Search

Cervical sagittal alignment is a critical component of successful surgical outcomes. Unrecognized differences in intervertebral alignment between supine and upright positions may affect clinical outcomes; however, these differences have not been quantified. Sixty-four patients scheduled to undergo one or two-level cervical arthrodesis for symptomatic pathology from C4-C5 to C6-C7, and forty-seven controls were recruited. Upright sagittal alignment was obtained through biplane radiographic imaging and measured using a validated process with accuracy better than 1° in rotation. Supine alignment was obtained from computed tomography scans. Coordinate systems used to measure supine and upright alignment were identical. Distances between adjacent bony endplates were measured to calculate disc height in each position. For both patients and controls, the C1-C2, C2-C3, and C3-C4 motion segments were in more lordosis when upright as compared with supine (all p 0.001). However, the C4-C5, C5-C6, and C6-C7 motion segments were in less lordosis when upright as compared with supine (all p ≤ 0.004). There was an interaction between group and position at the C1-C2 (p = 0.002) and C2-C3 (p = 0.001) motion segments, with the controls demonstrating a greater increase in lordosis at both motion segments when moving from supine to upright. The results indicate that cervical motion segment alignment changes between supine and upright positioning, those changes differ among motion segments, and cervical pathology affects the magnitude of these changes. Clinical Significance: Surgeons should be mindful of the differences in alignment between supine and upright imaging and the implications they may have on clinical outcomes.

BACKGROUND: The Patient-Report Outcomes Measurement Information System (PROMIS) is increasingly used as a general-purpose tool for measuring orthopaedic surgery outcomes. This set of questionnaires is efficient, precise, and correlates well with specialty-specific measures, but impactful implementation of patient-specific data, especially at the point of care, remains a challenge. Although clinicians may have substantial experience with established patient-reported outcome measures in their fields, PROMIS is relatively new, and the real-life meaning of PROMIS numerical summary scores may be unknown to many orthopaedic surgeons. QUESTIONS/PURPOSES: We aimed to (1) identify a small subset of important items in the PROMIS Physical Function (PF) item bank that are answered by many patients with orthopaedic conditions and (2) graphically display characteristic responses to these items across the physical function spectrum in order to translate PROMIS numerical scores into physical ability levels using clinically relevant, familiar terms. METHODS: In a cross-sectional study, 97,852 PROMIS PF assessments completed by 37,517 patients with orthopaedic conditions presenting to a tertiary-care academic institution were pooled and descriptively analyzed. Between 2017 and 2020, we evaluated 75,354 patients for outpatient orthopaedic care. Of these, 67% (50,578) were eligible for inclusion because they completed a PROMIS version 2.0 physical function assessment; 17% (12,720) were excluded because they lacked information in the database on individual item responses, and another < 1% (341) were excluded because the assessment standard error was greater than 0.32, leaving 50% of the patients (37,517) for analysis. The PROMIS PF is scored on a 0-point to 100-point scale, with a population mean of 50 and SD of 10. Anchor-based minimum clinically important differences have been found to be 8 to 10 points in a foot and ankle population, 7 to 8 points in a spine population, and approximately 4 points in a hand surgery population. The most efficient and precise means of administering the PROMIS PF is as a computerized adaptive test (CAT), whereby an algorithm intelligently tailors each follow-up question based on responses to previous questions, requiring only a few targeted questions to generate an accurate result. In this study, the mean PROMIS PF score was 41 ± 9. The questions most frequently used by the PROMIS CAT software were identified (defined in this study as any question administered to > 0.1% of the cohort). To understand the ability levels of patients based on their individual scores, patients were grouped into score categories: < 18, 20 ± 2, 25 ± 2, 30 ± 2, 35 ± 2, 40 ± 2, 45 ± 2, 50 ± 2, 55 ± 2, 60 ± 2, and > 62. For each score category, the relative frequency of each possible response (ranging from “cannot do” to “without any difficulty”) was determined for each question. The distribution of responses given by each score group for each question was graphically displayed to generate an intuitive map linking PROMIS scores to patient ability levels (with ability levels represented by how patients responded to the PROMIS items). RESULTS: Twenty-eight items from the 165-question item bank were used frequently (that is, administered to more than 0.1% of the cohort) by the PROMIS CAT software. The top four items constituted 63% of all items. These top four items asked about the patient’s ability to perform 2 hours of physical labor, yard work, household chores, and walking more than 1 mile. Graphical displays of responses to the top 28 and top four items revealed how PROMIS scores correspond to patient ability levels. Patients with a score of 40 most frequently responded that they experienced “some difficulty” with physical labor, yard work, household chores, and walking more than 1 mile, compared with “little” or “no” difficulty for patients with a score of 50 and “cannot do” for patients with a score of 30. CONCLUSION: We provided a visual key linking PROMIS numerical scores to physical ability levels using clinically relevant, familiar terms. Future studies might investigate whether using similar graphical displays as a patient education tool enhances patient-provider communication and improves the patient experience. CLINICAL RELEVANCE: The visual explanation of PROMIS scores provided by this study may help new users of the PROMIS understand the instrument, feel empowered to incorporate it into their practices, and use it as a tool for counseling patients about their scores.

Study Design: Systematic review and meta-analysis. Objectives: Malposition of pedicle screws during instrumentation in the lumbar spine is associated with complications secondary to spinal cord or nerve root injury. Intraoperative triggered electromyographic monitoring (t-EMG) may be used during instrumentation for early detection of malposition. The association between lumbar pedicle screws stimulated at low EMG thresholds and postoperative neurological deficits, however, remains unknown. The purpose of this study is to assess whether a low threshold t-EMG response to lumbar pedicle screw stimulation can serve as a predictive tool for postoperative neurological deficit. Methods: The present study is a meta-analysis of the literature from PubMed, Web of Science, and Embase identifying prospective/retrospective studies with outcomes of patients who underwent lumbar spinal fusion with t-EMG testing. Results: The total study cohort consisted of 2,236 patients and the total postoperative neurological deficit rate was 3.04%. 10.78% of the patients incurred at least 1 pedicle screw that was stimulated below the respective EMG alarm threshold intraoperatively. The incidence of postoperative neurological deficits in patients with a lumbar pedicle screw stimulated below EMG alarm threshold during placement was 13.28%, while only 1.80% in the patients without. The pooled DOR was 10.14. Sensitivity was 49% while specificity was 88%. Conclusions: Electrically activated lumbar pedicle screws resulting in low t-EMG alarm thresholds are highly specific but weakly sensitive for new postoperative neurological deficits. Patients with new postoperative neurological deficits after lumbar spine surgery were 10 times more likely to have had a lumbar pedicle screw stimulated at a low EMG threshold.

STUDY DESIGN Prospective cohort study. OBJECTIVE The aim of this study was to identify surgical factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography. SUMMARY OF BACKGROUND DATA Previous studies investigated the effect of surgical factors on spine kinematics as a potential etiology for adjacent segment disease (ASD). Those studies used static flexion-extension radiographs to evaluate range of motion. However, measurements from static radiographs are known to be unreliable. Furthermore, those studies were unable to evaluate the effect of ACDF on adjacent segment axial rotation. METHODS Patients had continuous cervical spine flexion/exten- sion and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific CT scans were matched to biplane radiographs using a previously validated tracking process. Dynamic kinematics, postoperative segmental kyphosis, and disc distraction were calculated from this tracking process. Plate-to-disc distance was measured on postoperative radiographs. Graft type was collected from the medical record. Multivariate linear regression was performed to identify surgical factors associated with 1-year post-surgery changes in adjacent segment kinematics. A secondary analysis was also performed to compare adjacent segment kinematics between each of the surgical factors and previously defined thresholds believed to be associated with adjacent segment degeneration. RESULTS Fifty-nine patients completed preoperative and postoperative testing. No association was found between any of the surgical factors and change in adjacent segment flexion/exten- sion or axial rotation range of motion (all P > 0.09). The secondary analysis also did not identify differences between adjacent segment kinematics and surgical factors (all P > 0.07). CONCLUSION Following ACDF for cervical spondylosis, factors related to surgical technique were not associated with short-term changes in adjacent segment kinematics that reflect the hypermobility hypothesized to lead to the development of ASD.Level of Evidence: 2.

