Osteomyelitis & Septic Arthritis

Jay Green

November 23, 2006

Outline Both

Risk factors, mechanism of infection, pathogens

Osteomyelitis Septic Arthritis

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

Question What are some risk factors for bone/joint

infections?

Who gets bone/joint infections?

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

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

Anatomy Review - FYI

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

Question By what mechanisms can a bone/joint

become infected?

Mechanism of Infection Hematogenous spread Contiguous spread Direct inoculation

Penetrating trauma Joint aspiration

Predisposed sites Long bone metaphysis, vertebral body

What bug? 12F from Angola

TB 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

Pathogens *Bacterial* Viral Fungal Parasitic

Depends on host/environmental factors

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

Pathogens – Key Points Pseudomonas – puncture wound to foot,

prosthetic implants, IV drug users

Pasteurella multocida – animal bites

Fungal – increasingly common

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

?Osteomyelitis?

Question What would you like to order?

Labs? Imaging?

Osteomyelitis - History 5 cardinal signs of inflammation

Pain, erythema, swelling, warmth, ↓ function

±Fever Systemic symptoms

H/A, fatigue, malaise, anorexia

Osteomyelitis – Physical Exam General

Not ill

Inspection Erythema, swelling

Palpation Point tenderness, warmth ±involucrum, ±sequestrum

Involucrum

New periosteal growth due to subperiosteal abscess

Sequestrum

Disengaged ischemic segments of bone

Return to case WBC 12,000 ESR 80mm/hr Plain x-ray – N (confirmed by radiology)

What do you think of her ESR?

Investigations Labs typically unhelpful

±↑WBC (N – 15,000) ↑ESR more sensitive

Mean ESR = 70 <8% have ESR < 15

Imaging Start with plain films May miss acute presentation

<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

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

Bone scan

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

Imaging – 99mTc MDPFlow Pool Delay Diagnosis

- - - Not OM

- - + Degenerative disease

+ + - Inflammation

+ + + OM, false +

Imaging – 99mTc MDP SN > 90% FP rate ~65%

Trauma, surgery, tumor, chronic soft tissue infection, healing fracture

Other radionuclides 67Ga citrate 111In oxine 99Tc hexamethylpropyleneamine oxime

?Useful in ED All have 24-48h wait time

CT Scan May miss acute presentation Better for:

Sternum, vertebrae, pelvic bones, calcaneus

Useful post-bone scan, guides sx/bx

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?

Question How do we find the bug? In ED

Blood culture+ in 50%– always if chronic

NOT cultures from fistulae/sinus Not in ED

Biopsy – needle, resection

Find bug in 80-90%

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

Management IV antibiotics

Typically empiric to begin 4-6 weeks

Surgery Debridement often necessary Can avoid in kids with acute hematogenous OM

Empiric Abx - AdultsOsteomyelitis Pathogen Therapy

Hematogenous S. aureus Cloxacillin or Cefazolin +/- Gentamicin

IVDU S. aureus

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 P. aeruginosa Prophylaxis: cipro

Treatment:pip-tazo + tobramycin

Post-op prosthetic joint S. aureus

S. epidermidis

Vancomycin +

Gentamicin

Empiric Abx - KidsOsteomyelitis Pathogen Therapy

Neonates GBS, S. aureus, Enterobacteriaceae

Cloxacillin + Cefotaxime

Children S. aureus, Strep, H. flu Cloxacillin

Sickle cell S. aureus, Salmonella sp. Cloxacillin + Cefotaxime

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

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

Question Are imaging or cultures of the pus useful in

chronic osteomyelitis?

Will IV/PO antibiotics be sufficient?

Chronic Osteomyelitis Usually complication of post-traumatic OM,

surgery, diabetic foot infection Recurrent course Sequestra Chronic draining sinus/fistulae Polymicrobial, commonly anaerobes

Chronic OM - Investigations Bone scan – limited use Cultures of tracts not reliable Need bone bx

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

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

Question How can we prevent OM in his R leg?

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

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

Question What would you like to order doctor?

Investigations Labs

WBC 11.2, ESR 14 Imaging

Plain films “?R hip effusion, suggest U/S”

U/S – effusion present

Ideas?

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%

Taylor GR, Clark NM. Management of the irritable hip: A review of hospital admission policy. Arch Dis Child 71:59, 1994.

Septic arthritis Synovitis

1) Severe hip pain/spasm 62% 12%

2) Tenderness on palpation 86% 17%

3) T >= 38°C 81% 8%

4) ESR >= 20mm/hr 90% 11%

Any 2 – SN 95%, SP 91% for septic arthritis

Question You’re convinced this is TS…

How would you like to treat this child?

Transient Synovitis - Management Outpatient F/U exam in 12-24hrs ± 2wks Rest

Initial non-weight bearing Gradual return to activity

NSAIDs

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

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

Question What would you like to do?

Labs? Imaging? Tap joint?

?Septic Arthritis?

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

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

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

Investigations Labs

Not consistently helpful ↑WBC in 50% ↑ESR in 90% +BC in 25-50% ±Culture of focus

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

Imaging Plain films

Effusion Bone erosions

Synovial attachment, subchondral Concurrent OM Air

Imaging Bone scan

Only if diagnostic uncertainty May risk further damage

U/S Effusion, help with aspiration

CT/MRI Better anatomy, ?used in ED

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

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

Question Your labs and joint aspiration results point

you towards septic arthritis…

What would you like to do doctor?

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

Septic Arthritis Abx - AdultsSeptic Arthritis 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 S. aureus, P. aeruginosa

Cloxacillin or cefazolin +/- gentamicin

Septic Arthritis Abx - KidsSeptic Arthritis 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

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?

Complications Local

Epiphyseal damage Impaired growth, length discrepancy

Tissue damage Bursae, tendons, ligaments, muscles

Ankylosis

Systemic Sepsis – elderly, immunocompromised

Question Mom says:

Wow, you seem so smart, can you tell me what my child’s chance of a full recovery is?

Prognosis Complete recovery

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

Question Any questions?

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.