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Figure. Magnetic resonance imaging of the lumbar spine. Credit: Dagan Cloutier, MPAS, PA-C.
A 65-year-old man presents to the emergency department with worsening lower back pain 4 months after a right-sided L3-L4 diskectomy. The pain from surgery never subsided and seems to be getting worse over the last 3 to 4 weeks. He denies having fevers but has noticed intermittent chills and sweats over the last few weeks as well. He is hemodynamically stable and is afebrile in the emergency department at 98.1 °F. On physical examination, he has no neurological deficits in the lower extremity and his prior lumbar incision is well healed without signs of infection. Blood cultures in the emergency department are positive for Staphylococcus aureus. Magnetic resonance imaging of the lumbar spine (Figure) shows bone marrow edema at the L3 and L4 vertebral bodies and fluid signal in the intervertebral space compatible with acute diskitis-osteomyelitis with surrounding prevertebral phlegmon and edema. No epidural abscess or neural compression is observed.
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The patient is presenting with vertebral osteomyelitis/diskitis that was caused by a postoperative infection. Other causes of diskitis other than surgical inoculation include hematogenous dissemination (most common), which may be from intravenous drug use or recent systemic infection.
The most common pathogen is Staphylococcus aureus followed by Staphylococcus epidermidis and then gram-negative organisms associated with respiratory or genital urinary infections. The most common symptoms of diskitis include diffuse lower back pain that is worse at night. The most common location for diskitis includes the lumbar spine followed by thoracic spine, then cervical spine, and lastly the sacrum. Fever is present in one-third of patients and neurological symptoms occur in less than 20% of patients.
Treatment involves identifying the causative organism, either by blood culture or computed tomography (CT)-guided bone biopsy, and administration of appropriate antibiotics. If blood cultures are positive, a CT biopsy can be avoided. Surgical management is recommended when evidence of neurological deficits, large abscess formation, or spinal instability is found.1,2
References
1. Ahsan K, Hasan S, Khan SI, Zaman N, Almasri SS, Ahmed N, Chaurasia B. Conservative versus operative management of postoperative lumbar discitis. J Craniovertebr Junction Spine. 2020;11(3):198-209. doi:10.4103/jcvjs.JCVJS_111_20.
2. Adult pyogenic vertebral osteomyelitis. www.orthobullets.com. Accessed September 10, 2022.
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