Diagnosis of spine pseudoarthrosis based on the biomechanical properties of bone.

BACKGROUND CONTEXT: Failure to fuse following anterior cervical discectomy and fusion (ACDF) may result in symptomatic pseudoarthrosis. Traditional diagnosis involves computerized tomography to detect bridging bone and/or flexion-extension radiographs to assess whether segmental motion is above specific thresholds; however, there are currently no well-validated diagnostic tests. We propose a biomechanically rational approach to achieve a reliable diagnostic test for pseudoarthrosis. PURPOSE: Develop and test a biomechanically based approach to the diagnosis of pseudoarthrosis. STUDY DESIGN: Literature review, development of theory, re-analysis of a previously published study with surgical exploration as the gold-standard, and retrospective analysis of pooled studies to understand time to fusion. METHODS: Fully automated methods were used to measure disc space strains (change in disc space height divided by initial height). Measurement error combined with the reported failure strain of trabecular bone led to a proposed strain threshold for diagnosis of pseudoarthrosis following ACDF. We reanalyzed previously reported flexion-extension radiographs for asymptomatic volunteers to assess whether flexion-extension radiographs, in the absence of fusion surgery, can be expected to provide sufficient stress on motion segments to allow for reliable strain-based fusion assessment. The sensitivity and specificity of strain- and rotation-based pseudoarthrosis diagnosis were assessed by reanalysis of previously reported post-ACDF flexion-extension radiographs, where intraoperative fusion assessments were also available. Finally, we assessed changes in strain over time using 9,869 flexion-extension radiographs obtained 6 weeks to 84 months post-ACDF surgery from 1,369 patients. RESULTS: The estimated error in automated measurement of disc space strain from radiographs was approximately 3%, and the reported failure strain of bridging bone was less than 2.5%. On that basis, we propose a 5% strain threshold for pseudoarthrosis diagnosis. Reanalysis of a study in which intraoperative fusion assessments were available revealed 67% sensitivity and 82% specificity for strain-based diagnosis of pseudoarthrosis, which was comparable to rotation-based diagnosis. Analysis of post-ACDF flexion-extension radiographs revealed rapid strain reduction for up to 24 months, followed by a slower decrease for up to 84 months. When rotation is less than 2 degrees, the strain-based diagnosis differed from the rotation-based diagnosis in approximately 14% of the cases. CONCLUSIONS: We propose steps for standardizing diagnosis of pseudoarthrosis based on the failure strain of bone, measurement error, and retrospective data. These steps include obtaining high-quality flexion-extension studies, the application of proposed diagnostic thresholds, and the use of image stabilization for conclusive diagnosis, when motion is near thresholds. The necessity for an accurate diagnosis with minimal radiation exposure underscores the need for further optimization and standardization in diagnosing pseudoarthrosis following ACDF surgery. CLINICAL SIGNIFICANCE: In a symptomatic postspine fusion patient, it is important to diagnose or rule-out pseudoarthrosis. There are currently no well-validated diagnostic tests for this condition. Incorporating strain-based intervertebral motion analysis into the diagnosis could lead to a standardized and validated test for detecting spine pseudoarthrosis.

Aneurysmal bone cyst on top of fibro-osseous lesion of the ethmoid sinus with orbital and intracranial extension in a child.

Objective: Aneurysmal bone cysts (ABCs) rarely involve the cranium. We report a case arising in the ethmoid sinus with orbital and intracranial invasion. Imaging suggested an associated fibro-osseous lesion. The lesion was completely resected. Histology confirmed the imaging diagnosis of ABC on top of an ossifying fibroma. A multidisciplinary approach is essential for optimal surgical outcomes. Methods: We report a case of an 8-year-old boy with a 5 week history of painless, increasing prominence of the left eye. Clinical examination revealed non-pulsatile left proptosis. Visual acuity and ocular movements were normal. CT and MRI scans of the maxillofacial regions showed a large space-occupying lesion involving the left ethmoid air cells with left orbital and left inferior frontal intracranial extension. Multiple fluid levels with blood products were seen. Areas of the bony component of the lesion showed ground-glass density on CT. Imaging was consistent with an ABC with an underlying fibro-osseous lesion; probably fibrous dysplasia which was confirmed after surgical removal of the lesion. A multidisciplinary team of maxillofacial, neurosusugery and ENT surgeons performed the surgery. Results: ABC arising from an osseous fibroma of the skull is rare. Total resection can be achieved with a multidisciplinary surgical approach. Post-operative histology confirmed by the imaging findings.

Developing a National Trauma Research Action Plan: Results from the Neurotrauma Research Panel Delphi Survey.

BACKGROUND: In 2016, the National Academies of Science, Engineering and Medicine called for the development of a National Trauma Research Action Plan. The Department of Defense funded the Coalition for National Trauma Research to generate a comprehensive research agenda spanning the continuum of trauma and burn care. Given the public health burden of injuries to the central nervous system, neurotrauma was one of 11 panels formed to address this recommendation with a gap analysis and generation of high-priority research questions. METHODS: We recruited interdisciplinary experts to identify gaps in the neurotrauma literature, generate research questions, and prioritize those questions using a consensus-driven Delphi survey approach. We conducted four Delphi rounds in which participants generated key research questions and then prioritized the importance of the questions on a 9-point Likert scale. Consensus was defined as 60% or greater of panelists agreeing on the priority category. We then coded research questions using an National Trauma Research Action Plan taxonomy of 118 research concepts, which were consistent across all 11 panels. RESULTS: Twenty-eight neurotrauma experts generated 675 research questions. Of these, 364 (53.9%) reached consensus, and 56 were determined to be high priority (15.4%), 303 were deemed to be medium priority (83.2%), and 5 were low priority (1.4%). The research topics were stratified into three groups-severe traumatic brain injury (TBI), mild TBI (mTBI), and spinal cord injury. The number of high-priority questions for each subtopic was 46 for severe TBI (19.7%), 3 for mTBI (4.3%) and 7 for SCI (11.7%). CONCLUSION: This Delphi gap analysis of neurotrauma research identified 56 high-priority research questions. There are clear areas of focus for severe TBI, mTBI, and spinal cord injury that will help guide investigators in future neurotrauma research. Funding agencies should consider these gaps when they prioritize future research. LEVEL OF EVIDENCE: Diagnostic Test or Criteria, Level IV.

The Risk of Nonunion in Smokers Revisited: A Systematic Review and Meta-Analysis.

STUDY DESIGN: Systemic review and meta-analysis. OBJECTIVE: To review and establish the effect of tobacco smoking on risk of nonunion following spinal fusion. METHODS: A systematic search of Medline, Embase, Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews from inception to December 31, 2020, was conducted. Cohort studies directly comparing smokers with nonsmokers that provided the number of nonunions and fused segments were included. Following data extraction, the risk of bias was assessed using the Quality in Prognosis Studies Tool, and the strength of evidence for nonunion was evaluated using the GRADE working group criteria. All data analysis was performed in Review Manager 5, and a random effects model was used. RESULTS: Twenty studies assessing 3009 participants, which included 1117 (37%) smokers, met inclusion criteria. Pooled analysis found that smoking was associated with increased risk of nonunion compared to not smoking ≥1 year following spine surgery (RR 1.91, 95% CI 1.56 to 2.35). Smoking was significantly associated with increased nonunion in those receiving either allograft (RR 1.39, 95% CI 1.12 to 1.73) or autograft (RR 2.04, 95% CI 1.54 to 2.72). Both multilevel and single level fusions carried increased risk of nonunion in smokers (RR 2.30, 95% CI 1.64 to 3.23; RR 1.79, 95% CI 1.12 to 2.86, respectively). CONCLUSION: Smoking status carried a global risk of nonunion for spinal fusion procedures regardless of follow-up time, location, number of segments fused, or grafting material. Further comparative studies with robust methodology are necessary to establish treatment guidelines tailored to smokers.

Type II Odontoid Fractures Case Series: History of Seizures a Risk Factor for Failure of Non-operative Treatment of Type II Odontoid Fractures.

Introduction: Odontoid fractures are one of the most common injuries to the cervical spine. Type II odontoid fracture treatment varies depending on age, co-morbidities, and fracture morphology. Treatment ranges from cervical orthosis to surgical intervention. CurrentlyAt present, fractures with high non-union rates are considered for operative management which includes displacement of >6 mm, increasing age (>40--60 years), fracture gap >1 mm, delay in treatment >4 days, posterior re-displacement >2 mm, increased angulation, and history of smoking. While re-displacement of >2 mm has been associated with increased risk of non-union;, to the best of our knowledge, no studies have looked at the risk factors for re-displacement. Case Report: We present two 26-year-old male patients who were found to have minimally displaced type II odontoid fractures initially treated in a cervical collar. These two patients were subsequently found to have displaced their odontoid fracture after having a documented seizure. Conclusion: We suggest that a history of seizures be considered a risk factor for re-displacement of non-displaced type II odontoid fractures.

Medical Malpractice Claims and Mitigation Strategies Following Spine Surgery.

STUDY DESIGN: Narrative review. OBJECTIVE: The aim of this narrative review is to examine trends in malpractice litigation arising from spine surgery. We also hope to detail mitigation strategies that surgeons can employ to decrease their risk of a claim. METHODS: A review of the relevant literature examining the prevalence, risks, and outcomes of malpractice litigation following spine surgery was conducted using the MEDLINE and Embase databases. RESULTS: Combined queries identified 1140 potentially relevant articles. After eliminating duplicate articles and screening by title and abstract, 38 articles underwent full-text review. Of these, 22 were deemed relevant to the research questions posed. Evaluation of references identified 1 additional relevant article. Spine surgery represents one of the most litigious specialties in the United States health care system. The available literature points to a consistent pattern of common allegations leading to litigation following spine surgery. While a majority of filed lawsuits end in the surgeon's favor, these cases carry high monetary and time expenditures regardless of outcome. Furthermore, the threat of a malpractice lawsuit motivates many surgeons to practice defensive medicine by utilizing unnecessary or unindicated tests and studies. CONCLUSION: Through the examination of trends in malpractice claims and case outcomes, surgeons may be able to adapt practices to minimize their risk of litigation. These changes can include, but are not limited to, identification of those procedures that are most litigious and a more thorough discussion of the informed consent process to include operative and nonoperative treatments prior to all procedures. More important, however, spine surgeons can potentially serve as advocates for change.

Innovative Technology System to Prevent Wrong Site Surgery and Capture Near Misses: A Multi-Center Review of 487 Cases.

Introduction: Wrong site surgery (WSS) is a preventable error. When these events do occur, they are often devastating to the patient, nursing staff, surgeon, and facility where the surgery was performed. Despite the implementation of protocols and checklists to reduce the occurrence of WSS, the rates are estimated to be unchanged. Materials and Methods: An innovative technology was designed to prevent WSS through a systems-based approach. The StartBox Patient Safety System was utilized at six sites by 11 surgeons. The incidence of near misses and WSS was reviewed. Results: The StartBox System was utilized for 487 orthopedic procedures including Spine, Sports Medicine, Hand, and Joint Replacement. There were no occurrences of WSS events. Over the course of these procedures, medical staff recorded 17 near misses utilizing the StartBox System. Conclusions: StartBox successfully performed all tasks without technical errors and identified 17 near miss events. The use of this system resulted in the occurrence of zero wrong site surgeries.

Correlating Psychological Comorbidities and Outcomes After Spine Surgery.

