Contribution of the patient microbiome to surgical site infection and antibiotic prophylaxis failure in spine surgery

Despite modern antiseptic techniques, surgical site infection (SSI) remains a leading complication of surgery. However, the origins of SSI and the high rates of antimicrobial resistance observed in these infections are poorly understood. Using instrumented spine surgery as a model of clean (class I) skin incision, we prospectively sampled preoperative microbiomes and postoperative SSI isolates in a cohort of 204 patients. Combining multiple forms of genomic analysis, we correlated the identity, anatomic distribution, and antimicrobial resistance profiles of SSI pathogens with those of preoperative strains obtained from the patient skin microbiome. We found that 86% of SSIs, comprising a broad range of bacterial species, originated endogenously from preoperative strains, with no evidence of common source infection among a superset of 1610 patients. Most SSI isolates (59%) were resistant to the prophylactic antibiotic administered during surgery, and their resistance phenotypes correlated with the patient's preoperative resistome (P = 0.0002). These findings indicate the need for SSI prevention strategies tailored to the preoperative microbiome and resistome present in individual patients.

Thoracic costotransversectomy characteristics and 90-day complications vary based on underlying diagnosis

OBJECTIVE

Thoracic costotransversectomies are among the most invasive spinal procedures performed and are associated with unanticipated medical and surgical complications. Few studies have specifically assessed medical and surgical complications after a thoracic corpectomy via a costotransversectomy approach (TCT) or compared complications between different diagnoses. The purpose of this study was to describe the differences in operative characteristics and rates of 90-day surgical and medical complications in patients undergoing TCTs based on underlying diagnosis.

METHODS

A retrospective chart review of 123 consecutive patients who underwent TCTs at a single academic referral center over a 10-year period was conducted. Surgical indication, corpectomy levels, intraoperative dural tears, pleural injuries, neurological injuries, 90-day mortality, 90-day reoperations, and hospital-based medical complications were evaluated.

RESULTS

One hundred twenty-three patients underwent a TCT, including 35 for infection, 42 for malignancy, 23 for trauma, and 23 for deformity. Fifty-nine patients (48.0%) had at least one medical or 90-day operative complication, with 22 patients (17.9%) having two or more complications. Patients with a diagnosis of infection were more likely to undergo two-level corpectomies (80% vs 26.1%, p < 0.0005). Patients with a diagnosis of malignancy had significantly higher 90-day mortality (19.0% vs 4.9%, p = 0.022) and were more likely to undergo three-level corpectomies (9.5% vs 3.7%, p = 0.002) and upper thoracic (T1-4) corpectomies (37.9% vs 12.4%, p = 0.001), and sustain a pleural injury (14.3% vs 2.5%, p = 0.019). Ninety-day reoperation rates (p = 0.970), postoperative ventilator days (p = 0.224), intensive care unit stays (p = 0.350), hospital lengths of stay (p = 0.094), neurological injuries (p = 0.338), and dural tears (p = 0.794) did not significantly vary between the different groups.

CONCLUSIONS

Nearly half of the patients undergoing a TCT will experience an unanticipated short-term complication related to the procedure. Short-term complications may vary with the underlying patient diagnosis.

Burst fractures of the fifth lumbar vertebra: Case series and systematic review

BACKGROUND

Burst fractures of the fifth lumbar vertebra (L5) are rare injuries and typically occur because of high-energy axial compressive load. Their unique anatomy and biomechanical characteristics distinguish them from other lumbar spine injuries. To the best of our knowledge, the treatment strategies for L5 burst fractures have not been thoroughly described. The aims of this case series and systematic review were to highlight the treatment strategies and outcomes of the L5 burst fractures.

METHODS

We performed a retrospective case series of 8 patients treated for burst L5 fractures in our institution between 2005 and 2020. Additionally, a systematic review via PubMed and Cochrane Library databases according to PRISMA guidelines was performed to review L5 burst fractures treatment strategies. Only Articles in English with full text available were included. The references of the selected studies were checked to find all possible related articles. Treatment strategies were conservative, posterior segmental instrumentation and fixation (PSIF), PSIF with anterior corpectomy (AC), and PSIF with posterior corpectomy (PC). Outcomes measures included neurological status, radiological regional alignment, and complications.

