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Background Context: Previous studies have analyzed the effect of laminectomy on intervertebral disc (IVD), facet-joint-forces (FJF), and range of motion (ROM), while only two have specifically reported stresses at the pars interarticularis (PI) with posterior element resection. These studies have been performed utilizing a single subject, questioning their applications to a broader population., Purpose: We investigate the effect of graded PI resection in a three-dimensional manner on PI stress to provide surgical guidelines for avoidance of iatrogenic instability following lumbar laminectomy. Additionally, quantified FJF and IVD stresses can provide further insight into the development of adjacent segment disease., Study Design: Biomechanical finite element (FE) method investigation of the lumbar spine., Methods: FE models of the lumbar spine of three subjects were created using the open-source finite element software, FEBio. Single-level laminectomy, two-level laminectomy, and ventral-to-dorsal PI resection simulations were performed with varying degrees of PI resection from 0% to 75% of the native PI. These models were taken through cardinal ROM under standard loading conditions and PI stresses, FJF, IVD stresses, and ROM were analyzed., Results: The three types of laminectomy simulated in this study showed a nonlinear increase in PI stress with increased bone resection. Axial rotation generated the most stress at the PI followed by flexion, extension and lateral bending. At 75% bone resection all three types of laminectomy produced PI stresses that were near the ultimate strength of human cortical bone during axial rotation. FJF decreased with increased bone resection for the three laminectomies simulated. This was most notable in axial rotation followed by extension and lateral bending. IVD stresses varied greatly between the nonsurgical models and likewise the effect of laminectomy on IVD stresses varied between subjects. ROM was mostly unaffected by the laminectomies performed in this study., Conclusions: Regarding the risk of iatrogenic spondylolisthesis, the combined results are sufficient evidence to suggest surgeons should be particularly cautious when PI resection exceeds 50% bone resection for all laminectomies included in this study. Lastly, the effects seen in FJF and IVD stresses indicate the degree to which the remainder of the spine must experience compensatory biomechanical changes as a result of the surgical intervention., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Study Design: Analysis of National Inpatient Sample (NIS), 2004 to 2015., Objective: Describe recent trends in US rates of lumbar fusion procedures and associated costs, by surgical indication., Summary of Background Data: Spinal fusion is appropriate for spinal deformity and instability, but evidence of effectiveness is limited for primary disc herniation and spinal stenosis without instability. It remains controversial for treatment of axial pain secondary to degenerative disc disease. There are potential non-instability, non-deformity indications for fusion surgery, including but not limited to severe foraminal stenosis and third-time disc herniation., Methods: Elective lumber fusion trends were reported using Poisson regression, grouped by indication as degenerative scoliosis, degenerative spondylolisthesis, spinal stenosis, disc herniation, and disc degeneration. Generalize linear regression was used to estimate trends in hospital costs, adjusted for age, sex, indication, comorbidity, and inflation., Results: Volume of elective lumbar fusion increased 62.3% (or 32.1% per 100,000 US adults), from 122,679 cases (60.4 per 100,000) in 2004 to 199,140 (79.8 per 100,000) in 2015. Increases were greatest among age 65 or older, increasing 138.7% by volume (73.2% by rate), from 98.3 per 100,000 (95% confidence interval [CI] 97.2, 99.3) in 2004 to 170.3 (95% CI 169.2, 171.5) in 2015. Although the largest increases were for spondylolisthesis (+47,390 operations, 111%) and scoliosis (+16,129 operations, 186.6%), disc degeneration, herniation, and stenosis combined to accounted for 42.3% of total elective lumbar fusions in 2015. Aggregate hospital costs increased 177% during these 12 years, exceeding $10 billion in 2015, and averaging more than $50,000 per admission., Conclusion: While the prevalence of spinal pathologies is not known, the rate of elective lumbar fusion surgery in the United States increased most for spondylolisthesis and scoliosis, indications with relatively good evidence of effectiveness. The proportion of fusions coded for indications with less evidence of effectiveness has slightly decreased in the most recent years., Level of Evidence: 3.

Background Context: Several studies have suggested that laboratory results have minimal impact on clinical decision making in surgery. Despite the widespread use of preoperative testing in spine surgery and the large volume of posterolateral lumbar fusions (PLFs) being performed each year, no study has assessed the ability of preoperative laboratories to predict adverse events following PLF., Purpose: The purpose of this study was to explore the relationship between commonly obtained preoperative laboratory results and postoperative complications following one- to two-level PLF., Study Design: This is a retrospective study of prospectively collected data., Patient Sample: The 2006-2013 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was employed to identify all patients who underwent one- to two-level PLF., Outcome Measures: The outcome variables of interest were 30-day postoperative complications, which were assessed as major complications, minor adverse events, and total complications., Materials and Methods: Demographics, comorbidities, and perioperative characteristics were collected for each patient. Preoperative laboratories included sodium, blood urea nitrogen, creatinine, albumin, bilirubin, serum glutamic oxaloacetic transaminase, alkaline phosphatase, white blood cell count, hematocrit, platelet count, prothrombin time, international normalized ratio, and partial thromboplastin time. Bivariate analysis and multivariate logistic regression modeling were used to explore the relationship between abnormal preoperative laboratories and the incidence of postoperative complications., Results: After controlling for age, ASA score, length of surgery, and all significant comorbidities, abnormal sodium (odds ratio [OR]=2.47, 95% confidence interval [CI]: 1.45-4.19, p=.001) and abnormal INR (OR=2.33, 95% CI: 1.09-4.98, p=.029) were significantly associated with the development of any complication. Sodium (OR=1.61, 95% CI: 1.01-2.54, p=.04) and platelets (OR=1.58, 95% CI: 1.02-2.44, p=.04) were associated with minor complications. Meanwhile, creatinine (OR=1.74, 95% CI: 1.02-2.99, p=.04) and platelets (OR=1.71, 95% CI: 1.02-2.89, p=.04) were significant predictors of major adverse events., Conclusions: This study represents the first attempt to assess the utility of preoperative laboratories in predicting postoperative complications in PLF. Although the majority of laboratories were not significantly associated with adverse events, abnormal sodium values, INR, creatinine, and platelets were shown to be predictive of various complications., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Finite element analysis has proven to be a viable method for assessing many structure-function relationships in the human lumbar spine. Several validated models of the spine have been published, but they typically rely on commercial packages and are difficult to share between labs. The goal of this study is to present the development of the first open-access models of the human lumbar spine in FEBio. This modeling framework currently targets three deficient areas in the field of lumbar spine modeling: 1) open-access models, 2) accessibility for multiple meshing schemes, and 3) options to include advanced hyperelastic and biphasic constitutive models.

