Juliet Batke

Patient and surgeon radiation exposure during spinal instrumentation using intraoperative computed tomography-based navigation

BACKGROUND CONTEXT Imaging modalities used to visualize spinal anatomy intraoperatively include X-ray studies, fluoroscopy, and computed tomography (CT). All of these emit ionizing radiation. PURPOSE Radiation emitted to the patient and the surgical team when performing surgeries using intraoperative CT-based spine navigation was compared. STUDY DESIGN/SETTING This is a retrospective cohort case-control study. PATIENT SAMPLE Seventy-three patients underwent CT-navigated spinal instrumentation and 73 matched controls underwent spinal instrumentation with conventional fluoroscopy. OUTCOME MEASURES Effective doses of radiation to the patient when the surgical team was inside and outside of the room were analyzed. The number of postoperative imaging investigations between navigated and non-navigated cases was compared. METHODS Intraoperative X-ray imaging, fluoroscopy, and CT dosages were recorded and standardized to effective doses. The number of postoperative imaging investigations was compared with the matched cohort of surgical cases. A literature review identified historical radiation exposure values for fluoroscopic-guided spinal instrumentation. RESULTS The 73 navigated operations involved an average of 5.44 levels of instrumentation. Thoracic and lumbar instrumentations had higher radiation emission from all modalities (CT, X-ray imaging, and fluoroscopy) compared with cervical cases (6.93 millisievert [mSv] vs. 2.34 mSv). Major deformity and degenerative cases involved more radiation emission than trauma or oncology cases (7.05 mSv vs. 4.20 mSv). On average, the total radiation dose to the patient was 8.7 times more than the radiation emitted when the surgical team was inside the operating room. Total radiation exposure to the patient was 2.77 times the values reported in the literature for thoracolumbar instrumentations performed without navigation. In comparison, the radiation emitted to the patient when the surgical team was inside the operating room was 2.50 lower than non-navigated thoracolumbar instrumentations. The average total radiation exposure to the patient was 5.69 mSv, a value less than a single routine lumbar CT scan (7.5 mSv). The average radiation exposure to the patient in the present study was approximately one quarter the recommended annual occupational radiation exposure. Navigation did not reduce the number of postoperative X-rays or CT scans obtained. CONCLUSIONS Intraoperative CT navigation increases the radiation exposure to the patient and reduces the radiation exposure to the surgeon when compared with values reported in the literature. Intraoperative CT navigation improves the accuracy of spine instrumentation with acceptable patient radiation exposure and reduced surgical team exposure. Surgeons should be aware of the implications of radiation exposure to both the patient and the surgical team when using intraoperative CT navigation.

Economic evaluation comparing intraoperative cone beam CT-based navigation and conventional fluoroscopy for the placement of spinal pedicle screws: a patient-level data cost-effectiveness analysis

BACKGROUND CONTEXT Pedicle screws are routinely used in contemporary spinal surgery. Screw misplacement may be asymptomatic but is also correlated with potential adverse events. Computer-assisted surgery (CAS) has been associated with improved screw placement accuracy rates. However, this technology has substantial acquisition and maintenance costs. Despite its increasing usage, no rigorous full economic evaluation comparing this technology to current standard of care has been reported. PURPOSE Medical costs are exploding in an unsustainable way. Health economic theory requires that medical equipment costs be compared with expected benefits. To answer this question for computer-assisted spinal surgery, we present an economic evaluation looking specifically at symptomatic misplaced screws leading to reoperation secondary to neurologic deficits or biomechanical concerns. STUDY DESIGN/SETTING The study design was an observational case-control study from prospectively collected data of consecutive patients treated with the aid of CAS (treatment group) compared with a matched historical cohort of patients treated with conventional fluoroscopy (control group). PATIENT SAMPLE The patient sample consisted of consecutive patients treated surgically at a quaternary academic center. OUTCOME MEASURES The primary effectiveness measure studied was the number of reoperations for misplaced screws within 1 year of the index surgery. Secondary outcome measures included were total adverse event rate and postoperative computed tomography usage for pedicle screw examination. METHODS A patient-level data cost-effectiveness analysis from the hospital perspective was conducted to determine the value of a navigation system coupled with intraoperative 3-D imaging (O-arm Imaging and the StealthStation S7 Navigation Systems, Medtronic, Louisville, CO, USA) in adult spinal surgery. The capital costs for both alternatives were reported as equivalent annual costs based on the annuitization of capital expenditures method using a 3% discount rate and a 7-year amortization period. Annual maintenance costs were also added. Finally, reoperation costs using a micro-costing approach were calculated for both groups. An incremental cost-effectiveness ratio was calculated and reported as cost per reoperation avoided. Based on reoperation costs in Canada and in the United States, a minimal caseload was calculated for the more expensive alternative to be cost saving. Sensitivity analyses were also conducted. RESULTS A total of 5,132 pedicle screws were inserted in 502 patients during the study period: 2,682 screws in 253 patients in the treatment group and 2,450 screws in 249 patients in the control group. Overall accuracy rates were 95.2% for the treatment group and 86.9% for the control group. Within 1 year post treatment, two patients (0.8%) required a revision surgery in the treatment group compared with 15 patients (6%) in the control group. An incremental cost-effectiveness ratio of

The Validity of Administrative Data To Classify Patients with Spinal Column and Cord Injuries

15,961 per reoperation avoided was calculated for the CAS group. Based on a reoperation cost of

Feasibility of patient recruitment into clinical trials of experimental treatments for acute spinal cord injury

12,618, this new technology becomes cost saving for centers performing more than 254 instrumented spinal procedures per year. CONCLUSIONS Computer-assisted spinal surgery has the potential to reduce reoperation rates and thus to have serious cost-effectiveness and policy implications. High acquisition and maintenance costs of this technology can be offset by equally high reoperation costs. Our cost-effectiveness analysis showed that for high-volume centers with a similar case complexity to the studied population, this technology is economically justified.

Adverse events in surgically treated cervical spondylopathic myelopathy: a prospective validated observational study.

International Classification of Diseases (ICD) codes are used to document patient morbidity in administrative databases. Although administrative data are used for research purposes, the validity of the data to accurately describe clinical diagnostic information is uncertain. We compared the clinical diagnoses for spinal cord and column injuries from a longitudinal patient registry, the Rick Hansen Spinal Cord Injury Registry (RHSCIR), to the ICD-10 spinal injury codes from the Discharge Abstract Database (DAD) at one institution. There were 603 RHSCIR participants with data describing the spinal cord injury, and 341 had data on the spinal column injury. The validity of DAD data to describe spinal injuries was evaluated using the sensitivity and positive predictive values of specific ICD-10 codes; 5.3% of the spinal column injuries and 10.9% of the spinal cord injuries documented in RHSCIR were missed in data from the DAD using ICD-10 codes. The most problematic spinal column ICD-10 code was the dislocation of the cervical vertebra (S13.1); only 14.0% of the dislocations of the cervical vertebrae in RHSCIR were correctly coded in the DAD. The most problematic spinal cord injury ICD-10 code was the incomplete lesion of the lumbar spinal cord (S34.1X); 66.7% of incomplete lesions of the lumbar spinal cord in RHSCIR were correctly coded in the DAD. The validity of DAD data to code spinal injuries is variable, and cannot be reliably used to classify all types of spinal injuries. Patient registries, such as RHSCIR, should be used if accurate detailed diagnostic data are required.

Incidence, impact, and risk factors of adverse events in thoracic and lumbar spine fractures: an ambispective cohort analysis of 390 patients

Clinical trials of experimental neuroprotective and neuroregenerative therapies for acute spinal cord injury (SCI) typically require large numbers of patients to be enrolled. An important factor in designing such trials is the number of patients that can be realistically recruited at a given institution. The total number of patients with acute SCI treated at a neurotrauma centre is typically considered when such a site becomes a recruiting centre for a clinical trial. However, only a fraction of patients may be truly eligible due to the inclusion and exclusion criteria of the trial. This study was conducted to estimate the proportion of patients with acute SCI who would theoretically satisfy basic inclusion criteria for such a hypothetical clinical trial. Using a local prospective database, we reviewed 406 patients with acute traumatic SCI admitted between 2005 and 2009. 259 of 406 patients (64%) presented within 12 hours of injury, 53 patients (13%) between 12 hours and 24 hours, and 30 patients (7%) between 24 hours and 48 hours. Patients were assessed on admission using the American Spinal Injury Association Impairment Scale: category A, 39% of patients; B, 11%; C, 17%; and D, 28%. The number of patients who presented with injuries or other conditions that would likely exclude them from enrolment was 30%. Thus, of a total of 406 patients with SCI admitted over four years, the number who would have been eligible for an acute clinical trial was disappointingly small. This study is the first to quantify this challenging aspect of conducting acute SCI clinical trials, and provides guidance for those planning such initiatives.

