The implementation and efficacy of the Northwestern High Risk Spine Protocol.

OBJECTIVE: The aims of this study were to determine the efficacy and feasibility of implementation of the intraoperative component of a high risk spine (HRS) protocol for improving perioperative patient safety in complex spine fusion surgery. METHODS: In this paired availability study, the total number of red blood cell units transfused was used as a surrogate marker for our management protocol efficacy, and the number of protocol violations was used as a surrogate marker for protocol compliance. RESULTS: The 548 patients (284 traditional vs. 264 HRS protocol) were comparable in all demographics, coexisting diseases, preoperative medications, type of surgery, and number of posterior levels instrumented. However, the surgical duration was 70 minutes shorter in the new group (range, 32-108 minutes shorter; P < 0.0001) and the new protocol patients received a median of 1.1 units less of total red blood cell units (range, 0-2.4 units less; P = 0.006). There were only 7 (2.6%) protocol violations in the new protocol group. CONCLUSIONS: The intraoperative component of the HRS protocol, based on two Do-Confirm checklists that focused on 1) organized communication between intraoperative team members and 2) active maintenance of oxygen delivery and hemostasis appears to maintain a safe intraoperative environment and was readily implemented during a 3-year period.

The impact of body mass index on hospital stay and complications after spinal fusion.

BACKGROUND: Obesity is a dominant public health concern and risk factor for disability, with few studies examining its impact in spinal surgery. Patients with a higher body mass index (BMI) have lower functional status, increased pain, and worse physical condition than those with ideal weight. OBJECTIVE: To determine associations between BMI categories on adverse patient outcomes after long-segment spinal fusions. METHODS: Consecutive, open, elective fusions (interbody and/or posterolateral arthrodesis) of more than 5 levels from 2007 to 2010 were retrospectively analyzed with follow-up of more than 1 year. Bivariate analyses examined outcome variables based on BMI categories. Linear regression analysis evaluated BMI, hospital stay, and complications at 1 and 2 years, controlling for confounders. Mean and median follow-up lengths were 2.1 and 2.0 years, respectively. RESULTS: A total of 189 surgeries on 112 patients, with a mean age of 59.5 years and a mean BMI of 29.8 kg/m, were analyzed. Morbidly obese patients had longer hospitalizations, worse Oswestry Disability Index (ODI), and more complications at 1 and 2 years than ideal weight patients. Multivariate linear regression modeling revealed sex, cardiac medications, cerebrospinal fluid leak, and BMI category of ideal vs nonideal influenced hospitalization length. Multivariate analysis showed BMI greater than 30 kg/m, preoperative ODI, and pedicle subtraction osteotomy influenced all complications at 1 year. Mean complications at 2 years for the morbidly obese were 3 times more than those underweight and 8 times more than those with ideal weight. Controlling for age, sex, and length of stay, obese and morbidly obese patients had more complications at 2 years; morbidly obese patients had a worse 2-year ODI. CONCLUSION: BMI is an independent predictor of hospitalization length and all complications at 1 and 2 years in patients receiving long-segment fusions.

Comprehensive assessment of prophylactic preoperative inferior vena cava filters for major spinal reconstruction in adults.