Study Design: An idealized biomechanical model., Objective: The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness., Summary of Background Data: Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern., Methods: An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration., Results: The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001)., Conclusion: In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage., Level of Evidence: N/A.

Study Design: Retrospective review., Objective: To define the geographic variation in costs of anterior cervical discectomy and fusion (ACDF) and posterolateral fusion (PLF)., Summary of Background Data: ACDF and lumbar PLF are common procedures that are used in the treatment of spinal pathologies. To optimize value, both the benefits and costs of an intervention must be quantified. Data on costs are scarce in comparison with data on total charges. This study aims at defining the costs of ACDF and PLF and describing the geographic variation within the United States., Methods: Medicare Provider Utilization and Payment data were used to investigate the costs associated with ACDF, PLF, and total knee arthroplasty (TKA). Average total costs of the procedures were compared by state and geographic region., Results: Combined professional and facility costs for a single-level ACDF had a national mean of $13,899. Total costs for a single-level PLF had a mean of $25,858. Total costs for a primary TKA had a national mean of $13,039. The cost increased to an average of $22,138 for TKA with major comorbidities. Analysis of geographic trends showed statistically significant differences in total costs of PLF, TKA, and TKA, with major complications or comorbidities between geographic regions (P < 0.01 for all)., Conclusion: Three of the 4 procedures (PLF, TKA, and TKA with major complications or comorbidities) showed statistically significant variation in cost between geographic regions. The Midwest provided the lowest cost for all procedures. Similar geographic trends in the cost of spinal fusions and TKAs suggest that these trends may not be limited to spine-related procedures. Surgical costs were found to correlate with cost of living but were not associated with the population of the state. These data shed light on the actual cost of common surgical procedures throughout the United States and will allow further progress toward the development of cost-effective, value-driven care., Level of Evidence: 3.

Object: S-2 alar-iliac (S2AI) screws are an attractive alternative to conventional fixation with iliac bolts because they are lower profile, require less muscle dissection, and have greater pullout strength. Few studies, however, compare outcomes between these techniques., Methods: The authors conducted a retrospective cohort study of consecutive adult patients at a single institution from December 2009 to March 2012 who underwent lumbopelvic fixation using S2AI screws or iliac bolts. Medical records were reviewed for patients with clinical failure, defined as an unplanned reoperation because of instrumentation failure and/or wound-related complications. Univariate, multivariate, and survival analyses were used to compare patients who required reoperation with those who did not. Method of pelvic fixation was the main predictor variable of interest, and the authors adjusted for potential confounding risk factors., Results: Of the 60 patients included, 23 received S2AI screws. Seventeen patients (28%) underwent an osteotomy. The mean follow-up was 22 months. A Kaplan-Meier survival model was used to evaluate the time to reoperation from the initial placement of lumbopelvic instrumentation. The failure-free rate was 96.6% at 6 months, 87.0% at 1 year, and 73.5% at 2 years. Reoperation was more common in patients with iliac bolts than in those with S2AI screws (13 vs 2; p = 0.031). Univariate analysis identified potential risk factors for unplanned reoperation, including use of iliac bolts (p = 0.031), absence of L5-S1 interbody graft (p = 0.048), previous lumbar fusion (p = 0.034), and pathology other than degenerative disease or scoliosis (p = 0.034). After adjusting for other risk factors, multivariate analysis revealed that the use of S2AI screws (OR 8.1 [1.5-73.5]; p = 0.030) was the only independent predictor for preventing unplanned reoperation., Conclusions: Both S2AI screws and iliac bolts were effective at improving fusion rates at the lumbosacral junction. The use of S2AI screws, however, was independently associated with fewer unplanned reoperations for wound-related complications and instrumentation failures than the use of iliac bolts.

Study Design: Retrospective comparative case series., Objective: Evaluate L5-S1 fusion rates when lower dose of bone morphogenic protein-2 (BMP-2) (average 3.2 mg) and pelvic fixation were used, with or without interbody fusion., Summary of Background Data: Pseudarthrosis at L5-S1 is one of the most common complications of long fusions to the sacrum in adult deformity surgery. Strategies for decreasing pseudarthrosis include interbody fusion, use of BMP-2 at the lumbosacral junction, and the use of sacropelvic fixation, individually or in combination. High-dose BMP-2 (20-40 mg) placed posterolaterally has shown comparable fusion rates with interbody fusion., Methods: Retrospective review of 61 consecutive patients with minimum 2-year follow-up at a single institution. All patients had an isolated posterior approach, 5 or more levels fused including L5-S1, use of pelvic fixation, and no prior L5-S1 procedures. The patients were divided in 2 groups for comparison on the basis of the use of an interbody cage/fusion at the L5-S1 level. Revision rates and implant-related complications were also reported., Results: The fusion rate at L5-S1 was 97% (59/61), with no difference between the interbody and no interbody fusion groups (97% vs. 96%, P = 1.0). There were no significant differences in the radiographical parameters or deformity correction between the groups. The mean amount of BMP-2 used in the interbody group was 4.1 mg (2-10), 2.5 mg (0-8) in the disc space, and 1.6 mg (0-4) in the interbody cage, whereas there was no difference in the amount of recombinant human bone morphogenic protein-2 placed posterolaterally between the 2 groups (interbody fusion = 1.6 vs. non-interbody fusion = 2.0 mg, P = 0.08) along with autograft and allograft. The overall revision rate for L5-S1 nonunion was 1.6%., Conclusion: The use of low dose of BMP-2 at the L5-S1 level in combination with sacropelvic fixation achieved satisfactory fusion rates in adult deformity surgery. No additional benefit was encountered by adding an interbody cage., Level of Evidence: 4.

Study Design: In vivo assessment of lumbar spinal fusion between a younger and older cohort of New Zealand white rabbits., Objective: Directly compare fusion within young and aged New Zealand white rabbits to establish an aged spinal fusion model translational research., Summary of Background Data: Prior studies have utilized skeletally mature young rabbits (6-12 mo old) that may not be appropriate as an analog for studying the aging human spine., Methods: Ten aged (>36 mo old) and 10 young (12 mo old) New Zealand white rabbits underwent a single-level, bilateral, L5-6 posterolateral intertransverse fusion using autogenous iliac crest bone graft. The animals were killed at 6 weeks postoperatively, and the specimens were then evaluated with quantitative microcomputerized tomography and manual palpation by 6 orthopedic surgeons. The fusions were graded as either fused or not fused by each examiner. The spines were then embedded in poly(methyl methacrylate) and cut into 2-mm-thick sections for histologic analysis., Results: A higher percentage of young rabbits were determined to be successfully fused through manual palpation testing compared with the aged rabbits. Micro-computed tomography (CT) analysis revealed a significantly greater fusion mass volume in the younger rabbits than in the older cohort. In addition, the fusion density of the younger rabbits was found to be significantly lower than that of the older rabbits when normalized to the bone density in the nonfused portion of the spine. Histologic analysis showed that the quality of the bone within the fusion mass was consistent between the young and old rabbits. A greater number of young animals had bilateral continuous bone graft compared with the aged animals., Conclusions: The aged (>36 mo) New Zealand white rabbit model appears to be a valid model to evaluate the effect of aging on lumbar fusion and has the potential to more accurately model conditions that are present in the older human spine.

Object: Cortical trajectory screw constructs, developed as an alternative to pedicle screw fixation for the lumbar spine, have similar in vitro biomechanics. The possibility of one screw path having the ability to rescue the other in a revision scenario holds promise but has not been evaluated. The objective in this study was to investigate the biomechanical properties of traditional pedicle screws and cortical trajectory screws when each was used to rescue the other in the setting of revision., Methods: Ten fresh-frozen human lumbar spines were instrumented at L3-4, 5 with cortical trajectory screws and 5 with pedicle screws. Construct stiffness was recorded in flexion/extension, lateral bending, and axial rotation. The L-3 screw pullout strength was tested to failure for each specimen and salvaged with screws of the opposite trajectory. Mechanical stiffness was again recorded. The hybrid rescue trajectory screws at L-3 were then tested to failure., Results: Cortical screws, when used in a rescue construct, provided stiffness in flexion/extension and axial rotation similar to that provided by the initial pedicle screw construct prior to failure. The rescue pedicle screws provided stiffness similar to that provided by the primary cortical screw construct in flexion/extension, lateral bending, and axial rotation. In pullout testing, cortical rescue screws retained 60% of the original pedicle screw pullout strength, whereas pedicle rescue screws retained 65% of the original cortical screw pullout strength., Conclusions: Cortical trajectory screws, previously studied as a primary mode of fixation, may also be used as a rescue option in the setting of a failed or compromised pedicle screw construct in the lumbar spine. Likewise, a standard pedicle screw construct may rescue a compromised cortical screw track. Cortical and pedicle screws each retain adequate construct stiffness and pullout strength when used for revision at the same level.

Study Design: Retrospective cohort analysis., Objective: To compare early treatment failures, survivorship, and clinical outcomes of 3 procedures used to treat symptomatic lumbar spinal stenosis and degenerative deformity., Summary of Background Data: Symptomatic lumbar stenosis is commonly seen in association with degenerative deformity, often leading to more complex surgical treatment, with laminectomy and fusion, supplanting laminectomy alone. More recently, the interspinous process spacer (ISP), developed to treat straightforward spinal stenosis, has been used in patients with spinal deformity to limit morbidity, although no studies have compared outcomes in this patient population., Methods: A retrospective cohort analysis of 90 consecutive patients, mean age 70 years, with 5-year mean follow-up (minimum, 2 yr), treated for stenosis with associated deformity with ISP device placement, laminectomy alone, or laminectomy and short-segment fusion. Early failure was defined as return to the operating room for revision of the index level or adjacent segment within 2 years. A Kaplan-Meier survival analysis was performed, and clinical outcomes and patient satisfaction was assessed., Results: Reoperation within 2 years was noted in 16.7% of patients treated for spinal stenosis and mild deformity. There was a significantly higher rate of same-level recurrence in the ISP group (33.3%), than the laminectomy (8.3%) and lami/fusion groups (0%) (P< 0.0001). Early reoperation due to adjacent segment pathology (ASP) was most common in the lami/fusion group (13.3%). Kaplan-Meier analysis revealed lowest survival for the ISP group and highest survival in the laminectomy-alone group at 2 years (P= 0.043) and 5 years (P= 0.007)., Conclusion: Early failure was significantly more common in patients treated with an ISP device for spinal stenosis and lumbar deformity, whereas reoperation due to symptomatic adjacent segment pathology was most common in patients treated with laminectomy and fusion. Laminectomy alone had the highest rate of survival., Level of Evidence: 3.