Editorial: separation surgery.

Study Design. Prospective observational study. Objective. Using validated tools to accurately identify and quantify incidence of and risks for inpatient adverse events (AEs) associated with surgical management of cervical spondylopathic myelopathy (CSM) with the goal of assisting physicians and patients in decision making. To identify patient-/disease-/technique-specific, independent risk factors for developing AEs perioperatively and affecting length of stay for patients treated surgically for CSM. Summary of Background Data. Previous studies have reported an overall perioperative complication rate between 15.6% and 18.52%. Methods. A total of 104 patients underwent surgery for CSM in our academic quaternary referral center. The average age was 60.3 years (range, 34–86 yr) with a male preponderance (n = 77, 74%). The severity of myelopathy and significant comorbidities was measured and was in keeping with previously assessed populations. Surgical approach was anterior-alone (39.4%), posterior-alone (55.8%), or combined (4.8%) surgery. Inpatient AE data were collected in a rigorous, contemporaneous fashion using the previously validated Spine Adverse Events Severity System (SAVES) tool. Results. A total AE rate of 42.3% was documented in surgically managed patients with CSM (intraoperative = 13.5%, postoperative = 37.5%). Statistically significant risk factors for postoperative AEs were identified, including number of comorbidities (P = 0.012), anterior surgical approach (P = 0.003), and number of levels operated on (P = 0.031). Multiple risk factors for length of stay were also identified, including number of AEs (P < 0.0001), Nurick Score (P < 0.0001), number of levels operated on (P = 0.006), and occurrence of deep wound infection (P < 0.0001). Conclusion. We report higher perioperative AE rates than previously recognized, due to the use of a validated, rigorous data collection tool. Multiple novel patient/disease severity/surgical factors with high statistical significance on perioperative AEs have been identified. Level of Evidence: 3

Timing of surgery and radiotherapy in the management of metastatic spine disease: expert opinion

BACKGROUND CONTEXT Adverse events (AEs) in thoracic and lumbar spine fractures are common, but little is known about the type of AEs that are specific to this population. Furthermore, very little is known about the incidence and clinical impact of these AEs on patients in the presence of traumatic spinal cord injury and whether they are treated operatively or nonoperatively. PURPOSE The purpose of this study was to determine primarily the incidence of AEs in patients with thoracic or lumbar spine fractures treated both operatively and nonoperatively and their impact on length of stay (LOS) and secondarily the difference in the incidence of AEs in both neurologically intact and compromised patients. STUDY DESIGN/SETTING This is an ambispective cohort study at a quaternary referral center. PATIENT SAMPLE Patients admitted at our institution with thoracic or lumbar fractures from January 2009 to December 2013 were identified. Patients with full Spine Adverse Events Severity System (SAVES) data were included. OUTCOME MEASURES Number and type of AEs collected from SAVES were assessed. Impact of AE on acute LOS was also determined. METHODS Data on intraoperative, preoperative, and postoperative AEs were prospectively collected using the SAVES data collection. Logistic regression was used to model the likelihood of experiencing at least one AE based on the patient characteristics. The impact of the total number of AEs experienced by a patient and that of each of the most common AEs on LOS was determined using Poisson regression. RESULTS Three hundred and ninety patients were included in the final analysis. Two hundred and seventy-six patients (70.8%) were treated operatively. One hundred and forty patients (36%) experienced neurologic deficit as a result of their initial injury. Adverse events occurred 56% of the time in the operatively treated patients and only 13% of the time in the nonoperative group. The presence of neurologic deficit increased the risk of AEs especially in high thoracic (T1-T6) trauma increasing the odds of having an AE by 12.1 (p<.0001). The most common AEs were urinary tract infections (19.7%), neuropathic pain (12.3%), pneumonias (11.8%), delirium (10.5%), and ileus (6.2%). Length of hospital stay increased significantly with pneumonia (p<.0001) and delirium (p=.0001). CONCLUSIONS The presence of neurologic injury and the need for operative fixation of thoracic or lumbar injuries lead to a greater risk of AEs. Only pneumonia and delirium consistently increase LOS.

Prospective analysis of adverse events in surgical treatment of degenerative spondylolisthesis.