STUDY DESIGN: A retrospective data analysis. OBJECTIVE: To report a comprehensive assessment of preoperative prophylactic inferior vena cava (IVC) filter placement in spine surgery. SUMMARY OF BACKGROUND DATA: Venous thromboembolism (VTE) is a serious complication after major spinal reconstructive surgery in adults. Specifically, pulmonary embolism (PE) can result in significant morbidity and mortality, and it has been reported in up to 13% of patients. Prophylactic IVC filter placement was initiated for all "high-risk" spinal surgery patients after a pilot study demonstrated decreased VTE-related morbidity and mortality. METHODS: After institutional review board approval, the medical records of all patients receiving an IVC filter at a single institution from 2000 to 2007 were reviewed. Age, sex, surgical approach, postoperative deep vein thrombosis (DVT), postoperative superficial thrombus, presence of pulmonary or paradoxical embolus, mortality, and IVC filter complications were all evaluated. Indications for IVC filter placement included history of DVT or PE, malignancy, hypercoagulability, prolonged immobilization, staged procedures of longer than 5 segment levels, combined anterior-posterior approaches, iliocaval manipulation during exposure, and anesthetic time of more than 8 hours. Descriptive statistics were used for the analysis of patient characteristics. Nonparametric frequency statistics (odds ratios [OR], χ) were used for analysis of main outcomes. RESULTS: A total of 219 patients (150 women, 69 men) with a mean age of 58.8 (range, 17-86) years, were analyzed. There were 2 complications from IVC filter placement (66 Greenfield filters; 157 retrievable filters). The incidence of lower extremity DVT was 18.7% (41/219) in 36 patients. PE incidence was 3.7% (8/219 patients), and the paradoxical embolus rate was 0.5% (1 patient). Prophylactic IVC filter use reduced the odds of developing a pulmonary embolus (OR = 3.7, P < 0.05) compared with population controls. Patients receiving Greenfield filters had significantly higher VTE incidence than those receiving retrievable filters (OR = 2.8, P = 0.008). Anesthesia duration of more than 8 hours significantly increases VTE incidence (P = 0.029). No statistical significance (P < 0.05) was noted with combined anterior-posterior approach (118 patients) versus posterior-only approach (101 patients) and the incidence of DVT (24/118, 20.3% for former; 17/101, 16.8% for latter). There were a total of 14 deaths; none related to PE or paradoxical embolism during an 8-year period. Mean and median follow-up was 2.8 and 2.4 years, respectively, with 126 achieving 2 or more years of follow-up. CONCLUSION: VTE-related morbidity and mortality have heightened the awareness within the spine community to the perioperative management of patients undergoing major spinal reconstruction. Prophylactic IVC filter placement significantly lowers VTE-related events, including PE development, than population controls.

Techniques for operative correction of proximal junctional kyphosis of the upper thoracic spine.

STUDY DESIGN: Retrospective study of a consecutive series of patients treated for proximal junctional kyphosis (PJK) of the upper thoracic and cervicothoracic spine. OBJECTIVE: To discuss corrective techniques for the management of symptomatic kyphosis at the junction of fused and mobile segments of the upper thoracic and cervicothoracic spine in patients who complain of pain, neurological deficit, ambulatory difficulty, and/or social isolation. SUMMARY OF BACKGROUND DATA: PJK is an unfortunately common, but important, complication seen in long instrumented fusions to the upper thoracic and cervicothoracic spine. Although often asymptomatic, its incidence and prevalence warrant a discussion on treatment options for symptomatic patients. METHODS: After the institutional review board confirmed approval, we retrospectively analyzed patients who received treatment of PJK from 2003 to 2009. Segmental instrumentation and intraoperative neurophysiological monitoring were used in all patients. Data acquisition was performed by reviewing electronic medical records and radiographs. Inclusion criteria were patients who underwent surgical correction of PJK of the cervicothoracic and upper thoracic spine and had more than 2-year follow-up. Preoperative lumbar lordosis, preoperative thoracic kyphosis, pre- and postoperative sagittal balance, and sagittal proximal junctional Cobb angle were obtained. All corrective procedures were performed in 2 stages, each patient receiving cervical traction between cases. RESULTS: Inclusion criteria were met in 7 patients (5 women and 2 men), with mean age of 55 years (range, 18-80 years). Six patients received multilevel Smith-Petersen osteotomies, with 2 patients receiving rib osteotomies, and 1 patient received a vertebral column resection. The mean preoperative and postoperative proximal junctional Cobb angles were 45° (range, 14°-89.7°) and 14° (range, 3.0°-38.0°), respectively. The mean degree of correction was 31° (range, 11°-79.2°). All patients had maintained or improved sagittal balance. No patient sustained a temporary or permanent neurological deficit after correction related to surgery. All patients had 2-year follow-up, and there were no mortalities. CONCLUSION: For a selected cohort of patients who develop PJK of the upper thoracic and cervicothoracic spine, osteotomies, cervical traction, and intraoperative manual reduction provide a significant improvement of proximal junctional Cobb angles. To our knowledge, this is the first study to address treatment for symptomatic patients with this condition.

