Outcomes of Surgical Treatment for Extradural Benign Primary Spinal Tumors in Patients Younger than 25 Years: An Ambispective International Multicenter Study.

Extradural primary spinal tumors were retrospectively analyzed from a prospective database of 1495 cases. All subjects with benign primary tumors under the age of 25 years, who were enrolled between 1990 and 2012 (Median FU was 2.4 years), were identified. Patient- and case-related characteristics were collected and statistically analyzed. Results: 161 patients (66f;95m; age 17.0 ± 4.7 years at time of diagnosis) were identified. The most common tumors were osteoblastomas n = 53 (32.9%), osteoid osteomas n = 45 (28.0%), and aneurysmal bone cysts n = 32 (19.9%). The tumor grade, according to the Enneking Classification S1/S2/S3, was 14/73/74 (8.7/45.3/46.0%), respectively. Tumor-related pain was present in 156 (96.9%) patients. Diagnosis was achieved by biopsies in 2/3 of the cases. Spinal fixation was used in >50% of the cases. Resection was Enneking appropriate in n = 100 (62.1%) of cases. Local recurrence occurred in 21 (13.1%) patients. Two patients died within a 10-year follow-up period. Conclusion: This is one of the largest international multicenter cohorts of young patients surgically treated for benign spinal tumors. The heterogenic young patient cohort presented at a mid-term follow-up without a correlation between the grade of aggressiveness in resection and local recurrence rates. Further prospective data are required to identify prognostic factors that determine oncological and functional outcomes for young patients suffering from these rare tumors.

Extradural Primary Malignant Spinal Tumors in a Population Younger than 25 Years: An Ambispective International Multicenter Study on Onco-Surgical Outcomes.

Extradural malignant primary spinal tumors are rare and outcome data, especially for younger patients, is limited. In a worldwide (11 centers) study (Predictors of Mortality and Morbidity in the Surgical Management of Primary Tumors of the Spine study; ClinicalTrials.gov Identifier NCT01643174) by the AO Spine Knowledge Forum Tumor, patients surgically treated for primary tumors of the spine between 1992 and 2012, were retrospectively analyzed from a prospective database of their medical history. Medical history, tumor characteristics, diagnostics, treatments, cross-sectional survival, and local recurrences were analyzed. Sixty-eight cases (32 f; 36 m), at an average age of 18.6 ± 4.7 years at the time of diagnosis, were identified (median follow-up 2.9 years). The most common entities were Ewing's sarcoma (42.6%). Of the patients, 28% had undergone previous spine tumor surgery in another center (84% with intralesional margins). Resection was considered "Enneking appropriate" (EA) in 47.8% of the cases. Of the patients, 77.9% underwent chemotherapy and 50% radiotherapy. A local recurrence occurred in 36.4%. Over a third of patients died within a 10-year follow-up period. Kaplan-Meier-analysis demonstrated statistically significant overall survival (p = 0.007) and local recurrence rates (p = 0.042) for tumors treated with EA surgery versus Enneking inappropriate surgery. Aggressive resection of extradural primary malignant spinal tumors combined with adjuvant therapy reveals low local recurrence rates and better outcomes overall in younger patients.

Surgical Management of the Metastatic Spine Disease: A Review of the Literature and Proposed Algorithm.

STUDY DESIGN: Narrative Review. The spine remains the most common site for bony metastasis. It is estimated that up to 70% of cancer patients harbor secondary spinal disease. And up to 10% will develop a clinically significant lesion. The last two decades have seen a substantial leap forward in the advancements of the management of spinal metastases. What once was a death sentence is now a manageable, even potentially treatable condition. With marked advancements in the surgical treatment and post-operative radiotherapy, a standardized approach to stratify and manage these patients is both prudent and now feasible. OBJECTIVES: This article looks to examine the best available evidence in the stratification and surgical management of patients with spinal metastases. So the aim of this review is to offer a standardized approach for surgical management and surgical planning of patients with spinal metastases.

Integrated Custom Composite Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR) in the Treatment of Bone Tumors of the Spine: A Preliminary Report From a Multicenter Study.