Background Context: The Thoracolumbar Injury Classification System (TLICS) system has been developed to improve injury classification and guide surgical decision-making, yet validation of this new system remains sparse., Purpose: This study evaluates the use of the TLICS in a large, consecutive series of patients., Study Design/setting: This is a retrospective case series., Patient Sample: A total of 458 patients treated for thoracic or lumbar spine trauma between 2000 and 2010 at a single, tertiary medical center were included in this study., Outcome Measures: American Spinal Injury Association (ASIA) status and crossover from conservative to surgical treatment were measured., Methods: Clinical and radiological data were evaluated, classifying the injuries by ASIA status, the Magerl/AO classification, and the TLICS system., Results: A total of 310 patients (67.6%) was treated conservatively (group 1) and 148 patients (32.3%) were surgically (group 2) treated. All patients in group 1 were ASIA E, except one (ASIA C). In this group, 305 patients (98%) had an AO type A fracture. The TLICS score ranged from 1 to 7 (mean 1.53, median 1). A total of 307/310 (99%) patients matched TLICS treatment recommendation (TLICS≤4), except three with distractive injuries (TLICS 7) initially misdiagnosed. Nine patients (2.9%) were converted to surgical management. In group 2, 105 (70.9%) were ASIA E, whereas 43 (29%) had neurological deficits (ASIA A-D). One hundred and three patients (69.5%) were classified as AO type A, 36 (24.3%) as type B, and 9 (6%) as type C. The TLICS score ranged from 2 to 10 (mean 4.29, median of 2). Sixty-nine patients (46.6%) matched the TLICS recommendation; all discordant patients (53.4%) were treated for stable burst fractures (TLICS=2). No neurological complications occurred in either group., Conclusions: The TLICS recommendation matched treatment in 307/310 patients (99%) in the conservative group. However, in the surgical group, 53.4% of patients did not match TLICS recommendations, all were burst fractures without neurological injury (TLICS=2). The TLICS system can be used to effectively classify thoracolumbar injuries and guide conservative treatment. Inconsistencies, however, remain in the treatment thoracolumbar burst fractures., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Study Design: This is a survey study designed to evaluate agreement among spine surgeons regarding treatment options for six clinical scenarios involving degenerative conditions of the cervical and lumbar spine., Objectives: The purpose was to evaluate whether or not surgeons agree on which cases require operative intervention and what type of surgery should be performed., Summary of Background Data: Agreement between spine surgeons on when to operate and what procedure to perform is a subject that has received increasing attention. This is an important question in the field of spine surgery, where "gold standards" that are based on large clinical trials are relatively sparse., Methods: Six clinical vignettes were presented to 19 members of the Degenerative Spine Study Group. Each vignette was accompanied by a series of radiographs and/or magnetic resonance imagings, followed by treatment options in multiple-choice format. Two months later, the same vignettes were sent out with identical instructions except that they were now told they were treating a close family member., Results: More than 76% of surgeons agreed on whether or not to recommend surgical intervention for the following four cases: lumbar degenerative spondylolisthesis with stenosis, cervical herniated nucleus pulposus, lumbar spondylosis, and lumbar herniated nucleus pulposus. Two scenarios had approximately 50% surgeon agreement: cervical stenosis and lumbar spondylolysis. However, despite good inter-rater agreement about who needed surgery, there was poor agreement regarding what procedure to perform if surgery was recommended. When repeating the survey in the setting of operating on a family member, only 17 (17.7%) of 96 recommendations were changed., Conclusion: Spine surgeons in this survey generally agreed on when to operate but failed to agree on what type of procedures to perform.

Study Design: Biomechanical study and the review of literature on lumbar interbody fusion constructs., Objective: To demonstrate the comparative stabilizing effects of lateral interbody fusion with various supplemental internal fixation options., Summary of Background Data: Lumbar interbody fusion procedures are regularly performed using anterior, posterior, and more recently, lateral approaches. The biomechanical profile of each is determined by the extent of resection of local supportive structures, implant size and orientation, and the type of supplemental internal fixation used., Methods: Pure moment flexibility testing was performed using a custom-built 6 degree-of-freedom system to apply a moment of ±7.5 Nm in each motion plane, while motion segment kinematics were evaluated using an optoelectronic motion system. Constructs tested included the intact spine, stand-alone extreme lateral interbody implant, interbody implant with lateral plate, unilateral and bilateral pedicle screw fixation. These results were evaluated against those from literature-reported biomechanical studies of other lumbar interbody constructs., Results: All conditions demonstrated a statistically significant reduction in range of motion (ROM) as a percentage of intact. In flexion-extension, ROM was 31.6% stand-alone, 32.5% lateral fixation, and 20.4% and 13.0% unilateral and bilateral pedicle screw fixation, respectively. In lateral bending, the trend was similar with greater reduction with lateral fixation than in flexion-extension; ROM was 32.5% stand-alone, 15.9% lateral fixation, and 21.6% and 14.4% unilateral and bilateral pedicle screw fixation. ROM was greatest in axial rotation; 69.4% stand-alone, 53.4% lateral fixation, and 51.3% and 41.7% unilateral and bilateral pedicle screw fixation, respectively., Conclusion: The extreme lateral interbody construct provided the largest stand-alone reduction in ROM compared with literature-reported ALIF and TLIF constructs. Supplemental bilateral pedicle screw-based fixation provided the overall greatest reduction in ROM, similar among all interbody approach techniques. Lateral fixation and unilateral pedicle screw fixation provided intermediate reductions in ROM. Clinically, surgeons may evaluate these comparative results to choose fixation options commensurate with the stability requirements of individual patients.