Purpose Inflammatory and oxidative stress upregulates matrix metalloproteinase (MMP) activity, leading to intervertebral disc degeneration (IDD). Gene therapy using human tissue inhibitor of metalloproteinase 1 (hTIMP1) has effectively treated IDD in animal models. However, persistent unregulated transgene expression may have negative side effects. We developed a recombinant adeno-associated viral (AAV) gene vector, AAV-NFκB-hTIMP1, that only expresses the hTIMP1 transgene under conditions of stress. Methods Rabbit disc cells were transfected or transduced with AAV-CMV-hTIMP1, which constitutively expresses hTIMP1, or AAV-NFκB-hTIMP1. Disc cells were selectively treated with IL-1β. NFκB activation was verified by nuclear translocation. hTIMP1 mRNA and protein expression were measured by RT-PCR and ELISA, respectively. MMP activity was measured by following cleavage of a fluorogenic substrate. Results IL-1β stimulation activated NFκB demonstrating that IL-1β was a surrogate for inflammatory stress. Stimulating AAV-NFκB-hTIMP1 cells with IL-1β increased hTIMP1 expression compared to unstimulated cells. AAV-CMV-hTIMP1 cells demonstrated high levels of hTIMP1 expression regardless of IL-1β stimulation. hTIMP1 expression was comparable between IL-1β stimulated AAV-NFκB-hTIMP1 cells and AAV-CMV-hTIMP1 cells. MMP activity was decreased in AAV-NFκB-hTIMP1 cells compared to baseline levels or cells exposed to IL-1β. Conclusion AAV-NFκB-hTIMP1 is a novel inducible transgene delivery system. NFκB regulatory elements ensure that hTIMP1 expression occurs only with inflammation, which is central to IDD development. Unlike previous inducible systems, the AAV-NFκB-hTIMP1 construct is dependent on endogenous factors, which minimizes potential side effects caused by constitutive transgene overexpression. It also prevents the unnecessary production of transgene products in cells that do not require therapy.

Study design Prospective cohort. Objective The aim of this study was to determine the effect of graft type on residual motion and the relationship among residual motion, smoking, and patient-reported outcome (PRO) scores following anterior cervical discectomy and fusion (ACDF). Summary of background data Although most patients develop solid fusion based on static imaging following ACDF, dynamic imaging has revealed that many patients continue to have residual motion at the arthrodesis. Methods Forty-eight participants performed dynamic neck flexion/extension and axial rotation within a biplane radiography system 1 year following ACDF (21 one-level, 27 two-level). PRO scores included the Short Form-36, Neck Disability Index, and Cervical Spine Outcomes Questionnaire. An automated model-based tracking process matched subject-specific bone models to the biplane radiographs with sub-millimeter accuracy. Residual motion was measured across the entire arthrodesis site for both one- and two-level fusions in patients who received either allograft or autograft. Patients were divided into "pseudarthrosis" (>3° of flexion/extension residual motion) and "solid fusion" groups. Residual motion and PROs were compared between groups using Student t tests. Results Patients who received allograft showed more total flexion/extension residual motion (4.1° vs. 2.8°, P = 0.12), although this failed to reach significance. No differences were noted in PROs based on graft type (all P > 0.08) or the presence of pseudarthrosis (all P > 0.13). No differences were noted in residual motion between smokers and nonsmokers (all P > 0.15); however, smokers who received allograft reported worse outcomes than nonsmokers who received allograft and smokers who received autograft. Conclusion Allograft may result in slightly more residual motion at the arthrodesis site 1 year after ACDF. However, there is minimal evidence that PROs are adversely affected by slightly increased residual motion, suggesting that the current definition of pseudarthrosis correlates poorly with clinically significant findings. Additionally, autograft appears to result in superior outcomes in patients who smoke.Level of Evidence: 2.

Study design Retrospective case-control study. Objective The aim of this study was to determine the influence of obesity on risk factors for adverse outcome after lumbar spine fusion (LSF). Summary of background data Obesity is risk factor for complications after LSF and poses unique challenges regarding optimization of care. Nonetheless, this patient population is not well-studied. Methods Adult patients undergoing LSF were identified the State Inpatient Database. Patients were identified as obese or nonobese using ICD-9 codes. Outcome variables were 90-day readmission, major medical complication, infection, and revision rates. Data were queried for demographics, comorbidities, surgery characteristics, and outcome variables. Logistic multivariate regression was utilized, serially testing interactions between obesity and other independent variables in separate models for each outcome. The Benjamini-Hochberg procedure was used to adjust statistical significance for multiple comparisons. Results A total of 262,153 patients were included: 31,062 obese and 231, 091 nonobese. For major complications, obese patients had lower odds ratios (ORs) versus nonobese patients for cerebrovascular accident, diabetes with chronic complications, age ≥65, congestive heart failure, history of myocardial infarction, renal disease, chronic pulmonary disease, Medicare/Medicaid payor, more than two levels fused, transforaminal/posterior lumbar interbody fusion, and female sex, and higher OR for non-White race. For readmission, obese patients had lower OR for age ≥65, history of MI, renal disease, and mental health disease, and higher OR for female sex. For revision, obese patients had higher OR for female sex and TLIF/PLIF. For infection, obese patients had lower OR for diabetes with and without chronic complications, and higher OR for female sex. Conclusion Many medical comorbidities have less impact in obese patients than nonobese patients in predicting adverse outcomes despite increased rates of adverse outcomes in obese patients. These findings reflect the impact of obesity as an independent risk factor and have important implications for preoperative optimization.Level of Evidence: 3.

Study Design: Prospective cohort. Objectives: Patient-Reported Outcome Measurement Information System (PROMIS) has been validated for lumbar spine. Use of patient-reported outcome (PRO) measures can improve clinical decision making and health literacy at the point of care. Use of PROMIS, however, has been limited in part because clinicians and patients lack plain language understanding of the meaning of scores and it remains unclear how best to use them at the point of care. The purpose was to develop plain language descriptions to apply to PROMIS Physical Function (PF) and Pain Interference (PI) scores and to assess patient understanding and preferences in presentation of their individualized PRO information. Methods: Retrospective analysis of prospectively collected PROMIS PF v1.2 and PI v1.1 for patients presenting to a tertiary spine center for back/lower extremity complaints was performed. Patients with missing scores, standard error >0.32, and assessments with 12 questions were excluded. Scores were categorized into score groups, specifically PROMIS PF groups were: 62; and PROMIS PI groups were: 82. Representative questions and answers from the PROMIS PI and PROMIS PF were selected for each score group, where questions with Results: In total, 12 712 assessments/5524 unique patients were included for PF and 14 823 assessments/6582 unique patients for PI. More than 90% of assessments were completed in 4 questions. The number of assessments and patients per scoring group were normally distributed. The mean PF score was 37.2 ± 8.2 and the mean PI was 63.3 ± 7.4. Plain language descriptions and compact clinical tool was were generated. Prospectively 100 consecutive patients were surveyed for their preference in receiving their T-score versus plain language description versus graphical presentation. A total of 78% of patients found receiving personalized PRO data helpful, while only 1% found this specifically not helpful. Overall, 80% of patients found either graphical or plain language more helpful than T-score alone, and half of these preferred plain language and graphical descriptions together. In total, 89% of patients found the plain language descriptions to be accurate. Conclusions: Patients at the point of care are interested in receiving the results of their PRO measures. Plain language descriptions of PROMIS scores enhance patient understanding of PROMIS numerical scores. Patients preferred plain language and/or graphical representation rather than a numerical score alone. While PROs are commonly used for assessing outcomes in research, use at point of care is a growing interest and this study clarifies how they might be utilized in physician-patient communication.

Study design Cohort study. Objective The aim of this study was to determine the rate of accurate conflict of interest (COI) disclosure within three prominent subspecialty Spine journals during a 4-year period. Summary of background data Industry-physician relationships are crucial for technological advancement in spine surgery but serve as a source of bias in biomedical research. The Open Payments Database (OPD) was established after 2010 to increase financial transparency. Methods All research articles published from 2014 to 2017 in Spine, The Spine Journal (TSJ), and the Journal of Neurosurgery: Spine (JNS) were reviewed in this study. In these articles, all author's COI statements were recorded. The OPD was queried for all author entries within the disclose period of the journal. Discrepancies between the author's self-reported COIs and the documented COIs from OPD were recorded. Results A total of 6816 articles meeting inclusion criteria between 2014 and 2017 in Spine, TSJ, and JNS with 39,869 contributing authors. Overall, 15.8% of all authors were found to have an OPD financial relationship. Of 2633 authors in Spine with financial disclosures, 77.1% had accurate financial disclosures; 42.5% and 41.0% of authors with financial relationships in the OPD had accurate financial disclosures in TSJ and JNS, respectively. The total value of undisclosed conflicts of interest between 2014 and 2017 was $421 million with $1.48 billion in accurate disclosures. Of undisclosed payments, 68.7% were $10,000. Undisclosed payments included $180 million in research funding and $188 million in royalties. Conclusion This study demonstrates that undisclosed COI is highly prevalent for authors in major Spine journals. This study indicates that there remains a need to standardize definitions and financial thresholds for significant COI as well as to shift the reporting burden for COI to journals who actively review potential COIs instead of relying on self-reporting. Level of evidence 3.

Study Design Retrospective cohort study Objectives To evaluate the effect of caudal instrumentation level on revision rates following posterior cervical laminectomy and fusion. Methods A retrospective review of a prospectively collected database was performed. Minimum follow-up was one year. Patients were divided into two groups based on the caudal level of their index fusion construct (Group 1-cervical and Group 2- thoracic). Reoperation rates were compared between the two groups, and preoperative demographics and radiographic parameters were compared between patients who required revision and those who did not. Multivariate binomial regression analysis was performed to determine independent risk factors for revision surgery. Results One hundred thirty-seven (137/204) patients received fusion constructs that terminated at C7 (Group 1), while 67 (67/204) received fusion constructs that terminated at T1 or T2 (Group 2). The revision rate was 8.33% in the combined cohort, 7.3% in Group 1, and 10.4% in Group 2. There was no significant difference in revision rates between the 2 groups ( P = .43). Multivariate regression analysis did not identify any independent risk factors for revision surgery. Conclusion This study shows no evidence of increased risk of revision in patients with fusion constructs terminating in the cervical spine when compared to patients with constructs crossing the cervicothoracic junction. These findings support terminating the fusion construct proximal to the cervicothoracic junction when indicated. Level of Evidence III

Study Design Observational Database Study. Objectives Prospective clinical trials in spinal surgery are expensive to conduct, especially when randomized, appropriately powered, and/or multicentered. Industry collaborations generate symbiotic relationships promoting technological advancement; however, they also allow for bias. To the authors’ knowledge, there is no known analysis of correlations between industry sponsorship and publication rates of spine-related clinical trials. This observational work evaluates such potential associations. Methods The ClinicalTrials.gov database was queried with terms spine, spinal, spondylosis, spondylolysis, cervical, lumbar, and compression fracture over an 11-year period. Design characteristics and outcomes were recorded from 822 spine surgery-related trials. Trials were stratified based on funding source and intervention class. Groups were compared via two-tailed chi-square test of independence or Fisher’s exact test (α = .05), based on completion status and publication rates of positive vs negative results. Results Industry-sponsored spine-related clinical trials were more likely to be terminated than their non-industry-sponsored counterparts (P < .001). Of the trials achieving publication, industry-sponsored trials reported positive results at a higher rate than did trials without industry funding (P = .037). Clinical trials examining devices were more likely to be terminated than those studying other intervention classes (P = .001). Conclusions High termination rates and positive result publication rates among industry-sponsored clinical trials in spinal surgery likely reflect industry’s influence on the research community. Such partnership alleviates financial burden and provides accessibility to cutting-edge innovation. It is essential that all parties remain mindful of the significant bias that funding source may impart on study outcome.

Study Design Retrospective cohort study. Objective Determine impact of standard/novel spinopelvic parameters on global sagittal imbalance, health-related quality of life (HRQoL) scores, and clinical outcomes in patients with multi-level, tandem degenerative spondylolisthesis (TDS). Methods Single institution analysis; 49 patients with TDS. Demographics, PROMIS and ODI scores collected. Radiographic measurements—sagittal vertical axis (SVA), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, sagittal L3 flexion angle (L3FA) and L3 sagittal distance (L3SD). Stepwise linear multivariate regression performed using full length cassettes to identify demographic and radiographic factors predictive of aberrant SVA (≥5 cm). Receiver operative curve (ROC) analysis used to identify cutoffs for lumbar radiographic values independently predictive of SVA ≥5 cm. Univariate comparisons of patient demographics, (HRQoL) scores and surgical indication were performed around this cutoff using two-way Student’s t-tests and Fisher’s exact test for continuous and categorical variables, respectively. Results Patients with increased L3FA had worse ODI (P = .006) and increased rate of failing non-operative management (P = .02). L3FA (OR 1.4, 95% CI) independently predicted of SVA ≥5 cm (sensitivity and specifity of 93% and 92%). Patients with SVA ≥5 cm had lower LL (48.7 ± 19.5 vs 63.3 ± 6.9 mm, P < .021), higher L3SD (49.3 ± 12.9 vs 28.8 ± 9.2, P < .001) and L3FA (11.6 ± 7.9 vs −3.2 ± 6.1, P < .001) compared to patients with SVA ≤5 cm. Conclusions Increased flexion of L3, which is easily measured by the novel lumbar parameter L3FA, predicts global sagittal imbalance in TDS patients. Increased L3FA is associated with worse performance on ODI, and failure of non-operative management in patients with TDS.

Biomechanical cadaver testing indicates adjacent segment motion increases after one-level anterior cervical spine arthrodesis, and two-level arthrodesis exacerbates these effects. There is little in vivo evidence to support those biomechanical studies. The purpose of this study was to assess the effects of one- and two-level cervical arthrodesis on adjacent segment motion. Fifty patients received either one-level C56 arthrodesis or two-level C456 or C567 arthrodesis and were tested preoperatively (PRE) and 1 year postoperatively (1YR-POST) along with 23 asymptomatic controls. A validated CT model-based tracking technique was used to measure 3D vertebral motion from biplane radiographs collected during dynamic flexion-extension and axial rotation of the cervical spine. Head and adjacent segment intervertebral end-range range of motion (ROM) and mid-range ROM were compared between one-level and two-level arthrodesis patients and controls. Small (2.3° or less) but non-significant increases in adjacent segment end-range ROM were observed from PRE to 1YR-POST. Mid-range flexion-extension ROM in the C67 motion segment inferior to the arthrodesis and mid-range axial rotation ROM in the C45 motion segment superior to the arthrodesis increased from PRE to 1YR-POST (all p0.022). This study provides in vivo evidence that contradicts long-held beliefs that adjacent segment end-range ROM increases appreciably after anterior cervical arthrodesis and that two-level arthrodesis exacerbates these effects. Mid-range ROM appears to be more useful than end-range ROM for detecting early changes in adjacent segment motion after cervical spine arthrodesis.

OBJECTIVE The aim of this study was to investigate the effect of degenerative spondylolisthesis (DS) on psoas anatomy and the L4–5 safe zone during lateral lumbar interbody fusion (LLIF). METHODS In this retrospective, single-institution analysis, patients managed for low-back pain between 2016 and 2021 were identified. Inclusion criteria were adequate lumbar MR images and radiographs. Exclusion criteria were spine trauma, infection, metastases, transitional anatomy, or prior surgery. There were three age and sex propensity-matched cohorts: 1) controls without DS; 2) patients with single-level DS (SLDS); and 3) patients with multilevel, tandem DS (TDS). Axial T2-weighted MRI was used to measure the apical (ventral) and central positions of the psoas relative to the posterior tangent line at the L4–5 disc. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch were measured on lumbar radiographs. The primary outcomes were apical and central psoas positions at L4–5, which were calculated using stepwise multivariate linear regression including demographics, spinopelvic parameters, and degree of DS. Secondary outcomes were associations between single- and multilevel DS and spinopelvic parameters, which were calculated using one-way ANOVA with Bonferroni correction for between-group comparisons. RESULTS A total of 230 patients (92 without DS, 92 with SLDS, and 46 with TDS) were included. The mean age was 68.0 ± 8.9 years, and 185 patients (80.4%) were female. The mean BMI was 31.0 ± 7.1, and the mean age-adjusted Charlson Comorbidity Index (aCCI) was 4.2 ± 1.8. Age, BMI, sex, and aCCI were similar between the groups. Each increased grade of DS (no DS to SLDS to TDS) was associated with significantly increased PI (p < 0.05 for all relationships). PT, PI-LL mismatch, center psoas, and apical position were all significantly greater in the TDS group than in the no-DS and SLDS groups (p < 0.05). DS severity was independently associated with 2.4-mm (95% CI 1.1–3.8 mm) center and 2.6-mm (95% CI 1.2–3.9 mm) apical psoas anterior displacement per increased grade (increasing from no DS to SLDS to TDS). CONCLUSIONS TDS represents more severe sagittal malalignment (PI-LL mismatch), pelvic compensation (PT), and changes in the psoas major muscle compared with no DS, and SLDS and is a risk factor for lumbar plexus injury during L4–5 LLIF due to a smaller safe zone.

Prospective cohort study.The aim was to identify patient factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography.The etiology of adjacent segment disease (ASD) may be multifactorial. Previous studies have investigated associations between patient factors and ASD, although few attempted to link patient factors with mechanical changes in the spine that may explain ASD development. Previous studies manually measured intervertebral motion from static flexion/extension radiographs, however, manual measurements are unreliable, and those studies failed to measure intervertebral motion during rotation.Patients had continuous cervical spine flexion/extension and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific computed tomography scans were matched to the biplane radiographs using a validated tracking process. Dynamic kinematics and preoperative disc height were calculated from this tracking process. Preoperative magnetic resonance imagings were evaluated for disc bulge. Patient age, sex, body mass index, smoking status, diabetes, psychiatric history, presence of an inciting event, and length of symptoms were collected. Multivariate linear regression was performed to identify patient factors associated with 1-year postoperative changes in adjacent segment kinematics.Sixty-three patients completed preoperative and postoperative testing. Superior adjacent segment disc height and disc bulge predicted the change in superior adjacent segment range of motion after surgery. Inferior adjacent segment disc bulge, smoking history, and the use of psychiatric medications predicted the change in inferior adjacent segment flexion/extension range of motion after surgery.Preexisting adjacent segment disc degeneration, as indicated by disc height and disc bulge, was associated with reduced adjacent segment motion after ACDF, while lack of preexisting adjacent disc degeneration was associated with increased adjacent segment motion after ACDF. These findings provide in vivo evidence supporting early instability and late stabilization in the pathophysiology of disc degeneration.

