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Study Design: Retrospective cohort study., Objectives: This study aims to analyze outcomes and complications of patients with thoracic and lumbar fractures in the setting of ankylosing spinal disorders (ASD) treated with minimally invasive surgery (MIS)., Methods: The operative logs from 2012 to 2019 from one academic, Level I trauma center were reviewed for cases of thoracic and lumbar spinal fractures in patients with ASD treated with a MIS approach. Variables were compared between patients with ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis (DISH), and advanced spondylosis., Results: A total of 48 patients with ASD and concomitant thoracic or lumbar spinal fracture managed with an MIS approach were identified. A total of 11 patients were identified with AS, 21 with DISH, and 16 with advanced spondylosis. A total of 27 (56.3%) patients experienced complications. Complications differed between groups; DISH patients experienced a greater number of post-operative complications compared to AS and advanced spondylosis patients ( P = .009). There was no significant difference in length of surgery, estimated blood loss, length of stay, readmission, and reoperation rates between AS and DISH patients. There were 3 mortalities unrelated to the surgery., Conclusion: Percutaneous stabilization of patients with ankylosing spinal disorder fractures remains a viable management method. Operative characteristics were similar between AS, DISH, and advanced spondylosis patients; however, DISH patients experienced a greater number of post-operative complications.

Study Design: Retrospective Case Series., Objective: This study aims to evaluate readmission rates, risk factors, and reason for unplanned 30-day readmissions after thoracolumbar spine trauma surgery., Methods: A retrospective chart review was conducted for patients undergoing operative treatment for thoracic or lumbar trauma with open or minimally invasive surgical approach at a Level 1 urban trauma center. Patients were divided into two groups based on 30-day readmission status. Reason for readmission, reoperation rates, injury type, trauma severity, and incidence of polytrauma were compared between the two groups., Results: A total of 312 patients, 69.9% male with an average age of 47 ± 19 years were included. The readmitted group included 16 patients (5.1%) of which 9 (56%) were readmitted for medical complications and 7 for surgical complications. Wound complications (31.3% of readmissions) were the most common cause of readmission, followed by non-wound related sepsis (18.9% of readmissions). A total of 6 patients (37.5%) required reoperation; 2 instrumentation failures underwent revision surgery, and 4 wound complications underwent irrigation and debridement. Patients with higher Injury Severity Scale (ISS) were more likely to be readmitted (27.8% vs 22.1%, P = .045). Concomitant lower limb surgery increased odds of readmission (OR, 4.40; 95% CI, 1.10-17.83; P = .037)., Conclusion: Spine trauma 30-day readmission rate was 5.1%, comparable to those reported in the elective spine surgery literature. Readmitted patients were more likely to sustain concomitant operative lower limb trauma. Wound complications were the most common cause of readmission, and almost half of the patients were readmitted due to surgery-related complications.

Objectives: Percutaneous pedicle instrumentation (PPI) has been used for the treatment of thoracic and thoracolumbar (TL) trauma. However, the ability of PPI to correct significant post-traumatic kyphosis requires further investigation. The objective of this study is to compare the amount of kyphosis correction achieved by PPI vs the traditional open posterior approach in patients presenting with significant kyphotic deformity following traumatic thoracic and TL spine injuries., Methods: Following Institutional Review Board approval, patients who underwent surgery for thoracic (T1-T9) or TL (T10-L2) fractures with at least 15° of focal kyphosis in a 5-year period were included in this study. Patients were separated into 2 cohorts based on surgical technique: traditional open posterior approach and minimally invasive PPI. Kyphosis correction was measured using Cobb angle 1 vertebrae above and 1 below the level of injury on sagittal preoperative computed tomography image, immediate and follow-up postoperative upright lateral radiographs. Initial degree of correction and loss of correction at the final follow-up were compared., Results: Of 91 patients included, 65 (71%) underwent open surgery and 26 (29%) underwent PPI. Open patients had 11° (95% CI, 9°-13°) of immediate correction compared with 11° (95% CI, 6°-15°) for PPI ( P = 0.81). Follow-up data were available for 70 patients with a median of 105.5 days. Both groups had 1° (95% CI, 0°-2°) of loss of correction at follow-up ( P = 0.82). Regardless of surgical technique, obesity (>30 kg/m 2 ) and AO type-A compression fractures had significantly less correction. For each unit of body mass index, there was a 0.75° decrease in correction achieved ( P < 0.0001). Other factors did not influence the degree of correction., Conclusions: PPI techniques provide equivalent postoperative angular correction and maintenance of correction compared with open surgery in thoracic and TL trauma patients., Clinical Relevance: This study provides evidence for spine surgeons to utilize either technique for treating significant traumatic kyphotic deformity., Level of Evidence: Therapeutic 3., Competing Interests: Declaration of Conflicting Interests: Daniel Cavanaugh reports consulting fees from AlphaTec. Eugene Koh reports consulting fees from Biomet. Dan Gelb reports royalties or licenses from DePuy Synthes; payment or honoraria from DePuy Synthes (lecturer/speaker) and AO Spine North America (course faculty/lecturer); and stock from the Advanced Spinal Intellectual Property. Steven Ludwig reports royalties or licenses from Theime and Quality Medical Publishers, DePuy Synthes Spine and K2M/Stryker; consulting fees from DePuy Synthes Spine and K2M/Stryker; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or education events from AO Spine North America; stock or stock options from Innovaite Surgical Designs and Advance Spinal Intellectual Property; and a leadership or fiduciary role in the following groups: Society for Minimally Invasive Spine Surgery, Cervical Spine Research Society, American Board of Orthopaedic Surgery, Maryland Development Corporation, Journal of Spinal Disorders and Techniques, The Spine Journal, Contemporary Spine Surgery, and Nuvasive. The remaining authors have no disclosures., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2022 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

Objective: In patients with traumatic cervical spinal cord injury (tCSCI), the potential role of intraoperative neuromonitoring as a prognostic tool has been insufficiently studied. This study aimed to determine if detectable signals during intraoperative neuromonitoring portend a greater likelihood of recovery for patients with tCSCI., Methods: Patients who underwent decompression and surgical fixation following tCSCI were retrospectively reviewed through previously prospectively collected data from the Surgical Timing in Acute Spinal Cord Injury Study. Improvement in American Spinal Injury Association (ASIA) motor score and ASIA Impairment Scale grade conversion rates at final follow-up were compared between patients with detectable intraoperative neuromonitoring somatosensory evoked potential (SSEP) signals and those without detectable signals., Results: Forty-nine patients had intraoperative neuromonitoring. Patients with incomplete tCSCI had detectable lower extremity SSEPs more often than patients with complete tCSCI (56.3% vs. 23.5%, P = 0.028). There was no difference in detectable upper extremity SSEPs between complete and incomplete tCSCI (65.6% vs. 58.8%, P = 0.638). Of the 17 patients with complete tCSCI, patients with detectable lower extremity SSEPs had ASIA motor scores similar to the nondetectable cohort on admission (21.5 vs. 16.2, P = 0.609) but higher ASIA motor scores at final follow-up (57.5 vs. 27.1, P = 0.041). Of the 32 patients with incomplete spinal cord injury, there was no difference in grade conversion or motor scores between detectable and nondetectable SSEP cohorts., Conclusions: The presence of upper extremity SSEP signals in patients who present with complete tCSCI portends greater improvement in ASIA motor scores and likelihood of American Spinal Injury Association Impairment Scale grade conversion at final follow-up., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures., Methods: Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision., Results: Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p < 0.05)., Conclusions: Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.

Background: Length of stay (LOS) is a meaningful outcome measure for more efficient and effective quality of care. However, algorithms to predict LOS have yet to be created for patients who undergo surgical management for traumatic spinal fractures., Objectives: The objectives of this study were to (1) identify preoperative, perioperative, and postoperative factors associated with increased LOS and (2) create predictive formulas to estimate LOS in thoracolumbar trauma patients who undergo surgical correction., Methods: This is a retrospective case series of 196 patients operated for thoracolumbar spine trauma from January 2012 to December 2017 at a level 1 trauma and academic institution. Bivariate analysis between LOS and various preoperative, perioperative, and postoperative factors was conducted to identify significant associations. Multivariate analysis was conducted to create models capable of predicting LOS., Results: LOS was significantly associated with various preoperative (eg, Charlson Comorbidity Index, Glasgow Coma Scale [GCS], injury severity score), operative (eg, length of surgery, number of instrumented segments, surgical technique), and postoperative variables (eg, complications, discharge location). Multivariate analysis of preoperative variables identified 5 significant independent predictors that could predict LOS with strong correlation with observed LOS ( ρ = 0.63). With all variables considered, multivariate analysis identified 8 variables (GCS, American Society of Anesthesiologists score, neurological status, polytrauma, packed red blood cell transfusion, number of unique postoperative complications, skin complications, and discharge facility) that could predict LOS with strong correlation ( ρ = 0.80)., Conclusions: Various preoperative, perioperative, and postoperative factors are significantly associated with LOS in traumatic thoracolumbar spine patients. We developed models with good predictive capacity for LOS. If validated, these models should help in risk stratifying patients for increased LOS and consequently improve perioperative patient counseling., Clinical Relevance: This article contributes to identifying and predicting patients who are high risk for extended LOS after traumatic thoracolumbar injuries., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Eugene Y. Koh reports consulting for Biomet and grants from the National Institutes of Health. Daniel E. Gelb reports royalties from DePuy Synthes and Globus Medical; stock ownership from Advanced Spinal Intellectual Property; speaking and/or teaching arrangements and Board of Directors for AO Spine North America. Charles Sansur reports consulting for DePuy Synthes, Medtronic, and Stryker, and speaker and/or teaching arrangements with DePuy Synthes and Gobus Medical. Steven C. Ludwig reports royaltoes from DePuy Synthes, Globus Medical, Theime, and Quality Medical Publishers; stock ownership in Innovaive Surgical Designs and the American Society for Investigative Pathology; consulting for DePuy Synthes, K2M, and Globus Medical; speaking and/or teaching arrangements with DePuy Synthes and K2M; Board or committee member for Globus Medical, the American Board of Orthopaedic Surgery, the American Orthopaedic Association, the Cervical Spine Research Society, and the Society for Minimally Invasive Surgery; research support from Pacira Pharmaceutical, AOA Omega Grant, and Nuvasive; and Fellowship support from AO Spine North America Spine Fellowship Support; Pacira Pharmaceutical; AOA Omega Grant, and Nuvasive. The remaining authors have no disclosures., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2022 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

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., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective Case Series., Objectives: Minimally invasive techniques have emerged as a useful tool in the treatment of neoplastic spine pathology due to decrease in surgical morbidity and earlier adjuvant treatment. The objective of this study was to analyze outcomes and complications in a cohort of unstable, symptomatic pathologic fractures treated with percutaneous pedicle screw fixation (PPSF)., Methods: A retrospective review was performed on consecutive patients with spinal stabilization for unstable pathologic neoplastic fractures between 2007 and 2017. Patients who underwent PPSF through a minimally invasive approach were included. Surgical indications included intractable pain, mechanical instability, and neurologic compromise with radiologic visualization of the lesion., Results: 20 patients with mean Tomita Score of 6.3 ± 2.1 points [95% CI, 5.3-7.2] were treated with constructs that spanned a mean of 4.7 ± 1.4 [95% CI, 4.0-5.3] instrumented levels. 10 (50%) patients were augmented with vertebroplasty. Majority of patients (65%) had no complications during their hospital stay and were discharged home (60%). Four patients received reoperation: two extracavitary corpectomies, one pathologic fracture at a different level, and one adjacent segment disease., Conclusion: Minimally invasive PPSF is a safe and effective option when treating unstable neoplastic fractures and may be a viable alternative to the traditional open approach in select cases., Level of Evidence: 4., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: MC, JEC, IBY, JJB, AET, JJJ, KB, DLC: No disclosures. SL: American Board of Orthopaedic Surgery, Inc: Board or committee member; American Orthopedic Association: Board or committee member; AO Spine North America Spine Fellowship Support: Research support; American Society for Investigative Pathology, Innovative Surgical Designs: Stock or stock options; Cervical Spine Research Society: Board or committee member; DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Paid presenter or speaker; Globus Medical: Paid consultant; Research support; Journal of Spinal Disorders and Techniques: Editorial or governing board; K2M spine: Research support; K2Medical: Paid consultant; OMEGA: Research support; Pacira: Research support; SMISS: Board or committee member; Synthes: Paid consultant; Paid presenter or speaker; Thieme, QMP: Publishing royalties, financial, or material support. DG: Advanced Spinal Intellectual Property: Stock or stock options; Depuy-Synthes Spine: IP royalties; Paid presenter or speaker; Globus Medical: IP royalties. EK: Biomet: Paid consultant; DePuy, A Johnson & Johnson Company: Paid presenter or speaker., (© 2022 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Objective: Minimally invasive surgery (MIS) techniques can effectively stabilize and decompress many thoracolumbar injuries with decreased morbidity and tissue destruction compared with open approaches. Nonetheless, there is limited direction regarding the breadth and limitations of MIS techniques for thoracolumbar injuries. Consequently, the objectives of this study were to 1) identify the range of current practice patterns for thoracolumbar trauma and 2) integrate expert opinion and literature review to develop an updated treatment algorithm., Methods: A survey describing 10 clinical cases with a range of thoracolumbar injuries was sent to 12 surgeons with expertise in spine trauma. The survey results were summarized using descriptive statistics, along with the Fleiss kappa statistic of interrater agreement. To develop an updated treatment algorithm, the authors used a modified Delphi technique that incorporated a literature review, the survey results, and iterative feedback from a group of 14 spine trauma experts. The final algorithm represented the consensus opinion of that expert group., Results: Eleven of 12 surgeons contacted completed the case survey, including 8 (73%) neurosurgeons and 3 (27%) orthopedic surgeons. For the 4 cases involving patients with neurological deficits, nearly all respondents recommended decompression and fusion, and the proportion recommending open surgery ranged from 55% to 100% by case. Recommendations for the remaining cases were heterogeneous. Among the neurologically intact patients, MIS techniques were typically recommended more often than open techniques. The overall interrater agreement in recommendations was 0.23, indicating fair agreement. Considering both literature review and expert opinion, the updated algorithm indicated that MIS techniques could be used to treat most thoracolumbar injuries. Among neurologically intact patients, percutaneous instrumentation without arthrodesis was recommended for those with AO Spine Thoracolumbar Classification System subtype A3/A4 (Thoracolumbar Injury Classification and Severity Score [TLICS] 4) injuries, but MIS posterior arthrodesis was recommended for most patients with AO Spine subtype B2/B3 (TLICS > 4) injuries. Depending on vertebral body integrity, anterolateral corpectomy or mini-open decompression could be used for patients with neurological deficits., Conclusions: Spine trauma experts endorsed a range of strategies for treating thoracolumbar injuries but felt that MIS techniques were an option for most patients. The updated treatment algorithm may provide a foundation for surgeons interested in safe approaches for using MIS techniques to treat thoracolumbar trauma.

Background: Hospitals seek to reduce costs and improve patient outcomes by decreasing length of stay (LOS), 30-day all-cause readmissions, and preventable complications. We evaluated hospital-reported outcome measures for elective single-level anterior cervical discectomy and fusions (ACDFs) between tertiary (TH) and community hospitals (CH) to determine location-based differences in complications, LOS, and overall costs., Methods: Patients undergoing elective single-level ACDF in a 1-year period were retrospectively reviewed from a physician-driven database from a single medical system consisting of 1 TH and 4 CHs. Adult patients who underwent elective single-level ACDF were included. Patients with trauma, tumor, prior cervical surgery, and infection were excluded. Outcomes measures included all-cause 30-day readmissions, preventable complications, LOS, and hospital costs., Results: A total of 301 patients (60 TH, 241 CH) were included. CHs had longer LOS (1.25 ± 0.50 versus 1.08 ± 0.28 days, P = .01). There were no differences in complication and readmission rates between hospital settings. CH, orthopaedic subspecialty, female sex, and myelopathy were predictors for longer LOS. Overall, costs at the TH were significantly higher than at CHs ($17 171 versus $11 737; Δ $ = 5434 ± 3996; P < .0001). For CHs, the total costs of drugs, rooms, supplies, and therapy were significantly higher than at the TH. TH status, orthopaedic subspecialty, and myelopathy were associated with higher costs., Conclusion: Patients undergoing single-level ACDFs at CHs had longer LOS, but similar complications and readmission rates as those at the TH. However, cost of ACDF was 1.5 times greater in the TH. To improve patient outcomes, optimize value, and reduce hospital costs, modifiable factors for elective ACDFs should be evaluated., Level of Evidence: 3., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2021 ISASS.)

Study Design: Retrospective case series., Objectives: Postoperative urinary retention (POUR) represents a common postoperative complication of all elective surgeries. The aim of this study was to identify demographic, comorbid, and surgical factors risk factors for POUR in patients who underwent elective thoracolumbar spine fusion., Methods: Following institutional review board approval, patients who underwent elective primary or revision thoracic and lumbar instrumented spinal fusion in a 2-year period in tertiary and academic institution were reviewed. Sex, age, BMI, preoperative diagnosis, comorbid conditions, benign prostatic hyperplasia, diabetes, primary or revision surgery status, narcotic use, and operative factors were collected and analyzed between patients with and without POUR., Results: Of the 217 patients reviewed, 54 (24.9%) developed POUR. The average age for a patient with POUR was 67 ± 9, as opposed to 59 ± 10 for those without ( P < .0001). Single-level fusions were associated with a 0% incidence of POUR, compared with 54.5% in 6 or more levels. The average hospital stay was increased by 1 day for those who had POUR (5.8 ± 3.3 vs 4.9 ± 3.9 days). There was no significant association with other demographic variables, comorbid conditions, or surgical factors., Conclusions: POUR was a common complication in our patient cohort, with an incidence of 24.9%. Our findings demonstrate that patients who developed POUR are significantly older and have larger constructs. Patients who developed POUR also had longer in-hospital stays. Although our study supports other findings in the spine literature, more prospective data is needed to define diagnostic criteria of POUR as well as its management.

Study Design: In silico finite element study., Objective: The aim of this study was to evaluate the effect of six construct factors on apical rod strain in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three- vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS)., Summary of Background Data: Rod fracture following lumbar PSO is frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material and diameter, and with CC or ACS to reduce mechanical demand or rod contouring. A comprehensive evaluation of these features on rod strain is lacking., Methods: A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Apical rod strain of primary and accessory rods was collected for 96 constructs across all six construct factors, and normalized to the Ti two-rod control., Results: Regardless of construct features, CoCr and SS material reduced strain across all rods by 49.1% and 38.1%, respectively; increasing rod diameter from 5.5 mm to 6.35 mm rods reduced strain by 32.0%. Use of CC or lumbosacral ACS minimally affected apical rod strain (<2% difference from constructs without CC or ACS). Compared to the ADG technique, traditional inline reconstruction reduced primary rod strain by 32.2%; however, ADG primary rod required 14.2° less rod contouring. The inline technique produced asymmetrical loading between left and right rods, only when three rods were used., Conclusion: The number of rods and position of accessory rods affected strain distribution on posterior fixation. Increasing rod diameter and using CoCr rods was most effective in reducing rod strain. Neither CC nor lumbosacral ACS affected apical rod strain., Level of Evidence: N/A.

Study Design: In silico finite element study., Objective: The aim of this study was to evaluate effects of six construct factors on rod and screw strain at the lumbosacral junction in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three-rod vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS)., Summary of Background Data: Implant failure and pseudoarthrosis at the lumbosacral junction following PSO are frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material, and diameter, and with CC or ACS to reduce mechanical demand. An evaluation of these features' effects on rod and screw strains is lacking., Methods: A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Lumbosacral rod and screw strain data were collected for 96 constructs across all six construct factors and normalized to the Ti 2-Rod control., Results: The inline technique resulted in 12.5% to 51.3% more rod strain and decreased screw strain (88.3% to 95%) compared to ADG at the lumbosacral junction. An asymmetrical strain distribution was observed in the three-rod inline technique in comparison to four-rod, which was more evenly distributed. Regardless of construct features, rod strain was significantly decreased by rod material (CoCr > SS > Ti), and increasing rod diameter from 5.5 mm to 6.35 mm reduced strain by 9.9% to 22.1%. ACS resulted in significant reduction of rod (37.8%-59.8%) and screw strains (23.2%-65.8%)., Conclusion: Increasing rod diameter, using CoCr rods, and ACS were the most effective methods in reducing rod strain at the lumbosacral junction. The inline technique decreased screw strain and increased rod strain compared to ADG., Level of Evidence: N/A.

Study Design: Prospective cohort study., Objectives: To determine the prevalence of bacterial infection, with the use of a contaminant control, in patients undergoing anterior cervical discectomy and fusion (ACDF)., Methods: After institutional review board approval, patients undergoing elective ACDF were prospectively enrolled. Samples of the longus colli muscle and disc tissue were obtained. The tissue was then homogenized, gram stained, and cultured in both aerobic and anaerobic medium. Patients were classified into 4 groups depending on culture results. Demographic, preoperative, and postoperative factors were evaluated., Results: Ninety-six patients were enrolled, 41.7% were males with an average age of 54 ± 11 years and a body mass index of 29.7 ± 5.9 kg/m 2 . Seventeen patients (17.7%) were considered true positives, having a negative control and positive disc culture. Otherwise, no significant differences in culture positivity was found between groups of patients. However, our results show that patients were more likely to have both control and disc negative than being a true positive (odds ratio = 6.2, 95% confidence interval = 2.5-14.6). Propionibacterium acnes was the most commonly identified bacteria. Two patients with disc positive cultures returned to the operating room secondary to pseudarthrosis; however, age, body mass index, prior spine surgery or injection, postoperative infection, and reoperations were not associated with culture results., Conclusion: In our cohort, the prevalence of subclinical bacterial infection in patients undergoing ACDF was 17.7%. While our rates exclude patients with positive contaminant control, the possibility of contamination of disc cultures could not be entirely rejected. Overall, culture results did not have any influence on postoperative outcomes.

Study Design: Retrospective cohort study., Objective: As hospital compensation becomes increasingly dependent on pay-for-performance and bundled payment compensation models, hospitals seek to reduce costs and increase quality. To our knowledge, no reported data compare these measures between hospital settings for elective lumbar procedures. The study compares hospital-reported outcomes and costs for elective lumbar procedures performed at a tertiary hospital (TH) versus community hospitals (CH) within a single health care system., Methods: Retrospective review of a physician-maintained, prospectively collected database consisting of 1 TH and 4 CH for 3 common lumbar surgeries from 2015 to 2016. Patients undergoing primary elective microdiscectomy for disc herniation, laminectomy for spinal stenosis, and laminectomy with fusion for degenerative spondylolisthesis were included. Patients were excluded for traumatic, infectious, or malignant pathology. Comparing hospital settings, outcomes included length of stay (LOS), rates of 30-day readmissions, potentially preventable complications (PPC), and discharge to rehabilitation facility, and hospital costs., Results: A total of 892 patients (n = 217 microdiscectomies, n = 302 laminectomies, and n = 373 laminectomy fusions) were included. The TH served a younger patient population with fewer comorbid conditions and a higher proportion of African Americans. The TH performed more decompressions ( P < .001) per level fused; the CH performed more interbody fusions ( P = .007). Cost of performing microdiscectomy ( P < .001) and laminectomy ( P = .014) was significantly higher at the TH, but there was no significant difference for laminectomy with fusion. In a multivariable stepwise linear regression analysis, the TH was significantly more expensive for single-level microdiscectomy ( P < .001) and laminectomy with single-level fusion ( P < .001), but trended toward significance for laminectomy without fusion ( P = .052). No difference existed for PPC or readmissions rate. Patients undergoing laminectomy without fusion were discharged to a facility more often at the TH ( P = .019)., Conclusions: We provide hospital-reported outcomes between a TH and CH. Significant differences in patient characteristics and surgical practices exist between surgical settings. Despite minimal differences in hospital-reported outcomes, the TH was significantly more expensive., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Gelb is a board member and fellowship committee chair for AOSpine NA. He receives payment for lectures and for development of educational presentations from AOSpine NA. He receives royalties from DePuy Synthes Spine and Globus Medical. He has stock in the American Society for Investigative Pathology. Dr Koh receives payment for consultancy from Biomet. His institution receives RO1 grant money from the National Institutes of Health. Dr Ludwig is a board member for Globus Medical, the American Board of Orthopaedic Surgery, the American Orthopaedic Association, the Cervical Spine Research Society, and the Society for Minimally Invasive Spine Surgery. He is a paid consultant for DePuy Synthes, K2M, and Globus Medical. He receives payment for lectures and travel accommodations from DePuy Synthes and K2M. He receives payment for patents and royalties from DePuy Synthes and Globus Medical. He has stock in Innovative Surgical Designs and the American Society for Investigative Pathology. He receives research support from AO Spine North America Spine Fellowship support, Pacira Pharmaceutical, and AOA Omega Grant. He is a board member of Maryland Development Corporation. He receives royalties from Thieme, Quality Medical Publishers. He is on the governing board of Journal of Spinal Disorders and Techniques, The Spine Journal, and Contemporary Spine Surgery. The authors have no further potential conflicts of interest to disclose., (© The Author(s) 2019.)