Morbidity and mortality after spinal deformity surgery in patients 75 years and older: complications and predictive factors.

OBJECT: As the population continues to age, relatively older geriatric patients will present more frequently with complex spinal deformities that may require surgical intervention. To the authors' knowledge, no study has analyzed factors predictive of complications after major spinal deformity surgery in the very elderly (75 years and older). The authors' objective was to determine the rate of minor and major complications and predictive factors in patients 75 years of age and older who underwent major spinal deformity surgery requiring a minimum 5-level arthrodesis procedure. METHODS: Twenty-one patients who were 75 years of age or older and underwent thoracic and/or lumbar fixation and arthrodesis across 5 or more levels for spinal deformity were analyzed retrospectively. The medical and surgical records were reviewed in detail. Age, diagnosis, comorbidities, operative data, hospital data, major and minor complications, and deaths were recorded. Factors predictive of perioperative complications were identified by logistic regression analysis. RESULTS: The mean patient age was 77 years old (range 75-83 years). There were 14 women and 7 men. The mean follow-up was 41.2 months (range 24-81 months). Fifteen patients (71%) had at least 1 comorbidity. A mean of 10.5 levels were fused (range 5-15 levels). Thirteen patients (62%) had at least 1 perioperative complication, and 8 (38%) had at least one major complication for a total of 17 complications. There were no perioperative deaths. Increasing age was predictive of any perioperative complication (p = 0.03). However, major complications were not predicted by age or comorbidities as a whole. In a subset analysis of comorbidities, only hypertension was predictive of a major complication (OR 10, 95% CI 1.3-78; p = 0.02). Long-term postoperative complications occurred in 11 patients (52%), and revision fusion surgery was necessary in 3 (14%). CONCLUSIONS: Patients 75 years and older undergoing major spinal deformity surgery have an overall perioperative complication rate of 62%, with older age increasing the likelihood of a complication, and a long-term postoperative complication rate of 52%. Patients in this age group with a history of hypertension are 10 times more likely to incur a major perioperative complication. However, the mortality risk for these patients is not increased.

Predicting ideal spinopelvic balance in adult spinal deformity.

OBJECTIVE: Spinopelvic balance is based on the theory that adjacent segments of the spine are related and influenced by one another. By understanding the correlation between the thoracolumbar spine and the pelvis, a concept of spinopelvic balance can be applied to adult deformity. The purpose of this study was to develop a mathematical relationship between the pelvis and spine and apply it to a population of adults who had undergone spinal deformity surgery to determine whether patients in spinopelvic balance have improved health measures. METHODS: Using values published in the literature, a mathematical relationship between the spine and pelvis was derived where pelvic incidence (PI) was divided by the sum of the lumbosacral lordosis (LL; T12-S1) plus the main thoracic kyphosis (TK; T4-12). The result was termed the spinopelvic constant (r): r = PI/(LL + TK). This was performed in patients in 2 age groups previously defined in the literature as "adult" (18-60 years of age) and "geriatric" (> 60 years). The equation was then constructed to relate an individual's measured PI to his or her predicted thoracolumbar curvature (LL + TK)(p) based on the age-specific spinopelvic constant: (LL + TK)(p) = r/PI. A retrospective review was then performed using cases involving patients who had undergone spine deformity surgery and were enrolled in our spinal deformity database. Sagittal balance, PI, and the sum of the main thoracic and lumbar curves were measured. The difference between the predicted sum of the regional curves (LL + TK)(p), based on the individual's measured PI and the age-specific spinopelvic constant, and the measured sum of the regional curves (LL + TK)(m) was then calculated to determine the degree of spinopelvic imbalance. Health status measures were then compared. RESULTS: Using the formula r = PI/(TK = LL) and normative values in the literature, the adult spinopelvic constant was calculated to be -2.57, and the geriatric constant -5.45. For the second portion of the study, 41 patients met inclusion criteria (13 classified as nongeriatric adults and 28 as geriatric patients). Application of these constants found a statistically significant decline in almost all outcome categories when the spinopelvic balance showed at least 10° of kyphosis more than predicted. While not statistically significant, the trend was that better outcomes were associated with a spinopelvic balance within 0 to +10° of the predicted value. The final analysis compared and separated outcomes from sagittal balance and spinopelvic balance. For patients to be considered in sagittal balance, they must be within 50 mm (± 50 mm) of neutral. For patients to be considered in spinopelvic balance, they must be within ± 10° of predicted spinopelvic balance. Patients in both sagittal and spinopelvic balance have statistically significant better outcomes than those in neither sagittal nor spinopelvic balance. Except for the mean SF-12 PCS (12-Item Short-Form Health Survey Physical Component Summary), there were no significant differences between those that were either in sagittal or spinopelvic balance, but not the other. CONCLUSIONS: Restoring a normative relationship between the spine and the pelvis during adult deformity correction may play an important role in determining surgical outcomes in these patients independent of sagittal balance.

Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient age.

STUDY DESIGN: Retrospective review of a prospective, multicenter database. OBJECTIVE: The purpose of this study was to assess whether elderly patients undergoing scoliosis surgery had an incidence of complications and improvement in outcome measures comparable with younger patients. SUMMARY OF BACKGROUND DATA: Complications increase with age for adults undergoing scoliosis surgery, but whether this impacts the outcomes of older patients is largely unknown. METHODS: This is a retrospective review of a prospective, multicenter spinal deformity database. Patients complete the Oswestry Disability Index (ODI), SF-12, Scoliosis Research Society-22 (SRS-22), and numerical rating scale (NRS; 0-10) for back and leg pain. Inclusion criteria included age 25 to 85 years, scoliosis (Cobb ≥ 30°), plan for scoliosis surgery, and 2-year follow-up. RESULTS: Two hundred six of 453 patients (45%) completed 2-year follow-up, which is distributed among age groups as follows: 25 to 44 (n = 47), 45 to 64 (n = 121), and 65 to 85 (n = 38) years. The percentages of patients with 2-year follow-up by age group were as follows: 25 to 44 (45%), 45 to 64 (48%), and 65 to 85 (40%) years. These groups had perioperative complication rates of 17%, 42%, and 71%, respectively (P < 0.001). At baseline, elderly patients (65-85 years) had greater disability (ODI, P = 0.001), worse health status (SF-12 physical component score (PCS), P < 0.001), and more severe back and leg pain (NRS, P = 0.04 and P = 0.01, respectively) than younger patients. Mean SRS-22 did not differ significantly at baseline. Within each age group, at 2-year follow-up there were significant improvements in ODI (P ≤ 0.004), SRS-22 (P ≤ 0.001), back pain (P < 0.001), and leg pain (P ≤ 0.04). SF-12 PCS did not improve significantly for patients aged 25 to 44 years but did among those aged 45 to 64 (P < 0.001) and 65 to 85 years (P = 0.001). Improvement in ODI and leg pain NRS were significantly greater among elderly patients (P = 0.003, P = 0.02, respectively), and there were trends for greater improvements in SF-12 PCS (P = 0.07), SRS-22 (P = 0.048), and back pain NRS (P = 0.06) among elderly patients, when compared with younger patients. CONCLUSION: Collectively, these data demonstrate the potential benefits of surgical treatment for adult scoliosis and suggest that the elderly, despite facing the greatest risk of complications, may stand to gain a disproportionately greater improvement in disability and pain with surgery.

Standardizing care for high-risk patients in spine surgery: the Northwestern high-risk spine protocol.

STUDY DESIGN: Review article of current literature on the preoperative evaluation and postoperative management of patients undergoing high-risk spine operations and a presentation of a multidisciplinary protocol for patients undergoing high-risk spine operation. OBJECTIVE: To provide evidence-based outline of modifiable risk factors and give an example of a multidisciplinary protocol with the goal of improving outcomes. SUMMARY OF BACKGROUND DATA: Protocol-based care has been shown to improve outcomes in many areas of medicine. A protocol to evaluate patients undergoing high-risk procedures may ultimately improve patient outcomes. METHODS: The English language literature to date was reviewed on modifiable risk factors for spine surgery. A multidisciplinary team including hospitalists, critical care physicians, anesthesiologists, and spine surgeons from neurosurgery and orthopedics established an institutional protocol to provide comprehensive care in the pre-, peri-, and postoperative periods for patients undergoing high-risk spine operations. RESULTS: An example of a comprehensive pre-, peri-, and postoperative high-risk spine protocol is provided, with focus on the preoperative assessment of patients undergoing high-risk spine operations and modifiable risk factors. CONCLUSION: Standardizing preoperative risk assessment may lead to better outcomes after major spine operations. A high-risk spine protocol may help patients by having dedicated physicians in multiple specialties focusing on all aspects of a patients care in the pre-, intra-, and postoperative phases.

