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Bone and Joint Infection
Mike Uglow
David G Little
Osteomyelitis
• Acute
• Chronic
– Sequel to Acute
– Specific
• TB, fungal
– Non-specific
• Metaphyseal / Epiphyseal Cavities
• Chronic multifocal osteomyelitis
– Post Trauma
Bacteria
• Staph aureus
• Streptococcus
• E coli (neonates)
• H Influenzae
• Gram negatives (open
fractures, spine)
• Pseudomonas
• Salmonella
Host Defence
• Humoral
• Cell Mediated
– Osteoblasts
– Osteoclasts
– Inflammatory cells
Pathogenesis of Acute
Osteomyelitis
• Metaphysis
• Epiphysis
• Synovial Joints
Pathogenesis
• Bacteraemia common in childhood
– 50% incidence after brushing teeth
• Initiating / compounding factors
– Trauma
– Immunocompromised host
Bacterial adherence
• Blood flow ? stasis
• Relative immonodeficiency of metaphysis
• Minor trauma
– Dead bone
• Attraction for staph aureus to hyaline
cartilage
Immune response
• Inflammatory exudate
– increased intramedullary pressure
– worsening blood flow
– ischaemia / necrosis
• Tissue destruction
– proteolytic enzyme release
– increased phagocytosis (osteoclasts)
Outcome
• Resolution
– Intervention aborts process with minimal tissue
destruction
• Chronicity
– sequestrum (dead bone) formation
– subperiosteal / intramedullary abscess
– sinus formation
– secondary joint infection
Sequelae
• Bone destruction
– regeneration unless blood supply destroyed
• Cartilage / Growth plate destruction
– repair (scarring)
– loss of function
• structural loss
• growth disturbance
• joint dysfunction
Treatment Goals in AHO
• Minimise tissue destruction
– Early diagnosis
– Effective therapy
• antibiotics
• surgery
AHO presentation
• Febrile, unwell, unhappy child
• Acute signs of inflammation in metaphysis
– redness
– warmth
– swelling
– point bony tenderness
– loss of nearby joint function
AHO Workup
• FBC, ESR, CRP
• Blood cultures
• Plain X ray
• TC99 bone scan*
*initiate empiric treatment prior to scan
after cultures
AHO treatment
• Appropriate IV bacteriocidal antibiotics
targeted at likely organism
– Flucloxacillin 200 mg / kg / day
– Cephotaxime 150 mg / kg / day
• Modify antibiotics once organism known
• Convert to oral antibiotics (age > 1) once
fever and CRP settled
• Total therapy three weeks
AHO treatment
• Observation / Investigation for abscess
formation
– Failure of fever / acute phase reactants to
resolve
– Ultrasound
– MRI
Surgery in AHO
• Drain subperiosteal abscess
• Drain joint sepsis
• Debride dead tissue
Neonates
• Immunocompromised
• Septicaemia
• Absent / minimal local signs
• Often multifocal, growth plate and joint
involvement
• Mostly staph, can be Group B strep, gram
negatives
• As joints largely cartilaginous, quickly
destroyed
Childhood
• Staph still common
• H influenzae now less common
• Refusal to walk / limp
• Any odd presentation - subacute forms
• Discitis
Subacute Osteomyelitis
• Metaphyseal /
epiphyseal cavities
• Diaphyseal
osteomyelitis
• Chronic multifocal
osteomyelitis
• Differential diagnosis
includes neoplasia
Subacute Osteomyelitis
• At least as common as acute osteomyelitis
• Mostly still staph Aureus
• Only recover organism in 30% of biopsies
• ? changing virulence pattern
• ? partially treated forms
Subacute Osteomyelitis
• Treatment
– Unlikely infection itself will cause growth
disturbance, surgery may do so
– Trial of antibiotics alone may be successful
– 3 to 6 months oral therapy
– Monitor therapeutic drug level and LFT’s
– Surgery for recalcitrant cases
Discitis
• Vertebral osteomyelitis spreads across disc
to contiguous vertebrae
• May present with bizarre gait, refusal to
walk
• Subacute presentation
– may be afebrile
Discitis
• Decreased spinal movement
• Disc space narrowing
• ESR / CRP likely to be elevated
• TC99 bone scan / Gallium scan positive
• MR may be helpful
• Treat with flucloxacillin
Septic Arthritis
• Emergency
– Joint poor immune defence
– Tissue destruction = loss of function
– Thick capsule does not allow spontaneous
drainage
– Proteolytic enzymes destroy hyaline cartilage in
24 - 48 hours
Septic Arthritis
• Clinical picture
– Usually febrile and unwell
– Unable to ambulate
– Severe restriction of joint motion
• Investigations
– Ultrasound documents hip effusion, not
infection
– Aspiration
Septic Arthritis
• Treatment
– Rapid surgical drainage
– IV antibiotics as for AHO
– Oral antibiotics for total 3 week course
• Sequelae
– Late cases = joint destruction
shortening
deformity
Chronic Osteomyelitis
• Long term disturbance of bone architecture
– pathological weakness / fracture
– ischaemia decreases antibiotic penetration
– dead bone harbours organisms
• adherence
• glycocalyx
• Treatment must be directed at these
deficiencies
Chronic Osteomyelitis
• Chronic from the onset
– Tuberculosis
– Fungal infection
– Parasitic infection
– ? Viral infection
Important Points
• Acute musculoskeletal sepsis relatively easy
to diagnose and treat
• Subacute forms now common
• Differential diagnosis
– Trauma
– Tumour
• Eosinophilic granuloma, chondroblastoma
• Ewings, osteosarcoma
• Leukaemia