Delayed Adjacent Level Spondylodiscitis after Initial Surgery with Instrumented Spinal Fusion: A Report of Three Cases and Review of the Literature

Abstract

To date, 2 cases of adjacent level spondylodiscitis occurring a few months after initial spinal fusion were reported. However, the development of delayed adjacent level spondylodiscitis is very rare. The authors report 3 cases of spondylodiscitis that occurred at the proximal adjacent level of the fused spine more than 1 year after the initial surgery. Antibiotic treatment was initially chosen in all three cases. In two of the cases, progressive neurological deficit occurred at the level of the infection due to compression of neural elements and spinal instability. For these patients, additional spinal fusion was performed. In each of the three cases, the selected treatment resulted in successful bony fusion at the level of the spondylodiscitis. According to the National Nosocomial Infections Surveillance System, deep wound infection is defined as occurring within 1 year after surgery with instrumentation. The spondylodiscitis in the present cases occurred more than 1 year after the initial surgery, suggesting that these cases may be considered as adjacent segment disease rather than surgical site infection.

Adjacent Segment Infection after Lumbar Fusion: A Case Report and the Literature Review

“…ASI after surgery of spondylodiscitis is considered as a rare complication (1.94%) via a large cohort study [2]. ASI in uninfected spinal surgery should be rarer, and in fact, only four case reports introduced it in conventional spinal fusion surgery [3][4][5][6]. In this present case, the patient developed ASI two months after the initial instrumented lumbar fusion surgery and achieved satisfactory outcome via debridement operation and autograft bone implantation fusion after failed conservative treatment.…”

“…According to Siam et al's study, the most commonly involved level was L3-4, the next were T12-L1 and L2-3. Nagoshi et al [6] reported three ASI cases which involved T11-12, L1-2, and L2-3. A case reported by Xin and He [5] occurred at level L3-4.…”

“…The pedicle screw instrument which allowed the pathogen to get into the vertebral body or directly penetrated the endplate was considered as the possible reason [4,5]. The pedicle screw close to the endplate could disrupt the arterial network of the endplate, leading to the formation of septic embolus and spondylodiscitis [6]. Nagoshi et al [6] also thought the pathogenesis of ASI was just like the adjacent segment degeneration (ASD), a result of the concentrated stress at the adjacent level of spinal fusion.…”

“…The pedicle screw close to the endplate could disrupt the arterial network of the endplate, leading to the formation of septic embolus and spondylodiscitis [6]. Nagoshi et al [6] also thought the pathogenesis of ASI was just like the adjacent segment degeneration (ASD), a result of the concentrated stress at the adjacent level of spinal fusion. The disruption of the annulus fibrosus in an adjacent segment was regarded as a kind of infective route by some authors [5].…”

“…In patients whose infection had been diagnosed early, they can be cured through conservative antibiotic treatment [5,6]. In these publications, the most common pathogenic bacteria were Staphylococci [4,6,7]. Serratia was only reported by Kulkarni and Hee [3].…”