STUDY DESIGN: Retrospective, multicenter chart, and radiologic review. OBJECTIVE: To present the first case series of bone tumors of the spine surgically reconstructed with a new custom, fully radiolucent, polyetheretherketone/carbon fiber (PEEK/CF) vertebral body replacement (VBR) integrated system. SUMMARY OF BACKGROUND DATA: Surgical resections of spinal tumors result in large defects and local recurrence remains a concern. Current titanium-based implants adversely affects postoperative imaging, directly affects ability to identify tumor recurrence, and for delivery of radiotherapy treatments. PEEK/CF spinal implants allows for improved tumor surveillance, precise pre-radiation Computed Tomography planning, and reduces interference with post-reconstructive adjuvant radiotherapy. METHOD: Thirteen patients with spinal tumors underwent vertebral body resection and reconstruction with an integrated, fully radiolucent, custom PEEK/CF vertebral body replacement, and radiolucent posterior PEEK/CF screw-rod system and/or radiolucent anterior PEEK/CF plate system. Clinical and radiographic data were tabulated. Need for adjuvant radiotherapy determined based on final tissue histology and extent of surgical margins. Postoperative surveillance imaging were reviewed for local tumor recurrence. RESULTS: The ability to integrate the PEEK/CF VBR connected to either the posterior screw-rod system, or anterior plate system provided immediate stability. The VBR was placed directly on cancellous vertebral body surface in 46.2% of cases. Loosening of the distal, or proximal, aspect of posterior system was seen in 15.4% of cases. There was no clinical or radiographic evidence of VBR migration and subsidence at latest follow up. Local recurrence occurred in one (7.7%) patient. CONCLUSION: This is the first series to describe the use of a fully-radiolucent, integrated, PEEK/CF implant system for spinal tumor reconstruction. The use of a PEEK/CF VBR system integrated to either the anterior plate, or posterior screw-rod system is feasible and allows for superior postoperative surveillance imaging and effective delivery of postoperative adjuvant radiotherapy.Level of Evidence: 4.

Calculating Utilities From the Spine Oncology Study Group Outcomes Questionnaire: A Necessity for Economic and Decision Analysis.

STUDY DESIGN: General population utility valuation study. OBJECTIVE: The aim of this study was to develop a technique for calculating utilities from the Spine Oncology Study Group Outcomes Questionnaire v2.0 (SOSGOQ2.0). SUMMARY OF BACKGROUND DATA: The ability to calculate quality-adjusted life-years (QALYs) for metastatic spine disease would enhance treatment decision-making and facilitate economic analysis. QALYs are calculated using utilities. METHODS: Using a hybrid concept-retention and factorial analysis shortening approach, we first shortened the SOSGOQ2.0 to eight items (SOSGOQ-8D). This was done to lessen the cognitive burden of the utility valuation exercise. A general population sample of 2730 adults was then asked to evaluate 12 choice sets based on SOSGOQ-8D health states in a Discrete Choice Experiment. A utility scoring rubric was then developed using a mixed multinomial-logit regression model. RESULTS: We were able to reduce the SOSGOQ2.0 to an SOSGOQ-8D with a mean error of 0.003 and mean absolute error of 3.078 compared to the full questionnaire. The regression model demonstrated good predictive performance and was used to develop a utility scoring rubric. Regression results revealed that participants did not regard all SOSGOQ-8D items as equally important. CONCLUSION: We provide a simple technique for converting the SOSGOQ2.0 to utilities. The ability to evaluate QALYs in metastatic spine disease will facilitate economic analysis and patient counseling. We also quantify the importance of individual SOSGOQ-8D items. Clinicians should heed these findings and offer treatments that maximize function in the most important items.Level of Evidence: 3.

Aneurysmal bone cysts in the spine, causing neurological compromise: safety and clinical efficacy of sclerotherapy utilizing sodium Tetradecyl sulfate foam.