Study Design: Retrospective cohort., Objective: Facet fusion in minimally invasive spine surgery (MISS) may reduce morbidity and promote long-term construct stability. The study compares the maintenance of correction of thoracolumbar (TL) trauma patients who underwent MISS with facet fusion (FF) and without facet fusion (WOFF) and evaluates instrumentation loosening and failure., Methods: TL trauma patients who underwent MISS between 2006 and 2013 were identified and stratified into FF and WOFF groups. To evaluate progressive kyphosis and loss of correction, Cobb angles were measured at immediate postoperative, short-term, and long-term follow-up. Evidence of >2 mm of radiolucency on radiographs indicated screw loosening. If instrumentation was removed, postremoval kyphosis angle was obtained., Results: Of the 80 patients, 24 were in FF and 56 were in WOFF group. Between immediate postoperative and short-term follow-up, kyphosis angle changed by 4.0° (standard error [SE] 1.3°) in the FF and by 3.0° (SE 0.4°) in the WOFF group. The change between immediate postoperative and long-term follow-up kyphosis angles was 3.4° (S.E 1.1°) and 5.2° (S.E 1.6°) degrees in the FF and WOFF groups, respectively. Facet fusion had no impact on the change in kyphosis at short term ( P = .49) or long term ( P = .39). The screw loosening rate was 20.5% for the 80 patients with short-term follow-up and 68.8% for the 16 patients with long-term follow-up. There was no difference in screw loosening rate. Fifteen patients underwent instrumentation removal-all from the FF group., Conclusion: FF in MISS does not impact the correction achieved and maintenance of correction in patients with traumatic spine injuries., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Gelb is a board member and fellowship committee chair for AOSpine NA. He receives payment for lectures and for development of educational presentations from AOSpine NA. He receives royalties from DePuy Synthes Spine and Globus Medical. He has stock in the American Society for Investigative Pathology. Dr Koh receives payment for consultancy from Biomet. His institution receives RO1 grant money from the National Institutes of Health. Dr Ludwig is a board member for Globus Medical, the American Board of Orthopaedic Surgery, the American Orthopaedic Association, the Cervical Spine Research Society, and the Society for Minimally Invasive Spine Surgery. He is a paid consultant for DePuy Synthes, K2M, and Globus Medical. He receives payment for lectures and travel accommodations from DePuy Synthes and K2M. He receives payment for patents and royalties from DePuy Synthes and Globus Medical. He has stock in Innovative Surgical Designs and the American Society for Investigative Pathology. He receives research support from AO Spine North America Spine Fellowship support, Pacira Pharmaceutical, and AOA Omega Grant. He is a board member of Maryland Development Corporation. He receives royalties from Thieme, Quality Medical Publishers. He is on the governing board of Journal of Spinal Disorders and Techniques, The Spine Journal, and Contemporary Spine Surgery. The authors have no further potential conflicts of interest to disclose., (© The Author(s) 2019.)

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., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Many of the authors have affiliations with organizations with financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in some of the products mentioned in the study. There are no conflicts of interest in reference to any product mentioned in the content of this article., (© The Author(s) 2020.)

Introduction: Percutaneous minimally invasive spine surgery (MISS) is a treatment option for thoracolumbar fractures and we aim to evaluate its outcomes., Methods: A retrospective matched cohort study of all patients with thoracolumbar fractures treated with MISS or open posterior approach., Results: We included 100 MISS and 155 open patients. After controlling for patient characteristics, our results statistically favor MISS in mean operative time, mean intraoperative blood loss, and number of patients requiring postoperative blood transfusions within 48 h., Conclusions: Advantages of using MISS for treatment of thoracolumbar fractures are decreased operative time, decreased blood loss, and fewer patients requiring transfusions., Competing Interests: Dr. Gelb is a board member and fellowship committee chair for AOSpine NA. He receives payment for lectures and for development of educational presentations from AOSpine NA. He receives royalties from DePuy Synthes Spine and Globus Medical. He has stock in the American Society for Investigative Pathology. Dr. Koh receives payment for consultancy from Biomet. His institution receives RO1 grant money from the National Institutes of Health. Dr. Ludwig is a board member for Globus Medical, the American Board of Orthopaedic Surgery, the American Orthopaedic Association, the Cervical Spine Research Society, and the Society for Minimally Invasive Spine Surgery. He is a paid consultant for DePuy Synthes, K2M, and Globus Medical. He receives payment for lectures and travel accommodations from DePuy Synthes and K2M. He receives payment for patents and royalties from DePuy Synthes and Globus Medical. He has stock in Innovative Surgical Designs and the American Society for Investigative Pathology. He receives research support from AO Spine North America Spine Fellowship support, Pacira Pharmaceutical, and AOA Omega Grant. He is a board member of Maryland Development Corporation. He receives royalties from Thieme, Quality Medical Publishers. He is on the governing board of Journal of Spinal Disorders and Techniques, The Spine Journal, and Contemporary Spine Surgery. The authors have no further potential conflicts of interest to disclose.