Study Design: Retrospective cohort study. Objective: To assess the impact of fondaparinux on venous thromboembolism (VTE) following elective lumbar spine surgery in high-risk patients. Methods: Matched patient cohorts who did or did not receive inpatient fondaparinux starting postoperative day 2 following elective lumbar spine surgery were compared. All patients received 1 month of acetyl salicylic acid 325 mg following discharge. The primary outcome was a symptomatic DVT (deep vein thrombosis) or PE (pulmonary embolus) within 30 days of surgery. Secondary outcomes included prolonged wound drainage, epidural hematoma, and transfusion. Results: A significantly higher number of DVTs were diagnosed in the group that did not receive inpatient VTE prophylaxis (3/102, 2.9%) compared with the fondaparinux group (0/275, 0%, P = .02). Increased wound drainage was seen in 18.5% of patients administered fondaparinux, compared with 25.5% of untreated patients ( P = .15). Deep infections were equivalent (2.2% with fondaparinux vs 4.9% control, P = .18). No epidural hematomas were noted, and the number of transfusions after postoperative day 2 and 90-day return to operating room rates were equivalent. Conclusions: Patients receiving fondaparinux had lower rates of symptomatic DVT and PE and a favorable complication profile when compared with matched controls. The retrospective nature of this work limits the safety and efficacy claims that can be made about the use of fondaparinux to prevent VTE in elective lumbar spine surgery patients. Importantly, this work highlights the potential safety of this regimen, permitting future high-quality trials.

Study Design: Retrospective cohort study. Objectives: To evaluate the impact of bariatric surgery on patient outcomes following elective instrumented lumbar fusion. Methods: A retrospective review of a prospectively collected database was performed. Patients who underwent a bariatric procedure prior to an elective instrumented lumbar fusion were evaluated. Lumbar procedures were performed at a large academic medical center from 1/1/2012 to 1/1/2018. The primary outcome was surgical site infection (SSI) requiring surgical debridement. Secondary outcomes were prolonged wound drainage requiring treatment, implant failure requiring revision, revision secondary to adjacent segment disease (ASD), and chronic pain states. A randomly selected, surgeon and comorbidity-matched group of 59 patients that underwent an elective lumbar fusion during that period was used as a control. Statistical analysis was performed using Student’s two-way t-tests for continuous data, with significance defined as P < .05. Results: Twenty-five patients were identified who underwent bariatric surgery prior to elective lumbar fusion. Mean follow-up was 2.4 ± 1.9 years in the bariatric group vs. 1.5 ± 1.3 years in the control group. Patients with a history of bariatric surgery had an increased incidence of SSI that required operative debridement, revision surgery due to ASD, and a higher incidence of chronic pain. Prolonged wound drainage and implant failure were equivalent between groups. Conclusion: In the present study, bariatric surgery prior to elective instrumented lumbar fusion was associated increased risk of surgical site infection, adjacent segment disease and chronic pain when compared to non-bariatric patients.

BACKGROUND CONTEXT Cervical decompression and fusion surgery remains a mainstay of treatment for a variety of cervical pathologies. Potential intraoperative injury to the spinal cord and nerve roots poses nontrivial risk for consequent postoperative neurologic deficits. Although neuromonitoring with intraoperative somatosensory evoked potentials (SSEPs) is often used in cervical spine surgery, its therapeutic value remains controversial. PURPOSE The purpose of the present study was to evaluate whether significant SSEP changes can predict postoperative neurologic complications in cervical spine surgery. A subgroup analysis was performed to compare the predictive power of SSEP changes in both anterior and posterior approaches. STUDY DESIGN The present study was a meta-analysis of the literature from PubMed, Web of Science, and Embase to identify prospective/retrospective studies with outcomes of patients who underwent cervical spine surgeries with intraoperative SSEP monitoring. PATIENT SAMPLE The total cohort consisted of 7,747 patients who underwent cervical spine surgery with intraoperative SSEP monitoring. METHODS Inclusion criteria for study selection were as follows: (1) prospective or retrospective cohort studies, (2) studies conducted in patients undergoing elective cervical spine surgery not due to aneurysm, tumor, or trauma with intraoperative SSEP monitoring, (3) studies that reported postoperative neurologic outcomes, (4) studies conducted with a sample size ≥20 patients, (5) studies with only adult patients ≥18 years of age, (6) studies published in English, (7) studies inclusive of an abstract. OUTCOME MEASURES The sensitivity, specificity, diagnostic odds ratio (DOR), and likelihood ratios of overall SSEP changes, reversible SSEP changes, irreversible SSEP changes, and SSEP loss for predicting postoperative neurological deficit were calculated. RESULTS The total rate of postoperative neurological deficits was 2.50% (194/7,747) and the total rate of SSEP changes was 7.36% (570/7,747). The incidence of postoperative neurological deficit in patients with intraoperative SSEP changes was 16.49% (94/570) while only 1.39% (100/7,177) in patients without. All significant intraoperative SSEP changes had a sensitivity of 46.0% and specificity of 96.7% with a DOR of 27.32. Reversible and irreversible SSEP changes had sensitivities of 17.7% and 37.1% and specificities of 97.5% and 99.5%, respectively. The DORs for reversible and irreversible SSEP changes were 9.01 and 167.90, respectively. SSEP loss had a DOR of 51.39, sensitivity of 17.3% and specificity 99.6%. In anterior procedures, SSEP changes had a DOR of 9.60, sensitivity of 34.2%, and specificity of 94.7%. In posterior procedures, SSEP changes had a DOR of 13.27, sensitivity of 42.6%, and specificity of 94.0%. CONCLUSIONS SSEP monitoring is highly specific but weakly sensitive for postoperative neurological deficit following cervical spine surgery. The analysis found that patients with new postoperative neurological deficits were nearly 27 times more likely to have had significant intraoperative SSEP change. Loss of SSEP signals and irreversible SSEP changes seem to indicate a much higher risk of injury than reversible SSEP changes.

In vitro biomechanical studies of the osteoligamentous spine are widely used to characterize normal biomechanics, identify injury mechanisms, and assess the effects of degeneration and surgical instrumentation on spine mechanics. The objective of this study was to determine how well four standards in vitro loading paradigms replicate in vivo kinematics with regards to the instantaneous center of rotation and arthrokinematics in relation to disc deformation. In vivo data were previously collected from 20 asymptomatic participants (45.5 ± 5.8 years) who performed full range of motion neck flexion-extension (FE) within a biplane x-ray system. Intervertebral kinematics were determined with sub-millimeter precision using a validated model-based tracking process. Ten cadaveric spines (51.8 ± 7.3 years) were tested in FE within a robotic testing system. Each specimen was tested under four loading conditions: pure moment, axial loading, follower loading, and combined loading. The in vivo and in vitro bone motion data were directly compared. The average in vitro instant center of rotation was significantly more anterior in all four loading paradigms for all levels. In general, the anterior and posterior disc heights were larger in the in vitro models than in vivo. However, after adjusting for gender, the observed differences in disc height were not statistically significant. This data suggests that in vitro biomechanical testing alone may fail to replicate in vivo conditions, with significant implications for novel motion preservation devices such as cervical disc arthroplasty implants.

Cervical radiculopathy is a relatively common neurological disorder, often resulting from mechanical compression of the nerve root within the neural foramen. Anterior cervical discectomy and fusion (ACDF) is a common treatment for radicular symptoms that do not resolve after conservative treatment. One mechanism by which ACDF is believed to resolve symptoms is by replacing degenerated disc tissue with bone graft to increase the neural foramen area, however in vivo evidence demonstrating this is lacking. The aim of this study was to evaluate the effects of age, pathology, and fusion on bony neural foramen area. Participants included 30 young adult controls (

The etiology of adjacent segment disease after anterior cervical discectomy and fusion (ACDF) remains controversial. Range of motion (ROM) is typically used to infer the effects of arthrodesis on adjacent segment motion following ACDF, however, ROM only measures the total amount of motion. In contrast, the helical axis of motion (HAM) quantifies how the motion occurs and may provide additional insight into the etiology of adjacent segment pathology. Synchronized biplane radiographs of the cervical spine were acquired at 30 images per second while 62 ACDF patients and 38 control participants performed dynamic neck flexion/extension. A validated tracking process matched digitally reconstructed radiographs created from subject-specific bone models to the radiographs with sub-millimeter accuracy. The intervertebral HAM was then calculated and compared between pre and 1 year post surgery in patients, and between patients and controls at corresponding motion segments using linear mixed-effects analysis. Small differences in the anterior/posterior location of the HAM were found between the symptomatic motion segments before surgery and corresponding motion segments in controls. No changes in the HAM of motion segments adjacent to the arthrodesis were observed from pre to 1-year post-surgery. No differences in adjacent segment HAM were found between patients with one- versus two-level arthrodesis. Neither symptomatic pathology nor arthrodesis appear to change the way motion occurs in the cervical spine during flexion/extension one year after one or two-level arthrodesis. These results suggest ACDF does not alter short-term adjacent segment kinematics in a way that would contribute to the development of adjacent segment disease.

Retrospective cohort study.Compare a novel two-step algorithm for indicating a computed tomography angiography (CTA) in the setting of a cervical spine fracture with established gold standard criteria.As CTA permits the rapid detection of blunt cerebrovascular injuries (BCVI), screening criteria for its use have broadened. However, more recent work warns of the potential for the overdiagnosis of BCVI, which must be considered with the adoption of broad criteria.A novel two-step metric for indicating CTA screening was compared with the American College of Surgeons guidelines and the expanded Denver Criteria using patients who presented with cervical spine fractures to a tertiary-level 1 trauma center from January 1, 2012 to January 1, 2016. The ability for each metric to identify BCVI and posterior circulation strokes that occurred during this period was assessed.A total of 721 patients with cervical fractures were included, of whom 417 underwent CTAs (57.8%). Sixty-eight BCVIs and seven strokes were diagnosed in this cohort. All algorithms detected an equivalent number of BCVIs (52 with the novel metric, 54 with the ACS and Denver Criteria, P = 0.84) and strokes (7/7, 100% with the novel metric, 6/7, 85.7% with the ACS and Denver Criteria, P = 1.0). However, 63% fewer scans would have been needed with the proposed screening algorithm compared with the ACS or Denver Criteria (261/721, 36.2% of all patients with our criteria vs. 413/721, 57.3% with the ACS standard and 417/721, 57.8%) with the Denver Criteria, P 0.0002 for each).A two-step criterion based on mechanism of injury and patient factors is a potentially useful guide for identifying patients at risk of BCVI and stroke after cervical spine fractures. Further prospective analyses are required prior to widespread clinical adoption.4.

The pathogenesis of lumbar adjacent segment disease is thought to be secondary to altered biomechanics resulting from fusion. Direct in vivo evidence for altered biomechanics following lumbar fusion is lacking. This study’s aim was to describe in vivo kinematics of the superior adjacent segment relative to the fused segment before and after lumbar fusion. This study analyzed seven patients with symptomatic lumbar degenerative spondylolisthesis (5 M, 2F; age 65 ± 5.1 years) using a biplane radiographic imaging system. Each subject performed two to three trials of continuous flexion of their torso according to established protocols. Synchronized biplane radiographs were acquired at 20 images per second one month before and six months after single-level fusion at L4-L5 or L5-S1, or two-level fusion at L3-L5 or L4-S1. A previously validated volumetric model-based tracking process was used to track the position and orientation of vertebrae in the radiographic images. Intervertebral flexion/extension and AP translation (slip) at the superior adjacent segment were calculated over the entire dynamic flexion activity. Skin-mounted surface markers were tracked using conventional motion analysis and used to determine torso flexion. Change in adjacent segment kinematics after fusion was determined at corresponding angles of dynamic torso flexion. Changes in adjacent segment motion varied across patients, however, all patients maintained or increased the amount of adjacent segment slip or intervertebral flexion/extension. No patients demonstrated both decreased adjacent segment slip and decreased rotation. This study suggests that short-term changes in kinematics at the superior adjacent segment after lumbar fusion appear to be patient-specific.

Inflammatory and oxidative stress upregulates matrix metalloproteinase (MMP) activity, leading to intervertebral disc degeneration (IDD). Gene therapy using human tissue inhibitor of metalloproteinase 1 (hTIMP1) has effectively treated IDD in animal models. However, persistent unregulated transgene expression may have negative side effects. We developed a recombinant adeno-associated viral (AAV) gene vector, AAV-NFκB-hTIMP1, that only expresses the hTIMP1 transgene under conditions of stress.Rabbit disc cells were transfected or transduced with AAV-CMV-hTIMP1, which constitutively expresses hTIMP1, or AAV-NFκB-hTIMP1. Disc cells were selectively treated with IL-1β. NFκB activation was verified by nuclear translocation. hTIMP1 mRNA and protein expression were measured by RT-PCR and ELISA, respectively. MMP activity was measured by following cleavage of a fluorogenic substrate.IL-1β stimulation activated NFκB demonstrating that IL-1β was a surrogate for inflammatory stress. Stimulating AAV-NFκB-hTIMP1 cells with IL-1β increased hTIMP1 expression compared to unstimulated cells. AAV-CMV-hTIMP1 cells demonstrated high levels of hTIMP1 expression regardless of IL-1β stimulation. hTIMP1 expression was comparable between IL-1β stimulated AAV-NFκB-hTIMP1 cells and AAV-CMV-hTIMP1 cells. MMP activity was decreased in AAV-NFκB-hTIMP1 cells compared to baseline levels or cells exposed to IL-1β.AAV-NFκB-hTIMP1 is a novel inducible transgene delivery system. NFκB regulatory elements ensure that hTIMP1 expression occurs only with inflammation, which is central to IDD development. Unlike previous inducible systems, the AAV-NFκB-hTIMP1 construct is dependent on endogenous factors, which minimizes potential side effects caused by constitutive transgene overexpression. It also prevents the unnecessary production of transgene products in cells that do not require therapy.

Sexual function (SF) is an important component of patient-focused health related quality of life (HRQoL), but it has not been well studied in spine surgery. This study aims to assess SF after cervical spine surgery and identify predictors of SF. This single-center retrospective study evaluates SF of adults who underwent cervical spine surgery 2007-2012. Predictor variables included demographics, medical/surgical history, operative information, HRQoL measures (Neck Disability Index, SF-12), validated SF surveys [Female Sexual Function Index (FSFI) and Brief Sexual Function Inventory (BSFI) for males], and a study-specific SF questionnaire. 59 patients (31M, 28F; mean age=56±8.4) had significantly lower SF scores compared to age-matched peers: average BSFI = 2.26±1.22 (vs. 06±0.74), average FSFI=13.05±11.42 (

Retrospective analysis of Nationwide Inpatient Sample (NIS) database.To analyze trends in utilization and hospital charges for multilevel spinal curvature surgery in patients over 60 from 2004 to 2011.Multilevel spinal curvature has been increasingly recognized as a major source of morbidity in patients over sixty years of age. The economic burden of non-operative management for spinal curvature is elusive and likely underestimated. Though patient reported outcomes suggest that surgical treatment of spinal curvature may be superior to non-operative treatment in selected patients, surgical utilization trends remain unclear.Data were obtained from the NIS between 2004 and 2011. The NIS is the largest all-payer inpatient care database with approximately eight million annual patient discharges throughout the United States. Analysis included patients over age 60 with a spinal curvature diagnosis treated with a multi-level spinal fusion (≥3 levels fused) determined by ICD-9-CM diagnosis and procedure codes. Population-based utilization rates were calculated from US census data.A total of 84,302 adult patients underwent multilevel spinal curvature surgery from 2004 to 2011. The annual number of ≥3 level spinal curvature fusions in patients over age 60 increased from 6,571 to 16,526, representing a 107.8% increase from 13.4 cases per 100,000 people in 2004 to 27.9 in 2011 (p.001). Utilization rates in patients 65-69 years old experienced the greatest growth, increasing by 122% from 15.8 cases per 100,000 people to 35.1. Average hospital charges increased 108% from $90,557 in 2007 to $188,727 in 2011 (p.001).Rates of surgical management of multilevel spinal curvature increased from 2004 to 2011, exceeding growth of the 60+ age demographic during the same period. Growth was observed in all age demographics, and hospital charges consistently increased from 2004 to 2011 reflecting a per-user increase in expenditure.III.

Postoperative spine infections are a devastating surgical complication. Historical literature reports postoperative infection rates as high as 20%. Improved surgical techniques and the use of intrawound vancomycin powder have dropped rates in recent years. Importantly, patients who experience a postoperative spine infection have a poorer perceived outcome of their surgery even if it is ultimately successful. In an era of patient-reported outcomes (PROs) driving practice patterns and an aging population undergoing increasing rates of high complexity spine surgery, infection, often complicated by biofilms, remains a key target for quality improvement. This article outlines contemporary standard of care practices for the diagnosis and treatment of postoperative spine infection with an emphasis on emerging concepts and broadly applicable surgical techniques including methylene blue staining as a disclosing agent to identify biofilm-burdened regions.

