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Bone and joint infection

Bone and joint infection. Dr. Katia Sitnitskaya. Osteomyelitis. Acute hematogenous osteomyelitis (AHO) Subacute contiguous osteomyelitis Chronic osteomyelitis (recurrence) . AHO. 1/2 in < 5 y.o. 1/3 report minor trauma Metaphyses of long bones: 85%

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Bone and joint infection

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  1. Bone and joint infection Dr. Katia Sitnitskaya

  2. Osteomyelitis • Acute hematogenous osteomyelitis (AHO) • Subacute contiguous osteomyelitis • Chronic osteomyelitis (recurrence)

  3. AHO • 1/2 in < 5 y.o. • 1/3 report minor trauma • Metaphyses of long bones: 85% • Multiple locations: 5%, in JRA

  4. AHO: pathogenesis • Source: episode of bacteremia • Slow blood flow in metaphyseal capillary loops • Microcolonies surrounded by glycocalix plug capillaries, blocking the access for PMNs and antibiotics • M/o escape through endothelial gaps to the tissue • Expression of adhesinsallows m/o to attach to the components of bone matrix, e.g. sialoglycoprotein • Staph. aureus survives in osteoblasts: hard to eradicate

  5. AHO: pathogenesis Attraction of inflammatory cells Cellulitis of bone marrow Lymphocytes release IL-I, TNF PMNs produce proteolytic enzymes Osteolysis Inraosseous spread + pressure Ischemia, necrosis, subperiosteal abscess

  6. AHO: sites Radius 4% ulna 3% Humerus 12% Pelvis 9% Femur 27% Hands & feet 13% Tibia 22%fibula 5%

  7. Joint involvement in AHO • Transphyseal vessels in < 18 mo.o. • Proximal femur / humerus: metaphysis is within joint capsule • Finland: in 16% of Staph. aureus AHO in a 3 mo-14 y.o (# 50) • Prospective LA study: 1988 – 96, # 58 AHO, 1 mo –17 y.o. (J. Ped Ortho, 2000) - Dx was based on bone and synovial cultures - 1/3 of AHO pts had septic joint (@ any age) - knee 31%, hip 23%, ankle 18%, shoulder 14% MRI demonstrated sub-periosteal spread of infection in a few images

  8. AHO: bacteriology • < 3 mo.o.: Staph. aureus, enteric GNRs, GBS (3%) • < 3 y.o.: Staph. aureus, HiB in non-immunized • > 3 y.o.: - 2/3 Staph. aureus - 15% GAS - 2% Pneumococcus

  9. AHO: presentation & WU • Fever: low-grade or high, may be absent • Localpain + tumor, rubor, color • Point tenderness, limping • WBC elevated in 1/3 • CRP (Finland. Ped, 1994) # 44 pts, 2 we – 14 y.o., culture-confirmed AHO CRP > 19 mg/L in 98%, peak on D # 2

  10. Sequela-prone AHO • 6% have sequaelae:- growth arrest - restricted motility - pathological Fx (very rare) • Costa Rica, 1992 – 94, # 83 AHO, 3 mo – 13 y., FU min 6 mo., 55 (-) sequelae vs. 28 (+) sequelae; bone drill in 3/4 Patients with sequalae had: - CRP > 50 mg/L on D # 1 – 6 - fever > 7 d. / local symptoms > 10 d. Sensitivity of the combination of 2 factors = 92% @ > 6 mo. FU (CID, 1997)

  11. AHO: imaging • Baseline x-ray:Fx, tumor the earliest sign = soft tissue swelling on D # 3 periosteal elevation / lytic lesions on 2d- 3d week lysis of bone is seen when up to ½ of bone matrix has been destroyed • Gallium67 scan : - uptake by PMNs, in 24 hrs - sensitivity: 91%

  12. Osteomyelitis

  13. AHO: imaging • 3-phase Tc99 scan: sensitivity: 92% 1-st phase = blood flow = “angiography” (in 20 sec) 2-d phase = soft tissue (in 10 min) 3-d phase = uptake by osteoblasts & WBCs(in 2 hrs) *Early: “cold” spot (ischemia), or may be false-(-) with prompt Tx • Tc99-tagged WBC scan: imaging in post-surgical or equivocal osteo 20 ml of blood, separation of WBCs, incubation with Tc99 x 2 hrs, scan in 3 hrs Gallium >> Tc uptake and incongruence of distribution indicates osteomyelitis

