1. Osteomyelitis & Septic Arthritis
Jay Green
November 23, 2006

2. Outline Both Osteomyelitis Septic Arthritis
Risk factors, mechanism of infection, pathogens
Osteomyelitis
Septic Arthritis

3. Case 61y.o. M, ↑R leg pain, fever, H/A, fatigue
PMH: DMII, CAD, smoker, COPD
Recent # R tibia  ORIF
Post-op exacerbation of COPD  still tx

4. Question What are some risk factors for bone/joint infections?
Who gets bone/joint infections?

5. Risk Factors IV drug users AIDS Post-sx – prosthetic implants
Iatrogenic immune suppression
Sickle cell anemia
Diabetes
Alcoholism
Pre-existing joint disease

6. Bone/Joint Infection – Fast Facts
Bimodal age distribution
<20 y.o. and >50 y.o.
Occur in healthy kids or adults with RF
Mortality (OM)
Pre-antibiotic era 20%
Today <5%
1% incidence in inpatients

7. Anatomy Review - FYI Bones: Cortex, medulla
Haversian canals in cortical bone run parallel to long axis and contain BS
Volkmann’s canals run perpendicular to Haversian canals and reach subperiosteal space
In OM infection takes place in haversian canals and causes local necrosis
Joints: double-layered capsule – dense fibrous tissue, synovial membrane

8. Case 51y.o. M, swollen, tender R knee
Seen in ED 2 weeks ago  fluid taken off
Last 2 weeks ↑↑pain/redness/swelling knee
Using ice, ibuprofen with some relief
Now fever, fatigue, nausea, myalgias

9. Question
By what mechanisms can a bone/joint become infected?

10. Mechanism of Infection
Hematogenous spread
Contiguous spread
Direct inoculation
Penetrating trauma
Joint aspiration
Predisposed sites
Long bone metaphysis, vertebral body
Hematogenous – kids, adult vertebrae
other adult OM – contiguous spread or direct inoculation
Metaphysis – slow-moving venous systems, relative lack of phagocytes

11. What bug? 12F from Angola 23M sexually active
N. gonorrhea
68M with DMII and foot ulcer
S. aureus, Anaerobes, enterobacteriaceae
12F bit by her cat
Pasteurella
21M bouncer bitten by drunk on elbow
Eikenella
51M stepped on nail
Pseudomonas

12. Pathogens *Bacterial* Viral Fungal Parasitic
Depends on host/environmental factors

13. Pathogens – Key Points S. aureus = #1 (except neonates – GBS)
H. influenzae B  gone
N. gonorrhea <30y.o.
Gram –ve in elderly
Polymicrobial – DM, post-trauma, chronic
DM foot OM, post-traumatic OM, chronic OM/SA

14. Pathogens – Key Points
Pseudomonas – puncture wound to foot, prosthetic implants, IV drug users
Pasteurella multocida – animal bites
Fungal – increasingly common
Fungal – esp in hospitalized pts (broad spectrum abx, immunosuppressive Rx, invasive monitoring devices, TPN)

15. Case 9F ↑ing pain R tibia x 4 days Malaise, H/A, fatigue, anorexia
No fever at home, no trauma
O/E:
Vitals: 375, 98/75, 88, 18
Gen: looks well
R leg: erythema, swelling, ++tender, warm

16. ?Osteomyelitis?

17. Question
What would you like to order?
Labs?
Imaging?

18. Osteomyelitis - History
5 cardinal signs of inflammation
Pain, erythema, swelling, warmth, ↓ function
±Fever
Systemic symptoms
H/A, fatigue, malaise, anorexia

19. Osteomyelitis – Physical Exam
General
Not ill
Inspection
Erythema, swelling
Palpation
Point tenderness, warmth
±involucrum, ±sequestrum
+- are in chronic advanced OM

20. Involucrum
New periosteal growth due to subperiosteal abscess

21. Sequestrum
Disengaged ischemic segments of bone

22. Return to case WBC 12,000 ESR 80mm/hr
Plain x-ray – N (confirmed by radiology)
What do you think of her ESR?
While waiting for your bone scan you pull out your palm to read about OM

23. Investigations Labs typically unhelpful ±↑WBC (N – 15,000)
↑ESR more sensitive
Mean ESR = 70
<8% have ESR < 15

24. Imaging Start with plain films May miss acute presentation Features?
<1/3 have abN x-ray if <10d of symptoms
Lucent areas  30-50% bone mineral lost
Features?
Lytic lesions, periosteal reaction, sequestra, involucrum
Soft tissue – deep swelling, distorted fascial planes, altered fat interfaces
Soft tissue – helpful in early stages (may start to see as early as d3-5)