STUDY DESIGN: Literature review. OBJECTIVE: The aim of this literature review is to examine the effects of psychological disorders on postoperative complications, surgical outcomes, and long-term narcotic use. We also hope to detail the value of preoperative identification and treatment of these pathologies. METHODS: A series of systematic reviews of the relevant literature examining the effects of psychological disorders and spine surgery was conducted using PubMed and Cochrane databases. RESULTS: Combined, the database queries yielded 2275 articles for consideration. After applying screening criteria, 96 articles were selected for inclusion. Patients with underlying psychological disease have higher rates of delirium, readmission, longer hospital stays, and higher rates of nonroutine discharge following spine surgery. They also have higher rates of chronic postoperative narcotic use and may experience worse surgical outcomes. Because of these defined issues, researchers have developed multiple screening tools to help identify patients with psychological disorders preoperatively for potential treatment. Treatment of these disorders prior to surgery may significantly improve surgical outcomes. CONCLUSION: Patients with psychological disorders represent a unique population with respect to their higher rates of spinal pain complaints, postoperative complications, and worsened functional outcomes. However, proper identification and treatment of these conditions prior to surgery may significantly improve many outcome measures in this population. Future investigations in this field should attempt to develop and validate current strategies to identify and treat individuals with psychological disorders before surgery to further improve outcomes.

Multiple-Layer Lumbosacral Pseudomeningocele Repair with Bilateral Paraspinous Muscle Flaps and Literature Review.

BACKGROUND: Pseudomeningocele is an uncommon but widely recognized complication of spinal surgery that can be challenging to correct. When conservative measures fail, patients frequently require reoperation to attempt primary closure of the durotomy, yet attempts at true watertight closures of the dura or fascia sometimes fall short. We describe a technique of lumbosacral pseudomeningocele repair involving a 2-layer pants-over-vest closure of the pseudomeningocele coupled with mobilization of bilateral paraspinal musculature to create a Z-plasty, or a Z-shaped flap. We have demonstrated a high success rate with our small series. METHODS: The technique used meticulous manipulation of the pseudomeningocele to make a 2-layer pants-over-vest closure. This closure coupled with wide mobilization and importation of paraspinous muscle into the wound effectively obliterated dead space with simultaneous tamponade of the dural tear. The lateral row perforators were left intact, providing excellent vascularity with adequate mobility to the patient. RESULTS: This technique was incorporated into the care of 10 patients between 2004 and July 2019. All wounds were closed in a single stage after careful flap section based on the wound's needs. We demonstrated successful pseudomeningocele resolution in all 10 patients with no observed clinical recurrence of symptomatic pseudomeningocele after at least 6 months of follow-up. CONCLUSIONS: This technique provides a straightforward option for the spine surgeon to manage these challenging spinal wounds with minimal, if any, need for further laminectomy as well as a high fistula control rate with minimal morbidity.

Perioperative Considerations in Urgent Surgical Care of Suspected and Confirmed COVID-19 Orthopaedic Patients: Operating Room Protocols and Recommendations in the Current COVID-19 Pandemic.

By April 7, 2020, severe acute respiratory syndrome coronavirus 2 was responsible for 1,383,436 confirmed cases of Coronavirus disease 2019 (COVID-19), involving 209 countries around the world; 378,881 cases have been confirmed in the United States. During this pandemic, the urgent surgical requirements will not stop. As an example, the most recent Centers of Disease Control and Prevention reports estimate that there are 2.8 million trauma patients hospitalized in the United States. These data illustrate an increase in the likelihood of encountering urgent surgical patients with either clinically suspected or confirmed COVID-19 in the near future. Preparation for a pandemic involves considering the different levels in the hierarchy of controls and the different phases of the pandemic. Apart from the fact that this pandemic certainly involves many important health, economic, and community ramifications, it also requires several initiatives to mandate what measures are most appropriate to prepare for mitigating the occupational risks. This article provides evidence-based recommendations and measures for the appropriate personal protective equipment for different clinical and surgical activities in various settings. To reduce the occupational risk in treating suspected or confirmed COVID-19 urgent orthopaedic patients, recommended precautions and preventive actions (triage area, emergency department consultation room, induction room, operating room, and recovery room) are reviewed.

An Update on Wrong-Site Spine Surgery.