Object: Thoracolumbar corpectomy is a procedure commonly required for the treatment of various pathologies involving the vertebral body. Although the biomechanical stability of anterior reconstruction with plating has been studied, the biomechanical contribution of posterior instrumentation to anterior constructs remains unknown. The purpose of this study was to evaluate biomechanical stability after anterior thoracolumbar corpectomy and reconstruction with varying posterior constructs by measuring bending stiffness for the axes of flexion/extension, lateral bending, and axial rotation., Methods: Seven fresh human cadaveric thoracolumbar spine specimens were tested intact and after L-1 corpectomy and strut grafting with 4 different fixation techniques: anterior plating with bilateral, ipsilateral, contralateral, or no posterior pedicle screw fixation. Bending stiffness was measured under pure moments of +/- 5 Nm in flexion/extension, lateral bending, and axial rotation, while maintaining an axial preload of 100 N with a follower load. Results for each configuration were normalized to the intact condition and were compared using ANOVA., Results: Spinal constructs with anterior-posterior spinal reconstruction and bilateral posterior pedicle screws were significantly stiffer in flexion/extension than intact spines or spines with anterior plating alone. Anterior plating without pedicle screw fixation was no different from the intact spine in flexion/extension and lateral bending. All constructs had reduced stiffness in axial rotation compared with intact spines., Conclusions: The addition of bilateral posterior instrumentation provided significantly greater stability at the thoracolumbar junction after total corpectomy than anterior plating and should be considered in cases in which anterior column reconstruction alone may be insufficient. In cases precluding bilateral posterior fixation, unilateral posterior instrumentation may provide some additional stability.

Lumbar disc arthroplasty is now a common treatment for lumbar degenerative disc disease. Whereas the immediate and delayed complications in patients with artificial lumbar discs are well reported, the durability of artificial disc hardware after severe spine trauma is unknown. The authors describe the management of a rare case of a traumatic lumbar burst fracture in a patient who had undergone disc arthroplasty. This 31-year-old male contractor had undergone placement of an L4-5 Charité artificial disc (DePuy Spine) and L5-S1 anterior lumbar fusion 10 months before he fell from a roof and sustained a traumatic L-3 burst fracture with significant canal compromise and cauda equina injury. Despite the considerable compressive load on his spine, the artificial disc (L4-5) remained intact without any radiological signs of hardware failure, and the vertebrae above (L-4) and below (L-5) the artificial disc had no signs of injury. For the L-3 burst fracture the patient underwent an open decompressive laminectomy at L2-3 and posterior fusion with instrumentation from L-2 to L-4. At 24 months postinjury, he had returned to full work activities as a contractor with minimal back pain and mild right lower-extremity sensory changes and weakness left over from the trauma. The total disc arthroplasty at L4-5 is functional and has preserved motion, and there is a solid fusion at L2-4 and L5-S1. This case demonstrates that a lumbar artificial disc can tolerate a significant load from trauma and remain functional without hardware failure even after a traumatic burst fracture at the adjacent lumbar vertebral body and shows the successful treatment of this fracture, with posterior fusion preserving the motion of an artificial disc.

Study Design: Case report; Review of Literature., Objective: To present an uncommon complication after anterior lumbar surgery as well as a treatment option and a review of the literature., Summary of Background Data: A number of complications have been reported after anterior lumbar surgery. Common complications include vascular, ureteral, and neurologic injuries. The development of a retroperitoneal lymphocele has been previously been described, but details regarding evaluation, diagnosis, and treatment options are lacking in the literature., Methods: The case of a single patient with a postoperative retroperitoneal lymphocele was identified and retrospectively reviewed. Permission was obtained from the patient to review and publish this information. A review of literature on lymphoceles and anterior lumbar complications was also performed using PubMed and Ovid databases., Results: A 76-year-old woman underwent anterior interbody fusion from L2-L3-L4-L5, followed by posterior T11-L5 fusion for degenerative scoliosis and spinal stenosis. Six weeks after surgery, she presented with severe abdominal pain, nausea, and emesis. Examination revealed a retroperitoneal lymphocele, which was confirmed after aspiration. The patient was treated with a laparoscopic marsupialization procedure without recurrence. At 12 months, the patient had no further abdominal symptoms, noted improvements in back and leg pain scores, and had stable radiographic findings., Conclusion: Retroperitoneal lymphocele is a rare complication after anterior lumbar interbody fusion. The different diagnosis should include infectious abscess, ureteral injury with urinoma, pancreatic injury with pseudocyst formation, and spinal fluid leak with pseudomeningocele. Diagnosis can be guided by serum and cyst fluid analysis. Although treatment options exist, surgical treatment may provide the most reliable results.

