Incidence and Recurrence of Deep Spine Surgical Site Infections

Abstract and Introduction

Abstract

Study Design: Systematic review and meta-analysis.

Objective: To determine a pooled incidence rate for deep surgical site infection (SSI) and compare available evidence for deep SSI management among instrumented spinal fusions.

Summary of Background Data: Deep SSI is a common complication of instrumented spinal surgery associated with patient morbidity, poorer long-term outcomes, and higher health care costs.

Materials and Methods: We systematically searched Medline and Embase and included studies with an adult patient population undergoing posterior instrumented spinal fusion of the thoracic, lumbar, or sacral spine, with a reported outcome of deep SSI. The primary outcome was the incidence of deep SSI. Secondary outcomes included persistent deep SSI after initial debridement, mean number of debridements, and microbiology. The subsequent meta-analysis combined outcomes for surgical site infection using a random-effects model and quantified heterogeneity using the χ ² test and the I ² statistic. In addition, a qualitative analysis of management strategies was reported.

Results: Of 9087 potentially eligible studies, we included 54 studies (37 comparative and 17 noncomparative). The pooled SSI incidence rate was 1.5% (95% CI, 1.1%–1.9%) based on 209,347 index procedures. Up to 25% of patients (95% CI, 16.8%–35.3%), had a persistent infection. These patients require an average of 1.4 (range: 0.8–1.9) additional debridements. Infecting organisms were commonly gram-positive, and among them, staphylococcus aureus was the most frequent (46%). Qualitative analysis suggests implant retention, especially for early deep SSI management. Evidence was limited for other management strategies.

Conclusions: The pooled incidence rate of deep SSI post-thoracolumbar spinal surgery is 1.5%. The rate of recurrence and repeat debridement is at least 12%, up to 25%. Persistent infection is a significant risk, highlighting the need for standardized treatment protocols. Our review further demonstrates heterogeneity in management strategies. Large-scale prospective studies are needed to develop better evidence around deep SSI incidence and management in the instrumented thoracolumbar adult spinal fusion population.

Introduction

Deep surgical site infection (SSI), generally defined as a subfascial infection, is a harmful complication after instrumented spinal fusion. It is associated with significant patient morbidity, prolonged hospitalization,^[1] poorer long-term outcomes,^[2] and high costs to the health care system.^[3,4] The exact incidence of deep SSI after posterior thoracolumbar instrumentation of the spine is poorly defined and reported to be anywhere between 2% and 20%.^[5–9] The approach to treatment for confirmed deep SSI involves surgical irrigation and debridement with subsequent antimicrobial therapy.^[10] Failure to eradicate infection after surgical debridement and antibiotic therapy has been reported in up to 24% of patients;^[11] however, the exact recurrence rate is not known, nor is the expected number of procedures required to ultimately eradicate infection in recalcitrant cases.

Specific management strategies used during surgical debridement vary. Factors during surgery include but are not limited to type and volume of irrigation used, implant exchange or removal,^[12,13] bone graft removal, postoperative antimicrobials,^[14] and vacuum-assisted closure (VAC) techniques. However, among high-volume adult spinal surgeons, there is relatively little consensus on surgical technique and management in the setting of instrumented thoracolumbar spine SSI.^[15]

The current state of evidence for the management of instrumented spinal SSI is in stark contrast to other surgical fields, such as hip and knee arthroplasty, where rigorous guidelines for diagnosis and management are widely accepted and used.^[16,17] The objective of this investigation was to systematically determine the global incidence of deep SSI after instrumented thoracolumbar surgery, determine the incidence of recurrence, and identify the evidence for various surgical treatment modalities.

Spine. 2023;48(16):E269-E285. © 2023 Lippincott Williams & Wilkins