The SPORT value compass: do the extra costs of undergoing spine surgery produce better health benefits?

BACKGROUND: The Spine Patient Outcomes Research Trial aimed to determine the comparative effectiveness of surgical care versus nonoperative care by measuring longitudinal values: outcomes, satisfaction, and costs. METHODS: This paper aims to summarize available evidence from the Spine Patient Outcomes Research Trial by addressing 2 important questions about outcomes and costs for 3 types of spine problem: (1) how do outcomes and costs of spine patients differ depending on whether they are treated surgically compared with nonoperative care? (2) What is the incremental cost per quality adjusted life year for surgical care over nonoperative care? RESULTS: After 4 years of follow-up, patients with 3 spine conditions that may be treated surgically or nonoperatively have systematic differences in value endpoints. The average surgical patient enjoys better health outcomes and higher treatment satisfaction but incurs higher costs. CONCLUSIONS: Spine care is preference sensitive and because outcomes, satisfaction, and costs vary over time and between patients, data on value can help patients make better-informed decisions and help payers know what their dollars are buying.

Developing a toolkit for comparing safety in spine surgery.

Safety information in spine surgery is important for informed patient choice and performance-based payment incentives, but measurement methods for surgical safety assessment are not standardized. Published reports of complication rates for common spinal procedures show wide variation. Factors influencing variation may include differences in safety ascertainment methods and procedure types. In a prospective cohort study, adverse events were observed in all patients undergoing spine surgery at two hospitals during a 2-year period. Multiple processes for adverse occurrence surveillance were implemented, and the associations between surveillance methods, surgery invasiveness, and observed frequencies of adverse events were examined. The study enrolled 1,723 patients. Adverse events were noted in 48.3% of the patients. Reviewers classified 25% as minor events and 23% as major events. Of the major events, the daily rounding team reported 38.4% of the events using a voluntary reporting system, surgeons reported 13.4%, and 9.1% were identified during clinical conferences. A review of medical records identified 86.7% of the major adverse events. The adverse events occurred during the inpatient hospitalization for 78.1% of the events, within 30 days for an additional 12.5%, and within the first year for the remaining 9.4%. A unit increase in the invasiveness index was associated with an 8.2% increased risk of a major adverse event. A Current Procedural Terminology-based algorithm for quantifying invasiveness correlated well with medical records-based assessment. Increased procedure invasiveness is associated with an increased risk of adverse events. The observed frequency of adverse events is influenced by the ascertainment modality. Voluntary reports by surgeons and other team members missed more than 50% of the events identified through a medical records review. Increased surgery invasiveness, measured from medical records or billing codes, is quantitatively associated with an increased risk of adverse events.

Accuracy of Stereovision-Updated Versus Preoperative CT-Based Image Guidance in Multilevel Lumbar Pedicle Screw Placement: A Cadaveric Swine Study.

Change in vertebral position between preoperative imaging and the surgical procedure reduces the accuracy of image-guided spinal surgery, requiring repeated imaging and surgical field registration, a process that takes time and exposes patients to additional radiation. We developed a handheld, camera-based, deformable registration system (intraoperative stereovision, iSV) to register the surgical field automatically and compensate for spinal motion during surgery without further radiation exposure. Methods: We measured motion-induced errors in image-guided lumbar pedicle screw placement in 6 whole-pig cadavers using state-of-the-art commercial spine navigation (StealthStation; Medtronic) and iSV registration that compensates for intraoperative vertebral motion. We induced spinal motion by using preoperative computed tomography (pCT) of the lumbar spine performed in the supine position with accentuated lordosis and performing surgery with the animal in the prone position. StealthStation registration of pCT occurred using metallic fiducial markers implanted in each vertebra, and iSV data were acquired to perform a deformable registration between pCT and the surgical field. Sixty-eight pedicle screws were placed in 6 whole-pig cadavers using iSV and StealthStation registrations in random order of vertebral level, relying only on image guidance without invoking the surgeon's judgment. The position of each pedicle screw was assessed with post-procedure CT and confirmed via anatomical dissection. Registration errors were assessed on the basis of implanted fiducials. Results: The frequency and severity of pedicle screw perforation were lower for iSV registration compared with StealthStation (97% versus 68% with Grade 0 medial perforation for iSV and StealthStation, respectively). Severe perforation occurred only with StealthStation (18% versus 0% for iSV). The overall time required for iSV registration (computational efficiency) was ∼10 to 15 minutes and was comparable with StealthStation registration (∼10 min). The mean target registration error was smaller for iSV relative to StealthStation (2.81 ± 0.91 versus 8.37 ± 1.76 mm). Conclusions: Pedicle screw placement was more accurate with iSV registration compared with state-of-the-art commercial navigation based on preoperative CT when alignment of the spine changed during surgery. Clinical Relevance: The iSV system compensated for intervertebral motion, which obviated the need for repeated vertebral registration while providing efficient, accurate, radiation-free navigation during open spinal surgery.