Study Design: Review of Literature., Objective: To review the published literature regarding revision lumbar total disc arthroplasty as well as potential options to avoid complications associated with the revision surgical approach., Summary of Background Data: The use of lumbar total disc arthroplasty in the United States has not achieved the same popularity as seen in Europe, where studies have reported favorable short- and intermediate-term results. In the United States, despite recognition that disc replacement may reduce the incidence of adjacent segment disease, the risk of potential complications associated with primary and revision total disc arthroplasty have diminished surgeon enthusiasm for the procedure. The use of adhesion barriers may address some of these concerns., Methods: A series of Ovid Medline and Pubmed-National Library of Medicine/National Institutes of Health (www.ncbi.nlm.nih.gov) searches were performed. Only articles written in English journals or published with English translations were included. Level of evidence of the selected articles was assessed., Results: The need for revision of lumbar total disc arthroplasty has been reported in a number of prospective, randomized trials (level I or II evidence). Suboptimal patient selection and/or surgical technique accounted for the majority of failed disc arthroplasties. Revision procedures have included posterior stabilization or anterior explantation with revision to arthroplasty or conversion to arthrodesis. The risk of injury to the great vessels and retroperitoneal structures is greater during revision than primary procedures. The use of a far lateral, or transpsoas approach to the anterior column may reduce these adverse events. The use of adhesion barriers has been shown to reduce adhesions in abdominal and pelvic surgery and may be of benefit in revision disc arthroplasty., Conclusion: Adherence to stringent indications and meticulous surgical technique may reduce the number ofrevision procedures. Further, the use of barriers to adhesion formation during the primary arthroplasty may also reduce risk to the retroperitoneal structures during revision approaches.

Background Context: Current surgical trends increasingly emphasize the minimization of surgical exposure and tissue morbidity. Previous research questioned the ability of unilateral pedicle screw instrumentation to adequately stabilize posterior fusion constructs. No study to date has addressed the effects of reduced posterior instrumentation mass on interbody construct techniques. Unilateral surgical exposure for transforaminal lumbar interbody fusion (TLIF) allows ipsilateral pedicle screw placement. Theoretically, percutanous contralateral facet screw placement could provide supplemental construct support without additional surgical exposure., Purpose: Identify the biomechanical effects of reduced spinal fusion instrumentation mass on interbody construct stability., Study Design: An in vitro biomechanical study using human lumbar spines comparing stability of TLIF constructs augmented by: (1) bilateral pedicle screw fixation, (2) unilateral pedicle screw fixation, or (3) a novel unilateral pedicle screw fixation supplemented with contralateral facet screw construct., Methods: Seven fresh frozen human cadaveric specimens were tested in random construct order in flexion/extension, lateral bending, and axial rotation using +/-5.0 Nm torques and 50 N axial compressive loads. Analysis of torque rotation curves determined construct stability. Using paired statistical methods, comparison of construct stiffness and total range of motion within each specimen were performed using the Wilcoxon signed ranks test with a Holm-Sidák multiple comparison procedure (alpha=0.05)., Results: In flexion/extension, lateral bending, and axial rotation, there were no measurable differences in either stiffness or range of motion between the standard bilateral pedicle screw and the novel construct after TLIF. After TLIF, the unilateral pedicle screw construct provided only half of the improvement in stiffness compared with bilateral or novel constructs and allows for significant off-axis rotational motions, which could be detrimental to stability and the promotion for fusion., Conclusions: All tested TLIF constructs with posterior instrumentation decreased segmental range of motion and increased segmental stiffness. While placing unilateral posterior instrumentation decreases overall implant bulk and dissection, it allows for significantly increased segmental range of motion, less stiffness, and produces off-axis movement. The technique of contralateral facet screw placement provides the surgical advantages of unilateral pedicle screw placement with stability comparable to TLIF with bilateral pedicle screws.

Study Design: Animal study., Objectives: To investigate the gross behavior and the histologic effect(s) of polymethylmethacrylate (PMMA) in primate vertebral bodies after percutaneous vertebroplasty and kyphoplasty., Summary of Background Data: PMMA is known to induce thermal osteonecrosis in exposed bone during tumor surgery and total joint arthroplasty, and barium sulfate as well as PMMA are known to induce a foreign body reaction, but the effects of PMMA on vertebral cancellous bone have not been well documented. Furthermore, little is known about the mechanisms of cement extravasation that occasionally occur during these procedures. Lastly, it is not known if differences exist between vertebroplasty and kyphoplasty with regards to the above occurrences., Methods: Six living, elderly, female baboons were used in this study. Seven vertebrae from T12 to L6 were investigated in each animal. Two levels underwent vertebroplasty, two underwent kyphoplasty, and one underwent cavity creation only without cement augmentation in each animal. Three animals were killed at 24 hours and three at 26 weeks after surgery. The specimens were examined macroscopically for cement migration, and histologically for evidence of thermal necrosis, foreign body reaction, cement migration, and intravascular extravasation., Results: Small zones of osteonecrosis were observed histologically at the bone-cement interface in only two kyphoplasty (2 of 6) and two vertebroplasty specimens (2 of 5) at 26 weeks after surgery. All of these necrotic segments of bone were associated with new bone formation. Foreign body reactions were observed in all specimens at 26 weeks after surgery, yet none of them was associated with bone resorption. The incidence of cement leak into the spinal canal and adjacent soft tissues was 6 of 11 and 4 of 11 in vertebroplasty specimens and 5 of 12 and 3 of 12 in kyphoplasty specimens, respectively. There was no statistical difference in the incidence of cement leakage into the spinal canal (P = 0.54) and adjacent soft tissues (P = 0.55) between vertebroplasty and kyphoplasty specimens. The incidence of intravascular cement was significantly greater in vertebroplasty (11 of 12, 91%) than in kyphoplasty (5 of 12, 42%) (P = 0.013)., Conclusions: PMMA caused relatively little necrotic exothermal effect. The presence of PMMA with barium sulfate induces a mild foreign body reaction. The use of a balloon tamp creates a void by displacing pieces of bone, which may result in a lower incidence of intravascular cement leak.

Lumbar disk degeneration is a ubiquitous and complex phenomenon. The etiology varies widely and may be dificult to identify. Many techniques have been proposed to manage the pain and disability resulting from disk degeneration. Medicines, bed rest, orthotics, physical therapy, chiropractics, selective injections, and intradiskal electrothermal therapy have been used. Some of these therapies have been more successful than others, but most have at least some role in the current techniques of helping patients deal with this syndrome. How best to use these tools in conjunction with patient education is critical to success.

Epidural steroid injections are widely used as part of the conservative care for symptomatic herniated lumbar discs. There are studies showing their effectiveness, and some studies demonstrating no clinical benefits. The purpose of this study was to evaluate the effectiveness of epidural steroid injections for patients with symptomatic lumbar disc herniations who were surgical candidates. Sixty-nine patients were diagnosed with a herniated disc in the lumbar spine and remained symptomatic despite conservative care, and were treated with an epidural injection in an attempt to avoid surgical discectomy. Of the total group of 69 patients (average age = 44.8 years, range 19-77 years, average follow-up = 1.5 years), 53 (77%) had successful resolution or significant decrease of their symptoms and were able to avoid surgery. Only 16 (23%) patients failed to have significant relief of their symptoms and required surgical treatment of their herniated disc. Epidural steroid injections have a reasonable success rate for the alleviation of radicular symptoms from lumbar herniated discs for up to twelve to twenty-seven months. Patients treated with injections may be able to avoid surgical treatment up to this period and perhaps even longer.

Implant retrieval programs have been effective in understanding implant failure and biomaterial compatibility in joint arthroplasty; however, its application has not been extended extensively to the assessment of spinal constructs and implants. The objective of this study is to determine the efficacy of implant retrieval analysis as a standard for the assessment of explanted spinal implants. The limitations of clinical radiographic assessment of fusion through metal interbody devices are also identified. The implant analysis protocol is shown through a case report of a titanium mesh spinal fusion cage retrieved from a 54-year-old woman who had a pseudoarthrosis at the T12 cage interface. The implant analysis techniques include backscattered electron imaging, high-resolution contact radiography, histology, and fluorochrome analysis. An implant retrieval analysis program similar to the one discussed in the presented case study will enable an accurate assessment of outcomes of these commonly used implants and will guide future development.

Study Design: Retrospective review. Objective: To determine the effectiveness of erector spinae plane (ESP) blocks at improving perioperative pain control and function following lumbar spine fusions. Methods: A retrospective analysis was performed on patients undergoing < 3 level posterolateral lumbar fusions. Data was stratified into a control group and a block group. We collected postop MED (morphine equivalent dosages), physical therapy ambulation, and length of stay. PROMIS pain interference (PI) and physical function (PF) scores, ODI, and VAS were collected preop and at the first postop visit. Chi-square and student's t-test (P =.05) were used for analysis. We also validated a novel fluoroscopic technique for ESP block delivery. Results: There were 37 in the block group and 39 in the control group. There was no difference in preoperative opioid use (P =.22). On postop day 1, MED was reduced in the block group (32 vs 51, P <.05), and more patients in the block group did not utilize any opioids (22% vs 5%, P <.05). The block group ambulated further on postop day 1 (312 ft vs 204 ft, P <.05), and had reduced length of stay (2.4 vs 3.2 days, P <.05). The block group showed better PROMIS PI scores postoperatively (58 vs 63, P <.05). The novel delivery technique was validated and successful in targeting the correct level and plane. Conclusions: ESP blocks significantly reduced postop opioid use following lumbar fusion. Block patients ambulated further with PT, had reduced length of stay, and had improved PROMIS PI postoperatively. Validation of the block demonstrated the effectiveness of a novel fluoroscopic delivery technique. ESP blocks represent an underutilized method of reducing opioid consumption, improving postoperative mobilization and reducing length of stay following lumbar spine fusion. [ABSTRACT FROM AUTHOR]

Background Context: Diabetes is a highly prevalent comorbid condition among patients undergoing spine surgery. Several studies have used legacy patient-reported outcome measures to implicate diabetes as a predictor of increased disability, pain, and decreased physical function and quality of life following spine surgery. The effect of diabetes on postoperative physical function has not yet been studied using the PROMIS Physical Function Computer Adaptive Test (PF CAT).Purpose: To understand the effect of diabetes on physical function outcomes among patients undergoing lumbar spine surgery, as reported by the PF CAT.Study Design/setting: A retrospective cohort study was performed at a single university-based spine clinic.Patient Sample: Patients who underwent lumbar spine surgery between October 1, 2013 and April 26, 2018 with both PF CAT and Oswestry Disability Index (ODI) scores available for review.Outcome Measures: PROMIS PF CAT. Secondary measures of disability included the ODI.Methods: PF CAT and ODI questionnaires were administered to patients via electronic tablets. Data from these questionnaires were collected prospectively, and retrieved from a university database. Wilcox tests, Exact Wilcox tests, linear regression models, and descriptive analytics were applied.Results: Patients meeting inclusion criteria included 233 nondiabetic patients and 65 diabetic patients. Mean PF CAT scores among diabetics were lower than those of nondiabetics at all time-points from preoperative through 12 months postoperative, with significance found at both 6 months (p=.035) and 12 months (p=.039) postoperative. Mean ODI scores among diabetics were significantly higher than those of nondiabetics at 3 months (p=.018) and 12 months (p=.027) postoperative. By 12 months postoperative, a smaller proportion of diabetics reached PF CAT and ODI minimum clinically important difference thresholds when compared to nondiabetics.Conclusions: Diabetes is associated with lower PF CAT scores up to one year following lumbar spine surgery. However, many of these patients achieve meaningful improvement in physical function during this time. The PF CAT is consistent with legacy outcome measures in assessing outcomes in diabetic patients undergoing lumbar spine surgery, with an added benefit of decreased patient burden. [ABSTRACT FROM AUTHOR]