Posterior vertebral column subtraction osteotomy for the treatment of tethered cord syndrome: review of the literature and clinical outcomes of all cases reported to date.

Tethered cord syndrome (TCS) is a debilitating condition of progressive neurological decline caused by pathological, longitudinal traction on the spinal cord. Surgical detethering of the involved neural structures is the classic method of treatment for lumbosacral TCS, although symptomatic retethering has been reported in 5%-50% of patients following initial release. Subsequent operations in patients with complex lumbosacral dysraphic lesions are fraught with difficulty, and improvements in neurological function are modest while the risk of complications is high. In 1995, Kokubun described an alternative spine-shortening procedure for the management of TCS. Conducted via a single posterior approach, the operation relies on spinal column shortening to relieve indirectly the tension placed on the tethered neural elements. In a cadaveric model of TCS, Grande and colleagues further demonstrated that a 15-25-mm thoracolumbar subtraction osteotomy effectively reduces spinal cord, lumbosacral nerve root, and filum terminale tension. Despite its theoretical appeal, only 18 reports of the use of posterior vertebral column subtraction osteotomy for TCS treatment have been published since its original description. In this review, the authors analyze the relevant clinical characteristics, operative data, and postoperative outcomes of all 18 reported cases and review the role of posterior vertebral column subtraction osteotomy in the surgical management of primary and recurrent TCS.

Diagnosis and management of metastatic spine disease. A review.

With continued growth of the elderly population and improvements in cancer therapies, the number of patients with symptomatic spinal metastases is likely to increase, and this is a condition that commonly leads to debilitating neurological dysfunction and pain. Advancements in surgical techniques of resection and spinal reconstruction, improvements in clinical outcomes following various treatment modalities, generally increased overall survival in patients with metastatic spine disease, and a recent randomized trial by Patchell and colleagues demonstrating the superiority of a combined surgical/radiotherapeutic approach over a radiotherapy-only strategy have led many to suggest increasingly aggressive interventions for patients with such lesions. Optimal management of spinal metastases encompasses numerous medical specialties, including neurosurgery, orthopedic surgery, medical and radiation oncology, radiology, and rehabilitation medicine. In this review, the clinical presentation, diagnosis, and management of spinal metastatic disease are discussed. Ultimately, the goal of treatment in patients with spinal metastases remains palliative, and clinical judgment is required to select the appropriate patients for surgical intervention.

The costs and benefits of nonoperative management for adult scoliosis.

STUDY DESIGN: A prospective cohort of adult scoliosis patients treated nonoperatively had a minimum of 2-year follow-up during which time data were collected on the type and quantity of nonoperative treatment used. OBJECTIVE: To quantify the use, cost, and effectiveness of nonoperative treatment for adult scoliosis. SUMMARY OF BACKGROUND DATA: A 2007 systematic review of nonsurgical treatment in adult scoliosis revealed minimal data, and concluded that evidence for nonoperative care was lacking. METHODS: Duration of use and frequency of visits were collected for 8 specific treatment methods: medication, physical therapy, exercise, injections/blocks, chiropractic care, pain management, bracing, and bed rest. Costs for each intervention were determined using the Medicare Fee schedule. Outcome measures were the SRS-22, SF-12, and ODI. Analysis was performed for the entire group, and for subsets of high (ODI, >40), mid (ODI = 21-40) and low (ODI,

Thoracic pedicle subtraction osteotomy for fixed sagittal spinal deformity.