STUDY DESIGN: Broad narrative review of current literature and adverse event databases. OBJECTIVE: The aim of this review is to report the current state of wrong-site spine surgery (WSSS), whether the Universal Protocol has affected the rate, and the current trends regarding WSSS. METHODS: An updated review of the current literature on WSSS, the Joint Commission sentinel event statistics database, and other state adverse event statistics database were performed. RESULTS: WSSS is an adverse event that remains a potentially devastating problem, and although the incidence is difficult to determine, the rate is low. However, given the potential consequences for the patient as well as the surgeon, WSSS remains an event that continues to be reported alarmingly as often as before the implementation of the Universal Protocol. CONCLUSIONS: A systems-based approach like the Universal Protocol should be effective in preventing wrong-patient, wrong-procedure, and wrong-sided surgeries if the established protocol is implemented and followed consistently within a given institution. However, wrong-level surgery can still occur after successful completion of the Universal Protocol. The surgeon is the sole provider who can establish the correct vertebral level during the operation, and therefore, it is imperative that the surgeon design and implement a patient-specific protocol to ensure that the appropriate level is identified during the operation.

Minimizing Blood Loss in Spine Surgery.

STUDY DESIGN: Broad narrative review. OBJECTIVE: To review and summarize the current literature on guidelines, outcomes, techniques and indications surrounding multiple modalities of minimizing blood loss in spine surgery. METHODS: A thorough review of peer-reviewed literature was performed on the guidelines, outcomes, techniques, and indications for multiple modalities of minimizing blood loss in spine surgery. RESULTS: There is a large body of literature that provides a consensus on guidelines regarding the appropriate timing of discontinuation of anticoagulation, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and herbal supplements prior to surgery. Additionally, there is a more heterogenous discussion the utility of preoperative autologous blood donation facilitated by erythropoietin and iron supplementation for healthy patients slated for procedures with high anticipated blood loss and for whom allogeneic transfusion is likely. Intraoperative maneuvers available to minimize blood loss include positioning and maintaining normothermia. Tranexamic acid (TXA), bipolar sealer electrocautery, and topical hemostatic agents, and hypotensive anesthesia (mean arterial pressure (MAP) <65 mm Hg) should be strongly considered in cases with larger exposures and higher anticipated blood loss. There is strong level 1 evidence for the use of TXA in spine surgery as it reduces the overall blood loss and transfusion requirements. CONCLUSION: As the volume and complexity of spinal procedures rise, intraoperative blood loss management has become a pivotal topic of research within the field. There are many tools for minimizing blood loss in patients undergoing spine surgery. The current literature supports combining techniques to use a cost- effective multimodal approach to minimize blood loss in the perioperative period.

Intradural extramedullary metastasis: a review of literature and case report.

Introduction: Intradural extramedullary (IDEM) metastatic disease is infrequently encountered by spine surgeons and consequently poorly understood. Discovery often corresponds with the onset of neurologic symptoms and no consensus exists regarding the importance of complete resection or anticipated postoperative outcome. We aim to elucidate treatment methodologies that exist in the literature. Case presentation: We present a unique case of a 57-year-old male with a known history of esophageal adenocarcinoma, including brain and visceral metastases, who presented with cauda equina syndrome. An IDEM metastatic esophageal adenocarcinoma lesion was identified on advanced imaging and biopsy. This was treated operatively without return of neurologic function. Discussion: We reviewed and summarized the existing literature. Trends are highlighted to further guide surgeons treating this unusual metastatic phenomenon. Conclusion: Intradural metastasis is a harbinger of advanced disease with a poor prognosis regardless of the etiology of the primary lesion. There are a number of proposed mechanisms for metastatic spread with little available literature for surgeon guidance. Most authors are advocates of a palliative, decompressive approach.

Longer follow-up continues to reveal no increased risk of cancer with the use of recombinant human bone morphogenetic protein in spine fusion.

