Infections of the Hip in children Ram Pulavarti

Septic arthritis of hip Thomas Smith 1874 - 21 cases of acute septic arthritis with mortality >50% Since the introduction antibiotics, mortality < 1% Early treatment Initial diagnosis must be on clinical basis

Importance Common problem ‘Irritable hip’ problems inherent to diagnosis and treatment Protean manifestations eg., pain, limp, septicemia, mimic tumor Other conditions such as JRA

After diagnosis What antibiotic before culture results are known? What if cultures are negative? Route of administration? How long? When is surgery indicated? Diversity of organisms, various possible locations Numerous conditions associated with bone and joint sepsis

Hip Disaster Risk of dislocation AVN Shorter leg Stiffness

Infections of the hip Non specific: bacterial Specific: TB, fungal, viral Haematogenous Post Traumatic Iatrogenic

Epidemiology Septic arthritis twice as common as osteomyelitis peak incidence in early years of the first decade Osteomyelitis : peak incidence in the later years of the first decade M > F A H O more in early autumn and late summer in both hemispheres (Gillespie, CORR 1973) Higher incidence New Zealand Maoris, Australian aborginals

Osteomyelitis (AHO) A changing disease A study from Glasgow: < 13 years of age AHO has dropped by more than 50% incidence of subacute infections increased from 12-42% Craigan MA et al JBJS Br 1992; 74:541 Jones NS et al JBJS Br 1987; 69:779

Frequency of osteomyelitis and septic arthritis according to age (yrs) McCarthy JJ et al JBJS 2004

Sites Knee (41%) Hip 23% Ankle 14% Elbow 12% Shoulder (4%) (Jackson and Nelson 1982)

Septic arthritis Primary seeding of synovium Secondary to metaphyseal infection eg., hip, shoulder, ankle, elbow Transepiphyseal vessels (up to 18 months) Directly from infection of epiphysis

Septic arthritis of hip in infancy

Pathogenesis of Haematogenous infection Septic emboli Trauma, haematoma Reduced immunity Glycocalyx (Biofilm)

Why metaphysis? Vascular loop theory Immature phagocytosis theory Injury theory Injection of bacteria as the hemorrhage is forming leads to infected haematoma (Morissy and Haynes 1989)

Course of metaphyseal abscess transphyseal vessels  into the joint Spreading infective thrombosis and periosteal stripping  dead bone Epiphysis may separate the hard cortex  sequestrum infection remains active as long as the sequestrum is present

Course of metaphyseal abscess involucrum formation Left alone, pus kills the periosteum and no new bone is formed Rupture of the periosteum: pus tracks through a soft-tissue planes ‘sinus’

Metaphyseal abscess

Septic arthritis Pathology a fibrin-rich exudate Clotted exudate – a cast in the joint Cartilage destruction: lysozymal enzymes dissolve the glycosaminoglycans of the articular cartilage. The femoral head + growth plate destruction Organisms may vary in their ability to dissolve cartilage : staphylococcus is most damaging Hemophilus inflenzae and Gonococcus are the least damaging

Diagnosis Clinical suspicion Examination : lap exam temp is often normal examine everything before trying the joint – because as soon as this touched, all cooperation is gone Look: is it swollen, warm, can the child move it

Temperature Klein et al: Temp below 380C in 31% Del Bacarro et al: Mean temp 38.10C degrees C Gandini Mean temp: 39.20C

Kocher criteria (for child with painful hip) non-weight-bearing on affect side, Sedimentation rate greater than 40 mm/hr, fever, and WBC count of >12,000 mm3; when 4/4 criteria are met, 99% chance that the child has septic arthritis; when 3/4 criteria are met, 93% chance of septic arthritis; when 2/4 criteria are met, 40% chance of septic arthritis; when 1/4 criteria are met, 3% chance of septic arthritis;           Ref: Kocher et al JBJS 2004,

Organisms Newborn Staphylococcus 36% Streptococcus (21%) E.coli 14% 1month to 5 yrs: hemophilus inflenzae (31%) Children over 5 years: staphylococcus Sexually active teenager - Gonococcus