The management of patients with spine metastases from a functional and health-related quality of life (HRQOL) perspective is one of the most challenging issues faced by both oncologists and spine surgeons. Higher levels of evidence have been achieved over the past decade in defining the positive impact of surgery and/or conventional external beam radiation therapy (cEBRT) in these patients.1,3 More recently, stereotactic radiosurgery (SRS) has provided a successful treatment option for traditionally radioresistant tumors, but has been limited in a setting where extensive epidural disease restricts radiation dose due to the threat of cord toxicity.2 In this patient group, maximally invasive surgery to achieve gross-total resection of the tumor was often necessary to prevent local recurrence and optimize HRQOL. This surgery is resource intensive, with a not-insignificant adverse event rate, so it is not ideal in those patients who are systemically compromised and have limited life expectancy. To address this problem, Laufer et al.4 report on a treatment method of surgically removing the epidural disease (separation surgery) and then administering high-dose SRS to the remaining tumor, thus providing a means of potentially achieving local control while minimizing surgical insult and cord toxicity. The study has a strong rationale and clear purpose: to determine local recurrence rate after separation surgery and SRS. The study design is a retrospective case series involving a relatively large consecutive patient cohort treated at a specialized cancer center between 2002 and 2011. The study design is reasonable for the research question, given the complexity of the patient population and the evolution of the treatment method, but not optimal with the number of potential confounders, treatment variability, and difficulty in accurately determining the primary or dependent outcome. Unfortunately, the validity or accuracy of local recurrence determination is difficult due to changes in technology over time, reviewer variability (imaging reports were used as well as neuroradiology and neurosurgeon review), lack of technique standardization (CT myelogram and MRI), effect of spinal implant imaging artifact, lack of standardized time periods, and quantitative evaluation. With these limitations, the magnitude of the group without local recurrence (82% of the patients) is questionable; however, such an impressive effect change cannot be ignored, and the positive effect is probably a true finding. The authors use a very appropriate and robust statistical analysis to try and overcome the treatment variability and aforementioned limitations. The variability leaves the study underpowered on a number of secondary outcomes, but trends can be observed. The study does not include a patient-focused HRQOL instrument to ensure that impressive imaging outcomes are correlated with those of the patient. This omission is not critical, given the research question being asked, and using local recurrence rate as the primary outcome is a reasonable surrogate for HROQL outcome in prospective tumor research. Finally, the generalizability of the study’s findings must be considered. The breadth and variability of the cohort supports external validity, but the specialization and technology of the center and subspecialization of the surgeons and oncologists may limit it. The management of patients with symptomatic spinal metastases is difficult. Carrying out high-quality clinical research involving patients whose quality of life you are trying to optimize for their remaining time is even more demanding. The authors should be congratulated for giving us evidence for a treatment method that potentially fills a therapeutic void in this truly deserving patient population. Can we implement the findings from this study into our clinical practice despite its being at the lower level of study design hierarchy? Though the study is statistically sound and optimal within the restraints of a retrospective design, its limitations diminish its impact. The effect size, external validity within the context of large cancer centers, and the unique patient population probably support cautious implementation of this treatment method. As the technique evolves and is used by more centers, prospective evaluation will be essential. (http://thejns.org/doi/abs/10.3171/2012.10.SPINE12743)

Economic Evaluation of Intraoperative Cone Beam CT-Based Navigation for the Placement of Spinal Pedicle Screws: A Patient Level Cost Effectiveness Analysis

Background Combined surgery and radiotherapy, in the treatment of metastatic disease of the spine, is now emerging as the gold standard of care where there is an indication for spinal stabilization and/or surgical decompression. However potential complications related to wound healing can occur with radiation delivered shortly before or after to surgery. The purpose of this study was to understand the practice of leading radiation oncologists and spine surgeons with regards to the timing of radiation (conventional and stereotactic) and surgery for the management of spinal metastases. Methods Questionnaires were sent to leading radiation oncologists and spine surgeons throughout North America and completed via mail, email or internet. Results Eighty-six responses were received from radiation oncologists and 27 from spine surgeons. A total of 58% recommended waiting either 1 or 2 weeks after radiotherapy before operating on patients with spinal metastases. With radiotherapy administered after surgery, 62% of respondents suggested either a 1 or 2 weeks interval was sufficient. Conclusions There appeared to be no significant difference in practice with the use of stereotactic radiotherapy though surgeons tend to accept a shorter interval in this subset of patients. We recommend that the interval between radiotherapy and surgery (and vice versa) should ideally be a minimum of 2 weeks.