A level-wise spine registration framework to account for large pose changes.

PURPOSES: Accurate and efficient spine registration is crucial to success of spine image guidance. However, changes in spine pose cause intervertebral motion that can lead to significant registration errors. In this study, we develop a geometrical rectification technique via nonlinear principal component analysis (NLPCA) to achieve level-wise vertebral registration that is robust to large changes in spine pose. METHODS: We used explanted porcine spines and live pigs to develop and test our technique. Each sample was scanned with preoperative CT (pCT) in an initial pose and rescanned with intraoperative stereovision (iSV) in a different surgical posture. Patient registration rectified arbitrary spinal postures in pCT and iSV into a common, neutral pose through a parameterized moving-frame approach. Topologically encoded depth projection 2D images were then generated to establish invertible point-to-pixel correspondences. Level-wise point correspondences between pCT and iSV vertebral surfaces were generated via 2D image registration. Finally, closed-form vertebral level-wise rigid registration was obtained by directly mapping 3D surface point pairs. Implanted mini-screws were used as fiducial markers to measure registration accuracy. RESULTS: In seven explanted porcine spines and two live animal surgeries (maximum in-spine pose change of 87.5 mm and 32.7 degrees averaged from all spines), average target registration errors (TRE) of 1.70 ± 0.15 mm and 1.85 ± 0.16 mm were achieved, respectively. The automated spine rectification took 3-5 min, followed by an additional 30 secs for depth image projection and level-wise registration. CONCLUSIONS: Accuracy and efficiency of the proposed level-wise spine registration support its application in human open spine surgeries. The registration framework, itself, may also be applicable to other intraoperative imaging modalities such as ultrasound and MRI, which may expand utility of the approach in spine registration in general.

Identifying survivors with traumatic craniocervical dissociation: a retrospective study.

BACKGROUND: Traumatic craniocervical dissociation (CCD), which includes atlanto-occipital dissociation and vertical distraction between C1-C2, is often an immediately fatal injury that has increasingly been associated with survival to the hospital. Our aim was to identify survivors of CCD based on clinical presentation. METHODS: We retrospectively reviewed the Harborview Medical Center Trauma Registry and the King County Medical Examiners database from 2001 to 2006. Patients>or=12 y old were identified by ICD-9 code, radiographic diagnosis on lateral cervical spine films, and CT. We examined age, gender, mechanism of injury, presentation and prehospital and hospital interventions, and radiographic findings to distinguish survivors and non-survivors. RESULTS: Of 69 patients with CCD, 47 were diagnosed post mortem, 22 were diagnosed in hospital, and seven survived to discharge. When comparing survivors and non-survivors, age, gender, and injury severity score were not significant. Survivors had significantly higher GCS, and were more likely to be normotensive; none had cervical cord injury; 80% of non-survivors had a basion-dental interval (BDI) of >or=16mm. CONCLUSIONS: Trauma patients diagnosed with CCD in the ED, with cervical cord injury, requiring CPR, and with GCS of 3 will not survive their injury. Wider BDI is associated with mortality.

Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults.