Background The most common reason for lower extremity amputation in developing countries is trauma, which is an increasingly recognised global epidemic. Despite the rising rates of traumatic injury and the level of disability experienced by amputees, there are few data focusing on this specific population in low-income and middle-income countries (LMICs). The purpose of this study is to investigate the causes and health-related outcomes of lower extremity amputations in Tanzania, and the socioeconomic barriers preventing access to prosthetics. Methods This was an observational pilot study conducted at the Muhimbili Orthopaedic Institute in Dar es Salaam, Tanzania, from 2015 to 2016. Adult patients who had undergone lower extremity amputation less than 1 year before enrolment were included. Baseline data on demographics, socioeconomic factors, and health-related information were collected at enrolment. Patients' health, health-related quality of life (using the EQ-5D questionnaire), and complication data were recorded 3 and 6 months later. Findings We enrolled 44 patients, 35 of whom were men, with a mean age of 39·5 years. 39 (89%) of the patients were employed (36 [82%] informally) and 36 (82%) had no health insurance. Below-knee amputations were the most common (23 [52%]) type of amputation. The most common cause of amputation was trauma (29 [66%]), followed by diabetes (7 [16%]), vascular pathology (3 [7%]), and tumours (2 [5%]). Complications including delayed healing, infection, and wound dehiscence were seen in 20 (51%) of the 39 patients who were followed up. Seven patients required reoperation. The average baseline EQ-5D index was 0·912. The population norm based on mean age is 0·889 for the USA and 0·793 for Zimbabwe (the only African country-specific norm available). The average EQ5D index at 3 months and 6 months decreased to 0·714 and 0·847, respectively. Only two amputees (5%) have received a prosthetic. Lack of materials, unsuitable wound, and cost were most commonly cited as barriers to prosthetics. Interpretation This study demonstrates that amputees in Tanzania experience a high rate of post-operative complications, poor quality of life, and extremely limited access to prosthetics. Educational initiatives to reduce wound-related complications and improved access to lower extremity prosthetics and rehabilitation are needed to address the dearth of knowledge and resources for amputees. Funding Global Research Initiative.

Background Hospital readmission after major surgery is a costly problem that has been associated with patient characteristics. Because hospitals are incentivized to join accountable care organizations, interventions on a hospital or health care system level may help reduce readmissions. Our objective was to identify hospital- and systems-level characteristics associated with readmissions after major operative procedures. Methods Retrospective analysis of California discharge abstracts with record linkage numbers for adult patients undergoing coronary artery bypass graft (CABG), colectomy or total hip/knee arthroplasty (TJA) in California acute, nonfederal hospitals in 2011. The record linkage number showed where patients were readmitted. Hierarchic logistic regression estimated the odds of readmission by hospital characteristics. Results There were 91,205 records analyzed: CABG (6.4%), colectomy (12.0%), and TJA (82.3%). There were 120 hospitals that performed CABG surgery; 296 performed colectomy; and 298 performed TJA. Readmission rates after CABG was 9.7%, colectomy 7.7%, and TJA 3.9%. After adjustment for patient factors, rural location was predictive of readmission after colectomy (odds ratio [OR] 2.08, 95% confidence interval [CI] 1.40–3.08). Low-volume (OR 1.54, 95% CI 1.13–2.10) and minority-serving hospitals (OR 1.18, 95% CI 1.05–1.33) were associated with greater odds of readmission after TJA. Conclusion Select hospital characteristics are associated with readmissions after major operative procedures. Because financial penalties may worsen performance in vulnerable or low-resource settings, policies aimed at reducing readmissions should be attentive to the potential unintended consequences.

Despite the interest in lumbar spinous process (SP)-based surgical innovation, there are no large published studies that have characterized the morphometry of lumbar SPs.To provide accurate level-specific morphometric data with respect to human lumbar SPs using a human cadaveric lumbar spine model and to describe the morphometric variation of lumbar SPs with respect to gender, race, and age.An anatomic observational study.This study used 2,955 cadaveric lumbar vertebrae from 591 adult spines at the Hamann-Todd Human Osteological Collection. Specimens were aged 20 to 79 years. Each vertebra was photographed in standardized positions and measured using ImageJ software. Direct measurements were made for the SP length, width, height, slope, and caudal morphology. Gender, race, and age were recorded and analyzed.Spinous process length was 24.8±4.6 mm (L5) to 33.9±3.9 mm (L3). Effective length varied from 19.5±2.6 mm (L1) to 24.6±3.3 mm (L4). Height was shortest at L5 (18.2±2.7 mm). Caudal width was greater than the cranial width. Slope, caudal morphology, and radius measures showed large interspecimen variation. Slope at L5 was steeper than other levels (23.7°±10.5°, p.0001). Most specimens demonstrated convex caudal morphology. L4 had the highest proportion of convexity (80.7%). L1 was the only level with predominantly concave morphology. Measurements for female SPs were smaller, but the slope was steeper. Anatomic and effective SP lengths were longer for specimens from white individuals. Specimens from black individuals had larger width and height, as well as steeper slope. Black specimens had more convex morphology at L4 and L5. With increasing age, the SP length, effective length, and width increased. Height increased with age only at L4 and L5. Slope and caudal radius of curvature decreased with age, and increasingly convex morphology was noted at most levels.This large cadaveric study provides level-specific morphometric data regarding the osseous dimensions of lumbar SPs relevant to techniques and devices targeting the lumbar SPs or the interspinous space. Of particular importance is the recognition that L5 has relatively different morphology when compared with more cranial levels. Potentially important differences were noted comparing women with men, black with white, and aging populations.

Objectives Risk factors portending poor outcome following elective spine deformity fusion remain in need of characterization and stratification in the elderly population. Methods Cases aged ≥60 years who underwent elective posterior or anterior-posterior ('combined') fusion were extracted from the American College of Surgeons National Surgical Quality Improvement Program years 2007-2013 and analyzed by surgical cohort (posterior vs. combined). The 30-day outcomes included operation time, hospital length of stay (HLOS), perioperative complications, and discharge destination. Multivariable regressions controlling for demographic/clinical variables were performed. Odds ratios (OR) and mean differences (B) were reported with 95% confidence intervals (CI). Results A total of 881 cases (18.2% combined; 81.8% posterior) aged 70 ± 6.2 years, 32.8% male, and 87.2% Caucasian were included. Posterior fusions associated with extreme body habitus (obese class II/III and underweight; P = 0.027), functional independence (97.5% vs. 91.8%; P = 0.010), and multi-level fusions (7-12 levels: 24.8% vs. 18.1%; ≥13 levels: 8.9% vs. 3.1%; P = 0.004). Overall operation time was 338.0 ± 150.2-min and HLOS 7.4 ± 6.6-days; 17.1% suffered early complications and 54.5% were discharged home. On multivariable analysis, combined (B = 63.8-min; P 0.001), and multi-level fusions (7-12: 61.0-min; P 0.001; ≥13: 133.8-min; p 0.001) associated with increased operation time. HLOS increased for multi-level fusions (7-12 levels: 1.3-days; P = 0.012; ≥13 levels: 2.2-days; P = 0.008). Overall complications did not differ by cohort or levels; on post hoc analysis combined fusions associated with pneumonia (OR = 3.05; P = 0.008). Multi-level fusions showed decreased odds of discharge home (7-12 levels: OR = 0.57; P = 0.003; ≥13-levels: OR = 0.41; P = 0.003). Conclusions The 30-day outcomes and early perioperative complications are comparable for posterior vs. combined approaches to correct deformity in the elderly. Multi-level fusions are associated with increased operation time, HLOS, and discharge to higher level of care.

Background Although asymptomatic mild limb length discrepancy (LLD) in children is generally treated non-operatively, there is limited high quality follow up data to support this recommendation. Hypothesis We hypothesized that there would be no association between LLD and arthritic changes with mild limb length discrepancy. Materials and methods We studied 576 well-preserved cadaveric skeletons ranging from 40 to 79 years of age. Limb length discrepancy was based on combined femoral and tibial lengths measured using digital calipers. Degenerative disease was hand graded in the spine, hips and knees using a previously described classification system. Power was set at 90%. Results Average age was 56 ± 10 years and average LLD was 4.8 ± 4.0 mm. Multiple regression analysis did not demonstrate any correlation between LLD and degenerative disease. After screening to find 26 additional specimens with LLD 10 mm or greater, and assessing a potentially quadratic relationship, we still did not find any detrimental effects of LLD. Discussion Our data support the general clinical recommendation of observation for mild asymptomatic LLD. These results do not apply to larger LLD nor LLD associated with other deformities or clinical symptoms. Level of evidence Not applicable, anatomic basic science study.

Background Current methods to identify infected tissue in periprosthetic joint infection (PJI) are inadequate. The purpose of this study was (1) to assess methylene blue–guided surgical debridement as a novel technique in PJI using quantitative microbiology and (2) to evaluate clinical success based on eradication of infection and infection-free survival. Methods Sixteen total knee arthroplasty patients meeting Musculoskeletal Infection Society criteria for PJI undergoing the first stage of 2-stage exchange arthroplasty were included in this prospective study. Dilute methylene blue (0.1%) was instilled in the knee before debridement, residual dye was removed, and stained tissue was debrided. Paired tissue samples, stained and unstained, were collected from the femur, tibia, and capsule during debridement. Samples were analyzed by neutrophil count, semiquantitative culture, and quantitative polymerase chain reaction (PCR). Clinical success was a secondary outcome. Results The mean age was 64.0 ± 6.0 years, and follow-up was 24.4 ± 3.5 months. More bacteria were found in methylene blue–stained vs unstained tissue-based on semiquantitative culture (P = .001). PCR for staphylococcal species showed 9-fold greater bioburden in methylene blue–stained vs unstained tissue (P = .02). Tissue pathology found 53 ± 46 polymorphonuclear leukocytes per high-power field in methylene blue–stained vs 4 ± 13 in unstained tissue (P = .0001). All subjects cleared their primary infection and underwent reimplantation. At mean 2-year follow-up, 25% of patients failed secondary to new infection with a different organism. Conclusion These results suggest a role for methylene blue in providing a visual index of surgical debridement in the treatment of PJI.