RESULTS

A total of 1449 publications were found, and 29 articles were finally selected for analysis. Of those, 15 were retrospective case reports, and 14 were retrospective case series. One hundred and sixty-nine patients were found in the review. The author's eight cases were added to the found in the literature for a methodological quality assessment. There were 52 (29%) patients managed non-operative, and 125 (71%) underwent surgery. One-hundred-two patients were neurologically intact, of whom 46 were managed non-operative. Canal compromise in intact patients ranged between 20 and 90%. Posterior segmental fixation and instrumentation with decompression was the preferred surgical strategy in patients with neurological deficits. Patients with combined anterior column restoration and anterior approach showed vertebral height and lordosis restoration. A 79% of the operative treated group reported neurological improvement. Patients with pre-operative neurological deficit managed non-operative reported the highest rate of complications (33.3%).

CONCLUSION

In the setting of L5 burst fractures, neurological injuries have a promising prognosis after surgery and are not correlated with the degree of canal stenosis. The compromise of the L5 vertebra affects the sagittal balance and its restoration can be achieved with an anterior corpectomy. Nonoperative management can be considered in cases of reasonable alignment, and no neurologic deficit.

Post-operative follow-up care after acute spinal trauma: What is the reality?

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Only 23.7% of acute spinal trauma patients who underwent instrumentation met or surpassed one-year of clinical follow-up care.

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Factors associated with lower rates of completed follow-up are ISS, presence of non-ambulatory spinal cord injury, history of IVDA, and insurance.

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Increased rates of completed follow-up were seen in patients with a Workers'.

"Floating Cervical Spine Injuries": Craniocervical Dissociation with Associated, Noncontiguous, Unstable Cervical or Cervicothoracic Spine Fracture

BACKGROUND

Advances in prehospital life support of patients who have sustained high-energy trauma have resulted in an increase in the number of patients with craniocervical dissociations (CCDs) surviving. With better imaging and more severely injured patients surviving, we are now seeing other associated injuries. CCDs in association with unstable, noncontiguous, subaxial spine injuries have not been described. The objective of this study was to (1) describe this injury pattern and its characteristics, including the mechanism of injury, injury levels, and neurological deficits, and (2) understand prognosis and outcome.

METHODS

After institutional review board approval, a retrospective study of patients who sustained CCD in association with an unstable, circumferential, subaxial, or cervicothroacic spine injury (C3-T2) between January 1, 2003, and August 31, 2018, was done. Review of imaging was performed to identify spine injury localization and type. Demographic data, mechanism of injury, neurological status, type of treatment, and patient outcomes were obtained from the electronic medical records.

RESULTS

One hundred seventeen patients with CCD were identified, of which 105 had full spine radiographs. Thirteen (8 male and 5 female) had an associated, noncontiguous, unstable cervical, or cervicothoracic injury. Mean age was 45.4 ± 19 years. No exam could be obtained in 6; in the other 7, 1 was American Spinal Injury Association (ASIA) E, 1 ASIA D, and 5 ASIA A. Operative management of both injuries was planned for all 13 patients; however, 2 died before surgery. At discharge, there were 9 survivors with mean follow up of 2 years; 4 patients were independent (3 ASIA D, 1 ASIA E), and 5 were dependent (1 ASIA C, 4 ASIA A).

CONCLUSIONS

Approximately 12% of patients with CCD have a floating cervical spine injury. Floating cervical spine injuries have an unfavorable prognosis with 69% surviving to hospital discharge but only 31% functioning independently (ASIA D or E).

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

Floating cervical spine injuries need to be recognized to optimize prognosis, yet even in the best of circumstances, prognosis is guarded.

Advanced compressive extension injuries of the subaxial cervical spine: do we really understand the nuances of this injury?