Background: One-fourth of the adult US population has or will experience back pain and has undergone one of a myriad of treatments. Understanding the outcomes of these many treatments from pharmacologic to surgical, from manipulation to modality, allows for a better understanding and value-driven decision making. Patient-reported outcome measures are the current standard and include general and disease-specific measures. The Oswestry Disability Index (ODI) is the most commonly used disease-specific patient-reported outcome tool to measure functional disability related to back pain. Few studies have evaluated its psychometric properties in a large patient sample using a modern tool such as the Rasch analysis model. This study aims to identify the benefits and deficiencies of the ODI as an outcome tool for assessing patients with back pain.Purpose: This study aimed to investigate the psychometric properties, performance, and applicability of the ODI in patients with back pain who visited a university-based outpatient clinic.Study Design: This study used a secondary analysis-assessment of diagnostic tool on consecutive patients.Patient Sample: The sample comprised 1,610 patients visiting an academic spine center.Outcome Measures: The ODI was the outcome measure.Methods: Detailed Rasch analysis of the ODI was performed. Standard descriptive statistics were also assessed.Results: The ODI performed well overall. It demonstrated suboptimal unidimensionality (ie, unexplained variance after accounting for the first dimension) of 8.3%. Person reliability was good, at 0.85, and item reliability was excellent, at 1.00. The overall item fit for the ODI was good with an outfit mean square of 1.02. The ODI had a floor effect of 29.9% and ceiling effect of 3.9%. The raw score to measure correlation of the ODI was excellent, at 0.944.Conclusions: The ODI performed relatively well overall, with some problematic findings. It had good person and item reliability, although it did not demonstrate strong evidence of unidimensionality. The ODI has moderately poor coverage, with a very large floor effect and small ceiling effect, which could present a challenge in interpreting results of scores at the end of the spectrum. [ABSTRACT FROM AUTHOR]

The article offers information on the updates in spine surgery as of 2016. It includes total disc replacement and degenerative cervical myelopathy in cervical spine, biologics in spine surgery and epidural corticosteroid injection efficacy in lumbar spine surgery. The increase of thoracolumbar injuries from 1998 to 2011 is also mentioned.

We previously reported inpatient and 30-day postoperative patient-reported outcomes (PROs) of a controlled, noncrossover pilot study using preoperative mindfulness-based stress reduction (MBSR) training for lumbar spine surgery. Our goal here was to assess 3-month and 12-month postoperative PROs of preoperative MBSR in lumbar spine surgery for degenerative disease. Intervention group participants were prospectively enrolled in a preoperative online MBSR course. A comparison standard care only group was one-to-one matched retrospectively by age, sex, surgery type, and prescription opioid use. Three-month and 12-month postoperative PROs for pain, disability, quality of life, and opioid use were compared within and between groups. Regression models were used to assess whether MBSR use predicted outcomes. Twenty-four participants were included in each group. At 3 months, follow-up was 87.5% and 95.8% in the comparison and intervention groups, respectively. In the intervention group, mean Patient-Reported Outcomes Measurement Information System–Physical Function (PROMIS-PF) was significantly higher, whereas mean Patient-Reported Outcomes Measurement Information System–Pain Interference (PROMIS-PI) and Oswestry Disability Index were significantly lower. The change from baseline in mean PROMIS-PF and PROMIS-PI was significantly greater than in the comparison group. At 12 months, follow-up was 58.3% and 83.3% in the comparison and intervention groups, respectively. In the intervention group, mean PROMIS-PI was significantly lower and change in mean PROMIS-PI from baseline was significantly greater. MBSR use was a significant predictor of change in PROMIS-PF at 3 months and in PROMIS-PI at 12 months. No adverse events were reported. Three-month and 12-month results suggest that preoperative MBSR may have pain control benefits in lumbar spine surgery. [ABSTRACT FROM AUTHOR]

Background Prescription opioid medications negatively affect postoperative outcomes after lumbar spine surgery. Furthermore, opioid-related overdose death rates in the United States increased by 200% between 2000 and 2014. Thus, alternatives are imperative. Mindfulness-based stress reduction (MBSR), a mind-body therapy, has been associated with improved activity and mood in opioid-using patients with chronic pain. This study assessed whether preoperative MBSR is an effective adjunct to standard postoperative care in adult patients undergoing lumbar spine surgery for degenerative disease. Methods The intervention group underwent a preoperative online MBSR course. The comparison group was matched retrospectively in a 1:1 ratio by age, sex, type of surgery, and preoperative opioid use. Prescription opioid use during hospital admission and at 30 days postoperatively were compared with preoperative use. Thirty-day postoperative patient-reported outcomes for pain, disability, and quality of life were compared with preoperative patient-reported outcomes. Dose-response effect of mindfulness courses was assessed using Mindful Attention Awareness Scale scores. Results In this pilot study, 24 participants were included in each group. Most intervention patients (70.83%) completed 1 session, and the mean Mindful Attention Awareness Scale score was 4.28 ± 0.71 during hospital admission. At 30 days, mean visual analog scale back pain score was lower in the intervention group (P = 0.004) but other patient-reported outcomes did not differ. Conclusions During hospital admission, no significant dose-response effect of mindfulness techniques was found. At 30 days postoperatively, MBSR use was associated with less back pain. Further research is needed to assess the effectiveness of preoperative MBSR on postoperative outcomes in lumbar spine surgery for degenerative disease. Highlights • During admission, there was no dose-response effect of mindfulness on opioid intake. • At 30 days, MBSR participants had lower mean VAS-BP scores. • There was no difference in morphine-equivalent dosing at 30-day follow-up. [ABSTRACT FROM AUTHOR]