Article Text

Postoperative back pain
  1. Keith Chapple,
  2. Clive Kelty,
  3. Les Irwin,
  4. R Mohan,
  5. Peter Millner
  1. Department of Orthopaedic Surgery, St James's University Hospital, Leeds, UK
  1. Mr K Chapple, Department of Surgery, Level 8, Clinical Sciences Building, St James's University Hospital, Leeds LS9 7TF, UK

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A 59-year-old woman underwent an Ivor-Lewis oesphagogastrectomy after being diagnosed with a lower oesophageal carcinoma. At operation the tumour was noted to be mobile and noninvasive. Histology of the resected specimen showed a poorly differentiated adenocarcinoma extending to the serosa, with clear resection margins and no lymph node involvement. Her postoperative course was unremarkable aside from a superficial wound infection in the thoracotomy scar which developed on day seven. A wound swab grewStaphylococcus aureus and the infection was successfully treated with a 7-day course of oral cephradine.

Five weeks later the patient sustained a minor fall and presented complaining of mild lower back ache. Examination was unremarkable. A lumbar spine X-ray was performed (figure 1). Four weeks later the patient noticed a small, tender swelling over the T12 / L1 area. A gibbus then developed at this site and over the next two weeks the swelling expanded to 20 × 15 cm. Magnetic resonance imaging (MRI) of the thoracolumbar spine was performed (figure2).  

Figure 1

Lateral X-ray of the lumbar spine

Figure 2

T2-weighted sagittal MRI scan of the lumbar spine

Questions

1
What do the figures show?
2
What is the diagnosis?
3
What was the cause of the swelling on the patient's back?

Answers

QUESTION 1

Figure 1 shows collapse of the vertebral body of L1 and loss of the definition of the body of T12. Figure 2 shows destruction of the vertebral bodies of T12 and L1, with infection of the intervertebral disc and posterior displacement of this infectious process into the spinal canal.

QUESTION 2

Vertebral osteomyelitis of T12 and L1.

QUESTION 3

The swelling was an abscess which had developed as a result of the infection tracking posteriorly around the spinal canal and into the superficial tissues at the thoracolumbar junction.

Clinical course

The swelling pointed and discharged pus, from whichStaphylococcus aureus was cultured. Treatment with fusidic acid, flucloxacillin and metronidazole was instituted. The abscess underwent a limited debridement and drainage and a sinus discharging alongside the ligamentum flavum at the T12 / L1 interspace was excised at the same time. Antibiotic therapy was continued for 6 weeks. Subsequent treatment necessitated excision of the necrotic spinous processes of T12, L1 and L2, with a local fasciocutaneous flap needed for coverage. Unfortunately this flap, a further flap and a skin graft all necrosed. She was mobilised in a thoracolumbar-sacral orthosis and the wound was allowed to heal by secondary intention.

Discussion

Vertebral osteomyelitis is an uncommon condition, accounting for only 2–4% of all cases of pyogenic osteomyelitis. It is seen almost exclusively in adults, with an incidence of 0.4–0.9 cases per 100 000 population.1 The condition is always secondary to a primary site, with spread occurring by either direct extension or via the bloodstream. Direct vertebral infection generally occurs after operations involving the spine or adjacent structures. Haematogenous spread is classically seen after genitourinary procedures or infections. Skin and soft tissue infections are a less common cause, although a wide variety of foci (boils, furuncles, carbuncles, sties,2 paronychia3 and intravenous cannula sepsis4) have been described. Wound infections can cause vertebral osteomyelitis but are invariably associated with contiguous spread from spinal operation wounds. In the case above, the wound infection in the thoracotomy scar was responsible for haematogenous spread of the infection.

In view of the patient's previous malignancy and the short history of back pain, an initial diagnosis of metastatic disease was erroneously made. Vertebral osteomyelitis normally presents with dull, constant back pain which develops over a number of months. Leg weakness, fever or cord compression are rarer presenting features and although a rapid onset of back pain developing within a few weeks of the infection has been described,1 this is unusual. Bony secondaries are unlikely so soon after potentially curative resection of oesophageal carcinoma.

Learning points

  • vertebral osteomyelitis is an uncommon condition but should always be considered in the differential diagnosis of back pain

  • infection of the spine involves the intervertebral disc and the two adjacent vertebrae and should be considered even after a relatively minor infection

  • morbidity is high and prompt diagnosis is essential to allow correct treatment

Complications are many and result in the condition having a high morbidity. Neurological complications are seen in up to 45% of cases5 and are due to mechanical pressure from bone collapse, sequestrum or pus, or to spinal artery thrombosis. Spinal deformities are unusual in the early stages although a common feature later on in the course of the disease. A gibbus occurs in up to 15% of patients2 but is more common with tuberculous infection. Secondary soft tissue abscesses are occasionally seen, normally in the lumbosacral and sacrococcygeal areas. The thoracolumbar region is rarely involved. Infection normally disseminates anteriorly, along the planes of cleavage and the iliopsoas muscle. Posterior spread from a vertebral body infection to form an extradural abscess is recognised, but further direct spread to involve the superficial tissues in the thoracolumbar area, as seen in the above patient, is uncommon as is the lack of any associated neurological symptoms.

This case illustrates some unusual complications of an uncommon condition and serves as a remainder that delayed diagnosis can have serious complications for the patient.

Final diagnosis

Vertebral osteomyelitis complicated by vertebral body destruction and superficial abscess formation.

References

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