STUDY DESIGN.: A retrospective clinical study. OBJECTIVE.: To find the corrective capacity of a thoracic pedicle subtraction osteotomy (PSO), determine if segmental correction is dependent on level, and to compute the impact of thoracic PSO on regional and global spinal balance. SUMMARY OF BACKGROUND DATA.: PSO is a technique popularized in the lumbar spine primarily for the correction of fixed sagittal imbalance. Despite several studies describing the clinical and radiographic outcome of lumbar PSO, there is no study in literature reporting its application in the thoracic spine. METHODS.: We retrospectively analyzed patients with fixed thoracic kyphosis who underwent thoracic PSOs for sagittal realignment. Segmental pedicle screw instrumentation and intraoperative neurophysiologic monitoring was used in all patients. Data acquisition was performed by reviewing medical charts and radiographs to determine sagittal correction (segmental/regional/global) and complications. Clinical outcome using the Scoliosis Research Society-22 (SRS-22) instrument was determined by interview. RESULTS.: A total of 25 thoracic PSOs were performed (mean: 1.7 PSOs/patient, range: 1-3) in 15 patients (9 M/6 F). The study population had an average age of 56 years (range, 36-81 years) and was followed up after surgery for a mean of 3.5 years (range, 24-75 months). The osteotomies were carried out in the proximal thoracic spine (T2-T4, n = 6), midthoracic spine (T5-T8, n = 12), and distal thoracic spine (T9-T12, n = 7). Mean correction at the PSO for all 25 levels was 16.3 degrees +/- 9.6 degrees . Stratified by region of the spine, thoracic PSO correction was as follows: T2-T4 = 10.7 degrees +/- 15.8 degrees , T5-T8 = 14.7 degrees +/- 4.6 degrees , and T9-T12 = 23.9 degrees +/- 4.1 degrees . Mean thoracic kyphosis (T2-T12 Cobb angle) was improved from 75.7 degrees +/- 30.9 degrees to 54.3 degrees +/- 21.4 degrees resulting in a significant regional sagittal correction of 21.4 degrees +/- 13.7 degrees (P < 0.005). Global sagittal balance was improved from 106.1 +/- 56.6 to 38.8 +/- 37.0 mm yielding a mean correction of 67.3 +/- 54.7 mm (P < 0.005). One patient, in whom there was segmental translation during osteotomy closure, had a decline in intraoperative somatosensory-evoked potentials. No patient sustained a temporary or permanent neurologic deficit after surgery. The mean SRS-22 Questionnaire score at final follow-up was 82.4 +/- 10.2. CONCLUSION.: Thoracic PSO can be performed safely. Segmental sagittal correction appears to vary based on the region of the thoracic spine the PSO is performed. The distal thoracic segments, which more closely resemble lumbar segments in morphology, rendered the greatest sagittal correction after PSO, approximately 24 degrees . There was no case of neurologic injury associated with thoracic PSO, and clinical outcomes according to the SRS-22 instrument were generally favorable.

Posterior vertebral column subtraction osteotomy: a novel surgical approach for the treatment of multiple recurrences of tethered cord syndrome.

Recurrent tethered cord syndrome (TCS) has been reported to develop in 5-50% of patients following initial spinal cord detethering operations. Surgery for multiple recurrences of TCS can be difficult and is associated with significant complications. Using a cadaveric tethered spinal cord model, Grande and colleagues demonstrated that shortening of the vertebral column by performing a 15-25-mm thoracolumbar osteotomy significantly reduced spinal cord, lumbosacral nerve root, and terminal filum tension. Based on this cadaveric study, spinal column shortening by a thoracolumbar subtraction osteotomy may be a viable alternative treatment to traditional surgical detethering for multiple recurrences of TCS. In this article, the authors describe the use of posterior vertebral column subtraction osteotomy (PVCSO) for the treatment of 2 patients with multiple recurrences of TCS. Vertebral column resection osteotomy has been widely used in the surgical correction of fixed spinal deformity. The PVCSO is a novel surgical treatment for multiple recurrences of TCS. In such cases, PVCSO may allow surgeons to avoid neural injury by obviating the need for dissection through previously operated sites and may reduce complications related to CSF leakage. The novel use of PVCSO for recurrent TCS is discussed in this report, including surgical considerations and techniques in performing PVCSO.