BACKGROUND CONTEXT: Large observational studies on potential oncogenic effects of recombinant human bone morphogenetic protein (rhBMP) in spine fusion surgery are limited by relatively short follow-up times. PURPOSE: To study the possible association between rhBMP and cancer risk in a long-term follow-up study. STUDY DESIGN: A retrospective cohort study using a combination of the Washington State Comprehensive Hospital Abstract Reporting System, the Washington State Cancer Registry, State of Washington death certificates, and the Washington State Department of Licensing. PATIENT SAMPLE: Participants were adults age ≥21 years who underwent spine fusion surgery enhanced by rhBMP for degenerative spine disease between January 1, 2002 and December 31, 2010. A comparison group matching each patient receiving rhBMP with three patients not receiving rhBMP was created using the indicators of age, sex, and year of treatment. We excluded patients receiving spine fusion for vertebral fractures or infection, and those with a diagnosis of cancer before or at the index procedure. OUTCOME MEASURES: The primary outcome was the first diagnosis of any cancer as identified in the records of the state cancer registry or death certificate through the end of 2015. METHODS: We compared cancer risk between those receiving spine fusion with and without rhBMP using survival analysis. We calculated incidence rates (hazards) by computing the ratio of the number of events and total time at risk. Unadjusted hazard ratios (HR) and adjusted HR (aHR) and their respective 95% confidence intervals (CI) were calculated assuming a Cox proportional hazard regression model. We adjusted the model to include the site of surgery (lumbar vs. cervical) as a covariate as this differed in frequency between the two treatment groups. To assess whether rhBMP adversely affects the progression of cancer, we compared mortality between rhBMP users and nonusers in those who developed cancer. Research support toward this study was received from Medtronic Sofamor Danek USA. The investigators alone, and not Medtronic, were solely responsible for the design, conduct, analysis, and reporting of this study. RESULTS: We included 16,914 patients who had spine fusion, of whom 4,246 received rhBMP. During the study period, 1,342 patients were diagnosed with some form of cancer. The incidence rate was similar between the two groups: 11.2 per 1,000 person years in the rhBMP group and 10.4 per 1,000 person years in the non-rhBMP group, with an aHR of 0.96; 95% CI, 0.85 to 1.10. Similarly, rhBMP use was not associated with an increased risk of commonly occurring individual cancer types, nor with cancer specific mortality after a cancer diagnosis, aHR, 0.92; 95% CI, 0.69 to 1.22. CONCLUSIONS: Long-term follow-up confirms previous findings that rhBMP application treated with elective spinal fusion did not result in an increased cancer risk in a large population of US adults.

The Science and Clinical Applications of Placental Tissues in Spine Surgery.

STUDY DESIGN: Narrative literature review. OBJECTIVES: Placental tissue, amniotic/chorionic membrane, and umbilical cord have seen a recent expansion in their clinical application in various fields of surgery. It is important for practicing surgeons to know the underlying science, especially as it relates to spine surgery, to understand the rationale and clinical indication, if any, for their usage. METHODS: A literature search was performed using PubMed and MEDLINE databases to identify studies reporting the application of placental tissues as it relates to the practicing spine surgeon. Four areas of interest were identified and a comprehensive review was performed of available literature. RESULTS: Clinical application of placental tissue holds promise with regard to treatment of intervertebral disc pathology, preventing epidural fibrosis, spinal dysraphism closure, and spinal cord injury; however, there is an overall paucity of high-quality evidence. As such, evidence-based guidelines for its clinical application are currently unavailable. CONCLUSIONS: There is no high-level clinical evidence to support the application of placental tissue for spinal surgery, although it does hold promise for several areas of interest for the practicing spine surgeon. High-quality research is needed to define the clinical effectiveness and indications of placental tissue as it relates to spine surgery.

Spontaneous spinal epidural hematoma: literature review.

Review the current literature regarding spontaneous spinal epidural hematomas (SSEHs) and report on the known risk factors, evaluation, and treatment of this rare entity. A literature search was performed using PubMed and Ovid to identify articles pertaining to SSEHs. Due to the rarity of the pathologic entity, only scattered case reports and associated reviews are available. SSEHs are a rare yet potentially life-altering event. The underlying risk factors are poorly understood, and SSEHs present with minimal or no antecedent trauma. SSEHs warrant urgent surgical intervention given the associated risk of permanent neurologic sequelae. Given the potential for persistent neurologic deficits, physicians must entertain a clinical suspicion of SSEH when a patient presents with a history of back pain followed by neurologic deficits. Even without clear risk factors for hemorrhage, the appropriate evaluation to include advanced imaging studies should be obtained to allow for identification of this entity and urgent surgical management.

