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Septic Arthritis vs. Transient Synovitis –A Practical Approach

Lindsay Crawford, M.D.

Assistant Professor

Department of Orthopaedic Surgery

Objectives

Definition/Epidemiology

Workup

History and Physical

Labs and Imaging

Aspiration

Treatment

Case Presentation

Transient Synovitis

Inflammation of the synovium of the hip

Can be associated with:

Trauma

Viral or Bacterial infection

Allergic Reaction

Benign course with marked improvement within 24-48

hours

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Transient Synovitis

Epidemiology

Most common cause of hip pain in the pediatric

population

Most common age group 4-8 yo

Boys affected 2X more often

Septic Arthritis

Culture positive joint fluid

Negative cultures and five of the following:

Temp >38.3

Pain with motion

Swelling

Systemic symptoms

Absence of other pathologic processes

Response to antibiotics

Septic arthritis

Epidemiology

5.5-12/100,000 children

Peak incidence is in kids < 3

Boys affected 2X more often

Lower extremity most commonly affected, with

the hip and knee most often involved

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Septic Arthritis

Caused by hematogenous seeding of synovium from transient bacteremia

Acute osteomyelitis and septic arthritis co-exists 20-30%

Metaphysis is intra-articular in four locations:

Proximal femur

Proximal humerus

Distal lateral tibia

Proximal radius

Direct inoculation from penetrating injury

History

Onset/Duration

Location of pain

Limping v refusal to bear weight

Constitutional symptoms- fever

History of recent trauma or illness

Evaluation

Physical Exam

Inability to bear weight, limp vs crawl

Erythema, swelling, warmth of affected area

Pain with range of motion

Hip flexed, abducted, externally rotated

Laboratory

CBC with diff, ESR, CRP

Blood cultures

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Transient synovitis

Child eating well

Often history of URI

or gastroenteritis

May have low grade

fever

Permits some hip

movement

Septic arthritis

Fever >101°F

Won’t walk

Poor appetite

Limited hip movement

Differential Diagnosis

Differential Dx

Transient synovitis

Septic arthritis

Reactive arthritis

Inflammatory arthropathies: JRA

Trauma

Neoplasm

Other infection

Septic arthritis vs transient synovitis

Kocher criteria:

History of fever

Non-weight bearing

ESR >40

WBC >12,000

93 % predictive of septic arthritis with 3 criteria

99.6 % with 4 criteria

Kocher, JBJS, 1999

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0

10

20

30

40

50

60

70

80

90

100

1 2 3 4

Number of PositivePredictors

Probability of Septic Arthritis vs.

Number of Predictors

Kocher, et.al.

J. Bone Joint Surg.

81A:1662, 1999

Recommendations

0 positive risk factors – Observe

2 positive risk factors – Aspirate (IR)

3-4 positive risk factors – To OR for aspiration and I&D

Kocher, et.al.

J. Bone Joint Surg.

81A:1662, 1999

Septic arthritis vs transient synovitis

Five variables:

Temp >38.5

WBC >12,000

ESR >40 mm/hm

CRP >2.0 mg/dL

Refusal to bear weight

Predicted probability of septic arthritis:

93.1% 4 criteria; 97.5% 5 criteria

CRP only risk factor associated with outcome

Caird et al. JBJS, 2006

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Septic arthritis vs transient synovitis

39/133 pts who underwent hip aspiration were diagnosed with septic arthritis

CRP:

Sensitivity: 41-90%

Specificity: 29-85%

PPV: 34-53%

NPV: 78-87%

CRP <1.0, 87 % probability patient does not have septic arthritis

Levine et al, JPO, 2003

Validation

Validation of Kocher’s criteria

4 criteria, area under the receiver operating

characteristic curve was 0.86

Kocher JBJS 2004

4 criteria, 59% predicted probability of septic

arthritis Luhmann JBJS 2004

5 criteria, 59.9% predictive, fever best predictor

Sultan JBJS Br 2010

Radiographs

Rule out

fracture/dislocation

Assess for joint effusion

Assess for boney

involvement

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Ultrasound

Assess for joint effusion

Low cost

Non-invasive

No sedation

Lack of specificity (5% false-neg rate)

Operator dependent

Useful to guide hip aspiration

Laine, JPO B, 2015

MRI

Evaluate for effusion

Assess for bone

involvement

Abscess or pyomyositis

Multifocal involvement

At Our Institution

MRI hip Osteo Protocol

Coronal T1

Coronal STIR

Axial T2 fat-sat

Axial DWI

Approximately 15 mins to perform

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MRI vs. Emergent Aspiration

Aspiration

68% diagnosed with septic hip

30% had MRI after non-response to treatment

32% incorrect/incomplete diagnosis

30% reoperation

MRI

17% did not require surgery

30% with septic arthritis has associated osteomyelitis

16.8% reoperation rate

Gottschalk, JPO 2014

MRI vs. Emergent Aspiration

Considerations:

Systems Based Practice

Need for sedation

Delay in operative treatment of septic arthritis

Aspiration

Synovial Fluid Analysis

WBC(000’s) Poly

Transient Synovitis 5-15 <25%

JRA 15-50 75%

Septic Arthritis 50-100 >75%

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Aspiration

Management of Aspiration WBC 25,000-75,000

Septic arthritis final diagnosis 48% >50,000 and 17%

<50,000

Other diagnoses: Lyme arthritis, transient synovitis

In patients >50,000, each Kocher’s criteria increased odds

of septic arthritis near fourfold

In patients <50,000, no association between increasing

number of Kocker criteria and diagnosis of septic arthritis

Heyworth, JBJS, 2015

Transient Synovitis

Treatment

Rest and NSAIDs

Follow fever curve

Close observation for:

Persistent/worsening limping

Fever

Signs of systemic illness

Septic Arthritis Treatment

Drainage in all cases- “when in doubt, wash out”

Multiple aspirations and irrigations

Unstable patient; Gonococcal infection

Arthroscopic drainage

Open surgical drainage

IV Antibiotics

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Complications: Septic Arthritis

Arthrofibrosis

Joint destruction

AVN

Physeal closure

Risk factors:

Symptoms >4 days

Associated AHO

Future Direction:

Clinical Practice Guidelines

Clinical Practice Guidelines

Kocher, JBJS, 2003

Lower rate of presumptive

drainage

Greater compliance with

recommended antibiotic

therapy

Faster change to oral

antibiotics

Shorter hospital stay

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Case Presentation

3 yo M presented as a transfer for fever and refusal to

bear weight on the right lower extremity. He reports the

pain to be in his knee

ED workup:

Temp 103.8

XR of entire right lower extremity and knee U/S

Labs: WBC 11.4, ESR 35, CRP 52.7

Case Presentation

Orthopedic evaluation

PE: RLE: Skin is intact. No erythema is present. No

swelling throughout. No knee effusion. He is nontender

to palpation over the proximal tibia or distal femur. He

has tenderness to palpation in the right thigh as well as

tenderness in the right hip anteriorly in the groin and

guards against range of motion to both hip and knee. He

holds extremity in hip and knee flexion with hip ER

Based on exam Hip U/S and MRI right femur ordered

Case Presentation

Hip U/S: Small right hip effusion

If I would not have been able to get MRI urgently, plan

would be for OR for right hip aspiration given criteria of

fever, refusal to bear weight, and CRP

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Case Presentation

MRI right femur:

1. Nonspecific myositis of the right right obturator internus/externus, pectineus and adductor longus muscles possibly indicating a muscle strain. Underlying infection cannot be entirely excluded.

2. Small right hip joint effusion which may be reactive to trauma or adjacent inflammation however cannot totally exclude an early septic arthritis.

3. No evidence of osteomyelitis. No evidence of abscess collection.

Case Presentation

Patient taken directly to the OR from the MRI suite for

open I&D of the right hip

Empiric IV antibiotics given after cultures obtained in the

OR

Blood culture and right hip culture: MSSA

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References: Kocher

Kocher MS, Zurakowski D, Kasser JR Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999 Dec;81(12):1662-70

Kocher MS, Mandiga R, Murphy JM, Goldmann D, Harper M, Sundel R, Ecklund K, Kasser JR A clinical practice guideline for treatment of septic arthritis in children: efficacy in improving process of care and effect on outcome of septic arthritis of the hip. J Bone Joint Surg Am. 2003 Jun;85-A(6):994-9.

Kocher MS, Mandiga R, Zurakowski D, Barnewolt C, KasserJR. Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am. 2004 Aug;86-A(8):1629-35

References

Caird MS, Flynn JM, Leung YL, Millman JE, D'Italia JG, Dormans JP. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006 Jun;88(6):1251-7

Gottschalk HP, Moor MA, Muhamad AR, Wenger DR, Yaszay B Improving diagnostic efficiency: analysis of pelvic MRI versus emergency hip aspiration for suspected hip sepsis. J Pediatr Orthop. 2014 Apr-May;34(3):300-6

Heyworth BE, Shore BJ, Donohue KS, Miller PE, Kocher MS, Glotzbecker MP. Management of pediatric patients with synovial fluid white blood-cell counts of 25,000 to 75,000 cells/mm³ after aspiration of the hip. J Bone Joint Surg Am. 2015 Mar 4;97(5):389-95

Laine JC, Denning JR, Riccio AI, Jo C, Joglar JM, Wimberly RL The use of ultrasound in the management of septic arthritis of the hip. J Pediatr Orthop B. 2015 Mar;24(2):95-8

Luhmann SJ, Jones A, Schootman M, Gordon JE, Schoenecker PL, Luhmann JD Differentiation between septic arthritis and transient synovitis of the hip in children with clinical prediction algorithms. J Bone Joint Surg Am. 2004 May;86-A(5):956-62

Thank you!