Abdominal complications following kyphosis correction in ankylosing spondylitis.

Spinal deformity surgery is associated with high rates of morbidity and a wide range of complications. The most significant abdominal complications following kyphosis correction, while uncommon, can certainly pose significant infectious and hemodynamic risks to the patient. Abdominal compartment syndrome is the most severe of the sequelae. It is the end result of elevated abdominal compartment pressure with physiological compromise and end organ system dysfunction. Although most commonly associated with trauma, abdominal compartment syndrome has also been witnessed following massive fluid shifts, which can occur during adult spinal deformity surgery. In this manuscript, we report on 2 patients with ankylosing spondylitis who developed significant abdominal pathology requiring exploratory laparotomy following kyphosis correction. In addition to describing the details of each case, we propose explanations of the relevant pathophysiology and review diagnostic and treatment strategies for such events. The key to effectively treating such a debilitating complication is to recognize it quickly and intervene rapidly and aggressively.

An assessment of the reliability of the Enneking and Weinstein-Boriani-Biagini classifications for staging of primary spinal tumors by the Spine Oncology Study Group.

STUDY DESIGN: Reliability analysis based on expert panel case series review and grading per the Enneking and Weinstein-Boriani-Biagini classification systems. OBJECTIVE: To assess the reliability of the Enneking and Weinstein-Boriani-Biagini classification systems. SUMMARY OF BACKGROUND DATA: The Enneking and Weinstein-Boriani-Biagini (WBB) classifications were developed to stage and facilitate treatment planning in patients with primary spine tumors. To date, their interobserver and intraobserver reliability has not been assessed-a fundamental step in facilitating broader clinical and research use. METHODS: Clinical information, imaging studies, and biopsy results were compiled from 15 selected patients with primary spinal tumors. Eighteen spine surgeons independently estimated and scored the cases for Enneking grade, tumor and metastasis categories, Enneking stage, Enneking-recommended surgical margin, WBB zones and layers, and WBB-recommended surgical procedures, with a second assessment performed after random resorting of cases. Interobserver and intraobserver reliability of each category were assessed by percent agreement or proportional overlap. The Fleiss, Cohen, and Mezzich kappa statistics (kappa) were then applied, determined by the type of variable analyzed. RESULTS: The kappa statistics for interobserver reliability were 0.82, 0.22, 0.00, 0.57, 0.47, 0.31, 0.58, and 0.54 for the fields of Enneking grade, tumor and metastasis categories, Enneking stage, Enneking-recommended surgical margin, WBB zones and layers, and WBB-recommended surgical procedures, respectively. The kappa statistics for intraobserver reliability were 0.97, 0.53, 0.47, 0.82, 0.67, 0.63, 0.79, and 0.79 for the same respective fields. According to Landis and Koch, the ranges of kappa values of 0.00 to 0.20, 0.21 to 0.40, 0.41 to 0.60, 0.61 to 0.80, and >0.80 imply slight, fair, moderate, substantial, and near-perfect agreement, respectively. CONCLUSION: Results indicate moderate interobserver reliability and substantial and near-perfect intraobserver reliability for both the Enneking and WBB classification in terms of staging and guidance for treatment, despite a less than moderate interobserver reliability in interpreting the Enneking local tumor extension and WBB sector. Before incorporating the classifications in the clinical practice and research studies, further work is required to investigate the validity of the classifications.

Endovascular embolization of a recurrent cervical giant cell neoplasm using N-butyl 2-cyanoacrylate.

Pre-operative endovascular embolization of spinal giant cell tumors (GCTs) has been an effective strategy to reduce blood loss during surgical resection. Traditionally, spinal GCTs have been embolized with polyvinyl acetate (PVA) particles. We present the pre-operative embolization of a recurrent cervical GCT with N-butyl 2-cyanoacrylate (NBCA) rather than PVA. The patient was a 17-year-old female who, 3 months prior, had undergone a surgical resection of a cervical GCT without pre-operative embolization. She returned with tumor recurrence in the approximate location. Resection was recommended, and pre-operative embolization was requested. The tumor was embolized with NBCA. Post-embolization angiography demonstrated significantly decreased tumor "blush" and a significant reduction of the vascular supply. This is the first reported use of NBCA for the pre-operative embolization of a cervical GCT. The benefits of NBCA over PVA particles include superior penetration, permanent tumor embolization and lower exposure to radiation due to shorter procedure time.