The Effects of Smoking and Smoking Cessation on Spine Surgery: A Systematic Review of the Literature.

Study Design Literature review. Objective The aim of this literature review was to detail the effects of smoking in spine surgery and examine whether perioperative smoking cessation could mitigate these risks. Methods A review of the relevant literature examining the effects of smoking and cessation on surgery was conducted using PubMed, Google Scholar, and Cochrane databases. Results Current smokers are significantly more likely to experience pseudarthrosis and postoperative infection and to report lower clinical outcomes after surgery in both the cervical and lumbar spines. Smoking cessation can reduce the risks of these complications depending on both the duration and timing of tobacco abstinence. Conclusion Smoking negatively affects both the objective and subjective outcomes of surgery in the lumbar and cervical spine. Current literature supports smoking cessation as an effective tool in potentially mitigating these unwanted outcomes. Future investigations in this field should be directed toward developing a better understanding of the complex relationship between smoking and poorer outcomes in spine surgery as well as developing more efficacious cessation strategies.

The Risk of Cancer With the Use of Recombinant Human Bone Morphogenetic Protein in Spine Fusion.

STUDY DESIGN: Retrospective cohort study using the Washington State Comprehensive Hospital Abstract Reporting System, the Washington State Cancer Registry, and Washington State death certificates. OBJECTIVE: To study the possible association between recombinant human bone morphogenetic protein (rhBMP) and cancer risk. SUMMARY OF BACKGROUND DATA: The use of rhBMP in spine fusion surgery remains controversial with respect to its possible role in tumorigenesis. METHODS: We compared adults who underwent spine fusion for degenerative disease with and without rhBMP between 2002 and 2010. Patients were matched on the basis of age, sex, and year of treatment. We excluded patients with a diagnosis of cancer before or at the index procedure. The primary outcome was the first diagnosis of cancer as identified in the records of the cancer registry. RESULTS: We included 16,914 patients who had spine fusion, of whom 4246 received rhBMP. During the study period, 449 patients received a diagnosis of cancer: 117 (2.76% of 4246) in the rhBMP group and 332 (2.62% of 12 668) in the no rhBMP group. The incidence rate was similar between the rhBMP and no rhBMP 9.5 and 9.0 per 1000 person years, respectively (hazard ratio, 1.06; 95% confidence interval, 0.86-1.30). There were no differences in the rate of cancer between the two groups in subgroups defined on the basis of site of fusion or surgical method. CONCLUSION: There was no increase in overall cancer incidence among those receiving rhBMP. An important limitation of this and other studies of rhBMP and cancer that have been conducted to date is their relatively limited duration of follow-up. The examination of cancer incidence following rhBMP administration must continue beyond just the first several years to adequately assess the potential of rhBMP to influence the occurrence of one or more types of malignancy. LEVEL OF EVIDENCE: 3.

The Effects of Obesity on Spine Surgery: A Systematic Review of the Literature.

Study Design Literature review. Objective The aim of this literature review is to examine the effects of obesity on postoperative complications and functional outcomes after spine surgery. Methods A review of the relevant literature examining the effects of obesity and spine surgery was conducted using PubMed, Google Scholar, and Cochrane databases. Results Obesity contributes to disk degeneration and low back pain and potentially increases the risk of developing operative pathology. Obese patients undergoing spine surgery have a higher risk of developing postoperative complications, particularly surgical site infection and venous thromboembolism. Though functional outcomes in this population may not mirror the general population, the treatment effect associated with surgery is at least equivalent if not better in obese individuals. This reduction is primarily due to worse outcomes associated with nonoperative treatment in the obese population. Conclusion Obese individuals represent a unique patient population with respect to nonoperative treatment, postoperative complication rates, and functional outcomes. However, given the equivalent or greater treatment effect of surgery, this comorbidity should not prohibit obese patients from undergoing operative intervention. Future investigations in this area should attempt to develop strategies to minimize complications and improve outcomes in obese individuals and also examine the role of controlled weight loss preoperatively to mitigate these risks.