Impact of surgical site infection and surgical debridement on lumbar arthrodesis: A single-institution analysis of incidence and risk factors

Highlights

• There is a high rate of pseudarthrosis in spine surgery complicated by infection.

• Use of interbody cage increases fusion rate following surgical site infection.

Abstract

This study identifies the rate of pseudarthrosis following surgical debridement for deep lumbar spine surgical site infection and identify associated risk factors. Patients who underwent index lumbar fusion surgery from 2013 to 2014 were included if they met the following criteria: 1) age >18 years, 2) had debridement of deep lumbar SSI, and had 3) lumbar spine AP, lateral and flexion/extension X-rays and computed tomography (CT) at 12 months or greater postoperatively. Criteria for fusion included 1) solid posterolateral, facet, or disk space bridging bone, 2) no translational or angular motion on flexion/extension X-rays, and 3) intact posterior hardware without evidence of screw lucency or breakage. Twenty-five patients (age 63.2 ± 12.6 years, 10 male) involving 58 spinal levels met inclusion criteria. They underwent fusion at a mean of 2.32 [range 1–4] spinal levels. Sixteen (64.0%) patients received interbody grafts at a total of 34 (58.6%) spinal levels. All underwent surgical debridement with removal of all non-incorporated posterior bone graft and devascularized tissue. At one-year postoperatively, (56%) patients and 30 (52%) spinal levels demonstrated radiographic evidence of successful fusion. Interbody cage during initial fusion was significantly associated with successful arthrodesis at follow-up (p = 0.017). There is a high rate of pseudoarthrosis in 44% of patients (48% of levels) undergoing lumbar fusion surgery complicated by SSI requiring debridement. Use of interbody cage during initial fusion was significantly associated with higher rate of arthrodesis.

Introduction

Advances in surgical techniques and patient selection have resulted in improved outcomes following spine fusion. However, these procedures still require the introduction of foreign hardware and significant tissue dissection and manipulation of native anatomy. As a result, spine fusion patients can experience significant postoperative pain and other less common complications including cerebrospinal fluid (CSF) leak, hardware failure, hematoma, and nerve damage [9]. Surgical site infection is another uncommon but morbid complication for lumbar spine fusion, and has an incidence of 0.3%-9%, depending on a multitude of factors including preoperative diagnosis, type of operation, and patient demographics [1], [11], [17], [21], [22], [23]. Following diagnosis of postoperative wound infection, patients typically undergo wound irrigation and debridement with removal of graft bone. Postoperatively, patients are then placed on oral or intravenous (IV) antibiotics and then monitored for resolution of infection [14].

Infection and debridement surgery has significant short-term and long-term sequelae including increased hospital stay, 30-day readmission, decreased quality of life and decreased satisfaction with the index procedure [7], [19], [26]. However, there is no consensus on the impact of irrigation and debridement or wound infection on long-term fusion rates. There has been previous laboratory data suggesting inflammatory markers associated with infection are beneficial in achieving bone growth [13], [25], [28]. However, other groups have not shown this association, and in fact, have suggested that the inflammatory response is detrimental for achieving successful arthrodesis [8]. Therefore, the authors designed a retrospective review to assess the rate of arthrodesis following irrigation and debridement following lumbar spine fusion. By doing so, the authors hope to better characterize the rate of arthrodesis following surgical debridement for wound infection, and identify any pre-, peri-, and post-operative factors predictive of either arthrodesis or pseudoarthrosis.