Pedicle subtraction osteotomy.

OBJECTIVE: Pedicle subtraction osteotomy (PSO) is an effective tool for the correction of fixed sagittal plane deformity. However, there is potentially significant perioperative morbidity associated with this technique. We report our perioperative morbidity rate in recently performed PSO cases treated with our present surgical, anesthetic, and monitoring techniques and discuss complication-avoidance strategies. METHODS: We conducted a retrospective study of 10 patients (mean age, 56 yr; range, 7-77 yr) undergoing thoracolumbar PSO at a single institution in the past 3 years. Two patients underwent PSO at T12, seven patients underwent PSO at L3, and one patient underwent PSO at L2. Eight of the patients had undergone at least one previous spine surgery in the region of the PSO, and nine of the patients had comorbidities that increased their surgical risk stratification. We identified all causes of perioperative morbidity. RESULTS: We classified perioperative complications into two categories: intraoperative and early postoperative. Intraoperative complications included dural tears in two patients, cardiovascular instability in one patient, and coagulopathy in two patients. Early postoperative complications included neurological deficit (one patient), wound infection (two patients), urinary tract infection (one patient), and delirium (two patients). All patients recovered fully from these complications. There was no mortality in this series. CONCLUSION: In this series, most patients undergoing PSO had multiple previous spine surgeries and comorbidities. The risk of perioperative morbidity for revision cases undergoing PSO was in excess of 50%. We discuss complication-avoidance strategies.

Spinal deformity: a new classification derived from neutral upright spinal alignment measurements in asymptomatic juvenile, adolescent, adult, and geriatric individuals.

OBJECTIVE: In this literature review, the authors analyze data from previously published studies that evaluated neutral upright spinal alignment (NUSA) from the occiput to the pelvis in asymptomatic individuals. Based on the data for NUSA in asymptomatic volunteers, a new classification is proposed for spinal deformity. METHODS: A review of the English literature was conducted to identify studies evaluating NUSA from the occiput to the pelvis in asymptomatic juvenile, adolescent, adult, and geriatric volunteers. From the literature review, 17 angles and displacements were selected to depict neutral upright coronal and axial spinal alignment, and 21 angles and displacements were selected to depict neutral upright sagittal spinal alignment. Pooled estimates of the mean and variance were calculated for the angles and displacements from the articles that met inclusion criteria. A new classification of spinal deformity was then developed based on age-dependent NUSA; spinal abnormality; deformity curve location, pattern, magnitude, and flexibility; and global spinal alignment. RESULTS: Despite a wide variation in the regional curves from the occiput to the pelvis in asymptomatic volunteers, global spinal alignment is maintained in a narrow range for preservation of horizontal gaze and balance of the spine over the pelvis and femoral heads. CONCLUSION: A new classification of spinal deformity is proposed that provides a structure for defining deformity of all patient ages and spinal abnormalities.

Maximizing the potential of minimally invasive spine surgery in complex spinal disorders.

Minimally invasive surgery (MIS) in the spine was primarily developed to reduce approach-related morbidity and to improve clinical outcomes compared with those following conventional open spine surgery. Over the past several years, minimally invasive spinal procedures have gained recognition and their utilization has increased. In particular, MIS is now routinely used in the treatment of degenerative spine disorders and has been shown to be as effective as conventional open spine surgeries. Although the procedures are not yet widely recognized in the context of complex spine surgery, the true potential in minimizing approach-related morbidity is far greater in the treatment of complex spinal diseases such as spinal trauma, spinal deformities, and spinal oncology. Conventional open spine surgeries for complex spinal disorders are often associated with significant soft tissue disruption, blood loss, prolonged recovery time, and postsurgical pain. In this article the authors review numerous cases of complex spine disorders managed with MIS techniques and discuss the current and future implications of these approaches for complex spinal pathologies.