical Examination

Decreased or absent ROM, joint tenderness, swelling, warmth, and erythema.

Joint position :

hip is flexed, abducted, and externally rotated.

The knee, ankle, and elbow are partially flexed.

shoulder is adducted and internally rotated.

Fever: mostly low-grade

DDX Transient Synovitis:

Kocher’s Criteria :

1) Fever +++

2) difficulty of bearing weight on a limb

3) ESR > 40 mm/hr

4) peripheral (WBC) > 12,000 cells/μL

were independent variables that best distinguished SA from transient synovitis.

Slipped capital femoral epiphysis

Perth's disease

Clinical features, imaging studies, and/or synovial fluid analysis usually differentiate these conditions from acute SA.

Workup

Diagnosis = clinical findings + synovial fluid analysis

 low threshold for performing arthrocentesis

Workup1-laboratory studies

Blood tests (CBC ,ESR ,C-RP , culture)

Synovial fluid WBC , Gram stain , culture , and susceptibility test.

Additional lab. Studies when particular organisms are suspected

Workup1-laboratory studies - Blood tests

Peripheral WBC +ESR+C-RP usually elevated…some cases mildly elevated

ESR and/or C-RP are better – than + predictors of SA.

ESR > 20 mm/hr in most children with SA …mean= 55mm/hr

rise for 35 days after institution of appropriate therapy …my still raised for 30 days.

C-RP mean=8.5 mg/dl…rise within 3650 hrs. of onset of infection and usually falls to normal within a week of successful treatment

Better than ESR to monitor response to treatment

Workup1-laboratory studies - Blood tests

aerobic blood cultures in all patients in whom SA is a consideration

anaerobic cultures should be obtained if anaerobic infection is a concern (eg, direct inoculation).

Blood cultures are positive in approximately 40% of cases and sometimes yield the pathogen when joint fluid cultures are negative .

Workup1-laboratory studies – synovial fluid

Aspiration ASAP = identification of organisms + joint decompression

Hip aspiration + imaging guidance to confirm joint entry

 heparinized syringe so that clot formation does not preclude enumeration of leukocytes

Workup1-laboratory studies – synovial fluid

synovial fluid should be obtained for (CBC), glucose, Gram stain, and culture.

Synovial culture has poor sensitivity (60-70%)

S. fluid WBC > 50,000/µL suggests SA, especially if> 100,000/mL or if a predominance of polymorphonuclear cells

The S. fluid glucose 30% of that in the serum,unique to SA.

The S. fluid WBC <50,000 cells/microL in patients with unusual causes of bacterial arthritis (eg, Brucella) and may >50,000 cells/microL in children with JIA, serum sickness, or reactive arthritis.

Workup1-laboratory studies – synovial fluid

Gram stain — bacteriostatic effects. Approximately 40- 50% of joint aspirates are sterile…

Culture — The identification of organisms in joint fluid is the primary criterion for the diagnosis of SA.

Synovial fluid cultures are positive in approximately 50-60% of patients with other clinical and laboratory findings of bacterial arthritis.

False negative synovial fluid cultures may occur with fastidious organisms, inadequate laboratory techniques, or prior treatment with antibiotics.

Workup1-laboratory studies – synovial fluid

Other studies

Polymerase chain reaction (PCR) testing for Kingella kingae and other fastidious pathogens.

Serology  for Borrelia antigens should be sent when Lyme-disease-related articular disease is suspected.

Workup2-imaging studies

 plain radiography

is insensitive… may be most helpful in screening for etiologies other than SA as a cause of joint pain. E.g. bony changes suggestive of osteomyelitis, bony tumors or fractures as the source of swelling, and Legg-Perthes disease or a slipped capital femoral epiphysis.

Ultrasonography

Hip effusion &  to guide the aspiration needle if an effusion is detected.

Scintigraphy

limited role ,  may be helpful if multifocal disease is suspected in neonates

assists with the detection of an associated osteomyelitis. 

Treatment

The Goals:

 sterilization and decompression of the joint space

removal of inflammatory debris to relieve pain and prevent deformity or functional sequelae .

Clinical decision making in the management of the child with bacterial arthritis includes the following questions :

How should the joint be drained and irrigated?

Which antibiotics should be administered?

What is the optimal duration of antimicrobial therapy?

When is it safe to switch from parenteral to oral therapy?

Treatment

Hospitalize

Obtain cultures initiate empiric antibiotics before culture results.

 immobilization 2-3 days then Encourage early passive ROM to stretch tendons and prevent contractures.

Medication- Drainage (arthrotomy , arthroscopy, needle aspiration)

Medications

ASAP after cultures

All antibiotics that have been studied readily enter the joint fluid after systemic administration; intraarticular injection of antibiotics is unnecessary.

Most children can be treated with sequential antibiotic therapy (parenteral oral) to minimize the length of hospital stay and complications from prolonged vascular access.

Adjunctive therapies:

Analgesia :Opioid (codeine or morphine)acetaminophen or ibuprofen

NSAIDs : reactive synovitis associated with bacterial arthritis

Dexamethasone ??!! :for the first four days of therapy//remains investigational

Medications

Empiric therapy:

- based on age ,clinical features , Gram stain, and local bacterial susceptibility patterns.

-  includes coverage for S. aureus in all ages.

-Commonly used drugs are listed in the table

MedicationEmpiric therapy

Birth to 3 months: S.aureus , GAS S. , G- bacilli

An antistaphylococcal agent (nafcillin, oxacillin, or vancomycin)

Gentamycin or cefotaxime

vancomycin should be included in the regimen for neonates who have been in the ICU for more than one week because of the risk of nosocomial infection with (MRSA) or coagulase-negative staphylococci.

MedicationEmpiric therapy Older than three months : S. aureus , G+ organisms (GAS S. ,

pneumococci). Additional coverage for other pathogens (K. kingae, [Hib], Neisseria gonorrhoeae) may be necessary in select populations.

antistaphylococcal and antistreptococcal agents :

nafcillin , clindamycin , vancomycin , Cefazolin

MedicationSpecific therapy

Specific therapy

S.aureus 3weeks

Pneumococci/N. meningitidis 2weeks

discontinue if ESR and/or CRP have returned to normal by these time points and there is no radiographic evidence of unsuspected osteomyelitis.

Longer courses may be necessary for SA of the hip, and for arthritis caused by Enterobacteriaceae or other unusual organisms.

1970s

MedicationSpecific therapy- Route

Start parenterally

In neonates (<1 month), the entire course should be administered parenterally .the gastrointestinal absorption is unpredictable

>1 month, continue parenterally at least until clinical and laboratory improvement have been demonstrated orally

Clear improvement usually is established 5 to 10 days after initiation of antibiotic therapy. It is indicated by achievement of each of the following conditions:

*The patient has been afebrile for 48 to 72 hours

* Local signs and symptoms of infection are reduced considerably

*WBC has normalized

*CRP and/or ESR has decreased

Oral Antibiotics Complete the course in ages >1 month providing unequivocal

improvement

 In randomized and observational studies, treatment of SA with IV antibiotics for short periods (approximately seven days) followed by oral therapy, was as successful as longer courses of parenteral therapy.

Subsequent oral therapy may be substituted for parenteral treatment provided that certain criteria are met:

1) Clear demonstration of clinical and laboratory improvement (ie, swelling, tenderness, and erythema, reduction of C-reactive protein)

2) Decreasing or absent fever

3) oral agent with appropriate coverage is available in a formulation that the child can swallow

4) Adherence to the antibiotic and monitoring regimen are assured

Oral Antibiotics

Cultures isolated organism susceptibility test

not isolated age, clinical features, Gram stain, and local bacterial susceptibility patterns.

Similar spectrum:

Cefazolin cephalexin

Clindamycin oral clindamycin

higher doses than antibitics used for treatment of other infections and recommended in package inserts

The initial doses of oral therapy should be administered while the child is in the hospital to ensure that the drug is tolerated.

DRAINAGE

Drainage V.S. no drainage ?? Human/animals

Arthroscopy alternative for drainage , particularly for SA of the knee.

successful arthroscopic drainage of the hip also has been reported, but the number of cases successfully managed is small and largely involves older children.

Successful management of SA of the shoulder joint of infants has also been described.

When arthroscopic drainage is performed, the surgeon must obtain a full view of the interior of the joint to ensure that no loculated pockets of purulent material remain after the procedure 

Needle aspiration

discomfortable. minimal morbidity , in the older child, may not

require general anesthesia  for uncomplicated SA involving joints other than the

hip or shoulder, serial needle aspirations are performed. 

These may be discontinued once fluid no longer reaccumulates.

RESPONSE TO THERAPY

Clinical and laboratory improvement is indicated by:

Resolution of fever Decreased joint pain, swelling, and erythema Increased joint mobility Decrease in peripheral WBC count and synovial fluid

WBC Decrease in ESR and/or CRP

Complications Joint laxity, subluxation, or dislocation

Joint restriction

Limb-length discrepancy (if the growth plate is involved)

Avascular necrosis

Enlargement of the femoral head (coxa magna) in bacterial arthritis of the hip

Pathologic fractures

The reported complication rates vary depending upon the patient population, the involved joint, and the duration of follow-up:

residual dysfunction is 10 to 25 percent.

Even with appropriate management, approximately 40% of patients with hip involvement and 10% of patients with knee involvement develop significant complications