DIAGNOSIS OF SEPTIC JOINT IN CHILDREN Sara Jane Shippee UW Orthopaedic Surgery, PGY-1 Seattle Children’s Hospital 11/1/2012

CASE A two-week-old infant presents with nonmovement of the left hip. History reveals that the patient was delivered 6 weeks premature by cesarean section. Examination reveals no fever, and there is mild swelling of the thigh. Passive movement of the hip appears to elicit tenderness and very limited hip motion. A radiograph of the pelvis shows mild subluxation of the left hip. The next step in evaluation should consist of: 1.Initiate IV antibiotics 2.A gallium scan 3.An MRI scan 4.Application of a Pavlik harness 5.Aspiration of the left hip

CLINICAL FEATURES Vary depending upon the AGE of the child SITE of infection ORGANISM

AGE Children and adolescents Fever and joint pain Constitutional symptoms (malaise, poor appetite, irritability, tachycardia) Cardinal feature: PAIN with active or passive range of motion In the lower extremity, limp or refusal to walk

AGE Young infants Septicemia Fever without a focus Positional preferences Pseudoparalysis Discomfort with handling Swelling NEWBORNS Prematurity C-section Pseudoparalysis Local swelling Pain on passive movement

SITE 80% lower extremity hematogenous direct extension from bone often from metaphysis

ORGANISM Neisseria gonorrhoeae Adolescents Group A beta-hemolytic streptococcus Follows varicella infection Group B streptococcus Neonates with community-acquired infection Staph Aureus most common in children over 2 years of age most common in nosocomial infections of neonates HACEK organisms

HISTORY Progression of symptoms Femoral venipuncture Direct innoculation Rash Recent use of antibiotics Recent or concurrent illness Family history of rheumatologic disease or IBD

PHYSICAL EXAM

LABS CBC w/diff ESR CRP Blood culture SYNOVIAL FLUID WBC w/diff >50,000 cells with >90% PMN Rarely <20,000 Gram stain Culture Susceptibility

CRP Levine et al Negative predictor More useful than ESR for monitoring response to treatment Better independent predictor of disease than ESR

ESR Klein et al 1997 In children 0-6 years old with septic hip: Only 5% had normal ESR 35% were afebrile 27% with normal leukocyte count Most sensitive indicator of septic arthritis of the hip

RADIOGRAPHY Plain radiographs HIP AP PELVIS Frog leg lateral

ULTRASOUND Identifying and quantifying effusion Most helpful for hip Guidance for aspiration Preferred to fluoroscopy in children < 8

MRI Osteomyelitis Bacterial arthritis vs. transient synovitis Failure to respond to antibiotics and aspiration Jik Yang et al. 2006

DIFFERENTIAL DIAGNOSIS Osteomyelitis (without septic joint) Deep cellulitis Abscess of obturator internus or psoas Septic bursitis Bacterial endocarditis Transient or toxic synovitis Trauma SCFE LCP Tumor

REFERENCES AAOS Comprehensive Review. Lieberman, JR, Ed. AAOS. Rosemont, IL: Klein, DM, et al. Sensitivity of objective parameters in the diagnosis of pediatric septic hips. Clin Orthopaed Relat Res May;338: Knudsen CJ, Hoffman EB. Neonatal osteomyelitis. J Bone Joint Surg Br Sep;72(5): Krogstad, Paul. Bacterial arthritis: clinical features and diagnosis in infants and children. Last updated Feb Jik Yang, W, et al. MR imaging of transient synovitis: differentiation from septic arthrits. Pediatr Radiol. 2006;36: