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.

"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.

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.

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.

Bisphosphonate therapy for spinal aneurysmal bone cysts.

PURPOSE: To assess the efficacy of bisphosphonate therapy in the management of spinal aneurysmal bone cysts (ABCs). METHODS: A prospective study of six consecutive patients aged between 7 and 22 years with spinal ABCs treated with pamidronate (1 mg/kg) or zoledronate (4 mg). A visual analogue scale (VAS) for pain and radiological (contrast-enhanced MRI and CT scan at 3 and 6 months, then yearly X-rays) follow-up was continued for a minimum of 6 years. RESULTS: One patient with an unstable C2/3 failed to respond to a single dose of bisphosphonate and required surgical resection and stabilisation with autologous bone grafting. Another, with a thoraco-lumbar ABC, experienced progression of neurological dysfunction after one cycle of bisphosphonate and, therefore, required surgical resection and stabilisation. In all other patients pain progressively improved and was resolved after two to four cycles (VAS 7.3-0). These patients all showed reduction in peri-lesional oedema and increased ossification by 3 months. No patients have had a recurrence within the timeframe of this study. CONCLUSIONS: Bisphosphonate therapy can be used as the definitive treatment of spinal ABCs, except in patients with instability or progressive neurology, where surgical intervention is required. Clinicians should expect a patients symptoms to rapidly improve, their bone oedema to resolve by 3 months and their lesion to partially or completely ossify by 6-12 months.