  14. Bone scan

  15. AHO: imaging • CT: - cortical destruction - periosteal reaction - sequestra - intraosseeous gas • MRI: T1 =low signal, T2 = high signal , sensitivity 97%, specificity: 92% - marrow inflammation / ischemia - poor interface between NL & abnormal marrow = acute - the best for spinal and pelvic osteo - the best for pre-operative evaluation

  16. CT scan & MRI CT scan MRI

  17. X-ray vs. MRI

  18. A bone abscess (Brodie's abscess) X-ray CT scan T99 scan

  19. AHO: bacteriology Needle aspiration: for “S” and SBT Bone culture (+) in 2/3 Blood culture (+) in 1/2 18 gauge spinal needle + Lidocaine “Needle is part of physical diagnosis”

  20. Empiric Tx of AHO

  21. Definitive Tx of AHO SBT: > 1:16serum @ 1 hr after 4-th dose is incubated with patient’s isolate x 18 hrs

  22. AHO: indications for surgery • Soft tissue or ubperiosteal abscess • Purulent aspirate • Failure of Abx in 72 hrs • Sequestrum **Debridement in proximity to the growth plate is risky

  23. AHO: duration of Tx Switch to PO: - resolution of symptoms and fever - CRP approaching NL - SBT > 1:8 + compliance assured Duration of Tx:- asymptomatic - CRP NL - min 3 weeks *Get an X-ray at the end of Tx (sequestrum?)

  24. AHO: duration of Tx Prospective randomized study of of Staph. aureus AHO # 50 pts,3 mo – 14 y.o., 1982 – 1996, Finland ( Ped, 1997) -Cephradine vs. Cld IV, switch to PO after 4 d. with defevrescence - 2/3 = no dril; no SBTs, no sequalae in 1 yr -CRP was NL (< 20 mg/L) within 9 days, total duration of Tx: 3 – 4 we

  25. Contiguous subacute osteomyelitis • Punctured wound (in 3 – 5 d.) Foot: osteo in 1.5% of injuries • Animal bite (cat) • Ulcer (anesthetic limb, decubiti) • 2o to sinusitis (Pott’s puffy tumor) / mastoiditis • Open Fx • Post ortho surgery ( in 2 – 4 we)

  26. Contiguous subacute osteomyelitis • D # 3 – 5: Staph. aureus, GNRs (incl. Pseudomonas), anaerobes >1/2 = polymicrobial • Usually NO fever, NL WBC count and CRP • Dx: biopsy culture • Recurrence rate: 40% • Tx: Timentin + Gent • Duration: - Pseud. = > 7 d. IV, total 3 – 4 we. - decubitus: debridement + up to 6 mo. ABx

  27. Contiguous subacute osteomyelitis NYU cohort of # 24 pts, 8 mo. – 18 y.o., 1980 – 85 • 15/18 (+) bone culture: 9 Staph. aur, 4 Pseud, 8 enteric GNRs • Compound Fx = 12, decubiti = 6, foot puncture = 3 • Post-Fx: 3/4 had purulent d/c • NL CBC = 60% & NL SED = 40%, only few had fever • Duration of Tx: min 4 we • Recurrence rate: 42%

  28. SCD: AHO vs. infarct • Pain, swelling, fever, high WBC coun, elevated SED • MRI: edema mimics osteo • T99 –colloid marrow scan (WBC uptake), followed by T99 methylene diphosphonate scan (osteoblast uptake) Infarct: NO uptake on marrow scan + abnormal bone scan Osteo: NL marrow uptake + abnormal bone scan • LA cohort of # pts with SCD, 9 mo – 19 y.o., 1988 – 1998 (JBJS, 2001) # 79 SCD # 4 NL m. /abn b. 3 confirmed osteo # 70 low m. / abn b. 66 no ABx, resolved # 5 NL m & b No ABx, resolved

