Treatment of Surgical Site Infection in Posterior Lumbar Interbody Fusion

Abstract

Study design: A retrospective observational and case control study.

Purpose: To identify appropriate treatment options according to the types of surgical site infections (SSI) in instrumented posterior lumbar interbody fusion (PLIF).

Overview of literature: There has been no agreement or consensus with regard to this matter.

Methods: Thirty-two consecutive SSIs were included and followed for more than one year. The elapsed time to diagnosis (ETD) according to the type of SSI was analyzed. The treatment options for each type and consequent clinical results were reviewed. The risk factors of removing the implants were analyzed.

Results: There were 6/32 (19%) superficial incisional, 6/32 (19%) deep incisional, and 20/32 (62%) organ/space infection cases (SII, DII, and O/SI, respectively) (p=0.002). ETD was 8.5±2.3 days in SII, 8.7±2.3 days in DII, and 164.5±131.1 days in O/SI (p=0.013). All cases of SII and DII retained implants and were treated by repeated irrigation and secondary closure. Among O/SIs, 10/20 were treated conservatively. Nine out of ten underwent posterior one stage simultaneous revision (POSSR) and in one case, the cage was removed anteriorly. Those who had ETDs longer than 3 months showed a significant risk of implant removal (p=0.008, odds ratio [OR]=40.3). The Oswestry disability index (ODI) improved from 47.3% to 33.8% in SII, from 55.0% to 32.3% in DII, and from 53.4% to 42.1% in O/SI (p=0.002). There was no difference among the three groups (p=0.106); however, there was a partial correlation between ETD and final ODI (r=0.382, p=0.034).

Conclusions: Latent O/SI was the most common type of SSI in PLIF. In cases of SII and DII, early aggressive wound management and secondary closure was effective and implant removal was not necessary. In some cases of O/SI, implant removal was unavoidable. However, implant removal could be averted by an earlier diagnosis. POSSR was feasible and safe. Functional outcomes were improved; however, disability increased as ETD increased.

Keywords: Implant removal; Posterior lumbar interbody fusion; Posterior one stage simultaneous revision; Surgical site infection; Treatment.

Fig. 1. (A) T1-weighted magnetic resonance (MR) image showing a low signal change around L45 interbody cages that suggests spondylitis. However, there is no draining sinus or pus collection in the posterior incisional route. (B) T1-weighted MR image of the same patient after 3 months of conservative treatment. The low signal change was completely recovered.

Fig. 2. (A) Lateral radiograph of the lumbar spine. (B) T1 sagittal magnetic resonance imaging. (C) Coronal computed tomography reconstruction views show loosening of screws and cage, bone marrow edema, endplate destruction, and osteolysis due to spondylitis of L4 and L5. (D) Spinal fusion is extended from L3 to S1. Spondylitis was cured and solid L4-L5 interbody fusion is seen while preserving the interbody cage.