25. Question WBC 12,000, ESR 80, plain film normal
What would you like to do now?

26. Bone scan

27. Imaging – Nuclear Medicine
Bone scan
Can detect OM within 48-72h
99mTc MDP
3-phase scan
Flow – within 60sec
Pool – 5-15min
Delayed – 2-4hrs
Technetium methylene diphosphonate
Technetium-labeled diphosphonates bind to hydroxyapatite crystals in bone matrix  greatest uptake in areas of OBL activity

28. Imaging – 99mTc MDP Flow Pool Delay Diagnosis - Not OM +
Degenerative disease
Inflammation
OM, false +

29. Imaging – 99mTc MDP SN > 90% FP rate ~65%
Trauma, surgery, tumor, chronic soft tissue infection, healing fracture

30. Other radionuclides 67Ga citrate 111In oxine
99Tc hexamethylpropyleneamine oxime
?Useful in ED
All have 24-48h wait time

31. CT Scan May miss acute presentation Better for:
Sternum, vertebrae, pelvic bones, calcaneus
Useful post-bone scan, guides sx/bx

32. MRI Comparable SN to bone scan Better resolution IV gadolinium
Bone vs. soft tissue infection
Normal vs. devitalized bone
Availability limited
?Replace bone scan altogether?

33. Question How do we find the bug? In ED Not in ED Find bug in 80-90%
Blood culture
+ in 50%
– always if chronic
NOT cultures from fistulae/sinus
Not in ED
Biopsy – needle, resection
Find bug in 80-90%

34. Question WBC 12, ESR 80, x-ray N, bone scan +
What would you like to do doctor?

35. Management IV antibiotics Surgery Typically empiric to begin 4-6 weeks
Debridement often necessary
Can avoid in kids with acute hematogenous OM

36. Empiric Abx - Adults Osteomyelitis Pathogen Therapy Hematogenous
S. aureus
Cloxacillin or Cefazolin +/- Gentamicin
IVDU
P. aeruginosa
Cloxacillin or Cefazolin
+ Gentamicin
Contiguous: vascular insufficiency, diabetic foot
Polymicrobial
Clinda + Cipro or
Ancef + Metronidazole
Severe: imipenem or pip-tazo
Nail-puncture of foot
Prophylaxis: cipro
Treatment:pip-tazo + tobramycin
Post-op prosthetic joint
S. epidermidis
Vancomycin +
Gentamicin

37. Empiric Abx - Kids Osteomyelitis Pathogen Therapy Neonates
GBS, S. aureus, Enterobacteriaceae
Cloxacillin + Cefotaxime
Children
S. aureus, Strep, H. flu
Cloxacillin
Sickle cell
S. aureus, Salmonella sp.
Post-op
S.aureus, GAS, Enterobacteriaceae
Cefazolin +/- Gentamicin
Post-op spinal rods or sternotomy
S. aureus, CNS, GAS, Enterobacteriaceae, Pseudomonas
Vancomycin + Gentamicin
Nail puncture of foot
Pseudomonas aeruginosa
Piperacillin+Tobra or
Ceftazidime + Tobra

38. Case 77M DMII, ankle ulcer x 1 yr
Draining pus, occasionally ↑pain/redness
Several courses of abx over past year

39. Question
Are imaging or cultures of the pus useful in chronic osteomyelitis?
Will IV/PO antibiotics be sufficient?

40. Chronic Osteomyelitis
Usually complication of post-traumatic OM, surgery, diabetic foot infection
Recurrent course
Sequestra
Chronic draining sinus/fistulae
Polymicrobial, commonly anaerobes

41. Chronic OM - Investigations
Bone scan – limited use
Cultures of tracts not reliable
Need bone bx
Bone scan - Difficult to predict improvement or ID active foci of infection

42. Chronic OM - Management
Surgery
Antibiotic-containing beads
Bone grafts
±HBO
Seems to be effective in case-series and non-randomized studies for DM foot osteomyelitis

43. Case 28 y.o. M Ped-MVC while biking to work Spinal precautions
Tachycardic, BP 90/65
GCS = 11
Multiple abrasions, open # R tibia

44. Question
How can we prevent OM in his R leg?

45. OM Prophylaxis In Open #
Cut away surrounding clothing
Pour sterile NS/water over bone
Cover with moist sterile gauze
Surface cultures?
Not predictive of future pathogens
Manipulate?
Only if severe vascular compromise
Early Abx
Ancef ± G- coverage
G- for contaminated with soil or # occuring in water