Study Design: A retrospective cohort study., Objective: The objective of this study was to assess the utility of routine in-hospital postoperative radiographs for identifying hardware failure following surgical treatment of traumatic thoracolumbar (TL) injuries., Background: Postoperative radiographs following spine surgery are considered standard of care despite a lack of evidence supporting their utility. Previous studies have concluded that postoperative radiographs following lumbar fusion for degenerative conditions have limited clinical value., Materials and Methods: A retrospective chart review was performed on patients who underwent surgical treatment of traumatic TL injuries between December 2006 and October 2015 at a level I trauma center. Before discharge, postoperative upright anteroposterior and lateral radiographs were obtained and reviewed by 1 surgeon and 1 radiologist as per protocol. Patients who subsequently underwent revision surgery during their initial hospital stay were identified. These patients were further analyzed to identify the indications for surgery and determine if the results of the radiographs obtained led to the subsequent revision surgery., Results: A total of 463 patients were identified who underwent surgical treatment following TL trauma. The rate of revision surgery during the initial hospitalization was 1.3% (6/463). Three patients underwent revision surgery due to worsening neurological status. One patient underwent reoperation because of advance imaging obtained for abdominal trauma. Two patients underwent revision surgery due to abnormal findings on postoperative radiographs. The overall sensitivity and specificity of routine postoperative radiographs was 33.3% and 100%, respectively., Conclusions: In the absence of new clinical signs and symptoms, obtaining routine in-hospital postoperative radiographs following surgical treatment of TL injuries provides minimal value. Clinical assessment should help determine if additional imaging is indicated for the patient. Avoiding unnecessary inpatient tests such as routine postoperative radiograph may offer multitude of benefits including lowering patient radiation exposure, reducing health care costs and better allocation of hospital resources., Level of Evidence: Level III.

Study Design: Meta-analysis of evidence level I to IV studies., Objective: To compare decompression alone versus decompression plus fusion in the treatment of grade I degenerative spondylolisthesis (DS)., Methods: Following established guidelines, we systematically reviewed 3 electronic databases to assess studies evaluating patients with grade I DS. We stratified all patients into 2 cohorts; the first cohort underwent a decompression-type surgery, and the second cohort underwent decompression plus fusion. We noted clinical outcomes, complications, reoperations, and surgical details such as blood loss. Descriptive statistics and random-effects models were used to determine the specified outcome metrics with 95% confidence intervals (CIs)., Results: In both cohorts, the pain (legs and lower back) significantly decreased and the physical component of the Short Form 36 showed better patient clinical outcomes. The decompression cohort had a 5.8% complication rate (95% CI = 1.7-2.1), and the decompression plus fusion cohort had an 8.3% complication rate (95% CI = 5.5-11.6). The reoperation rate was higher in the decompression-only cohort (8.5%; 95% CI = 2.9-17.0) compared with the decompression plus fusion cohort (4.9%; 95% CI = 2.5-7.9)., Conclusions: There does not appear to be any advantage of one procedure over the other. Patients undergoing decompression alone tended to be older with a higher percentage of leg pain, whereas patients additionally undergoing fusion tended to be younger with more lower back pain. The decompression-only cohort had fewer complications but a higher revision rate., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Steven Ludwig: American Board of Orthopaedic Surgery, Inc, Board member; American Orthopaedic Association, Board member; AO Spine North America, Spine Fellowship Support, research support; ASIP, ISD, stock; Cervical Spine Research Society, Board member; DePuy, A Johnson & Johnson Company, IP royalties, paid consultant, paid speaker; Globus Medical, paid consultant, research support; Journal of Spinal Disorders and Techniques, Editorial Board; K2M Spine, research support; K2Medical, paid consultant; OMEGA, research support; Pacira, research support; SMISS, Board member; Synthes, paid consultant, paid speaker; Thieme, QMP, publishing royalties, financial or material support. Daniel Gelb: Advanced Spinal Intellectual Property, stock; DePuy-Synthes Spine, IP royalties, paid speaker; Globus Medical, IP royalties. Eugene Koh: Biomet, paid consultant; DePuy, A Johnson & Johnson Company, paid speaker. Kelley Banagan: Johnson & Johnson, employee; Orthofix, Inc, material support. The remaining authors have no conflicts of interest to declare.

