Acute Hematogenous Osteomyelitis

Acute Hematogenous Osteomyelitis is first coined by Reynaud (17^th Century) and later popularized by Nelaton (1834)

Organisms

• Staphylococcus aureus (> 70%)
• Group A B-hemolytic streptococcus (Streptococcus pyogens)
• Group B streptococcus
• Alpha hemolytic streptococcus
• Hemolytic influenza
• Kingella kinger
• E.coli, Pseudomonas, Proteus

Why Metaphysis is a common site for abscesses?

1. Hairpin bend arrangements of arterioles
2. Relatively less phagocytosis
3. Sluggish flow
4. Torturous blood vessels and skimming of bacterias
5. Dead (apoptotic) and degenerative cartilages cell from physeal plate serve as a medium for bacterial growth
6. Microfracture and local hematoma common in young active children
7. Fine vessels in hypertrophic zones of physics may more easily allow bacterias to pass through and adhere to Type I collagen of that area

In infants where there is anastomosis between metaphysics and epiphyseal blood vessels , infection can also reach epiphysis

Cause of Diaphyseal Osteomyelitis:

1. Long-standing Osteomyelitis in children
2. Post-traumatic Osteomyelitis
3. Implant related Osteomyelitis
4. Tubercular Osteomyelitis
5. Drug abusers (Heroins addict- Pseudomonas)
6. Immunocompromised (Fungal)
7. Salmonella Osteomyelitis (Often bilateral and may be symmetrical)

Morrey’s and Peterson’s criteria for Acute Osteomyelitis

Likely	Typical clinical setting and definite radiographic evidence of osteomyelitis are present and there is a response to antibiotic therapy
Probable	Blood culture (+)in the setting of clinical and radiographic features of osteomyelitis
Definite	Pathogen isolated from bone or adjacent soft tissue or there is histological evidence of osteomyelitis

Pathologenesis of Acute Hematogenous Osteomyelitis

1. Stage of inflammation
2. Stage of suppuration
3. Stage of bone necrosis
4. Stage of reactive new bone formation
5. Stage of resolution and healing
6. Stage of Chronicity

Involucrum: Encasing Sequestrum

Sinus: Cloacae in involucrum

Causes of Chronicity of Infection

1. Presences of unabsorbed and retained sequestra serving a constant source of infection
2. Unobliterated cavities (dead spaces)
3. Microbiological shift ( Changes of aerobic cocci to gram-negative/ anaerobic)
4. Multiple types of bacteria ” mixed infection” and anti-microbial resistance

Periosteal reaction is not seen in

• HIV associated Osteomyelitis
• Tubercular Osteomyelitis
• Long-standing resolving Osteomyelitis

Septic arthritic secondary to acute Osteomyelitis is seen in

1. In infants < 6 months; the physiological connection between epiphyseal and metaphyseal vasculature through epiphyseal plate
2. Intraarticular location of metaphysis- proximal humerus, neck of femur, proximal radius, distal fibula in adults

Peltola and Vahuvanen’s criterias

4 criteria

1. Purulent material on the aspiration of the affected bone
2. The positive finding of bone tissue or blood culture
3. Localized classic findings
   • Bony tenderness
   • Overlying soft-tissue edema, erythema
4. Positive radiological imaging

Diagnostic Imaging

Plain X-Ray

Osteoporosis is a feature of metabolically active, and thus living bone . Segment that fails to become osteoporotic is metabolically inactive and possible dead

USG

CT Scan

Radionucleotide Scanning

SPECT/CT

MRI

Role of ⁹⁹Tc bone Scintigraphy

It is a screening tool (< 10 % specificity)

• Phase I: Arterial (flow) phase
• Phase II: Venous phase
• Phase III: Focal bone uptake

Phase I + Phase II = Positive Phase III = Negative	Soft tissue infections
Phase I + Phase II + Phase III = Positive	True bone infections

Ga⁶⁷ Scintigraphy: For vertebral osteomyelitis

In¹¹¹ Labeled leukocyte imaging: Else where infection in the body

Leukocyte imaging In¹¹¹ if used in conjunction with a sulpher colloid scan that delineates areas of normal bone activity whereas a leukocyte scan highlights the involved regions

Incongruences of In¹¹¹ labeled leukocyte scans and Sulpher colloids scans is highly suggestive of infection

Laboratory Investigations

• Aspirate Pus
• Blood Culture (If fever >38°C)
• CRP (Usually elevated in 12-24 hrs) Normal in (2-4 weeks)
• ESR in 24 to 48 hrs
• WBC count: Rises
• ASO titer may be elevated

Under evaluation

• IL-6
• alpha-defensin immunity

Treatment of Acute Hematogenous Osteomyelitis

General Principles of Infection Control

Principles

1. Appropriate microbial therapy
2. Surgical drainage if required
3. Splinting and rest of the affected part
4. Supportive treatment for pain and dehydration

Injectable antibiotics (after culture sensitivity), CRP level (Normal) (2-4 weeks) + Patient condition improves, then oral antibiotics for next 3-6 weeks

Age group	Organisms	Drugs
Neonates- 6 months	Penicillin resistance S.aureus Group B streptococcus Gram (-) organisms	Flucloxacillin + 3rd generation cephalosporins Alternatively, – flucloxacillin – benzylpenicillin – gentamycin
6 months – 6 years	H. influenza	Combination of i.v. flucloxacillin + cefotaxime/ cefuroxime
Older children and previously fit adults	Staphylococcus Streptococcal	Fusidic acid + I.V. flucloxacillin Benzylpenicillin (better)
Elderly and previously not fit patients	Risk of Gram (-) infections (Respi, UTI, GI)	Flucloxacillin + Second/third cephalosporins
Patients with sickle cell disease	Salmonella and gram (-) organisms	Chloramphenicol or 3rd generation cephalosporin + fluoroquinolone (Ciprofloxacin)
Heroin addicts and immunocompromised patient	Pseudomonas Proteus or aerobics	3rd generation cephalosporin or fluoroquinolones
Patient considered to be at risk of MRSA (Previously hospitalized with MRSA, hospitalized)	MRSA	IV Vancomycin or teicoplanin +3rd generation cephalosporin

Surgical drainage

If clinical features do not improve within 36 hours of initiating treatment or even earlier if

• there is a sign of pus (swelling, edema. fluctuation)
• Pus is aspirated

When there is no pus:

• Drill a few holes in the bones in various direction

And if the extensive intramedullary abscess

• Drainage can be achieved by cutting a small window in the cortex

The wound is closed with/ without drain and splinting is applied

Once signs of infection subside, movements are encouraged and the child is allowed to walk with crutches (full weight bearing)

Splinttage

• Prevents joint contracture
• Prevents dislocation ( in the hip)- skin traction

General Supportive treatment

• Intravenous fluids

Complications

• Epiphyseal damage and altered bone growth
• Supportive arthritis
• Metastatic infection
• Pathological fractures
• Chronic infections

See also: Subacute hematogenous osteomyelitis

See also: Chronic Osteomyelitis

See also: Multifocal Non-suppurative Osteomyelitis and Caffey’s Disease

See also: Septic Arthritis in Infants/ Children