Author(s): Toogood, Paul; Shaw, Jeremy; Nussenbaum, Fernando; Acosta, Anna; Dawson, Jack; Perkins, Christopher; Firoozabadi, Reza; Lee, Nicolas | Abstract: BackgroundThe time dedicated to the study of human anatomy within medical school curriculums has been substantially reduced. The effect of this on the knowledge of incoming orthopaedic trainees is unknown. The current study aimed to evaluate both the subjective perceptions and objective anatomic knowledge of fourth-year medical students applying for orthopaedic residency.MethodsA multicenter prospective study was performed that assessed 224 students during the course of their interview day for an orthopaedic residency. Participants provided demographic data and a subjective assessment of the quality of their anatomic education, and completed either an upper or lower extremity anatomic examination. Mean total scores and subscores for various anatomic regions and concepts were calculated.ResultsStudents on average rated the adequacy of their anatomic education as 6.5 on a 10-point scale. Similarly, they rated the level of importance their medical school placed on anatomic education as 6.2 on a 10-point scale. Almost 90% rated the time dedicated to anatomy as good or fair. Of six possible methods for learning anatomy, dissection was rated the highest.On objective examinations, the mean score for correct answers was 44.2%. This improved to 56.4% when correct and acceptable answers were considered. Regardless of anatomic regions or concepts evaluated, percent correct scores did not reach 50%. There were no significant correlations between performance on the anatomic examinations and either prior academic performance measures or the student's subjective assessment of their anatomic education.ConclusionsCurrent students applying into orthopaedic residency do not appear to be adequately prepared with the prerequisite anatomic knowledge. These deficits must be explicitly addressed during residency training to produce competent, safe orthopaedic surgeons.

BACKGROUND CONTEXT Obesity is an important risk factor for complications after lumbar spine fusion, and poses unique challenges regarding safety and quality of care. Nonetheless, this patient population is not well studied. PURPOSE To determine risk factors for readmission in obese and morbidly obese patients. STUDY DESIGN/SETTING Retrospective aase control study. PATIENT SAMPLE Adult patients age >18 undergoing primary posterior lumbar fusion in the State Inpatient Databases of New York, Florida, North Carolina, Utah, and California. OUTCOME MEASURES Odds ratios of demographics, comorbidities, and surgery characteristics in multivariate analysis of 90-day readmission. METHODS Data were queried using ICD-9 codes. Patients who underwent surgery in the last quarter of the data set, revision surgery, or surgery for cancer, infection, or trauma were excluded. Independent analyses were performed for three separate groups of patients: patients were identified as obese using codes for obesity or BMI >30, but not morbid obesity or BMI > 40, severely obese using codes for morbid obesity or BMI > 40, and normal if they had none of the above codes nor codes for overweight or underweight. Data were queried for demographics, comorbidities, surgery characteristics, and 90-day hospital readmission. Logistic multivariate regressions were performed to determine risk factors for readmission. RESULTS We analyzed 24,349 obese, 9,835 severely obese patients and 257,986 normal patients. The 90-day hospital readmission rate was 14.5%, 17.5%, and 12.1% in the obese, severely obese, and normal groups, respectively. In the obese group, risk factors for readmission included female gender, Black or Hispanic race, Medicare or Medicaid insurance, the addition of anterior or lateral interbody fusion, >3 levels treated, cerebrovascular disease, chronic pulmonary disease, congestive heart failure (CHF), diabetes without and with chronic complication, myocardial infarction, peptic ulcer disease, peripheral vascular disease, renal disease, and mental health disease, In the severely obese group, risk factors for readmission included female gender, Medicare or Medicaid insurance, >3 levels, CHF, diabetes without and with chronic complication, hemi or paraplegia, mild liver disease, and renal disease. In the normal group, all studied variables were risk factors for readmission. CONCLUSIONS Ninety-day hospital readmission rates in obese and severely obese patients undergoing elective posterior lumbar fusion are high. Risk factors include demographic variables such as race and insurance status, as well as various comorbid conditions, but not age. Similar risk factors were seen in normal weight patients, however with less risk, suggesting a synergistic effect of obesity with other risk factors. This study provides valuable insight into modifiable risk factors that may be potential targets for preoperative optimization and guidance on risk adjustment in this unique patient population.

BACKGROUND CONTEXT Tenacious bacterial biofilms pose a major challenge in treating deep spine infections. Biofilms provide bacteria substantial protection against antimicrobial agents, the host immune response, and are invisible to the naked eye. Biofilms are notoriously difficult to eradicate, and to that end, methylene blue has shown promise as a biofilm disclosing agent in the arthroplasty literature in both in vitro and in vivo settings. PURPOSE The objective of the present study was to assess the intensity of methylene blue staining at varying concentrations as a biofilm disclosing agent in vitro for common biofilm forming bacterial infections and to determine performance characteristics across a range of spine implant materials. STUDY DESIGN/SETTING Microbiology. METHODS S. aureus biofilms were grown to maturity in bioreactors according to established lab protocol on titanium, cobalt chromium, and polyetherketone (PEEK) wafers. Biofilms were stained with 0.05% and 0.01% methylene blue solutions for 5-minutes and then washed with normal saline for 1-minute. Gross images were obtained to compare the visual sensitivity of the blue dye at different dilutions. Scanning electron microscopy was performed to confirm the presence or absence of biofilm on methylene blue stained areas. Images were compared to controls. RESULTS S. aureus biofilms were grown for 7days on double sided titanium, cobalt chromium, and PEEK wafers (n=4 each). There appeared to be a visible dose – dependent relationship based on the staining and dye concentration. At each dilution, biofilms demonstrated visible blue staining after immersion in methylene blue solution; however, blue dye was visible only where biofilms were present as confirmed by SEM. There was no evidence that methylene blue was able to stain titanium, cobalt chromium, or PEEK. CONCLUSIONS Methylene blue functions as an effective disclosing agent for S. aureus biofilm in vitro. Currently, there are no techniques for identifying bacterial biofilm in vivo once it has formed. Given the low cost, favorable safety profile and FDA approval, methylene blue may be considered a first-in-class agent for disclosure of biofilm and may allow surgeons to see biofilms on implants and host tissue in vivo. In so doing, it may allow for efforts at eradicating these biofilms once visualized. Additional work is needed to further elucidate this concept.

Background context Spinous process fracture is a recognized complication associated with interspinous process spacer (IPS) surgery. Although occasionally identified by plain radiographs, computed tomography (CT) appears to identify a higher rate of such fractures. Although osteoporotic insufficiency fracture is considered a contraindication for IPS surgery, a formal risk factor analysis for this complication has not previously been reported. Purpose To identify risk factor(s) associated with early spinous process fracture after IPS surgery. Study design/setting Prospective cohort study of 39 consecutive patients with lumbar stenosis and neurogenic claudication undergoing IPS surgery at a single institution. Methods Patients underwent preoperative dual-energy X-ray absorptiometry (DXA) scans, lumbar spine CT, and plain radiographs. Postoperatively, patients underwent repeat CT imaging within 6 months of surgery and serial radiographs at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year. Preoperative CT scans were analyzed by calculating average Hounsfield units for a 1 cm 2 area of the midsagittal reconstructed image for four separate locations: midvertebral body, subcortical bone subjacent to the superior margin of the midspinous process, subcortical bone above the inferior margin of the midspinous process, and the midspinous process. Results Thirty-eight patients underwent IPS surgery at a total of 50 levels (38 L4–L5, 12 L3–L4; 26 one-level, 12 two-level). One patient underwent laminectomy at index surgery and was excluded from the analysis. Implants included 34 titanium X-STOP (Medtronic, Memphis, TN, USA), 8 polyaryletheretherketone X-STOP (Medtronic, Memphis, TN, USA), and 8 Aspen (Lanx, Broomfield, CO, USA) devices. Eleven spinous process fractures were identified by CT in 11 patients (22.0% of levels). No fractures were apparent on plain radiographs. The rate of spondylolisthesis observed on preoperative radiographs was 100% (11 of 11) among patients with fractures compared with 33.3% (9 of 27) of patients without fracture (p=.0001). Overall, 21 of 39 patients in this series had spondylolisthesis, and the rate of fracture in this group was 52%. Among patients without spondylolisthesis, the fracture rate was 0%. A trend was observed toward decreased DXA lumbar spine and hip T-scores among fracture patients versus nonfracture patients (0.2±1.7 vs. 0.8±1.7; p=.389; −1.1±1.4 vs. −0.3±1.4; p=.201), but these differences were not significant. Similarly, bone density based on CT measurements at four different locations revealed a trend toward decreased density among fracture patients, but these differences were not significant. Conclusions Degenerative spondylolisthesis appears strongly associated with the occurrence of spinous process fracture after IPS surgery. There is a trend toward increased fracture risk in patients with decreased bone mineral density as measured by both DXA scan and CT-based volume averaging of Hounsfield units, but osteoporosis appears to be a relatively weaker risk factor. The association between spondylolisthesis and fracture observed in this study may account for the relatively poorer outcome of IPS surgery in patients with spondylolisthesis that has been reported in previous series.