OBJECTIVE: To assess the clinical efficacy, technical feasibility, and safety profile of percutaneous sclerotherapy utilizing sodium tetradecyl-sulfate foam (STS) as a first-line treatment strategy for aggressive spinal aneurysmal bone cysts (sABCs) presenting with neurological compromise. MATERIALS AND METHODS: Between July 2013 and September 2019, eight consecutive patients (5 males; 3 females; mean age 22±17, range 7-52) underwent fluoroscopic/CT-guided intraosseous sclerotherapy for sABCs. Pain and/or neurological compromise was the primary indications. Procedural data, complications, imaging, and clinical results were analyzed. RESULTS: Technical success was achieved in all cases. Mean procedure time was 25±15 min (range 6-167); 1 to 5 repeat treatment cycles (mean 3.7±1.2) utilizing a mean 2.6mls±1.3 (range 1-6) of agitated 3% STS, with a DLP mean dose of 158±91 mGy*cm (range 62-331) per procedure. One reported a minor complication (pain), but no significant complications. Two patients had persistent neurological deficit due to cord compression despite successful sclerotherapy, requiring surgical resection (and were thereby excluded from the final outcome analysis). The remaining six patients demonstrated a significant reduction in tumor volume (p = 0.028), pain (p = 0.027), and SINS (spinal instability neoplastic score) (p = 0.027) at up to 5 years of follow-up (mean 20 ± 16.7, range 7-51 months). CONCLUSION: Percutaneous sclerotherapy with STS is a minimally invasive, technically feasible, safe, and effective first-line treatment for primary sABCs causing pain and neurological compromise, alleviating the need for extensive surgery. It is most effective with three or more treatment cycles, in patients with higher SINS, pain scores, or tumor volumes at the initial presentation.

Feasibility of achieving planned surgical margins in primary spine tumor: a PTRON study.

OBJECTIVE: Oncological resection of primary spine tumors is associated with lower recurrence rates. However, even in the most experienced hands, the execution of a meticulously drafted plan sometimes fails. The objectives of this study were to determine how successful surgical teams are at achieving planned surgical margins and how successful surgeons are in intraoperatively assessing tumor margins. The secondary objective was to identify factors associated with successful execution of planned resection. METHODS: The Primary Tumor Research and Outcomes Network (PTRON) is a multicenter international prospective registry for the management of primary tumors of the spine. Using this registry, the authors compared 1) the planned surgical margin and 2) the intraoperative assessment of the margin by the surgeon with the postoperative assessment of the margin by the pathologist. Univariate analysis was used to assess whether factors such as histology, size, location, previous radiotherapy, and revision surgery were associated with successful execution of the planned margins. RESULTS: Three hundred patients were included. The surgical plan was successfully achieved in 224 (74.7%) patients. The surgeon correctly assessed the intraoperative margins, as reported in the final assessment by the pathologist, in 239 (79.7%) patients. On univariate analysis, no factor had a statistically significant influence on successful achievement of planned margins. CONCLUSIONS: In high-volume cancer centers around the world, planned surgical margins can be achieved in approximately 75% of cases. The morbidity of the proposed intervention must be balanced with the expected success rate in order to optimize patient management and surgical decision-making.

Sacral insufficiency fractures are a risk of massive bleeding during sacrectomy: patient series.

BACKGROUND: Sacrectomy carries significant risk of bleeding; however, specific risk factors, apart from medical comorbidities and tumor type, for this life-threatening complication remain unclear. This study describes two cases of massive bleeding, including one death during sacrectomy attributable to adherence of the internal iliac vein (IIV) and its neuroforaminal tributaries from sacral insufficiency fractures. OBSERVATIONS: The authors presented two cases involving patients who received sacrectomy for a chordoma and experienced massive bleeding from the IIV due to adherence of the IIV and its neuroforaminal tributaries around sacral insufficiency fractures. They assessed their institution's previous two decades' experience of sacrectomies to determine risk factors for massive bleeding and performed anatomical dissection of 20 hemipelvises, which revealed the close proximity of the IIV to the sacral foraminae and the consistency of neuroforaminal tributaries arising from the foraminae. LESSONS: Sacral insufficiency fractures may cause scarring that adheres to the IIV and its neuroforaminal tributaries, which risks massive bleeding during sacrectomy.

En Bloc Resection of Isolated Spinal Metastasis: A Systematic Review Update.