46. Case 4y.o. M, R hip pain x 2d, refusing to walk No trauma
Cough, runny nose, sore throat last week
O/E:
Vitals normal (T = 37.5°C)
Refusing to walk, knee/ankle normal
R leg in flexion, slight abd, slight ER
Pain at end range of IR

47. Question
What would you like to order doctor?

48. Investigations Labs Imaging Ideas? WBC 11.2, ESR 14 Plain films
“?R hip effusion, suggest U/S”
U/S – effusion present
Ideas?
U/S – effusion present in 60-70%

49. Transient Synovitis Diagnosis of exclusion
Most common cause of hip pain in kids
Typically ages 3-6yrs
Usually affects hip>knee
Pain can be referred to knee/thigh
U/S – effusion present in 60-70%
Up to 3% of kids get it

50. Severe hip pain/spasm 62% 12% Tenderness on palpation 86% 17%
Taylor GR, Clark NM. Management of the irritable hip: A review of hospital admission policy. Arch Dis Child 71:59, 1994.
Septic arthritis Synovitis
Severe hip pain/spasm 62% %
Tenderness on palpation 86% %
T >= 38°C 81% %
ESR >= 20mm/hr 90% %
Any 2 – SN 95%, SP 91% for septic arthritis
Found 4 criteria more indicative of septic arthritis than transient synovitis
The case notes of all children admitted during the preceding five years for observation with painful hips (509 patients) were analysed to determine significant diagnostic factors and thus to design and admission policy. Most orthopaedic disorders (62 patients) were apparent on the initial radiographs, with the important exception of osteomyelitis/septic arthritis (21 patients). The remaining 426 patients were diagnosed by exclusion as having an irritable hip. The latter two groups were similar with respect to age, sex, and duration and nature of symptoms. A number of clinical features and laboratory investigations recorded within 12 hours of admission, however, were shown to have significant discriminative value. These were severe spasm, tenderness, pyrexia > or = 38 degrees C, and an erythrocyte sedimentation rate of > or = 20 mm/hour (the white cell count was not significant). Combination of any two of these produced a specificity and sensitivity for sepsis of 91% and 95% respectively (95% confidence interval 0.64 to 0.97). A protocol designed from this data analysis is now being tested and is expected to result in a significant reduction in admission rates.

51. Question You’re convinced this is TS…
How would you like to treat this child?

52. Transient Synovitis - Management
Outpatient
F/U exam in 12-24hrs ± 2wks
Rest
Initial non-weight bearing
Gradual return to activity
NSAIDs
Full activity when pain-free and no limp

53. Transient Synovitis - Outcome
75% - 2 weeks
88% - 4 weeks
12% - persistent pain x 8 weeks
These should have U/S for ?persistent effusion
Long-term
Relapse, asymptomatic coxa magna, mild cystic changes of femoral neck, LCP disease
If they have pain past 4 weeks – should have U/S to evaluate for persistent effusion – concerning for LCP development
Coxa magna – enlargement and deformity of the femoral head and neck caused by hypertrophy of cartilage 2ry to inflammation
Cystic changes – no functional disability

54. Case 51y.o. M, swollen, tender R knee
Seen in ED 2 weeks ago  fluid taken off
Last 2 weeks ↑↑pain/redness/swelling knee
Using ice, ibuprofen with some relief
Now fever, fatigue, nausea, myalgias

55. Question What would you like to do? Labs? Imaging? Tap joint?
WBC not SN – 30% with septic arthritis have WBC < 50,000
Glucose – not reliable in immunocomp, chronic jt dz
If you do get WBC < 10,000 and fluid glucose N  septic arthritis is unlikely

56. ?Septic Arthritis?
While waiting on labs/imaging/fluid results you pull out the palm

57. Septic Arthritis – The Bad, The Ugly
Infection  effusion  decreased nutrients into jt  dormant m/o  resistance to abx
PMN enzymes degrade cartilage
Hyaline cartilage cannot re-grow
Other structures at risk
Bursae, tendons, bone
PMN e’s – and also pressure necrosis from accumulation of purulent synovial fluid also compromises synovium/cartilage
Degree of cartilage destruction – most NB factor that determines morbidity

58. Septic Arthritis - History
Joint pain, refusal to use limb
Minimal in immunocomp/steroids
Fever
40% adults, 80% kids
±Constitutional symptoms
Weakness, malaise, anorexia, nausea, myalgias
Risk factors
RF – DM, pre-existing joint dz, IVDU, etc