Negative cultures Because many patients with septic arthritis have negative cultures, it is important to use criteria that include those patients

Diagnosis CBC ESR: most sensitive test; 90% elevated to medium levels CRP Blood cultures Sickle-cell test for black children X ray: to rule out preexisting lesions; Bone Scan: useless at distinguishing septic from nonseptic joints Ultrasound Definitive test: needle aspiration of a septic joint

Laboratory Leukocyte count – not reliable in early stages Only 25% of infants and children with osteomyelitis have a leukocyte count above normal for their age Only 65% of infants and children with osteomyelitis had the differential count abnormal

Most useful lab test in bone and joint sepsis: Laboratory Most useful lab test in bone and joint sepsis: CRP ESR

Laboratory data Normal ESR, CRP or WCC does not exclude the presence of infection Average ESR between 37-94mm/hr Del Becarro et al. ESR 44 in septic arth :: 19 trans synovitis Klein et al average ESR 51mm/h, 95% had an ESR >20mm Gandini 2003: ESR 65mm/hr; all children >20mm/hr CRP mean CRP 144mg/L, all > 20mg/L

ESR non specific unreliable in a neonate, anaemia, sickle cell disease, on steroids almost always elevated 48-72hrs of onset of infection returns to normal over 2-4 weeks after elimination of the infection less reliable in the first 48hrs than after 48hrs continues to rise for 3-5 days after institution of successful therapy therefore not a good means of response to treatment in the first week

CRP inflammation or trauma May rise within 6hrs then increases several hundred fold peak within 36-50hrs Falls quickly to normal with successful treatment early diagnosis and resolution of inflammation

Aspirate rinse with heparin before aspirate Gram stain : organisms in about one third of bone and joint aspirates

Cultures Blood culture: 30-50% yield The yield from cultures decreases with previous antibiotic therapy

Microbiology Gandini: 27% joint fluid positive culture 72% blood cultures no Haemophilus influenza cases Bennet and Namnyak joint fluid positive culture in 91% Blood culture: 42.5%

No string in turbid fluid of septic joints hyaluronate is broken down by enzymes

Differential diagnosis The Hip – leukemia, pelvic osteomyelitis, transient synovitis, discitis, appendicitis Rheumatoid arthritis hardly ever, begins in the hip

Organisms causing AHO Age group Organism Antibiotic Neonates Group B streptococcus, Sta. aureus, gram-negative rods Cefotaxime or Oxacillin and gentamicin Infants and children Sta. aureus (90%) Oxacillin Pts with sickle cell disease Staphylococcus aureus or Sa,monella Oxacillin and ampicillin or cefotaxime or chroamphenicol

Negative cultures Five of the six criteria to diagnose septic arthritis: (Morey et al.) Temp > 38.30 c Pain in suspected joint made worse by motion Swelling of suspected joint Systemic symptoms Absence of other pathologic processes A satisfactory response to antibiotic

Treatment Drainage Move the joint: to prevent intraarticular adhesions Dislocated hip should be abducted to reduce it Monitor serum bactericidal titers – changes to oral antibiotics at 1 wk Abs for 3-6 wks when ESR returns to normal

Any child with spontaneous acute metaphyseal pain and tenderness Never let the sun set on pus under pressure Any child with spontaneous acute metaphyseal pain and tenderness has osteomyelitis until proven otherwise

Treatment Parenteral antibiotics Duration of antibiotic – 2weeks to 4 months

Sequelae of Septic Arthritis of the Hip Partial or complete destruction of the proximal femoral physis Osteonecrosis of the femoral head Trochanteric overgrowth Pseudarthrosis of the femoral neck Complete dissolution of the femoral neck and head Progressive limb-length discrepancy Varus or valgus alignment of the femoral head Hip dislocation Ankylosis of the hip joint

This is not so hard!

Bottom line Early, accurate diagnosis of septic arthritis of the hip in children is critical Poor outcomes with a delay in diagnosis High degree of suspicion and Clinical judgement