STUDY DESIGN: This work was a systematic review. OBJECTIVE: The objective of this work was to review the literature on the outcomes of en bloc resection of isolated spinal metastasis. SUMMARY: Of background data: En bloc resection of isolated spinal metastasis is rarely performed and its utility debated, with the last review of the literature being performed over a decade ago. With significant advances in adjunctive oncology treatments, an updated review of whether there remains a role for this type of surgery is necessary. METHODS: The authors performed a systematic review of English literature over the last decade on en bloc resection of isolated spinal metastasis in adults using the PubMed, Google Scholar, OVID, and Cochrane database. They excluded studies with <5 reported cases. The studies were appraised by 2 coauthors and examined for the patient and tumor characteristics, surgical time, estimated blood loss, length of hospital stay, cost, complications, functional outcomes, rates of local recurrence, metastasis, and survival. RESULTS: Only 5 articles (148 patients) were included in this study. The average operative time was 6.5 hours, and estimated blood loss was 1742 mL. Only 73% of patients maintained their functional independence, but 35.1% experienced a complication, 6.1% had local recurrence, and the overall survival was 52% with an average time to death of 15 months. CONCLUSIONS: There remains a paucity of data limiting the understanding of the value of en bloc resection for isolated spinal metastasis. However, despite this limitation, our literature review suggests that en bloc resection offers a low local recurrence rate (6.1%) and maintained functional independence (73%), but requires long operative times (mean 6.5 h), causes significant blood loss (mean 1742 mL), and results in high complication rates (35.1%) with poor overall survival (52% with an average time to death of 15 mo).

Preventing iatrogenic facial pressure ulcers during spinal surgery: Prospective trial using a novel method and review of literature.

To assess the outcome of a novel method of preventing facial pressure ulcers in spinal surgery and a review of literature. A prospective trial using a novel method of facial protection using paraffin tulle gras dressing to cover bony prominences during spinal surgical procedures was performed. Patients were reviewed at 24 hours and 6 weeks. A telephone survey was also conducted post discharge. Over an 8-month period, 12 patients (7F:5M, age 9-72 years) underwent spine surgery for tumour stabilisation (n = 7), deformity correction (n = 4), and degenerative presentation (n = 1) with mean operative time of 472 minutes (range 150-785 minutes) in prone position. All patients were managed by the same team using an agreed protocol. No pressure ulcers were noted in our study. One patient sustained minimal erythema, which resolved after 24 hours. All patients were satisfied with the care received. Facial pressure ulcers though much reduced are still common in spinal surgery. The common factors are the long duration of surgery, shear, friction, moisture, and intrinsic factors. Our strategy of an appropriate facial support and constant vigilance helped eliminate the incidence of iatrogenic facial ulcers in spinal surgery.

Total en bloc resection of primary and metastatic spine tumors.

Primary and metastatic tumors of the spine represent a significant cause of patient morbidity, and present a management challenge to treating providers. From a neurosurgical standpoint, resection surgery may be warranted in cases of spinal instability, progressive disease, neurological compromise, or intractable symptoms. Removal of a tumor "en bloc" offers a more aggressive modality over more conservative resection techniques. En bloc resection entails the removal of the entirety of a tumor without violation of its capsule, and may offer improved rates of local control and overall survival in appropriately selected patients. Conversely, this technique carries a higher complication rate, and requires a unique set of technical skills as compared to more traditional resection. Here, we describe the technical aspects of en bloc resection, as well as specific indications and considerations when employing this operative technique.

Oxford Video Informed Consent Tool (OxVIC): a pilot study of informed video consent in spinal surgery and preoperative patient satisfaction.

OBJECTIVES: The British Association of Spinal Surgeons recently called for updates in consenting practice. This study investigates the utility and acceptability of a personalised video consent tool to enhance patient satisfaction in the preoperative consent giving process. DESIGN: A single-centre, prospective pilot study using questionnaires to assess acceptability of video consent and its impacts on preoperative patient satisfaction. SETTING: A single National Health Service centre with individuals undergoing surgery at a regional spinal centre in the UK. OUTCOME MEASURE: As part of preoperative planning, study participants completed a self-administered questionnaire (CSQ-8), which measured their satisfaction with the use of a video consent tool as an adjunct to traditional consenting methods. PARTICIPANTS: 20 participants with a mean age of 56 years (SD=16.26) undergoing spinal surgery. RESULTS: Mean patient satisfaction (CSQ-8) score was 30.2/32. Median number of video views were 2-3 times. Eighty-five per cent of patients watched the video with family and friends. Eighty per cent of participants reported that the video consent tool helped to their address preoperative concerns. All participants stated they would use the video consent service again. All would recommend the service to others requiring surgery. Implementing the video consent tool did not endure any significant time or costs. CONCLUSIONS: Introduction of a video consent tool was found to be a positive adjunct to traditional consenting methods. Patient-clinician consent dialogue can now be documented. A randomised controlled study to further evaluate the effects of video consent on patients' retention of information, preoperative and postoperative anxiety, patient reported outcome measures as well as length of stay may be beneficial.