CONTEXT: In recent decades, the fastest growth in lumbar surgery occurred in older patients with spinal stenosis. Trials indicate that for selected patients, decompressive surgery offers an advantage over nonoperative treatment, but surgeons often recommend more invasive fusion procedures. Comorbidity is common in older patients, so benefits and risks must be carefully weighed in the choice of surgical procedure. OBJECTIVE: To examine trends in use of different types of stenosis operations and the association of complications and resource use with surgical complexity. DESIGN, SETTING, AND PATIENTS: Retrospective cohort analysis of Medicare claims for 2002-2007, focusing on 2007 to assess complications and resource use in US hospitals. Operations for Medicare recipients undergoing surgery for lumbar stenosis (n = 32,152 in the first 11 months of 2007) were grouped into 3 gradations of invasiveness: decompression alone, simple fusion (1 or 2 disk levels, single surgical approach), or complex fusion (more than 2 disk levels or combined anterior and posterior approach). MAIN OUTCOME MEASURES: Rates of the 3 types of surgery, major complications, postoperative mortality, and resource use. RESULTS: Overall, surgical rates declined slightly from 2002-2007, but the rate of complex fusion procedures increased 15-fold, from 1.3 to 19.9 per 100,000 beneficiaries. Life-threatening complications increased with increasing surgical invasiveness, from 2.3% among patients having decompression alone to 5.6% among those having complex fusions. After adjustment for age, comorbidity, previous spine surgery, and other features, the odds ratio (OR) of life-threatening complications for complex fusion compared with decompression alone was 2.95 (95% confidence interval [CI], 2.50-3.49). A similar pattern was observed for rehospitalization within 30 days, which occurred for 7.8% of patients undergoing decompression and 13.0% having a complex fusion (adjusted OR, 1.94; 95% CI, 1.74-2.17). Adjusted mean hospital charges for complex fusion procedures were US $80,888 compared with US $23,724 for decompression alone. CONCLUSIONS: Among Medicare recipients, between 2002 and 2007, the frequency of complex fusion procedures for spinal stenosis increased while the frequency of decompression surgery and simple fusions decreased. In 2007, compared with decompression, simple fusion and complex fusion were associated with increased risk of major complications, 30-day mortality, and resource use.

Hand-Held Stereovision System for Image Updating in Open Spine Surgery.

BACKGROUND: Image guidance in open spinal surgery is compromised by changes in spinal alignment between preoperative images and surgical positioning. We evaluated registration of stereo-views of the surgical field to compensate for vertebral alignment changes. OBJECTIVE: To assess accuracy and efficiency of an optically tracked hand-held stereovision (HHS) system to acquire images of the exposed spine during surgery. METHODS: Standard midline posterior approach exposed L1 to L6 in 6 cadaver porcine spines. Fiducial markers were placed on each vertebra as "ground truth" locations. Spines were positioned supine with accentuated lordosis, and preoperative computed tomography (pCT) was acquired. Spines were re-positioned in a neutral prone posture, and locations of fiducials were acquired with a tracked stylus. Intraoperative stereovision (iSV) images were acquired and 3-dimensional (3D) surfaces of the exposed spine were reconstructed. HHS accuracy was assessed in terms of distances between reconstructed fiducial marker locations and their tracked counterparts. Level-wise registrations aligned pCT with iSV to account for changes in spine posture. Accuracy of updated computed tomography (uCT) was assessed using fiducial markers and other landmarks. RESULTS: Acquisition time for each image pair was <1 s. Mean reconstruction time was <1 s for each image pair using batch processing, and mean accuracy was 1.2 ± 0.6 mm across 6 cases. Mean errors of uCT were 3.1 ± 0.7 and 2.0 ± 0.5 mm on the dorsal and ventral sides, respectively. CONCLUSION: Results suggest that a portable HHS system offers potential to acquire accurate image data from the surgical field to facilitate surgical navigation during open spine surgery.

Measuring protein biomarker concentrations using antibody tagged magnetic nanoparticles.

Under physiological conditions biomarker concentrations tend to rise and fall over time e.g. for inflammation. Ex vivo measurements provide a snapshot in time of biomarker concentrations, which is useful, but limited. Approaching real time monitoring of biomarker concentration(s) using a wearable, implantable or injectable in vivo sensor is therefore an appealing target. As an early step towards developing an in vivo biomarker sensor, antibody (AB) tagged magnetic nanoparticles (NPs) are used here to demonstrate the in vitro measurement of ~5 distinct biomarkers with high specificity and sensitivity. In previous work, aptamers were used to target a given biomarker in vitro and generate magnetic clusters that exhibit a characteristic rotational signature quite different from free NPs. Here the method is expanded to detect a much wider range of biomarkers using polyclonal ABs attached to the surface of the NPs. Commercial ABs exist for a wide range of targets allowing accurate and specific concentration measurements for most significant biomarkers. We show sufficient detection sensitivity, using an in-house spectrometer to measure the rotational signatures of the NPs, to assess physiological concentrations of hormones, cytokines and other signaling molecules. Detection limits for biomarkers drawn mainly from pain and inflammation targets were: 10 pM for mouse Granzyme B (mGZM-B), 40 pM for mouse interferon-gamma (mIFN-γ), 7 pM for mouse interleukin-6 (mIL-6), 40 pM for rat interleukin-6 (rIL-6), 40 pM for mouse vascular endothelial growth factor (mVEGF) and 250 pM for rat calcitonin gene related peptide (rCGRP). Much lower detection limits are certainly possible using improved spectrometers and nanoparticles.