Study Design. Prospective observational study. Objective. To provide a more accurate estimate of the rate of acute spinous process fractures associated with IPS surgery. Summary of Background Data. Biomechanical cadaveric studies have suggested adequate spinous process strength to support placement of interspinous process spacers (IPS). Postoperative spinous process fractures have been reported in one%—to 5.8% of patients in previous series based on routine biplanar radiographic evaluation. However, most fractures occur between the base and midportion of the spinous process in an area that is typically difficult to visualize on plain radiographs due to device design. Methods. All patients underwent preoperative biplanar plain radiographs and computed tomography (CT) of the lumbar spine to confirm anatomy favorable for IPS placement and rule out fracture or spondylolysis. Postoperatively, all patients underwent repeat CT imaging within six months of surgery, biplanar radiographs at two weeks, six weeks, three months, six months, and one year. All studies were reviewed independently by a neuroradiologist and two orthopedic spine surgeons. Results. Fifty implants (38 L4–5, 12 L3–4) were placed in 38 patients who completed follow-up and were included in final analysis. Three IPS designs were included (34 Medtronic X-STOP titanium, 8 X-STOP PEEK, 8 Lanx Aspen). Postoperative CT revealed 11 nondisplaced spinous process fractures in 11 patients (28.9% of patients, 22% of levels). Five fractures were associated with mild to moderate lumbar back pain and six fractures were asymptomatic. No patient reported a traumatic incident. No fracture was identifiable on plain radiographs. One fracture displaced during follow-up evaluation. Three patients underwent IPS removal and laminectomy. Three fractures healed by CT in one year. Overall, patients with fractures tended toward poorer outcomes by Zurich Claudication Questionnaire (ZCQ) (28.5% vs. 34.8% improvement in symptom severity, P = 0.496; 21.4% vs. 30.7% improvement in physical function, P = 0.199) and tended toward lower satisfaction rates (50% vs. 73.7%, P = 0.24) at one year compared to patients without fracture. Conclusion. Interspinous process spacer surgery appears associated with a higher rate of early postoperative spinous process fracture than previously reported. In all cases, in this series, plain radiographs were inadequate to identify fractures because all fractures were initially minimal or nondisplaced, many patients were osteopenic, and the metallic wings of the devices often obscured fractures. Moreover, in most patients, fractures were associated with mild or no acute localized pain. This study suggests that unrecognized spinous process fracture may be responsible for a significant number of patients who experience unsatisfactory outcome after IPS surgery. CT imaging is required to identify the vast majority of such fractures.

Background Although asymptomatic mild limb length discrepancy (LLD) in children is generally treated non-operatively, there is limited high quality follow up data to support this recommendation. Hypothesis We hypothesized that there would be no association between LLD and arthritic changes with mild limb length discrepancy. Materials and methods We studied 576 well-preserved cadaveric skeletons ranging from 40 to 79 years of age. Limb length discrepancy was based on combined femoral and tibial lengths measured using digital calipers. Degenerative disease was hand graded in the spine, hips and knees using a previously described classification system. Power was set at 90%. Results Average age was 56 ± 10 years, and average LLD was 4.8 ± 4.0 mm. Multiple regression analysis did not demonstrate any correlation between LLD and degenerative disease. After screening to find 26 additional specimens with LLD 10 mm or greater, and assessing a potentially quadratic relationship, we still did not find any detrimental effects of LLD. Discussion Our data support the general clinical recommendation of observation for mild asymptomatic LLD. These results do not apply to larger LLD nor LLD associated with other deformities or clinical symptoms. Level of evidence Not applicable, anatomic basic science study.

Background: Anterior cruciate ligament (ACL) reconstruction is performed commonly, with a low risk of complication. Osteonecrosis of the knee is a potentially devastating condition and has been observed both spontaneously and after meniscectomy, although osteonecrosis has not been described as a complication after ACL reconstruction. Purpose: To describe the development of osteonecrosis of the knee in 5 patients after arthroscopic ACL reconstruction. Study Design: Case series; Level of evidence, 4. Methods: This study involved 5 patients (mean age, 33.2 years) who developed osteonecrosis of the knee after ACL reconstruction. A retrospective chart review was performed to identify clinical characteristics and surgical factors present in each of the 5 cases. Results: In 4 cases, the pathologic changes were present in both the medial and lateral femoral condyles, with isolated lateral condyle changes in the other case. The mean time to diagnosis was 11.6 months. These patients underwent an average of 1.8 additional surgical procedures after the diagnosis of osteonecrosis. Conclusion: Osteonecrosis of the knee is a rare outcome after ACL reconstruction. We are unable to identify clear risk factors for the development of this complication, although we hope the presentation of these cases will help promote the identification of other cases in future studies.

Surgical site infection has been identified as one of the most important preventable sources of morbidity and mortality associated with medical treatment. The purpose of the present study was to evaluate the feasibility and efficacy of an institutional prescreening program for the preoperative detection and eradication of both methicillin-resistant and methicillin-sensitive Staphylococcus aureus in patients undergoing elective orthopaedic surgery.Data were collected prospectively during a single-center study. A universal prescreening program, employing rapid polymerase chain reaction analysis of nasal swabs followed by an eradication protocol of intranasal mupirocin and chlorhexidine showers for identified carriers, was implemented. Surgical site infection rates were calculated and compared with a historical control period immediately preceding the start of the screening program.During the study period, 7019 of 7338 patients underwent preoperative screening before elective surgery, for a successful screening rate of 95.7%. One thousand five hundred and eighty-eight (22.6%) of the patients were identified as Staphylococcus aureus carriers, and 309 (4.4%) were identified as methicillin-resistant Staphylococcus aureus carriers. A significantly higher rate of surgical site infection was observed among methicillin-resistant Staphylococcus aureus carriers (0.97%; three of 309) compared with noncarriers (0.14%; seven of 5122) (p = 0.0162). Although a higher rate of surgical site infection was also observed among methicillin-sensitive Staphylococcus aureus carriers (0.19%; three of 1588) compared with noncarriers, this difference did not achieve significance (p = 0.709). Overall, thirteen cases of surgical site infection were identified during the study period, for an institutional infection rate of 0.19%. This rate was significantly lower than that observed during the control period (0.45%; twenty-four cases of surgical site infection among 5293 patients) (p = 0.0093).Implementation of an institution-wide prescreening program for the identification and eradication of methicillin-resistant and methicillin-sensitive Staphylococcus aureus carrier status among patients undergoing elective orthopaedic surgery is feasible and can lead to significant reductions in postoperative rates of surgical site infection.Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Streptococcus mutans is the primary causative agent of human dental caries, a ubiquitous infectious disease for which effective treatment strategies remain elusive. We investigated a 25-kDa SloR metalloregulatory protein in this oral pathogen, along with its target genes that contribute to cariogenesis. Previous studies have demonstrated manganese- and SloR-dependent repression of the sloABCR metal ion transport operon in S. mutans . In the present study, we demonstrate that S. mutans coordinates this repression with that of certain virulence attributes. Specifically, we noted virulence gene repression in a manganese-containing medium when SloR binds to promoter-proximal sequence palindromes on the S. mutans chromosome. We applied a genome-wide approach to elucidate the sequences to which SloR binds and to reveal additional “class I” genes that are subject to SloR- and manganese-dependent repression. These analyses identified 204 S. mutans genes that are preceded by one or more conserved palindromic SloR recognition elements (SREs). We cross-referenced these genes with those that we had identified previously as SloR and/or manganese modulated in microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) experiments. From this analysis, we identified a number of S. mutans virulence genes that are subject to transcriptional upregulation by SloR and noted that such “class II”-type regulation is dependent on direct SloR binding to promoter-distal SREs. These observations are consistent with a bifunctional role for the SloR metalloregulator and implicate it as a target for the development of therapies aimed at alleviating S. mutans -induced caries formation.

• Accurate data regarding anatomic dimensions of the lumbar spinal canal are relevant for establishing diagnostic criteria for stenosis and assessing surgical outcomes. • Previous studies utilized advanced imaging techniques such as CT and MRI to provide population-based data. • However, we believe that direct measurements of a large cadaveric collection provide valuable normative data. Cranial View of Cadaveric L3 Purpose