Primary Bone Tumor of the Spine-An Evolving Field: What a General Spine Surgeon Should Know.

STUDY DESIGN: A narrative review of the literature. OBJECTIVE: This article reviews the general principles of treatment and investigation for primary bone tumors of the spine. Furthermore, it explores the emerging alternatives. METHODS: A review was performed using Medline, Embase, and Cochrane databases. RESULTS: Primary bone tumors of the spine are rare entities that general spine surgeons may encounter only a few times in their career. The treatment algorithm of these complex tumors is filled with nuances and is evolving constantly. For these reasons, patients should be referred to experienced tertiary or quaternary centers who can offer a comprehensive multidisciplinary approach. For most malignant spinal bone tumors, surgery remains the cornerstone of treatment. Respecting oncologic principles has been associated with improved survival and decreased local recurrence in multiple settings. However, even in experienced centers, these surgeries carry a significant risk of adverse events and possible long-term neurologic impairment. The associated morbidity of these procedures and the challenges of local recurrence have encouraged professionals caring for these patients to explore alternatives or adjuncts to surgical treatment. CONCLUSIONS: Over the past few years, several advances have occurred in medical oncology, radiation oncology and interventional radiology, changing the treatment paradigm for some tumors. Other advances still need to be refined before being applied in a clinical setting.

Neuroendocrine Tumor Arising in a Tailgut Cyst: A Rare Presacral Tumor.

A tailgut cyst (retrorectal cystic hamartoma) is an uncommon lesion that develops in the presacral (retrorectal) space. Malignant change in a tailgut cyst is extremely rare and presents as a soft tissue (presacral) or bone (sacral) neoplasm. We report a case of tailgut cyst in which a neuroendocrine tumor developed in a 25-year-old female. Computed tomography and magnetic resonance imaging scans revealed a sacrococcygeal malformation with absent left S4 and S5 and a partly cystic lesion within the right presacral space. Histologically, the lesion contained cystic and solid elements. The cysts were lined by columnar and stratified squamous epithelial cells with underlying patchy smooth muscle. The solid element was a partly necrotic neuroendocrine tumor composed mainly of ribbons of tumor cells, which showed mitotic activity and expressed cytokeratin, chromogranin, and synaptophysin. Histologically, tailgut cysts are lined by epithelium and contain scattered smooth muscle bundles in the cyst wall. Although rare, the possibility of tailgut cyst with neuroendocrine tumor should be included in the differential diagnosis of an enlarging presacral tumor.

Current treatment strategy for newly diagnosed chordoma of the mobile spine and sacrum: results of an international survey.

OBJECTIVEThe purpose of this study was to investigate the spectrum of current treatment protocols for managing newly diagnosed chordoma of the mobile spine and sacrum.METHODSA survey on the treatment of spinal chordoma was distributed electronically to members of the AOSpine Knowledge Forum Tumor, including neurosurgeons, orthopedic surgeons, and radiation oncologists from North America, South America, Europe, Asia, and Australia. Survey participants were pre-identified clinicians from centers with expertise in the treatment of spinal tumors. The suvey responses were analyzed using descriptive statistics.RESULTSThirty-nine of 43 (91%) participants completed the survey. Most (80%) indicated that they favor en bloc resection without preoperative neoadjuvant radiation therapy (RT) when en bloc resection is feasible with acceptable morbidity. The main area of disagreement was with the role of postoperative RT, where 41% preferred giving RT only if positive margins were achieved and 38% preferred giving RT irrespective of margin status. When en bloc resection would result in significant morbidity, 33% preferred planned intralesional resection followed by RT, and 33% preferred giving neoadjuvant RT prior to surgery. In total, 8 treatment protocols were identified: 3 in which en bloc resection is feasible with acceptable morbidity and 5 in which en bloc resection would result in significant morbidity.CONCLUSIONSThe results confirm that there is treatment variability across centers worldwide for managing newly diagnosed chordoma of the mobile spine and sacrum. This information will be used to design an international prospective cohort study to determine the most appropriate treatment strategy for patients with spinal chordoma.

Neoadjuvant denosumab for the treatment of a sacral osteoblastoma.

