Incidence

2-4% of all osteomyelitis~ 70 % of cases are over 50 yoany level can be affected – most common lumbar, least common cervical

Aetiology

S. aureus in over 50%gram neg organisms are becoming more commonE. coli in urinary and enteric infectionsPseudomonas esp in IV drug users, immune compromisedMultiple organism infection is rare

Pathology

Thought to be a secondary manifestation of infection elsewhereMechanisms of spread -Venous – advocated by Batson ( Ann. Surg. 112: 138, 1940)Arterial – advocated by Wiley and Trueta ( JBJS 41B: 796, 1959)The arterial theory is current as -high pressures are needed to fill Batsons plexus which has only small branches to the vertebral bodiesrich arterial supply to vertebral bodies – correlates with most common site of infectionNB: change of blood supply to the spine with ageduring infancy and childhood there is an end arterial supply to the disc – this regresses in the first 3 decadesThis explains why in the child the most common infection is discitis and in the adult is anterior metaphyseal infection beginning near the end plate

Clinically

may be acute or chronicGeneralsigns of sepsis – fever, malaise, anorexia, wght lossLocal localised spinal pain – unrelieved by rest, worse with motionmay have referred paintenderness to deep palpation or spinal percussionreduced motionhip contracture due to psoas abscessdeformity – esp angular kyphosis – in chronic casesNeurologicalsigns seen in ~ 15%due to pressureabscess, spinal instability from bone destructionseptic thrombosis of spinal artery

Investigation

Bloods:WCC, ESR, CRPBlood cultures esp in temp spike


RadiologyPlain filmsearly are normal1-3 wks see bone destructionlater – healing with schlerosisNB if TB see soft tissue calcification, less schlerotic responseCT (+/- contrast)useful in diagnosis – see bony destruction, abscessesalso useful in treatment – biopsyMRI:useful in diagnosisassessment of neural structures and soft tissue abscessesBone scangood for showing early disease when plain films normal


Diagnosis:based on combination of the above – need the organism and its sensitivity

Differential

Acute


malignant depositsother infection: eg discitis, TBRetroperitoneal pathology eg renal stones


Chronic


here the main problem is deformitythus TB, EG, old trauma ie causes of angular kyphos

Treatment

RestIV antibiotics as per sensitivities – ? how long – min 6 wks IV + 6 wks oralindications for surgical intervention

  1. failure of adequate surgical treatment
  2. to obtain tissue for culture if needle biopsy fails
  3. drainage of abscess
  4. neural compromise
  5. gross bony destruction with instability

Surgery is anterior ( posterior surgery may further destabilise the spine)with adequate debridement and antibiotics bone grafts used for stabilisation do well with over 90% fusionwith anterior surgery need post op immobilisation or supplementary stabilisation