Background Context: Adjacent segment disease (ASD) is a well-known complication after lumbar fusion. Lumbar lateral interbody fusion (LLIF) may provide an alternative method of treatment for ASD while avoiding the morbidity associated with revision surgery through a traditional posterior approach. This is the first biomechanical study to evaluate the stability of lateral-based constructs for treating ASD in existing multilevel fusion model., Purpose: We aimed to evaluate the biomechanical stability of anterior column reconstruction through the less invasive lateral-based interbody techniques compared with traditional posterior spinal fusion for the treatment of ASD in existing multilevel fusion., Study Design/setting: Cadaveric biomechanical study of laterally based interbody strategies for treating ASD., Methods: Eighteen fresh-frozen cadaveric specimens were nondestructively loaded in flexion, extension, and lateral bending. The specimens were randomized into three different groups according to planned posterior spinal instrumented fusion (PSF): group 1: L5-S1, group 2: L4-S1, and group 3: L3-S1. In each group, ASD was considered the level cranial to the upper-instrumented vertebrae (UIV). After testing the intact spine, each specimen underwent PSF representing prior fusion in the ASD model. The adjacent segment for each specimen then underwent (1) Stand-alone LLIF, (2) LLIF + plate, (3) LLIF + single screw rod (SSR) anterior instrumentation, and (4) LLIF + traditional posterior extension of PSF. In all conditions, three-dimensional kinematics were tracked, and range of motion (ROM) was calculated for the comparisons., Results: ROM results were expressed as a percentage of the intact spine ROM. LLIF effectively reduces ROM in all planes of ROM. Supplementation of LLIF with plate or SSR provides further stability as compared with stand-alone LLIF. Expansion of posterior instrumentation provides the most substantial stability in all planes of ROM (p <.05). All constructs demonstrated a consistent trend of reduction in ROM between all the groups in all bending motions., Conclusions: This biomechanical study suggests potential promise in exploring LLIF as an alternative treatment of ASD but reinforces previous studies' findings that traditional expansion of posterior instrumentation provides the most biomechanically stable construct., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background Context: The incidence of pyogenic vertebral osteomyelitis (PVO) continues to increase in the United States, highlighting the need to recognize unique challenges presented by these cases and develop effective methods of surgical management. To date, no prior research has focused on the outcomes of PVO requiring two or more contiguous corpectomies., Purpose: To describe our experience in the operative management of PVO in 56 consecutive patients who underwent multilevel corpectomies (≥2 vertebral bodies) via a combined approach., Study Design/setting: Single institution retrospective cohort review between January 2002 and December 2015. All patients had been treated at an academic tertiary referral center by one of two fellowship-trained orthopedic spine surgeons., Patient Sample: Patient records were cross-referenced with International Classification of Diseases osteomyelitis codes and paravertebral abscess code. Inclusion criteria for the study were patients within the cohort who had adequate medical records for review, a minimum patient age of 18 years, active vertebral osteomyelitis as an indication for surgical intervention, a minimum of 1-year radiographic follow-up, and surgical intervention that included at least two complete vertebral corpectomies. Subsequently, 56 patients met the inclusion criteria and were reviewed for this retrospective analysis., Outcome Measures: Outcomes of interest were readmission and reoperation rates related to treatment of PVO, 30-day and 1-year mortality rates, radiographic outcomes, perioperative complications, infection control, and length of stay., Methods: After obtaining approval from the Institutional Review Board, retrospective review was performed on records of all adults with PVO refractory to standard nonoperative treatment who underwent complete corpectomy of two or more contiguous vertebrae at a single institution between January 2002 and December 2015. This study was not funded, and no potential conflict of interest-associated biases were present., Results: Fifty-six patients were identified (63% men; mean age 56.8 years; mean radiographic follow-up 2.8 years). Median length of stay was 13 days with nearly half readmitted (47%) after a median of 222.5 days after surgery. Twelve (22%) posterior revisions were required after a median 54 days for infection, painful or failed hardware, proximal junction kyphosis, adjacent level disease, or extension of the fusion. Thirty-day and 1-year mortality rates were 7.14% and 19.6%, respectively, with an infectious etiology as the most common cause of death., Conclusions: Multilevel vertebral corpectomy for treatment of refractory vertebral osteomyelitis is associated with relatively high rates of complications and mortality compared with historical controls for 1 or 2 level procedures. We found clinical resolution and absence of complications requiring return to the operating room in 75% of patients when complete extirpation of the involved vertebrae is achieved. Our findings suggest multilevel anterior corpectomies with posterior stabilization may be a reasonable surgical option when approaching patients with complicated spondylodiscitis., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Study Design: A retrospective review (2001-2014) was conducted using prospectively collected data at a level I trauma center., Objective: We sought to determine the incidence and characteristics of complications occurring secondary to therapeutic anticoagulation in adult spine trauma patients., Summary of Background Data: Numerous studies have assessed prophylactic anticoagulation after spine surgery, but none has investigated the risks of therapeutic doses of anticoagulation for treatment of postoperative thromboembolic events., Methods: Patients were included if they sustained a postoperative thromboembolic event (deep venous thrombosis, pulmonary embolism, or myocardial infarction). Patients were excluded if anticoagulation was subtherapeutic. Of 1712 patients, 62 who received therapeutic anticoagulation and 174 propensity-matched control patients who did not receive therapeutic anticoagulation were included in the study., Results: Initial anticoagulation was obtained by heparin infusion (51%), low-molecular-weight heparin (LMWH, 46%), and warfarin (3%). Complications requiring unplanned reoperation occurred in 18% of anticoagulated patients and 10% of nonanticoagulated patients (P = 0.17). The reoperation rate after heparin infusion was 31% and after LMWH was 6.5% (P = 0.02). Epidural hematoma occurred in 3% and 1% of anticoagulated and nonanticoagulated patients, respectively. Multivariate logistic regression analysis of the two groups showed a trend toward increased risk of reoperation in the anticoagulation group. Analysis of the heparin infusion subgroup separate from the LMWH subgroup compared with the control group showed an increased risk of reoperation for any complication (odds ratio, 3.57; P = 0.01) and for bleeding complications (odds ratio, 43.1; P = 0.01)., Conclusion: This is the first study to quantify complications secondary to postoperative therapeutic anticoagulation in spine patients. Postoperative spine trauma patients who underwent therapeutic anticoagulation experienced an unplanned reoperation rate of 18%, including a 3% incidence of spinal epidural hematoma. Therapeutic anticoagulation using heparin infusion seems to drive the overall rate of reoperation (31%) compared with LMWH., Level of Evidence: 3.

Study Design: Retrospective cohort study., Objective: To determine whether a low-density (LD) screw construct can achieve curve correction similar to a high-density (HD) construct in adolescent scoliosis., Methods: Patients treated operatively for idiopathic scoliosis between 2007 and 2011 were identified through a database review. A consistent LD screw construct was used. Radiographic assessment included percent correction of major and fractional lumbar curves, T5-T12 kyphosis, and angle of lowest instrumented vertebra (LIV). Costs were compared with HD constructs., Results: Thirty-five patients were included in the analysis. Ages ranged from 12 to 19 years (mean = 14.9 years). Average screw density was 1.2 screws per level (range = 1.07-1.5 screws). Mean percent curve correction at latest follow-up: major curve, 66.9%; fractional lumbar curve, 63%. Average postoperative thoracic kyphosis: 29.5°. Mean LIV angle: 5.6°. Average construct cost was $14 871 per case compared with $23 840 per case if all levels had been instrumented with 2 screws, amounting to an average savings of $9000., Conclusions: Our LD screw construct is among the lowest density constructs reported and achieves curve correction comparable to HD constructs at substantially lower cost., Competing Interests: Declaration of Conflicting Interests: DG received a consulting fee from DePuy Synthes Spine. On an ongoing basis, DG receives payment from AOSpine North America for lectures when serving as faculty at courses. In the past, DG has received payment from DePuy Synthes Spine for lectures presented at a resident leaders’ course. DG currently receives royalties from DePuy Synthes Spine for oracle instrumentation and from Globus Medical for the gateway plate. Dr Ludwig reports grants from AO Spine North America for Spine Fellowship support, Globus Medical, K2M Pacira Pharmaceuticals, and OMeGA. SL receives personal fees and royalties from DePuy Synthes. No other relationships, conditions, or circumstances exist that present a potential conflict of interest. The remaining authors declare no conflicts of interest.