PURPOSE: To present a case of aggressive sacral osteoblastoma (OB) treated with neoadjuvant denosumab therapy and en bloc resection. METHODS: Case report of a 14-year-old male with an aggressive OB affecting the superior articular process of the left first sacral segment. The lesion was lytic and metabolically active and involved the left-sided posterior elements of S1-S3 with extension into the spinal canal, affecting the left S1, S2, S3, S4 and S5 nerve roots. He was treated for 1 month with neoadjuvant denosumab followed by en bloc resection. RESULTS: Denosumab therapy caused regression of the tumour and converted the diffuse infiltrative mass into a well-defined solid (osteoma-like) structure, aiding surgical resection and preserving the S1, S4 and S5 nerve roots. Histologically, the treated lesion showed abundant sclerotic woven bone and osteoblasts with absence of osteoclasts. CONCLUSIONS: A short course of denosumab caused tumour regression, ossification and conversion of an aggressive OB into a sclerotic, well-defined lesion thus aiding surgical resection and preservation of neural structures. Neoadjuvant therapy reduced osteoclast numbers but PET showed that the lesion remained FDG avid post-therapy.

Systematic Review of the Outcomes of Surgical Treatment of Prostate Metastases to the Spine.

STUDY DESIGN: Systematic review. OBJECTIVE: Surgical decompression and reconstruction of symptomatic spinal metastases has improved the quality of life in cancer patients. However, most data has been collected on cohorts of patients with mixed tumor histopathology. We systematically reviewed the literature for prognostic factors specific to the surgical treatment of prostate metastases to the spine. METHODS: A systemic review of the literature was conducted to answer the following questions: Question 1. Describe the survival and functional outcomes of surgery or vertebral augmentation for prostate metastases to the spine. Question 2. Determine whether overall tumor burden, Gleason score, preoperative functional markers, and hormonal naivety favor operative intervention. Question 3. Establish whether clinical outcomes vary with the evolution of operative techniques. RESULTS: A total of 16 studies met the preset inclusion criteria. All included studies were retrospective series with a level of evidence of IV. Included studies consistently showed a large effect of hormone-naivety on overall survival. Additionally, studies consistently demonstrated an improvement in motor function and the ability to maintain/regain ambulation following surgery resulting in moderate strength of recommendation. All other parameters were of insufficient or low strength. CONCLUSIONS: There is a dearth of literature regarding the surgical treatment of prostate metastases to the spine, which represents an opportunity for future research. Based on existing evidence, it appears that the surgical treatment of prostate metastases to the spine has consistently favorable results. While no consistent preoperative indicators favor nonoperative treatment, hormone-naivety and high Karnofsky performance scores have positive effects on survival and clinical outcomes.

Surgical management of spinal osteoblastomas.

OBJECTIVE Osteoblastoma is a rare primary benign bone tumor with a predilection for the spinal column. Although of benign origin, osteoblastomas tend to behave more aggressively clinically than other benign tumors. Because of the low incidence of osteoblastomas, evidence-based treatment guidelines and high-quality research are lacking, which has resulted in inconsistent treatment. The goal of this study was to determine whether application of the Enneking classification in the management of spinal osteoblastomas influences local recurrence and survival time. METHODS A multicenter database of patients who underwent surgical intervention for spinal osteoblastoma was developed by the AOSpine Knowledge Forum Tumor. Patient data pertaining to demographics, diagnosis, treatment, cross-sectional survival, and local recurrence were collected. Patients in 2 cohorts, based on the Enneking classification of the tumor (Enneking appropriate [EA] and Enneking inappropriate [EI]), were analyzed. If the final pathology margin matched the Enneking-recommended surgical margin, the tumor was classified as EA; if not, it was classified as EI. RESULTS A total of 102 patients diagnosed with a spinal osteoblastoma were identified between November 1991 and June 2012. Twenty-nine patients were omitted from the analysis because of short follow-up time, incomplete survival data, or invalid staging, which left 73 patients for the final analysis. Thirteen (18%) patients suffered a local recurrence, and 6 (8%) patients died during the study period. Local recurrence was strongly associated with mortality (relative risk 9.2; p = 0.008). When adjusted for Enneking appropriateness, this result was not altered significantly. No significant differences were found between the EA and EI groups in regard to local recurrence and mortality. CONCLUSIONS In this evaluation of the largest multicenter cohort of spinal osteoblastomas, local recurrence was found to be strongly associated with mortality. Application of the Enneking classification as a treatment guide for preventing local recurrence was not validated.