59. Septic Arthritis – Physical Exam
General
Fever, other vitals N
±Focus (skin, nose, ears, pharynx)
±Referred pain
Inspection
Motionless limb, slight flexion
Swelling, erythema
Palpation
Warmth
Tenderness
Joint movement  ++painful

60. Investigations Labs Not consistently helpful ↑WBC in 50% ↑ESR in 90%
±Culture of focus
WBC not SN – 30% with septic arthritis have WBC < 50,000
Glucose – not reliable in immunocomp, chronic jt dz
If you do get WBC < 10,000 and fluid glucose N  septic arthritis is unlikely

61. Question
What are you looking for on the x-ray?

62. Imaging Plain films Effusion Bone erosions Concurrent OM Air
Synovial attachment, subchondral
Concurrent OM
Air
Less helpful in pts with pre-existing joint disease and early in septic arthritis
Subchondral – 1-3 weeks into course

63. Imaging Bone scan U/S CT/MRI Only if diagnostic uncertainty
May risk further damage
U/S
Effusion, help with aspiration
CT/MRI
Better anatomy, ?used in ED

64. Joint Aspiration - Technique
Anteromedial Approach
Position: knee in full extension or 20° flexion with towel under knee
18-ga needle, 60cc syringe
Middle/superior portion of the medial patella
1 cm medial to the anteromedial patellar edge
Direct needle posteriorly ±elevate patella
Can milk suprapatellar pouch
Direct needle post - between the posterior surface of the patella and the intercondylar femoral notch

66. Investigations Joint aspiration Definitive test – culture
Gram stain, smear
Cell count/diff
WBC > 50,000 (90% have S.A.), PMN’s
Fasting fluid/serum glucose < 1:2 (or ↓fluid glu)
WBC < 10,000 and glucose N  S.A. unlikely
Priority – culture, smear, Gram stain, cell count, glucose

67. Question
Your labs and joint aspiration results point you towards septic arthritis…
What would you like to do doctor?

68. Management Early IV antibiotics Admission
Medical vs. surgical decompression
No RCT’s
Animal evidence – surgical > medical
Definitely surgery in:
Septic hip (esp. kids), ±shoulder
Infected prosthesis
Medical – repeated aspirations
Surgical – arthrotomy, arthroscopy, and can leave joint tube in place for repeated irrigation and drainage

69. Septic Arthritis Abx - Adults
Pathogen
Antibiotics
Adults (native joint +/- penetrating trauma)
S. aureus, P. aeruginosa
Cloxacillin or cefazolin +/- gentamicin
Gonococcal
N. gonorrhoeae
Cefotaxime
Rheumatoid arthritis
S. aureus, Strep sp, Enterobacteriaceae
Cefazolin +/- gentamicin
Prosthetic joint
S. aureus, S. epidermidis, others
Vancomycin + gentamicin
IVDU

70. Septic Arthritis Abx - Kids
Pathogen
Antibiotics
Neonates
GBS, S. aureus, Enterbacteriaceae
Cloxacillin + Cefotaxime
Children
S. aureus, Strep sp., rarely H. flu
<5yrs: cefuroxime
>5yrs:Cloxacillin or cefazolin
Sexually active
N. gonorrhoeae
Cefotaxime

71. Case 8y.o. F Your dx: R shoulder septic arthritis
Pt being admitted, on IV abx
Mom asks:
Is this going to lead to any short or long term problems doctor?

72. Complications Local Systemic Epiphyseal damage Tissue damage Ankylosis
Impaired growth, length discrepancy
Tissue damage
Bursae, tendons, ligaments, muscles
Ankylosis
Systemic
Sepsis – elderly, immunocompromised
Ankylosis with destruction of articular cartilage

73. Question
Mom says:
Wow, you seem so smart, can you tell me what my child’s chance of a full recovery is?

74. Prognosis Complete recovery Long-term complications 66%
Tx initiated within 1 week of onset
Long-term complications
33%
↓mobility, ankylosis, pain, chronic infection, sepsis, death
Delay in dx/tx, RA, polyarticular, +BC

75. Question
Any questions?

76. References
Le Saux et al. Shorter courses of parenteral antibiotic therapy do not appear to influence response rates for children with acute hematogenous ostermyelitis: a systematic review. BMC Inf Disease. 2:16, 2002.
Marx: Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th ed., Copyright © 2006 Mosby, Inc.
Roberts: Clinical Procedures in Emergency Medicine, 4th ed., Copyright © 2004 Saunders, An Imprint of Elsevier
Taylor GR, Clark NM. Management of the irritable hip: A review of hospital admission policy. Arch Dis Child 71:59, 1994.