  29. AHO in SCD • Second most common infection after pneumonia • Salmonella 70%, Staph. aureus 10%, Pneumoc, Proteus, Serratia • Diaphyses of long bones, flat bones, small bones of hands and feet • May be multifocal, symmetrical involvement • Longer IV Tx: up to 6 –8 we

  30. Septic arthritis • Peak incidence: < 3 y.o., common Hx of trauma • > 90% monoarticular ( multiple in N.gon) • Knee (40%) >> hip (1/4) > ankle > elbow • Staph. aureus >> GAS > Pneumococcus ( in < 5 y.o.) • Sequalae = late (15%): - stiff joint (cartilage damage) - unstable joint (chronic dislocation) - arrest of bone growth

  31. SA: high risk for sequalae • < 6 mo. o. • joint + bone • hip & shoulder • > 4 d. delay in aspiration and ABx • long sterilization time

  32. Septic arthritis: pathogenesis • Highly vascular synovial tissue, no basal membrane • Hematogenous spread, adhesion to sialoprotein in synovial fluid • Chondrocytes and synovial WBCs release proteases that destroy ground substance of articular surface • Bacterial endotoxins stimulate release of IL-1 & TNF that induce release of proteases

  33. Septic arthritis • Fever, pain, swelling, redness, decreased motility • Hip: favoring = “frog position” (flection + abduction) • Elevated WBC count and CRP in 1/2 • Synovial fluid: WBC > 50 000, PMN > 90%, glu: low / NL • Aspirate culture (+) in > 2/3, Gram stain (+) in 1/2 * send in a blood bottle + container for Gram stain • Blood culture (+) in 1/3

  34. Imaging:- US: fluid collection (hip, shoulder) - X-ray: swelling of the capsule, widened joint space- MRI: most sensitive early, the best for sacroiliitis & bone involvement

  35. Imaging Marked widening of the medial joint space in the R hip as compared to the left hip (arrows) Michael Richardson, 1994, University ofWashington

  36. Septic arthritis: differential Dx SA = only 6% of acute arthritis Always save some fluid (Rapid Strep, Lyme PCR)

  37. SA: principles of Tx • Open drainage: - SA of hip & shoulder - need in aspiration on D # 4 • Aspirate for c/s prior to Tx • Prompt IV ABx, switch to PO when: - afebrile x 48 hrs - improvement of symptoms - no need in repeated aspiration • SBT 1 hr after 4-th dose: > 1:8 • Duration: - 2 we afebrile - min 3 we (GAS, Pneum.: min 2 we)

  38. SA: empiric Tx

  39. SA: duration of Tx Retrospective review of # 20 cases of proven SA of the hip Hospital for sick children, Torronto (J Ped Ortho, 2000) • Infants # 9, pre-school # 5, 5 – 15 y.o. # 6, 1992 – 96 • Staph. aureus 9, Pneumococcus 5, other hemolytic Streps 4 • All had surgical drainage (# 3 had repeated I & D for fever) • IV ABx: 16/20 < 10 d. • Mean duration of Tx: 4 we • FU: mean 14 mo. No recurrence.

  40. Lyme arthritis • 1 – 2 mo. after EM • Knee > shoulder > elbow > temporomand. > ankle • Sudden onset of pain & swelling, usually in 1 joint • Not ill, afebrile, moderate limitation of movements • PCR (+) • Synovial: WBC > 50 K, PMN > 75% • Amox/Doxy x 4 we • Recurrence: Ceftriaxone x 2 – 3 we

  41. Reactive arthritis • Sterile inflammation, but (+) DNA / AGs • 80% have HLA type B27 • 1 – 3 we. after Chlamydia, Yersinia, Campylobac., Shigella • Large joints of lower extremity, oligoarticular • Synovial fluid: WBC < 50 K, PMN > 2/3 • Tx: NSAID • Recurrence: rare in children

  42. Gonococcal arthritis • 1% of acute GU infection, within 1 mo • Low-grade fever, often during menstruation • Rash: in 40%, few papules on extremities (inf. vasculitis) • Septic: knee > hands. Sterile arthritis: hands > knee • Polyarthritis in 1/2 • GU culture (+) in 80%, blood c/s (+) in < 10% • Synovial: Gram stain (+) in < 1/4, c/s (+) in 1/3 • Tx: Ceftriaxone x 7 – 14 d.

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