Study Design: A comparative study of facet joint violation (FJV) using two percutaneous surgical techniques., Objective: To compare the rate of iatrogenic FJV and medial pedicle wall breach between two methods of percutaneous pedicle screw instrumentation in the thoracic and lumbar spine., Summary of Background Data: Variable iatrogenic damage to the facet joints has been reported to occur with percutaneous pedicle screw techniques, compared with the open approach, which has been associated with adjacent segment disease. Technical variations of percutaneous pedicle screw placement may pose different risks to the facet joint., Methods: Attending spine surgeons percutaneously placed pedicle screws in seven human cadaveric spines from T2 to L5. At each level, screws were instrumented on one side using the 9 or 3 o'clock reference point of the pedicle on the posteroanterior view with a lateral-to-medial trajectory (LMT) and on the contralateral side using the center of the pedicle with an owl's eye trajectory (OET). Postoperative screw placement was assessed with computed tomography and then open cadaveric dissection. Outcome measures included FJV and medial pedicle wall breach., Results: Overall, 17 of 105 screws placed with an LMT versus 49 of 105 screws placed with an OET violated or abutted the facet joint (P <0.0001). This significant difference was observed at the thoracic (T2-T10), thoracolumbar (T11-L1), and lumbar (L2-L5) levels (P = 0.003, 0.035, and 0.018, respectively). Medial pedicle wall breach occurred with 11 LMT screws and seven OET screws (P = 0.077), and no breach was considered critical., Conclusion: A significantly higher FJV rate was observed using the OET versus the LMT in the thoracic, thoracolumbar, and lumbar spine. No statistically significant differences in medial pedicle wall breach occurred between the techniques. Thus, the LMT of minimally invasive pedicle screw fixation may reduce iatrogenic damage to the facet joints., Level of Evidence: 3.

Objective: We sought to determine the role of lumbopelvic fixation (LPF) in the treatment of zone II sacral fractures with varying levels of sacral comminution combined with anterior pelvic ring (PR) instability. We also sought to determine the proximal extent of LPF necessary for adequate stabilization and the role of LPF in complex sacral fractures when only 1 transiliac-transsacral (TI-TS) screw is feasible., Materials and Methods: Fifteen L4 to pelvis fresh-frozen cadaveric specimens were tested intact in flexion-extension (FE) and axial rotation (AR) in a bilateral stance gliding hip model. Two comminution severities were simulated through the sacral foramen using an oscillating saw, with either a single vertical fracture (small gap, 1 mm) or 2 vertical fractures 10 mm apart with the intermediary bone removed (large gap). We assessed sacral fracture zone (SZ), PR, and total lumbopelvic (TL) stability during FE and AR. The following variables were tested: (1) presence of transverse cross-connector, (2) presence of anterior plate, (3) extent of LPF (L4 vs. L5), (4) fracture gap size (small vs. large), (5) number of TI-TS screws (1 vs. 2)., Results: The transverse cross-connector and anterior plate significantly increased PR stability during AR (P = 0.02 and P = 0.01, respectively). Increased sacral comminution significantly affected SZ stability during FE (P = 0.01). Two versus 1 TI-TS screw in a large-gap model significantly affected TL stability (P = 0.04) and trended toward increased SZ stabilization during FE (P = 0.08). Addition of LPF (L4 and L5) significantly improved SZ and TL stability during AR and FE (P < 0.05). LPF in combination with TI-TS screws resulted in the least amount of motion across all 3 zones (SZ, PR, and TL) compared with all other constructs in both small-gap and large-gap models., Conclusions: The role of LPF in the treatment of complex sacral fractures is supported, especially in the setting of sacral comminution. LPF with proximal fixation at L4 in a hybrid approach might be needed in highly comminuted cases and when only 1 TI-TS screw is feasible to obtain maximum biomechanical support across the fracture zone.

Background Context: Conditions of the atlantoaxial complex requiring internal stabilization can result from trauma, malignancy, inflammatory diseases, and congenital malformation. Several techniques have been used for stabilization and fusion. Posterior wiring is biomechanically inferior to screw fixation. C1 lateral mass screws and C1 posterior arch screws are used for instrumentation of the atlas. Previous studies have shown that unicortical C1 lateral mass screws are biomechanically stable for fixation. No study has evaluated the biomechanical stability of C1 posterior arch screws or compared the two techniques., Purpose: The purpose of the study was to assess the differences in the pullout strength between C1 lateral mass screws and C1 posterior arch screws., Study Design: Biomechanical testing of pullout strengths of the two atlantal screw fixation techniques., Methods: Thirteen fresh human cadaveric C1 vertebrae were harvested, stripped of soft tissues, evaluated with computed tomography for anomalies, and instrumented with unicortical C1 lateral mass screws on one side and unicortical C1 posterior arch screws on the other. Screw placement was confirmed with postinstrumentation fluoroscopy. Specimens were divided in the sagittal plane and potted in polymethylmethacrylate. Axial load to failure was applied with a material testing device. Load displacement curves were obtained, and the results were compared with Student t test. DePuy Spine, Inc. (Raynham, MA, USA) provided the hardware used in this study., Results: Mean pullout strength of the C1 lateral mass screws was 821 N (range 387-1,645 N ± standard deviation [SD] 364). Mean pullout strength of the posterior arch screws was 1,403 N (range 483-2,200 N ± SD 609 N). The difference was significant (p=.009). Five samples (38%) in the posterior arch group experienced bone failure before screw pullout., Conclusions: Both unicortical lateral mass screws and unicortical posterior arch screws are viable options for fixation in the atlas. Unicortical posterior arch screws have superior resistance to pullout via axial load compared with unicortical lateral mass screws in the atlas., (Copyright © 2013 Elsevier Inc. All rights reserved.)