BACKGROUND CONTEXT

The Allen and Ferguson classification of cervical spine injuries is widely used. They described compressive Extension (CE) injuries as having five progressive stages. Stage 4(CE4) and 5(CE5) have been described as having a posterior vertebral arch fracture involving two motion segments accompanied by displacement (dislocation) of the vertebral body at a single level. However, in their original work, CE4 was described only as a hypothetical stage, while CE5 was found in only three patients. Beyond this, little is understood about these injuries.

PURPOSE

To identify characteristics of compression extension injuries with vertebral body displacement (CE4 and CE5) from a series of surgically treated subaxial cervical spine fractures. A secondary aim was to identify specific characteristics that may guide treatment or affect prognosis.

DESIGN

Retrospective case series.

PATIENT SAMPLE

Twenty-four patients who underwent surgical stabilization of CE4 and CE5 cervical spine fracture-dislocations in non-ankylosed spines over a 14-year period.

OUTCOME MEASURES

Radiographic categorization of CE injury type, treatment rendered, postoperative spinal alignment, presence of nonunion, loss of fixation, hardware-related and neurologic complications.

METHODS

After IRB approval, patients with CE injuries were identified through billing data and radiology records at a level I trauma center between January 2005 and September 2018. Demographic data, ISS, ASA, motor score, and complications during the hospitalization were collected from the patient's EMR. CT scans were reviewed to assess fracture pattern, level, and location of the vertebral arch fracture, vertebral body displacement, spinal canal diameter and method of surgical stabilization. Injuries were classified according to the classification of Allen and Ferguson, and the AO subaxial cervical spine classification.

RESULTS

Of 221 patients identified with CE mechanism, 24 had CE4 or CE5 injuries. High-energy mechanism occurred in 92% of the patients, with motor vehicle accidents being the most common. The average ASIA motor score was 80 preoperatively and 84 at average 398 days follow-up. All CE4 and CE5 injuries occurred at C6-C7 or C7-T1. Average anterolisthesis was 6.26 mm (SD ± 2.3 mm) for CE4 and 16.8 mm (SD ± 1.8 mm) for CE5. Average spinal canal diameter at the level of dislocation was 20 mm (SD ± 0.4 mm) for CE4 and 30.5 mm (range 29.6 - 31.4 mm) for CE5. The surgical approach was anterior in 5 patients, posterior in 12 patients, and combined in 7 patients. Four patients had single-evel fixation, all of whom had CE4 injuries, and 20 patients had fixation across two or more levels. Thirty percent of patients had complications, none of which included postoperative spinal malalignment, nonunion or hardware-related complications, or worsening of neurologic exam. Three deaths occurred in the postoperative hospitalization period (7 to 15 days).

CONCLUSION

CE4 and CE5 injuries represented 10% and 1% of all CE injuries in our series respectively occurring only at the C6-C7 and C7-T1 levels. Though by original description these are two-level injuries, in patients with milder posterior element injury, single level stabilization was used successfully. We have therefore proposed designating CE4 into less severe CE4a and more severe CE4b injuries. Because this fracture pattern typically results in widening of the spinal canal as the anterior displacement of the vertebral body occurs independent of the fractured posterior elements, spinal cord injuries are neither as severe nor as common as in fracture-dislocation from other mechanisms.

Incidence and degrees of neurologic decline following thoracic costotransversectomy

BACKGROUND CONTEXT

Thoracic costotransversectomies (TCT) are amongst the most invasive spine procedures performed. Of greatest concern to the patient and surgeon is the risk of iatrogenic neurologic injury associated with these procedures. Most available studies limit their assessment of neurologic function to nonspecific scales such as the broader ASIA scoring system of A to E and have not comprehensively described the rates of iatrogenic injury following these procedures by looking more precisely with ASIA motor scoring (0-100) which allows for more in-depth analysis.

PURPOSE

The purpose of this study is to investigate the rates and degree of iatrogenic neurologic decline following TCT and subsequent rates and degree of motor recovery.

STUDY DESIGN/SETTING

Retrospective medical record review at a single institution.

PATIENT SAMPLE

Around 116 consecutive patients undergoing TCT operations.

OUTCOME MEASURES

Neurological changes from preprocedure to final follow-up assessed by lower extremity motor score.

METHODS

A retrospective chart review of patients undergoing TCT between May 2008 and April 2018 was carried out. Clinical, surgical, and intraoperative neuromonitoring data were collected. Patients who demonstrated an initial postoperative decline in lower extremity motor scores (LEMS) were followed through their final follow up to assess recovery.

RESULTS

Around 116 patients underwent TCT between T2 and T12 between May 2008 and April 2018. Seven (6.0%) patients demonstrated an immediate postoperative decline as defined by a drop of more than 4 points (mean 15.1; range 5-50) in motor score. All patients who demonstrated an initial postoperative motor score decline returned to within 4 LEMS points of their preoperative LEMS by final follow up. IOMN changes were noted only in half of all monitored patients who were noted to have a decline.

CONCLUSIONS

In our series, 6.0% of patients undergoing TCT experienced an initial decline in motor score with 94.0% demonstrating an unchanged or improved examination compared to preoperative exam. In our series, all patients who exhibited a decline recovered to within 4 points of the preoperative motor score within the first year postoperatively.

2021 Young Investigator Award Winner: Anatomic Gradients in the Microbiology of Spinal Fusion Surgical Site Infection and Resistance to Surgical Antimicrobial Prophylaxis

STUDY DESIGN

Retrospective hospital-registry study.

OBJECTIVE

To characterize the microbial epidemiology of surgical site infection (SSI) in spinal fusion surgery and the burden of resistance to standard surgical antibiotic prophylaxis.

SUMMARY OF BACKGROUND DATA

SSI persists as a leading complication of spinal fusion surgery despite the growth of enhanced recovery programs and improvements in other measures of surgical quality. Improved understandings of SSI microbiology and common mechanisms of failure for current prevention strategies are required to inform the development of novel approaches to prevention relevant to modern surgical practice.

METHODS

Spinal fusion cases performed at a single referral center between January 2011 and June 2019 were reviewed and SSI cases meeting National Healthcare Safety Network criteria were identified. Using microbiologic and procedural data from each case, we analyzed the anatomic distribution of pathogens, their differential time to presentation, and correlation with methicillin-resistant Staphylococcus aureus screening results. Susceptibility of isolates cultured from each infection were compared with the spectrum of surgical antibiotic prophylaxis administered during the index procedure on a per-case basis. Susceptibility to alternate prophylactic agents was also modeled.

RESULTS

Among 6727 cases, 351 infections occurred within 90 days. An anatomic gradient in the microbiology of SSI was observed across the length of the back, transitioning from cutaneous (gram-positive) flora in the cervical spine to enteric (gram-negative/anaerobic) flora in the lumbosacral region (correlation coefficient 0.94, P < 0.001). The majority (57.5%) of infections were resistant to the prophylaxis administered during the procedure. Cephalosporin-resistant gram-negative infection was common at lumbosacral levels and undetected methicillin-resistance was common at cervical levels.

CONCLUSION

Individualized infection prevention strategies tailored to operative level are needed in spine surgery. Endogenous wound contamination with enteric flora may be a common mechanism of infection in lumbosacral fusion. Novel approaches to prophylaxis and prevention should be prioritized in this population.Level of Evidence: 3.

The mandible-C2 angle: a new radiographic assessment of occipitocervical alignment

BACKGROUND CONTEXT

Occipitocervical fusion is a rare and often challenging surgical procedure. Significant morbidity can result if care is not taken to achieve physiologic alignment. This is especially true for patients needing occipitocervical fusion in the setting of trauma where preoperative alignment is unknown.

PURPOSE

To assess the radiographic angles normally subtended between the C2 body and the mandible ramus, in a series of patients with neutral physiologic alignment and no pathology, and to assess its validity as a possible intraoperative radiographic tool to determine a neutral craniocervical alignment.

DESIGN

Validation and reliability study of radiographic parameters.

PATIENT SAMPLE

Hundred lateral, neutral, cervical radiographs from patients with "normal" radiographic findings.

OUTCOME MEASURES

Radiographic parameters of occipital-cervical alignment with assessment of reliability and correlation in data.

METHODS

One hundred neutral lateral cervical spine radiographs in the upright position of patients with no complaints or known pathology were obtained from two medical clinics between December of 2014 and January of 2017. Three physicians, at different levels of spine surgery training, took measurements of radiographic parameters. The new technique used four different angles measured between the C2-body/dens complex and the mandibular ramus (anterior/posterior C2 body and anterior/posterior mandible lines angles), and compared these with the Occipito-C2 angle, which is a validated assessment of occipitocervical alignment. Statistical analysis was performed to assess correlation in data and measure reproducibility.

RESULTS

Between the three reviewers, the mean±standard deviation were 18.0°±6.5° for Occipito-C2 angle (O-C2A), -4.2°±5.4° for anterior C2-body/anterior mandible line angle (AB/AM), -4.2°±5.9° for anterior C2-body/posterior mandible line angle (AB/PM), 5.1°±5.8° for posterior C2 body/anterior mandible line angle (PB/AM) and 5.6°±6.2° for posterior C2 body/ posterior mandible line angle (PB/PM). Overall the measurements obtained were correlative with an appropriate range for the standard deviation. Mean intraclass correlation coefficient were 0.889 for O-C2A, 0.795 for AB/AM, 0.859 for AB/PM, 0.876 for PB/AM, and 0.750 for PB/PM, showing high interobserver reliability for all the radiographic measures. Across the five techniques, 87%-92% of measurements fell within 10° of the median, 76%-83% fell within 7.5°, and 55%-66% within 5°.

CONCLUSIONS

The mandible-C2 angle offers a reproducible alternative to the validated O-C2A technique for determining appropriate intraoperative occipitocervical alignment, which may be especially useful when preoperative radiographic alignment is unknown, such as occurs with trauma patients, with the goal of decreasing alignment-related complications in the setting of occipitocervical stabilization.

Is routine MRI of the spine necessary in trauma patients with ankylosing spinal disorders or is a CT scan sufficient?

BACKGROUND

Ankylosing spinal disorder (ASD) patients are at a greater risk for spinal fractures due to osteoporosis and rigidity of the spinal column. These fractures are associated with a high risk of neurologic compromise resulting from delayed or missed diagnoses. Although computed tomography (CT) is usually the initial imaging modality, magnetic resonance imaging (MRI) has been proposed as mandatory to help identify spinal injuries in ASD patients with unexplained neck or back pain or known injuries to help identify noncontiguous fractures. However, some studies have also shown that neurological injury can result from the required patient transfer and positioning for an MRI.

PURPOSE

The purpose of our study was to assess the frequency with which an MRI identified an injury not previously identified with CT, and whether this affected the treatment and outcome of the patient. Secondarily, we attempted to identify clinical or CT findings that may render an MRI particularly useful.

STUDY DESIGN

Retrospective review.

PATIENT SAMPLE

Patients with ASD who sustained acute spine fractures from 2005 to 2015.

OUTCOME MEASURES

Acute fractures identified by CT scan and MRI upon admission; neurologic status upon admission and discharge, mode of injury, type of fracture, and final intervention before and after MRI assessment.

METHODS

A total of 124 patients with a diagnosis of diffuse idiopathic skeletal hyperostosis (DISH) or ankylosing spondylitis (AS) were identified by searching the radiology database of a level I trauma center with diagnosis keywords. Final radiology reports were assessed to determine presence and type of fracture(s) from CT. MRI report was then reviewed to assess if additional fractures or injuries were identified beyond that already known from the CT. Neurologic status upon admission and discharge, mode of injury, type of fracture, and final intervention were determined by inpatient notes and/or operative reports. No source funding or conflict of interest was present pertaining to this study.

RESULTS

In the designated time frame, 124 ASD patients with injuries of the spine were identified who had obtained both a baseline CT and MRI. Six patients (4.8%) had additional injuries on MRI that had not been identified with CT. Four of these six patients had a change in treatment plan (three operative and one nonoperative) based on subsequent MRI findings. These included a (1) C4-5 hyperextension injury, (2) C6-7 hyperextension injury, (3) C7 bony fracture with C5-T4 epidural hematoma, and (4) C5-C6 hyperextension injury treated in a brace. Two of the six patients that had additional injuries identified on MRI had no change in their treatment plan. One patient had an additional lumbar extension injury identified above a previously diagnosed injury on CT, which was managed with a Thoracolumbosacral Orthosis (TLSO) according to the original plan. One patient died who had a known odontoid fracture and a suspected C6-7 hyperextension injury, and was identified on MRI as also having a C3-C4 hyperextension injury and a C2 spinal cord transection.

CONCLUSIONS

In this study, 3.2% (4/124) of patients with ASD who presented to a level I trauma center with an acute spine injury identified with CT required a change in their treatment plan based on subsequent MRI findings. Only one fracture was missed on CT imaging, with the other missed injuries all being either disco-ligamentous hyperextension injuries through mobile discs or intracanal pathology. Our recommendation is that the routine use of MRI be limited to patients with nonankylosed levels in which a disco-ligamentous injury may have occurred, and in patients with neurological deficits that require investigation of the spinal canal to assess for causes of neurological injury.

Anterior Bone Loss in Cervical Disc Arthroplasty

Study Design

Retrospective, longitudinal observational study.

Purpose

To describe the natural history of anterior bone loss (ABL) in cervical disc arthroplasty (CDA) and introduce a classification system for its assessment.

Overview of Literature

ABL has recently been recognized as a complication of CDA, but its cause and clinical effects remain unknown.

Methods

Patients with non-keeled CDA (146) were retrospectively reviewed. X-rays were examined at 6 weeks, 3, 6, 9, 12, 18, and 24 months, and annually thereafter for a minimum of 5 years. These were compared with the initial postoperative X-rays to determine the ABL. Visual Analog Scale pain scores were recorded at 3 months and 5 years. Neck Disability Index was recorded at postoperative 5 years. The natural history was determined and a classification system was introduced.

Results

Complete radiological assessment was available for 114 patients with 156 cervical disc replacements (CDRs) and 309 endplates (average age, 45.3 years; minimum, 28 years; maximum, 65 years; 57% females). ABL occurred in 57.1% of CDRs (45.5% mild, 8.3% moderate, and 3.2% severe) and commenced within 3 months of the operation and followed a benign course, with improvement in the bone stock after initial bone resorption. There was no relationship between ABL degree and pain or functional outcome, and no implants were revised.

Conclusions

ABL is common (57.1%). It occurs at an early stage (within 3 months) and typically follows a non-progressive natural history with stable radiographic features after the first year. Most ABL cases are mild, but severe ABL occurs in approximately 3% of CDAs. ABL does not affect the patients’ clinical outcome or the requirement for revision surgery. Surgeons should thus treat patients undergoing CDA considering ABL.

Erratum to: Delayed post-operative tension pneumocephalus and pneumorrhachis

Unfortunately, two author names were missed out in author group of the original publication.

Delayed post-operative tension pneumocephalus and pneumorrhachis

INTRODUCTION

The incidence of pneumocephalus and pneumorrhachis after spinal surgery is unknown, with a paucity of literature on this complication.

MATERIALS AND METHODS

We present the first published case of delayed onset tension pneumocephalus and pneumorrhachis associated with spinal surgery.

RESULTS

This complication occurred from a cerebro-spinal fluid (CSF) leak after posterior instrumentation removal and was successfully treated with emergent wound debridement and the formation of a CSF fistula.

CONCLUSIONS

This case illustrates that delayed post-operative tension pneumocephalus and pneumorrhachis can occur after spinal surgery in a patient with a CSF leak. It also illustrates that pneumocephalus and pneumorrhachis can be easily diagnosed with cross-sectional CT imaging. Furthermore, in a patient with rapid deterioration emergent surgical debridement may be necessary. Lastly, if the dural tear cannot be identified intra-operatively, the formalization of a CSF fistula should be considered.