Background 

• 2-4% of osteomyleitis infections 
• Mortality is 1-20% 
• Delay in diagnosis = 3 months 
• Average duration of treatment = 12 months 
• Costly treatment 
• Hibbs and Albee = fusion for treatment of tuberculosis 

Biology 

• Intervertebral disc 
  • 3 zones of endplate (marrow cavities) 
    1. Central – numerous small homes 
       • Good nutrient flow centrally 
    2. Peripheral – few large holes 
    3. Epiphyseal ring around endplate 
  • Bony endplate 
  • Cartilaginous endplate 
    • High vascular 
    • Where blood supply ends 
    • Hyaline cartilage 
    • Disc firmly adherent in periphery 
    • Loosely in centre 
      • Good nutrient flow centrally 
• Venous Drainage 
  • Batson plexus 
    • Pelvic veins drained into spinal venous plexus 
      • Pelvic tumors and mets to spine 
• Inoculation 
  • Direct 
    • Surgical 
    • Percutaenous 
    • Subphrenic recess 
  • Hematogenous 
    • Pyogenic 
      • Endplate of vertebra 
      • Attack intervertebral disc 
    • Tuberculosis 
      • Batson plexus 
        • Low flow 
        • No valves 
      • Experiments injecting into renal vein 
      • Spare intervertebral disc 

Microbiology 

• Staph aureus most common 
  • Decreasing incidence but increasing resistance 
• IV drug users 
  • Pseudomonas aeurginoas 
• Non pyogenic 
  • Mycobacter Tuberculosis 

Presentation 

• Etiology 
  • Spinal surgery is most common iatrogenic 
  • Genitourinary tract most common hematogenous 
• Risk Factor – immunosuppression 
  • Age, Diabetes, Alcohol, Rheumatoid, Renal disease 
• Physical Exam 
  • Pain (85%) 
    • Mechanical (with activity or position change) 
  • Recent infection 
  • Paraspinal spasm 
  • Inguinal ligament tenderness – psoas extension 
  • Torticollis – cervical spine tenderness 
  • Kernig sign – hamstring severe tightness 
  • Immune supressing disease 
  • Rarely radicular 
  • Paralysis 
    • 2/3 central cord 
    • 1/3 anterior cord 
  • Puig-Guri syndromes 
    • Hip joint syndrome 
      • Pain, flexion contracture 
    • Abdominal syndrome 
      • Acute appendicitis 
    • Meningeal syndrome 
      • Acute suppurative 
      • TB 
    • Back pain syndrome 
      • Acute or insidious 
      • Mild or moderate pain

Laboratory Studies 

• ESR 
  • mm/hour (erythrocyte sedimentation rate) 
  • >50 in 60%, >100 in 30% 
  • Elevated post op 
    • 25 
    • Decreases by 4 weeks post op 
    • Persistence elevation indicates infection 
  • CRP 
    • More sensitive 
    • Peaks POD2, then declines rapidly 
    • Continued elevation POD 4-7 

Biopsy 

• No antibiotics pre-biopsy 
• Long delay between symptoms and biopsy – negative 
• Local anesthesia 
• XR or CT guidance 
• 70-96% success 

DDX 

• Metabolic diseases with bony collapse 
• Primary and secondary malignancy 
• Charcot spine 
• RA, AS 
• Contiguous structural infecion (psoas abscess) 

Natural History of Pyogenic 

• Bloodborne 
• Sepsis = non-spine source primary 
• End plate capillary loop  
• Sludging  
  • Suppurative inflammation 
  • Tissue necrosis 
  • See below 
    • Anterior extension 
      • Paravertebral abscess 
      • Sinus 
    • Longitudinal extension 
      • Discitis 
      • Adjacent vertebrae 
      • Mediastinitis 
    • Posterior extension 
      • Epidural abscess 
      • Meningitis 
      • myelitis 
• Neurologic deficits 
  • Direct posterior extension 
  • Bony collapse 
    • Retropulsed bone or debris 
  • FOUR RISK FACTRS 
    • Age 
    • High/ cervical infection 
    • Staph Aurues 
    • Debilitating/ chronic disease 
      • DM, RA, chronic steroids