1. Hip Pain and Septic Arthritis

2. Objectives
Recognize the clinical presentation of a septic joint and transient synovitis
Be able to differentiate septic arthritis and transient synovitis based on evidence based medicine
Develop an approach to the assessment of patients with a swollen or painful joint
Know the appropriate management of septic arthritis

3. Definition
Septic Arthritis - disorder of joint where joint capsule is infiltrated by bacteria
Transient synovitis - nonspecific inflammation and hypertrophy of the synovial membrane

4. Incidence Transient Synovitis Age 3 – 8 years old Male : Female 2:1
% of pediatric admissions to ER
Child’s risk of developing during lifetime is 3%
?Seasonal
Septic Arthritis
Unknown number
Non-gonococcal  before age 5
male: female 2:1)
Gonococcal  adolescent females

5. Etiology of Transient Synovitis (or so we think)
Viral agent
Fourfold increase in viral titers in 45% of patients with diagnosis (Tolat et al)
Elevated serum interferon levels in 43% patients
Trauma
17-30% of patients with diagnosis
Local contusion as self-limiting chemical synovitis
Allergy – response to antihistamines??

6. Etiology of Septic Arthritis
Metaphysis – tiny blood vessel loops where low flow and O2 content  traumatic rupture may provide area of bacterial growth
Synovial membrane receptors may have predilection for bacteria

7. Anatomy of Region

8. Sequence of Events Bacteria deposited in subsynovial capillary network
Immune response – may abort at this point if bacterial growth halted
Inflammatory cascade initiated with release of proteolytic enzymes and toxins
Articular cartilage degradation
Increased fluid and pus leading to pressure and ischemia from compression

9. Physical Examination Unilateral joint (90%) No traumatic lesion
+/- fever and other signs of infection including: n/v, diarrhea,headache
Limp or refusal to bear weight
Decreased range of motion
Palpation of effusion and tenderness
Prefer position of hip to be slightly flexed and externally rotated  maximize joint space to decrease pressure

10. Current Standards of Care
Labs: CBC, ESR (or CRP)
Blood Culture – in 1 study only 50% of patients with documented septic arthritis had positive blood culture
Radiography of hip: AP and frog leg views of hip  some studies question need for these X-rays
Gold standard – aspiration of fluid for cell count, gram stain, culture and sensitivity (97% sensitivity)
Another study showed 12/23 (52%) and 19/33 (58%) had pathogens isolated

11. Other Imaging Modalities
Standard US – demonstrates an effusion but cannot differentiate an infectious from noninfectious etiology
Doppler Sonography (1998) – look at increase blood flow; preliminary evidence shows poor sensitivity but high specificity
MRI – signal intensity changes seen in bone marrow of septic arthritis (no difference in signal of soft tissue or in grade of effusion)
MRI was preliminary study involving 9 patients who had septic arthritis with 14 patients with transient synovitis

12. How can one be sure a painful hip with effusion is not a septic joint???

13. Evidence Based Medicine Study 1
Retrospective study looked at 509 patients who presented with irritable hip and limp.
Presence of any two of these clinical criteria (see next page for graph and criteria) was 95% sensitive and 91% specific for septic arthritis.

14. Clinical Criteria – Study 1
Retrospective study looked at 509 patient patients who presented with irritable hip and limp.
Presence of any two of these clinical criteria was 95% sensitive and 91% specific for septic arthritis.

15. EBM – Study 2 Four Predictors: Recommendation: Fever
Non-weight bearing
ESR > 40
WBC > 12
Recommendation:
3-4 predictors good candidates for aspiration in OR b/c high likelihood that arthrotomy and drainage will be needed
2 predictors aspirate with U/S or fluroscopy

16. Clinical Criteria – Study 2
Fever 2.Non-weight bearing 3.ESR > WBC > 12
Recommendation:
3-4 predictors good candidates for aspiration in OR b/c high likelihood that arthrotomy and drainage will be needed
2 predictors aspirate with U/S or fluroscopy

17. Predicted Probability – Study 2

18. Treatment & Prognosis Transient synovitis Septic Arthritis
Tx  rest and anti-inflammatory agents
Lasts 3-10 days
Septic Arthritis
Treatment:
Naficillin and 3rd generation cephalosporin
Vanco and aminoglycoside
Oxacillin and gentamicin
Most important prognostic indicators:
4 to 5 days to begin treatment to avoid long-term consequences
Evidence of osteomyelitis  poor prognosis

19. Complications of Septic Arthritis
Osteonecrosis
Cartilage destruction
Postinfectious degenerative arthritis
Joint instability
Deformity

20. Bibliography
Do Twee T. Transient synovitis as a cause of painful limps in children. Current Opinion in Pediatrics. 12 (1):
Klein D, Barbera C, Gray S, Spero C, Perrier G, Teicher, J. Sensitivity of objective parameters in the diagnosis of pediatric septic hips. Clinical Orthopaedics and Related Research. 338:
Kocher M, Zurakowski D, Kasser J. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. The Journal of Bond and Joint Surgery.
Chen C, Ko J, Li C, Wang C. Acute septic arthritis of the hip in children. Archives of Orthopedic Trauma Surgery. 121: