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OBJECTIVE The American Spine Registry (ASR) is a collaborative effort between the American Academy of Orthopaedic Surgeons and the American Association of Neurological Surgeons. The goal of this study was to evaluate how representative the ASR is of the national practice with spinal procedures, as recorded in the National Inpatient Sample (NIS). METHODS The authors queried the NIS and the ASR for cervical and lumbar arthrodesis cases performed during 2017–2019. International Classification of Diseases, 10th Revision and Current Procedural Terminology codes were used to identify patients undergoing cervical and lumbar procedures. The two groups were compared for the overall proportion of cervical and lumbar procedures, age distribution, sex, surgical approach features, race, and hospital volume. Outcomes available in the ASR, such as patient-reported outcomes and reoperations, were not analyzed due to nonavailability in the NIS. The representativeness of the ASR compared to the NIS was assessed via Cohen’s d effect sizes, and absolute standardized mean differences (SMDs) of < 0.2 were considered trivial, whereas > 0.5 were considered moderately large. RESULTS A total of 24,800 arthrodesis procedures were identified in the ASR for the period between January 1, 2017, and December 31, 2019. During the same time period, 1,305,360 cases were recorded in the NIS. Cervical fusions comprised 35.9% of the ASR cohort (8911 cases) and 36.0% of the NIS cohort (469,287 cases). The two databases presented trivial differences in terms of patient age and sex for all years of interest across both cervical and lumbar arthrodeses (SMD < 0.2). Trivial differences were also noted in the distribution of open versus percutaneous procedures of the cervical and lumbar spine (SMD < 0.2). Among lumbar cases, anterior approaches were more common in the ASR than in the NIS (32.1% vs 22.3%, SMD = 0.22), but the discrepancy among cervical cases in the two databases was trivial (SMD = 0.03). Small differences were illustrated in terms of race, with SMDs < 0.5, and a more significant discrepancy was identified in the geographic distribution of participating sites (SMDs of 0.7 and 0.74 for cervical and lumbar cases, respectively). For both of these measures, SMDs in 2019 were smaller than those in 2018 and 2017. CONCLUSIONS The ASR and NIS databases presented a very high similarity in proportions of cervical and lumbar spine surgeries, as well as similar distributions of age and sex, and distribution of open versus endoscopic approach. Slight discrepancies in anterior versus posterior approach among lumbar cases and patient race, and more significant discrepancies in geographic representation were also identified, yet decreasing trends in differences suggested the improving representativeness of the ASR over the course of time and its progressive growth. These conclusions are important to underline the external validity of quality investigations and research conclusions to be drawn from analyses in which the ASR is used.

OBJECTIVE Bertolotti syndrome is a clinical diagnosis given to patients with low-back pain arising from a lumbosacral transitional vertebra (LSTV). While biomechanical studies have demonstrated abnormal torques and range of motion occurring at and above this type of LSTV, the long-term effects of these biomechanical changes on the LSTV adjacent segments are not well understood. This study examined degenerative changes at segments superjacent to the LSTV in patients with Bertolotti syndrome. METHODS This study involved a retrospective comparison of patients between 2010 and 2020 with an LSTV and chronic back pain (Bertolotti syndrome) and control patients with chronic back pain with no LSTV. The presence of an LSTV was confirmed on imaging, and the caudal-most mobile segment above the LSTV was assessed for degenerative changes. Degenerative changes were assessed by grading the intervertebral disc, facets, degree of spinal stenosis, and spondylolisthesis using well documented grading systems. All computations were performed in R, version 4.1.0. All tests were two-sided, and p values < 0.05 was considered statistically significant. Separate logistic regression analyses were run with the associated dependent variables for each aim, with age at MRI and sex included as covariates. Odds ratios and 95% confidence intervals were computed. RESULTS A total of 172 patients were included, 101 with Bertolotti syndrome and 71 controls. Control patients consisted of patients with low-back pain but no diagnosis of Bertolotti syndrome or an LSTV. Fifty-six Bertolotti (55.4%) and 27 control (38.0%) patients were female, (p = 0.03). After adjusting for age at MRI and sex, Bertolotti patients had pelvic incidence (PI) that was 9.83° greater than control patients (95% CI 5.15°–14.50°, p < 0.001). Sacral slope was not significantly different between the Bertolotti and control groups (beta estimate 3.10°, 95% CI −1.07° to 7.27°; p = 0.14). Bertolotti patients had 2.69 times higher odds of having a high disc grade at L4–5 (3–4 vs 0–2), compared with control patients (OR 2.69, 95% CI 1.28–5.90; p = 0.01). There were no significant differences between Bertolotti patients and controls for spondylolisthesis, facet grade, or spinal stenosis grade. CONCLUSIONS Patients with Bertolotti syndrome had a significantly higher PI and were more likely to have adjacent-segment disease (ASD; L4–5) compared with control patients. However, after controlling for age and sex, PI and ASD did not appear to have a significant association within the cohort of Bertolotti patients. The altered biomechanics and kinematics in this condition may be a causative factor in this degeneration, although proof of causation is not possible in this study. This association may warrant closer follow-up protocols for patients being treated for Bertolotti syndrome, but further prospective studies are needed to establish if radiographic parameters can serve as an indicator for biomechanical alterations in vivo.

OBJECTIVE The US-based Spinal Laminectomy versus Instrumented Pedicle Screw (SLIP) trial reported improvement in disability following laminectomy with fusion versus laminectomy alone for patients with lumbar spondylolisthesis. Despite using similar methods, a concurrent Swedish trial investigating the same question did not reach the same conclusion. The authors performed a simulation-based analysis to elucidate potential causes of these divergent results. METHODS The mean and standard deviation of the preoperative and 2-year postoperative Oswestry Disability Index (ODI) scores for each study group (laminectomy with fusion and laminectomy alone) were collected from the spondylolisthesis stratum of the Swedish trial and used to create a MATLAB simulator using linear transformations to predict postoperative ODI distributions. Applying this simulator to both varied and published preoperative ODI distributions from the SLIP trial, the authors simulated the results of the US-based trial using treatment effects from the Swedish study and compared simulated US results to those published in the SLIP trial. RESULTS Simulated US results showed that as preoperative disability increased, the difference in postoperative ODI scores grew between treatment groups and increasingly favored laminectomy alone (p < 0.0001). In 100 simulations of a similarly sized US trial, the average mean change in ODI scores postoperatively was significantly higher than was published for laminectomy alone in the SLIP trial (−21.3 vs −17.9), whereas it was significantly lower than published for fusion (−16.9 vs −26.3). CONCLUSIONS The expected benefit of surgical treatments for spondylolisthesis varied according to preoperative disability. Adapting Swedish-estimated treatment effects to the US context mildly overapproximated the improvement in postoperative disability scores for laminectomy, but more severely underapproximated the improvement reported for laminectomy and fusion in the SLIP trial. The observed heterogeneity between these studies is influenced more by patient response to fusion than response to laminectomy. This analysis paves the way for future studies on the impact of preoperative treatment group heterogeneity, differences in surgical methods, and empirical design on reported clinical benefits. Although bayesian reanalysis of published randomized controlled trial data is susceptible to biases that typically limit post hoc analyses, the authors’ method offers a simple and cost-effective approach to improve the understanding of published clinical trial results and their implications for future studies.

OBJECTIVE The purpose of this study was to evaluate the safety and efficacy of a posterior facet replacement device, the Total Posterior Spine (TOPS) System, for the treatment of one-level symptomatic lumbar stenosis with grade I degenerative spondylolisthesis. Posterior lumbar arthroplasty with facet replacement is a motion-preserving alternative to lumbar decompression and fusion. The authors report the preliminary results from the TOPS FDA investigational device exemption (IDE) trial. METHODS The study was a prospective, randomized controlled FDA IDE trial comparing the investigational TOPS device with transforaminal lumbar interbody fusion (TLIF) and pedicle screw fixation. The minimum follow-up duration was 24 months. Validated patient-reported outcome measures included the Oswestry Disability Index (ODI) and visual analog scale (VAS) for back and leg pain. The primary outcome was a composite measure of clinical success: 1) no reoperations, 2) no device breakage, 3) ODI reduction of ≥ 15 points, and 4) no new or worsening neurological deficit. Patients were considered a clinical success only if they met all four measures. Radiographic assessments were made by an independent core laboratory. RESULTS A total of 249 patients were evaluated (n = 170 in the TOPS group and n = 79 in the TLIF group). There were no statistically significant differences between implanted levels (L4–5: TOPS, 95% and TLIF, 95%) or blood loss. The overall composite measure for clinical success was statistically significantly higher in the TOPS group (85%) compared with the TLIF group (64%) (p = 0.0138). The percentage of patients reporting a minimum 15-point improvement in ODI showed a statistically significant difference (p = 0.037) favoring TOPS (93%) over TLIF (81%). There was no statistically significant difference between groups in the percentage of patients reporting a minimum 20-point improvement on VAS back pain (TOPS, 87%; TLIF, 64%) and leg pain (TOPS, 90%; TLIF, 88%) scores. The rate of surgical reintervention for facet replacement in the TOPS group (5.9%) was lower than the TLIF group (8.8%). The TOPS cohort demonstrated maintenance of flexion/extension range of motion from preoperatively (3.85°) to 24 months (3.86°). CONCLUSIONS This study demonstrates that posterior lumbar decompression and dynamic stabilization with the TOPS device is safe and efficacious in the treatment of lumbar stenosis with degenerative spondylolisthesis. Additionally, decompression and dynamic stabilization with the TOPS device maintains segmental motion.

Interviews are critical to the neurosurgery resident application process. The COVID-19 pandemic forced residency interview activities are conducted virtually. To maintain a degree of control during a period of uncertainty, our department implemented a standardized survey for interviewers to evaluate the noncognitive attributes and program compatibility of applicants. Our objective was to assess the reliability and biases associated with our standardized interviewer survey implemented in neurosurgical residency interviews. A 5-question interviewer survey to assess applicant interview performance and program compatibility was implemented during the 2020 to 2021 interview season. After the application cycle, survey metrics were retrospectively reviewed. Multiple cohort analyses were performed by dividing interviewers into cohorts based on status (faculty or resident) and sex. Applicant scores were assessed within sex subgroups for each aforementioned interviewer cohort. Intraclass correlation coefficients (ICCs) were calculated to assess survey reliability. Fifteen interviewers (8 faculty and 7 residents) and 35 applicants were included. Female applicants (17%) and interviewers (20%) comprised the minority. There were no differences between resident and faculty reviewer scores; however, female reviewers gave higher overall scores than male reviewers ( P = .003). There was no difference in total scores between female and male applicants when evaluating all reviewers or subgroups of faculty, residents, females, or males. ICC analysis demonstrated good (ICC 0.75-0.90) or excellent (ICC0.90) reliability for all questions and overall score. The standardized interviewer survey was a feasible and reliable method for evaluating noncognitive attributes during neurosurgery residency interviews. There was no perceptible evidence of sex bias in our single-program experience.

Bertolotti syndrome is a clinical diagnosis given to patients with back pain arising from a lumbosacral transitional vertebra (LSTV). A particular class of LSTV involves a pseudoarticulation between the fifth lumbar transverse process and the sacral ala, and surgical resection of the pseudoarticulation may be offered to patients failing conservative management. Bertolotti syndrome is still not well understood, particularly regarding how patients respond to surgical resection of the LSTV pseudoarticulation.To examine change in quality-of-life (QOL) and patient satisfaction following surgical resection of the LSTV pseudoarticulation in patients with Bertolotti syndrome.Ambidirectional observational cohort study of patients seen at a single institution's tertiary spine center over a 10-year period.Cohort consisted of 31 patients with Bertolotti Syndrome who underwent surgical resection of the pseudoarticulation.Preoperative and postoperative Patient-Reported Outcomes Measurement Information System Global Health (PROMIS-GH) Mental and Physical Health T-scores, and a single-item postoperative satisfaction questionnaire.Patients were identified through diagnostic and procedural codes. Immediate preoperative PROMIS-GH scores available in the chart were gathered retrospectively, and postoperative PROMIS-GH and satisfaction scores were gathered prospectively through a mail-in survey.Mean (SD) improvement of PROMIS-GH Physical Health T-score was 8.7 (10.5) (p.001). Mean (SD) improvement of PROMIS-GH Mental Health T-scores was 5.9 (9.2) (p=.001). When stratifying PROMIS-GH T-scores by response to the patient satisfaction survey, there were significant group differences in mean change for Physical Health T-scores (p.001), and Mental Health T-score (p=.009). Patients who stated, "The treatment met my expectations" had much greater mean improvement in the PROMIS-GH T-scores.Patients undergoing a pseudoarticulation resection procedure may experience a significant improvement in quality-of-life as measured by PROMIS-GH Mental and Physical Health.

Primary malignant non-osseous spinal tumors are relatively rare and this has led to a paucity of studies specifically examining the epidemiology of malignant spinal tumors.To provide an updated and more comprehensive study examining the epidemiology and relative survival of these rare tumors.Data was retrospectively acquired from the Central Brain Tumor Registry of the United States (CBTRUS).Primary malignant non-osseous spinal tumor cases diagnosed between 2000 and 2017 in the United States.Incidence rates (IRs), relative survival rates, and hazard ratios (HR) were measured.IRs were calculated only for histologically-confirmed cases between 2000 and 2017. Relative survival estimates were calculated from survival information on malignant spinal tumors between 2001 and 2016 for death from any cause. Multivariable Cox proportional hazards regression models were constructed to control for age, sex, race, and ethnicity.From 2000 to 2017, approximately 587 new cases of malignant non-osseous spinal tumors were diagnosed every year in the United States. The overall IR was 0.178 per 100,000 persons. Ependymomas were the most commonly diagnosed tumor in all age groups. The 10-year relative survival rates were 94.1%, 62.1%, 62.0%, and 13.3% for ependymomas, lymphomas, diffuse astrocytomas, and high-grade astrocytomas, respectively. Females have a significantly lower risk of death as compared with males for ependymomas (HR: 0.74, p.001) and diffuse astrocytomas (HR: 0.70, p=.005). African-Americans have a significantly higher risk of death compared with Caucasians when diagnosed with ependymomas (HR: 1.52, p=.009) or lymphomas (HR: 1.55, p=.009).Primary malignant non-osseous spinal tumors are primarily diagnosed in adulthood or late adulthood. Ependymal tumors are the most commonly diagnosed primary malignant non-osseous spinal tumors and have the highest 10-year relative survival rates. High-grade astrocytomas are rare and portend the worst prognosis.

OBJECTIVE Excessive stress and motion at the L5–S1 level can lead to degenerative changes, especially in patients with posterior instrumentation suprajacent to L5. Attention has turned to utilization of L5–S1 anterior lumbar interbody fusion (ALIF) to stabilize the lumbosacral junction. However, questions remain regarding the effectiveness of stand-alone ALIF in the setting of prior posterior instrumented fusions terminating at L5. The purpose of this study was to assess the biomechanical stability of an L5–S1 ALIF with increasing lengths of posterior thoracolumbar constructs. METHODS Seven human cadaveric spines (T9–sacrum) were instrumented with pedicle screws from T10 to L5 and mounted to a 6 degrees-of-freedom robot. Posterior fusion construct lengths (T10–L5, T12–L5, L2–5, and L4–5) were instrumented to each specimen, and torque-fusion level relationships were determined for each construct in flexion-extension, axial rotation, and lateral bending. A stand-alone L5–S1 ALIF was then instrumented, and L5–S1 motion was measured as increasing pure moments (2 to 12 Nm) were applied. Motion reduction was calculated by comparing L5–S1 motion across the ALIF and non-ALIF states. RESULTS The average motion at L5–S1 in axial rotation, flexion-extension, and lateral bending was assessed for each fusion construct with and without ALIF. After adding ALIF to a posterior fusion, L5–S1 motion was significantly reduced relative to the non-ALIF state in all but one fused surgical condition (p < 0.05). Longer fusions with ALIF produced larger L5–S1 motions, and in some cases resulted in motions higher than native state motion. CONCLUSIONS Posterior fusion constructs up to L4–5 could be appropriately stabilized by a stand-alone L5–S1 ALIF when using a nominal threshold of 80% reduction in native motion as a potential positive indicator of fusion. The results of this study allow conclusions to be drawn from a biomechanical standpoint; however, the clinical implications of these data are not well defined. These findings, when taken in appropriate clinical context, can be used to better guide clinicians seeking to treat L5–S1 pathology in patients with prior posterior thoracolumbar constructs.

STUDY DESIGN Meta-analyses. OBJECTIVE This study aims to document the most common Patient-reported Outcome Measures (PROMs) used to assess lumbar fusion surgery outcomes and provide an estimate of the average improvement following surgical treatment. SUMMARY OF BACKGROUND DATA As health care institutions place more emphasis on quality of care, accurately quantifying patient perceptions has become a valued tool in measuring outcomes. To this end, greater importance has been placed on the use of PROMs. This is a systemic review and meta-analysis of randomly controlled trials published between 2014 and 2019 assessing surgical treatment of degenerative spondylolisthesis. METHODS A fixed effect size model was used to calculate mean difference and a 95% confidence interval (95% CI). Linear regression was used to calculate average expected improvement, adjusted for preoperative scores. RESULTS A total of 4 articles (7 study groups) were found for a total of 444 patients. The 3 most common PROMs were Oswestry Disability Index (ODI) (n=7, 100%), Short-Form-12 or Short-Form-36 (SF-12/36) (n=4, 57.1%), and visual analog scale-back pain (n=3, 42.8%). Pooled average improvement was 24.12 (95% CI: 22.49-25.76) for ODI, 21.90 (95% CI: 19.71-24.08) for SF-12/36 mental component score, 22.74 (95% CI: 20.77-24.71) for SF-12/36 physical component score, and 30.87 (95% CI: 43.79-47.97) for visual analog scale-back pain. After adjusting for preoperative scores, patients with the mean preoperative ODI (40.47) would be expected to improve by 22.83 points postoperatively. CONCLUSIONS This study provides a range of expected improvement for common PROMs used to evaluate degenerative spondylolisthesis with the goal of equipping clinicians with a benchmark value to use when counseling patients regarding surgery. In doing so, it hopes to provide a comparison point by which to judge individual patient improvement. LEVEL OF EVIDENCE Level II.

OBJECTIVE The direct lateral approach is an alternative to the transoral or endonasal approaches to ventral epidural lesions at the lower craniocervical junction. In this study, the authors performed, to their knowledge, the first in vitro biomechanical evaluation of the craniovertebral junction after sequential unilateral C1 lateral mass resection. The authors hypothesized that partial resection of the lateral mass would not result in a significant increase in range of motion (ROM) and may not require internal stabilization. METHODS The authors performed multidirectional in vitro ROM testing using a robotic spine testing system on 8 fresh cadaveric specimens. We evaluated ROM in 3 primary movements (axial rotation [AR], flexion/extension [FE], and lateral bending [LB]) and 4 coupled movements (AR+E, AR+F, LB + left AR, and LB + right AR). Testing was performed in the intact state, after C1 hemilaminectomy, and after sequential 25%, 50%, 75%, and 100% C1 lateral mass resection. RESULTS There were no significant increases in occipital bone (Oc)–C1, C1–2, or Oc–C2 ROM after C1 hemilaminectomy and 25% lateral mass resection. After 50% resection, Oc–C1 AR ROM increased by 54.4% (p = 0.002), Oc LB ROM increased by 47.8% (p = 0.010), and Oc–C1 AR+E ROM increased by 65.8% (p < 0.001). Oc–C2 FE ROM increased by 7.2% (p = 0.016) after 50% resection; 75% and 100% lateral mass resection resulted in further increases in ROM. CONCLUSIONS In this cadaveric biomechanical study, the authors found that unilateral C1 hemilaminectomy and 25% resection of the C1 lateral mass did not result in significant biomechanical instability at the occipitocervical junction, and 50% resection led to significant increases in Oc–C2 ROM. This is the first biomechanical study of lateral mass resection, and future studies can serve to validate these findings.

The coronavirus disease 2019 (COVID-19) pandemic has changed health care delivery across the United States. Few analyses have specifically looked at quantifying the financial impact of the pandemic on practicing neurosurgeons. A survey analysis was performed to address this need.A 19-question survey was distributed to practicing neurosurgeons in the United States and its territories. The questions evaluated respondents' assessments of changes in patient and procedural volume, salary and benefits, practice expenses, staffing, applications for government assistance, and stroke management. Responses were stratified by geographic region.The response rate was 5.1% (267/5224). Most respondents from each region noted a50% decrease in clinic volume. Respondents from the Northeast observed a 76% decrease in procedure volume, which was significantly greater than that of other regions (P = 0.003). Northeast respondents were also significantly more likely to have been reassigned to nonneurosurgical clinical duties during the pandemic (P0.001). Most respondents also noted decreased salary and benefits but experienced no changes in overall practice expenses. Most respondents did not experience significant reductions in nursing or midlevel staffing. These trends were not significantly different between regions.The COVID-19 pandemic has led to decreases in patient and procedural volume and physician compensation despite stable practice expenses. Significantly more respondents in the Northeast region noted decreases in procedural volume and reassignment to nonneurosurgical COVID-related medical duties. Future analysis is necessary as the pandemic evolves and the long-term clinical and economic implications become clear.

BACKGROUND CONTEXT Bertolotti Syndrome is a diagnosis given to patients with lower back pain arising from a lumbosacral transitional vertebra (LSTV). These patients can experience symptomatology similar to common degenerative diseases of the spine, making Bertolotti Syndrome difficult to diagnose with clinical presentation alone. Castellvi classified the LSTV seen in this condition and specifically in types IIa and IIb, a “pseudoarticulation” is present between the fifth lumbar transverse process and the sacral ala, resulting in a semi-mobile joint with cartilaginous surfaces.Treatment outcomes for Bertolotti Syndrome are poorly understood but can involve diagnostic and therapeutic injections and ultimately surgical resection of the pseudoarticulation (pseudoarthrectomy) or fusion of surrounding segments. PURPOSE To examine spine and regional injection patterns and clinical outcomes for patients with diagnosed and undiagnosed Bertolotti Syndrome. DESIGN Retrospective observational cohort study of patients seen at a single institution's tertiary spine center over a 10-year period. PATIENT SAMPLE Cohort consisted of 67 patients with an identified or unidentified LSTV who were provided injections or surgery for symptoms related to their chronic low back pain and radiculopathy. OUTCOME MEASURES Self-reported clinical improvement following injections and pseudoarthrectomy. METHODS Patient charts were reviewed. Identification of a type II LSTV was confirmed through provider notes and imaging. Variables collected included demographics, injection history and outcomes, and surgical history for those who underwent pseudoarthrectomy. RESULTS A total of 22 out of 67 patients (33%) had an LSTV that was not identified by their provider. Diagnosed patients underwent fewer injections for their symptoms than those whose LSTV was never previously identified (p = 0.031). Only those diagnosed received an injection at the LSTV pseudoarticulation, which demonstrated significant symptomatic improvement at immediate follow up compared to all other injection types (p = 0.002). Patients who responded well to pseudoarticulation injections were offered a pseudoarthrectomy, which was more likely to result in symptom relief at most recent follow up than patients who underwent further injections without surgery (p CONCLUSIONS Undiagnosed patients are subject to a higher quantity of injections at locations less likely to provide relief than pseudoarticulation injections. These patients in turn cannot be offered a pseudoarthrectomy which can result in significant relief compared to continued injections alone. Proper and timely identification of an LSTV dramatically alters the clinical course of these patients as they can only be offered treatment directed towards the LSTV once it is identified.

Bertolotti Syndrome is a diagnosis given to patients experiencing pain caused by the presence of a lumbosacral transitional vertebra (LSTV), which is characterized by enlargement of the L5 transverse process(es), with potential pseudoarticulation or fusion with the sacrum. The Castellvi classification system is commonly utilized to grade LSTVs based on the degree of contact between the L5 transverse process(es) and the sacrum. LSTVs present a diagnostic dilemma to the treating clinician, as they may remain unidentified on plain x-rays and even advanced imaging; additionally, even if the malformation is identified, patients with a LSTV may be asymptomatic or have nonspecific symptoms, such as low back pain with or without radicular symptoms. With low back pain being extremely prevalent in the general population; it can be difficult to implicate the LSTV as the source of this pain. Care should be taken however, to exclude Bertolotti Syndrome in patients under 30 years old presenting with persisting low back pain given its congenital origin. If a LSTV is identified, typically with acquisition of a MRI or CT scan of the lumbosacral spine, and there is an absence of a more compelling or obvious source for the patient's symptoms, a conservative, step-wise management plan is recommended. This may include assessing for improvement in symptoms with injections prior to proceeding with surgical intervention. Additional concerns arise from the biomechanical alterations that a LSTV induces in adjacent spinal levels, predisposing this patient population to a more rapid-onset of adjacent segment disease, raising the question as to the most appropriate surgery (resection of LSTV pseudoarticulation with or without fusion). Postoperative outcome data for patients undergoing surgical treatment is limited in the literature with promising, but variable, results. More large-scale, controlled studies must be performed to gain further insight into the ideal work-up and management of this pathology.

Background The goal of this study was to identify predictors of prolonged operative time (OT) in patients receiving posterior/transforaminal lumbar interbody fusion (P/TLIF) and examine the relationship between prolonged OT and perioperative outcomes in this population. Methods The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients undergoing single-level P/TLIF (Common Procedural Terminology code) between 2012 and 2018. Multivariable linear regression models were constructed to identify factors independently associated with changes in OT and examine the relationship between prolonged OT and perioperative outcomes (overall complications, surgical complications, medical complications, 30-day readmission, 30-day reoperation, and length of stay). All models were adjusted for sociodemographic variables, comorbidities, and procedure-specific variables. Results Our cohort included 6260 patients. After adjusting for baseline covariates, age between 19 and 39 years increased OT by 15.14 minutes, male sex increased OT by 12.91 minutes, African American race increased OT by 17.82 minutes, other race increased OT by 18.13 minutes, obesity class III increased OT by 27.80 minutes, and the use of navigation increased OT by 10.83 minutes. Our multivariate logistic regression also found that after 2 hours, each additional hour of OT was associated with an increased risk of any complication (3–3.99 hours, odds ratio [OR], 1.68; 4–4.99 hours, OR, 2.33; and >5 hours, OR, 4.65). Incremental increases in OT were also associated with an increased risk of extended length of stay, readmission, and return to the operating room. Conclusions The results of this study highlight several factors associated with prolonged OT and underscore its association with poorer perioperative outcomes. These data can be used to risk stratify patients before single-level P/TLIF.

Osteobiologics are engineered materials that facilitate bone healing and have been increasingly used in spine surgery. Autologous iliac crest bone grafts have been used historically, but morbidity associated with graft harvesting has led surgeons to seek alternative solutions. Allograft bone, biomaterial scaffolds, growth factors, and stem cells have been explored as bone graft substitutes and supplements.To review current and emerging osteobiologic technologies.A literature review of English-language studies was performed in PubMed. Search terms included combinations of "spine," "fusion," "osteobiologics," "autologous," "allogen(e)ic," "graft," "scaffold," "bone morphogenic protein," and "stem cells."Evidence supports allograft bone as an autologous bone supplement or replacement in scenarios where minimal autologous bone is available. There are promising data on ceramics and P-15; however, comparative human trials remain scarce. Growth factors, including recombinant human bone morphogenic proteins (rhBMPs) 2 and 7, have been explored in humans after successful animal trials. Evidence continues to support the use of rhBMP-2 in lumbar fusion in patient populations with poor bone quality or revision surgery, while there is limited evidence for rhBMP-7. Stem cells have been incredibly promising in promoting fusion in animal models, but human trials to this point have only involved products with questionable stem cell content, thereby limiting possible conclusions.Engineered stem cells that overexpress osteoinductive factors are likely the future of spine fusion, but issues with applying viral vector-transduced stem cells in humans have limited progress.

OBJECTIVE In a healthcare landscape in which costs increasingly matter, the authors sought to distinguish among the clinical and nonclinical drivers of patient length of stay (LOS) in the hospital following elective lumbar laminectomy—a common spinal surgery that may be reimbursed using bundled payments—and to understand their relationships with patient outcomes and costs. METHODS Patients ≥ 18 years of age undergoing laminectomy surgery for degenerative lumbar spinal stenosis within the Cleveland Clinic health system between March 1, 2016, and February 1, 2019, were included in this analysis. Generalized linear modeling was used to assess the relationships between the day of surgery, patient discharge disposition, and hospital LOS, while adjusting for underlying patient health risks and other nonclinical factors, including the hospital surgery site and health insurance. RESULTS A total of 1359 eligible patients were included in the authors’ analysis. The mean LOS ranged between 2.01 and 2.47 days for Monday and Friday cases, respectively. The LOS was also notably longer for patients who were ultimately discharged to a skilled nursing facility (SNF) or rehabilitation center. A prolonged LOS occurring later in the week was not associated with greater underlying health risks, yet it nevertheless resulted in greater costs of care: the average total surgical costs for lumbar laminectomy were 20% greater for Friday cases than for Monday cases, and 24% greater for late-week cases than for early-week cases ultimately transferred to SNFs or rehabilitation centers. A Poisson generalized linear model fit the data best and showed that the comorbidity burden, surgery at a tertiary care center versus a community hospital, and the incidence of any postoperative complication were associated with significantly longer hospital stays. Discharge to home healthcare, SNFs, or rehabilitation centers, and late-week surgery were significant nonclinical predictors of LOS prolongation, even after adjusting for underlying patient health risks and insurance, with LOSs that were, for instance, 1.55 and 1.61 times longer for patients undergoing their procedure on Thursday and Friday compared to Monday, respectively. CONCLUSIONS Late-week surgeries are associated with a prolonged LOS, particularly when discharge is to an SNF or rehabilitation center. These findings point to opportunities to lower costs and improve outcomes associated with elective surgical care. Interventions to optimize surgical scheduling and perioperative care coordination could help reduce prolonged LOSs, lower costs, and, ultimately, give service line management personnel greater flexibility over how to use existing resources as they remain ahead of healthcare reforms.

The spine is a frequent site of cancer metastasis leading to intractable pain, functional impairment, and poor quality of life. When analgesic regimens and nonpharmacological interventions fail, spine surgery may be indicated. For patients with advanced disease, the decision to operate can become a dilemma. A patient with colon cancer metastatic to his spine, who had undergone multiple procedures for back pain, was admitted to a palliative care unit, where pain persisted despite high-dose opioids and adjuvant analgesics. Owing to progressive disease, he was told of a prognosis of six months by his oncologist. He eventually underwent percutaneous pedicle screw fixation. Shortly after surgery, he settled on a regimen merely equivalent to 45 mg of morphine per day. The article explores the role of palliative spine surgery in managing intractable cancer-related back pain. The authors offer a guide when considering surgical procedures for patients with limited prognosis.

OBJECTIVE Patient demographics, comorbidities, and baseline quality of life (QOL) are major contributors to postoperative outcomes. The frequency and cost of lumbar spine surgery has been increasing, with controversy revolving around optimal management strategies and outcome predictors. The goal of this study was to generate predictive nomograms and a clinical calculator for postoperative clinical and QOL outcomes following lumbar spine surgery for degenerative disease. METHODS Patients undergoing lumbar spine surgery for degenerative disease at a single tertiary care institution between June 2009 and December 2012 were retrospectively reviewed. Nomograms and an online calculator were modeled based on patient demographics, comorbidities, presenting symptoms and duration of symptoms, indication for surgery, type and levels of surgery, and baseline preoperative QOL scores. Outcomes included postoperative emergency department (ED) visit or readmission within 30 days, reoperation within 90 days, and 1-year changes in the EuroQOL-5D (EQ-5D) score. Bootstrapping was used for internal validation. RESULTS A total of 2996 lumbar surgeries were identified. Thirty-day ED visits were seen in 7%, 30-day readmission in 12%, 90-day reoperation in 3%, and improvement in EQ-5D at 1 year that exceeded the minimum clinically important difference in 56%. Concordance indices for the models predicting ED visits, readmission, reoperation, and dichotomous 1-year improvement in EQ-5D were 0.63, 0.66, 0.73, and 0.84, respectively. Important predictors of clinical outcomes included age, body mass index, Charlson Comorbidity Index, indication for surgery, preoperative duration of symptoms, and the type (and number of levels) of surgery. A web-based calculator was created, which can be accessed here: https://riskcalc.org/PatientsEligibleForLumbarSpineSurgery/. CONCLUSIONS The prediction tools derived from this study constitute important adjuncts to clinical decision-making that can offer patients undergoing lumbar spine surgery realistic and personalized expectations of postoperative outcome. They may also aid physicians in surgical planning, referrals, and counseling to ultimately lead to improved patient experience and outcomes.

Objective: There is a paucity of evidence describing the price information that is publicly available to patients wishing to undergo neurosurgical procedures. We sought to investigate the public availability and usefulness of price estimates for non-emergent, elective neurosurgical interventions. Methods: Google was used to search for price information related to 15 procedures in 8 major U.S. health care markets. We recorded price information that was published for each procedure and took note of whether itemized prices, potential discounts, and cross-provider price comparisons were available. Results: Online searches yielded 2356 websites, of which 228 (9.7%) offered geographically relevant price information for neurosurgical procedures. Although accounting for only 16.4% of total search results, price transparency websites provided most treatment price estimates (74.1% of all estimates), followed by clinical sites (19.3%), and other related sites (5.3%). The number of websites providing price information varied significantly by city and procedure. websites rarely divulged data sources, specified how prices were estimated, indicated how frequently price estimates were updated, offered itemized breakdowns of prices, or indicated whether price estimates encompassed the full spectrum of possible health care charges. Conclusions: Under 10% of websites queried yield geographically relevant price information for non-emergent neurosurgical imaging and operative procedures. Even when this information is publicly available, its usefulness to patients may be limited by various factors, including obscure data sources and methods, as well as sparse information on discounts and bundled price estimates. Inconsistent availability and clarity of price information likely impede patients' ability to discern expected costs of treatment and engage in cost-conscious, value-based neurosurgical decision-making.

Study design This was a retrospective consecutive cohort analysis. Objective This study aimed to examine the association between commonly prescribed medications and outcomes following posterior lumbar spine surgery. Summary of background data Postoperative complications and prolonged length of stay significantly increase costs following posterior lumbar spine surgery and worsen patient outcomes. To control costs and complications, providers should focus on modifiable risk factors, such as preoperative medications. Antihypertensive and anticholinergic drugs are among the most commonly prescribed medications but can carry significant risks in the perioperative period. Materials and methods This study was a retrospective cohort analysis of patients undergoing posterior lumbar spine surgery from January 2014 through December 2015 at a large tertiary care center. The variable selection followed by multivariable logistic and negative binomial regressions were performed. An α threshold of 0.0056 was used for significance after correction for multiple comparisons. A secondary analysis was performed to evaluate confounding or effect modifying variables. Results This study included 1577 patients. Postoperative urinary retention risk was increased in patients taking loop diuretics. Acute kidney injury risk was increased for patients on nondihydropyridine calcium-channel blockers. Surgical site infection risk was increased for patients on aldosterone receptor blockers. Urinary tract infection risk was increased for patients on anticholinergics for urinary incontinence. Length of stay was decreased for patients on angiotensin II antagonists and angiotensin-converting enzyme inhibitors. Conclusion A care path should be established in the perioperative period for patients who are deemed to be at higher risk due to medication status to either modify medications or improve postoperative monitoring. Level of evidence Level III.

Study design Retrospective review. Objective The aim of this study was to examine the association between preoperative depression and patient satisfaction in the outpatient spine clinic after lumbar surgery. Summary of background data The Clinician and Group Assessment of Healthcare Providers and Systems (CG-CAHPS) survey is used to measure patient experience in the outpatient setting. CG-CAHPS scores may be used by health systems in physician incentive programs and quality improvement initiatives or by prospective patients when selecting spine surgeons. Although preoperative depression has been shown to predict poor patient-reported outcomes and less satisfaction with the inpatient experience following lumbar surgery, its impact on patient experience with spine surgeons in the outpatient setting remains unclear. Methods Patients who underwent lumbar surgery and completed the CG-CAHPS survey at postoperative follow-up with their spine surgeon between 2009 and 2017 were included. Data were collected on patient demographics, Patient Health Questionnaire 9 (PHQ-9) scores, and Patient-Reported Outcome Measurement Information System Global Health Physical Health (PROMIS-GPH) subscores. Patients with preoperative PHQ-9 scores ≥10 (moderate-to-severe depression) were included in the depressed cohort. The association between preoperative depression and top-box satisfaction ratings on several dimensions of the CG-CAHPS survey was examined. Results Of the 419 patients included in this study, 72 met criteria for preoperative depression. Depressed patients were less likely to provide top-box satisfaction ratings on CG-CAHPS metrics pertaining to physician communication and overall provider rating (OPR). Even after controlling for patient-level covariates, our multivariate analysis revealed that depressed patients had lower odds of reporting top-box OPR (odds ratio [OR]: 0.19, 95% confidence interval [CI]: 0.06-0.63, P = 0.007), feeling that their spine surgeon provided understandable explanations (OR: 0.32, 95% CI: 0.11-0.91, P = 0.032), and feeling that their spine surgeon provided understandable responses to their questions or concerns (OR: 0.19, 95% CI: 0.06-0.63, P = 0.007). Conclusion Preoperative depression is independently associated with lower OPR and satisfaction with spine surgeon communication in the outpatient setting after lumbar surgery.Level of Evidence: 3.

OBJECTIVEThe authors sought to describe the long-term recurrence patterns, prognostic factors, and effect of adjuvant or salvage radiotherapy (RT) on treatment outcomes for patients with spinal myxopapillary ependymoma (MPE).METHODSThe authors reviewed a tertiary institution IRB-approved database and collected data regarding patient, tumor, and treatment characteristics for all patients treated consecutively from 1974 to 2015 for histologically confirmed spinal MPE. Key outcomes included relapse-free survival (RFS), postrecurrence RFS, failure patterns, and influence of timing of RT on recurrence patterns. Cox proportional hazards regression and Kaplan-Meier analyses were utilized.RESULTSOf the 59 patients included in the study, the median age at initial surgery was 34 years (range 12–74 years), 30 patients (51%) were female, and the most common presenting symptom was pain (n = 52, 88%). Extent of resection at diagnosis was gross-total resection (GTR) in 39 patients (66%), subtotal resection (STR) in 15 (25%), and unknown in 5 patients (9%). After surgery, 10 patients (17%) underwent adjuvant RT (5/39 GTR [13%] and 5/15 STR [33%] patients). Median follow-up was 6.2 years (range 0.1–35.3 years). Overall, 20 patients (34%) experienced recurrence (local, n = 15; distant, n = 5). The median RFS was 11.2 years (95% CI 77 to not reached), and the 5- and 10-year RFS rates were 72.3% (95% CI 59.4–86.3) and 54.0% (95% CI, 36.4–71.6), respectively.STR was associated with a higher risk of recurrence (HR 6.45, 95% CI 2.15–19.23, p < 0.001) than GTR, and the median RFS after GTR was 17.2 years versus 5.5 years after STR. Adjuvant RT was not associated with improved RFS, regardless of whether it was delivered after GTR or STR. Of the 20 patients with recurrence, 12 (60%) underwent salvage treatment with surgery alone (GTR, n = 6), 4 (20%) with RT alone, and 4 (20%) with surgery and RT. Compared to salvage surgery alone, salvage RT, with or without surgery, was associated with a significantly longer postrecurrence RFS (median 9.5 years vs 1.6 years; log-rank, p = 0.006).CONCLUSIONSAt initial diagnosis of spinal MPE, GTR is key to long-term RFS, with no benefit to immediate adjuvant RT observed in this series. RT at the time of recurrence, however, is associated with a significantly longer time to second disease recurrence. Surveillance imaging of the entire neuraxis remains crucial, as distant failure is not uncommon in this patient population.

Spine surgery has evolved over centuries from first being practiced with Hippocratic boards and ladders to now being able to treat spinal pathologies with minimal tissue invasion. With the advent of new imaging and surgical technologies, spine surgeries can now be performed minimally invasively with smaller incisions, less blood loss, quicker return to daily activities, and increased visualization. Modern minimally invasive procedures include percutaneous pedicle screw fixation techniques and minimally invasive lateral approach for lumbar interbody fusion (i.e., minimally invasive transforaminal lumbar interbody fusion, extreme lateral interbody fusion, oblique lateral interbody fusion) and midline lumbar fusion with cortical bone trajectory screws. Just as evolutions in surgical techniques have helped revolutionize the field of spine surgery, imaging technologies have also contributed significantly. The advent of computer image guidance has allowed spine surgeons to advance their ability to refine surgical techniques, increase the accuracy of spinal hardware placement, and reduce radiation exposure to the operating room staff. As the field of spine surgery looks to the future, many novel technologies are on the horizon, including robotic spine surgery, artificial intelligence, and machine learning to help improve preoperative planning, improve surgical execution, and optimize patient selection to ensure improved postoperative outcomes and patient satisfaction. As more spine surgeons begin incorporating these novel minimally invasive techniques into practice, the field of minimally invasive spine surgery will continue to innovate and evolve over the coming years.

BACKGROUND CONTEXT Anterior lumbar interbody fusion (ALIF) exposes the anterior aspect of the spine through a retroperitoneal approach. Access to the anterior spine requires mobilization of intra-abdominal viscera/vasculature, which can become complicated as scarring and/or adhesions develop from prior abdominal surgical interventions, increasing risk of intraoperative complications. The literature suggests that “significant prior abdominal surgery” is a relative contraindication of ALIF surgery; however, there is no consensus within the literature as to what defines “major/significant” abdominal surgeries. Additionally, the association between the number of prior abdominal surgeries and perioperative complications in ALIF surgery has not been explored within the literature. PURPOSE This study seeks to explore the association between perioperative complications of ALIF surgery and the type (major and/or minor) and number of prior abdominal surgeries. DESIGN A retrospective cohort study was performed to examine perioperative complications in ALIF patients with or without prior history of abdominal surgery. PATIENT SAMPLE All consecutive patients undergoing ALIF with or without a history of prior abdominal surgery from 2008 to 2018 at a single tertiary center were evaluated. Patients under the age of 18, patients with spinal malignancy, or patients who had ALIF above L3 were excluded. OUTCOME MEASURES Perioperative complications included intraoperative complications during ALIF surgery and postoperative complications within 90 days of ALIF surgery. Intraoperative complications include vascular injury, ureter injury, retroperitoneal hematoma, etc. Postoperative complications include urinary tract infection, revision of abdominal scar, ileus, deep vein thrombosis, pulmonary embolism, etc. Other outcome measures include readmission within 90 days, length of ALIF surgery, and length of hospital stay. METHODS Electronic medical records of 660 patients who underwent ALIF between 2008 and 2018 were retrospectively reviewed. Patient demographics, Charleston Comorbidity Index (CCI), level of fusion, past abdominal surgical history, use of access surgeon during exposure, intraoperative, and postoperative complications were collected. Predictors of intraoperative and postoperative complications were analyzed using simple and multivariable logistic regression. Statistical analysis was performed using JMP 14.0 (SAS, Cary, NC, USA) software. RESULTS After controlling for age, length of ALIF, gender, multilevel ALIF, and the use of an access surgeon, there was no significant association between the type of prior abdominal surgery (major and/or minor) and intraoperative complications on multivariable logistic regression analysis (Minor: odds ratio [OR]=1.68; 95% confidence interval [CI]: 0.58–4.86 & Major: OR=1.99; 95% CI: 0.80–4.91). On multivariable logistic regression, the odds of developing an intraoperative complication increases by 52% for each additional prior abdominal surgery after adjusting for age, length of ALIF, gender, multilevel ALIF, and the use of an access surgeon (OR=1.52, 95% CI: 1.10–2.11). Iliac vein laceration was the most common intraoperative complication (n=27, 4%). Neither the type (major and/or minor) nor the number of prior abdominal surgeries were significant predictors of postoperative complications (Minor: OR=1.29; 95% CI: .72–2.31, Major: OR=1.24; 95% CI: 0.77–2.00, & Number: OR=1.03; 95% CI: .84–1.26). CONCLUSION With each additional prior abdominal surgery, accumulation of scarring and adhesions can likely obscure anatomical landmarks and increase the risk of developing an intraoperative complication. Therefore, the number of prior abdominal surgeries should be taken into consideration during planning and operative exposure of the anterior spine via a retroperitoneal approach.

STUDY DESIGN Retrospective population database study. OBJECTIVE To investigate the relationship of preoperative hyponatremia to postoperative morbidity and mortality in lumbar interbody fusion patients. SUMMARY OF BACKGROUND DATA Optimization of preoperative patient selection and perioperative management can improve patient outcomes in spinal surgery. Hyponatremia, incidentally identified in 1.7% of the US population, has previously been tied to poorer postoperative outcomes in both the general surgery and orthopedic surgery populations. MATERIALS AND METHODS Using the National Surgical Quality Improvement Program database, the authors identified all lumbar interbody fusion patients treated between 2012 and 2014. Patients were classified as hyponatremic (Na

Study Design: Narrative review. Objectives: Artificial intelligence (AI) and machine learning (ML) have emerged as disruptive technologies with the potential to drastically affect clinical decision making in spine surgery. AI can enhance the delivery of spine care in several arenas: (1) preoperative patient workup, patient selection, and outcome prediction; (2) quality and reproducibility of spine research; (3) perioperative surgical assistance and data tracking optimization; and (4) intraoperative surgical performance. The purpose of this narrative review is to concisely assemble, analyze, and discuss current trends and applications of AI and ML in conventional and robotic-assisted spine surgery. Methods: We conducted a comprehensive PubMed search of peer-reviewed articles that were published between 2006 and 2019 examining AI, ML, and robotics in spine surgery. Key findings were then compiled and summarized in this review. Results: The majority of the published AI literature in spine surgery has focused on predictive analytics and supervised image recognition for radiographic diagnosis. Several investigators have studied the use of AI/ML in the perioperative setting in small patient cohorts; pivotal trials are still pending. Conclusions: Artificial intelligence has tremendous potential in revolutionizing comprehensive spine care. Evidence-based, predictive analytics can help surgeons improve preoperative patient selection, surgical indications, and individualized postoperative care. Robotic-assisted surgery, while still in early stages of development, has the potential to reduce surgeon fatigue and improve technical precision.

BACKGROUND CONTEXT Bertolotti syndrome (BS) is caused by pseudoarticulation between an aberrant L5 transverse process and the sacral ala, termed a lumbosacral transitional vertebra (LSTV). BS is thought to cause low back pain and is treated with resection or fusion, both of which have shown success. Acquiring cadavers with BS is challenging. Thus, we combined 3D printing, based on BS patient CT scans, with normal cadaveric spines to create a BS model. We then performed biomechanical testing to determine altered kinematics from LSTV with surgical interventions. Force sensing within the pseudojoint modeled nociception for different trajectories of motion and surgical conditions. PURPOSE This study examines alterations in spinal biomechanics with LSTVs and with various surgical treatments for BS in order to learn more about pain and degeneration in this condition, in order to help optimize surgical decision-making. In addition, this study evaluates BS histology in order to better understand the pathology and to help define pain generators—if, indeed, they actually exist. STUDY DESIGN/SETTING Model Development: A retrospective patient review of 25 patients was performed to determine the imaging criteria that defines the classical BS patient. Surgical tissue was extracted from four BS patients for 3D-printing material selection. Biomechanical Analysis. This was a prospective cadaveric biomechanical study of seven spines evaluating spinal motions, and loads, over various surgical conditions (intact, LSTV, and LSTV with various fusions). Additionally, forces at the LSTV joint were measured for the LSTV and LSTV with fusion condition. Histological Analysis: Histologic analysis was performed prospectively on the four surgical specimens from patients undergoing pseudoarthrectomy for BS at our institution to learn more about potential pain generators. PATIENT SAMPLE The cadaveric portion of the study involved seven cadaveric spines. Four patients were prospectively recruited to have their surgical specimens assessed histologically and biomechanically for this study. Patients under the age of 18 were excluded. OUTCOME MEASURES Physiological measures recorded in this study were broken down into histologic analysis, tissue biomechanical analysis, and joint biomechanical analysis. Histologic analysis included pathologist interpretation of Hematoxylin and Eosin staining, as well as S-100 staining. Tissue biomechanical analysis included stiffness measurements. Joint biomechanical analysis included range of motion, resultant torques, relative axis angles, and LSTV joint forces. METHODS This study received funding from the American Academy of Neurology Medical Student Research Scholarship. Three authors hold intellectual property rights in the simVITRO robotic testing system. No other authors had relevant conflicts of interest for this study. CT images were segmented for a representative BS patient and cadaver spines. Customized cutting and drilling guides for LSTV attachment were created for individual cadavers. 3D-printed bone and cartilage structural properties were based on surgical specimen stiffness, and specimens underwent histologic analysis via Hematoxylin and Eosin, as well as S-100 staining. Joint biomechanical testing was performed on the robotic testing system for seven specimens. Force sensors detected forces in the LSTV joint. Kruskal-Wallis tests and Dunnett's tests were used for statistical analysis with significance bounded to p RESULTS LSTV significantly reduces motion at the L5–S1 level, particularly in lateral bending and axial rotation. Meanwhile, the LSTV increases adjacent segment motion significantly at the L2–L3 level, whereas other levels have nonsignificant trends toward increased motion with LSTV alone. Fusion involving L4–S1 (L4–L5 and L5–S1) to treat adjacent level degeneration associated with an LSTV is associated with a significant increase in adjacent segment motion at all levels other than L5–S1 compared to LSTV alone. Fusion of L5–S1 alone with LSTV significantly increases L3–L4 adjacent segment motion compared to LSTV alone. Last, ipsilateral lateral bending with or without ipsilateral axial rotation produces the greatest force on the LSTV, and these forces are significantly reduced with L5–S1 fusion. CONCLUSIONS BS significantly decreases L5–S1 mobility, and increases some adjacent segment motion, potentially causing patient activity restriction and discomfort. Ipsilateral lateral bending with or without ipsilateral axial rotation may cause the greatest discomfort overall in these patients, and fusion of the L5–S1 or L4–S1 levels may reduce pain associated with these motions. However, due to increased adjacent segment motion with fusions compared to LSTV alone, resection of the joint may be the better treatment option if the superior levels are not unstable preoperatively. CLINICAL SIGNIFICANCE This study's results indicate that patients with BS have significantly altered spinal biomechanics and may develop pain due to increased loading forces at the LSTV joint with ipsilateral lateral bending and axial rotation. In addition, increased motion at superior levels when an LSTV is present may lead to degeneration over time. Based upon results of LSTV joint force testing, these patients’ pain may be effectively treated surgically with LSTV resection or fusion involving the LSTV level if conservative management fails. Further studies are being pursued to evaluate the relationship between in vivo motion of BS patients, spinal and LSTV positioning, and pain generation to gain a better understanding of the exact source of pain in these patients. The methodologies utilized in this study can be extrapolated to recreate other spinal conditions that are poorly understood, and for which few native cadaveric specimens exist.

Prospective randomized Food and Drug Administration investigational device exemption clinical trial.The purpose of the present study is to report the 1-year clinical and radiographic outcomes and safety profile of patients who underwent lumbar facet arthroplasty through implantation of the Total Posterior Spine System (TOPS) device.Lumbar facet arthroplasty is one proposed method of dynamic stabilization to treat grade-1 spondylolisthesis with stenosis; however, there are currently no Food and Drug Administration-approved devices for facet arthroplasty.Standard demographic information was collected for each patient. Radiographic parameters and patient-reported outcome measures were assessed preoperatively and at regular postoperative intervals. Complication and reoperation data were also collected for each patient.At the time of this study, 153 patients had undergone implantation of the TOPS device. The mean surgical time was 187.8 minutes and the mean estimated blood loss was 205.7cc. The mean length of hospital stay was 3.0 days. Mean Oswestry Disability Index, Visual Analog Score leg and back, and Zurich Claudication Questionnaire scores improved significantly at all postoperative time points (P0.001). There were no clinically significant changes in radiographic parameters, and all operative segments remained mobile at 1-year follow-up. Postoperative complications occurred in 11 patients out of the 153 patients (7.2%) who underwent implantation of the TOPS device. Nine patients (5.9%) underwent a total of 13 reoperations, 1 (0.6%) of which was for device-related failure owing to bilateral L5 pedicle screw loosening.Lumbar facet arthroplasty with the TOPS device demonstrated a statistically significant improvement in all patient-reported outcome measures and the ability to maintain motion at the index level while limiting sagittal translation with a low complication rate.

Study Design Biomechanical cadaveric study. Objectives Multi-rod constructs maximize posterior fixation, but most use a single pedicle screw (PS) anchor point to support multiple rods. Robotic navigation allows for insertion of PS and cortical screw (CS) within the same pedicle, providing 4 points of bony fixation per vertebra. Recent studies demonstrated radiographic feasibility for dual-screw constructs for posterior lumbar spinal fixation; however, biomechanical characterization of this technique is lacking. Methods Fourteen cadaveric lumbar specimens (L1–L5) were divided into 2 groups (n = 7): PS, and PS + CS. VCF was simulated at L3. Bilateral posterior screws were placed from L2–L4. Load control (±7.5Nm) testing performed in flexion-extension (FE), lateral bending (LB), axial rotation (AR) to measure ROM of: (1) intact; (2) 2-rod construct; (3) 4-rod construct. Static compression testing of 4-rod construct performed at 5 mm/min to measure failure load, axial stiffness. Results Four-rod construct was more rigid than 2-rod in FE ( P < .001), LB ( P < .001), AR ( P < .001). Screw technique had no significant effect on FE ( P = .516), LB ( P = .477), or AR ( P = .452). PS + CS 4-rod construct was significantly more stable than PS group ( P = .032). Stiffness of PS + CS group (445.8 ± 79.3 N/mm) was significantly greater ( P = .019) than PS (317.8 ± 79.8 N/mm). Similarly, failure load of PS + CS group (1824.9 ± 352.2 N) was significantly greater ( P = .001) than PS (913.4 ± 309.8 N). Conclusions Dual-screw, 4-rod construct may be more stable than traditional rod-to-rod connectors, especially in axial rotation. Axial stiffness and ultimate strength of 4-rod, dual-screw construct were significantly greater than rod-to-rod. In this study, 4-rod construct was found to have potential biomechanical benefits of increased strength, stiffness, stability.