Lateral lumbar interbody fusion at L4-L5 has a low rate of complications in appropriately selected patients when using a standardized surgical technique.

Aims: The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique. Methods: This was a multicentre retrospective study involving consecutively enrolled patients who underwent L4-L5 LLIF by seven surgeons at seven institutions in three countries over a five-year period. The demographic details of the patients and the details of the surgery, reoperations and complications, including femoral and non-femoral neuropraxia, thigh pain, weakness of hip flexion, and abdominal complications, were analyzed. Neurological and psoas-related complications attributed to LLIF or posterior instrumentation and persistent symptoms were recorded at one year postoperatively. Results: A total of 517 patients were included in the study. Their mean age was 65.0 years (SD 10.3) and their mean BMI was 29.2 kg/m2 (SD 5.5). A mean of 1.2 levels (SD 0.6) were fused with LLIF, and a mean of 1.6 (SD 0.9) posterior levels were fused. Femoral neuropraxia occurred in six patients (1.2%), of which four (0.8%) were LLIF-related and two (0.4%) had persistent symptoms one year postoperatively. Non-femoral neuropraxia occurred in nine patients (1.8%), one (0.2%) was LLIF-related and five (1.0%) were persistent at one year. All LLIF-related neuropraxias resolved by one year. A total of 32 patients (6.2%) had thigh pain, 31 (6.0%) were LLIF-related and three (0.6%) were persistent at one year. Weakness of hip flexion occurred in 14 patients (2.7%), of which eight (1.6%) were LLIF-related and three (0.6%) were persistent at one year. No patients had bowel injury, three (0.6%) had an intraoperative vascular injury (not LLIF-related), and five (1.0%) had ileus. Reoperations occurred in five patients (1.0%) within 30 days, 37 (7.2%) within 90 days, and 41 (7.9%) within one year postoperatively. Conclusion: LLIF involving the L4-L5 disc level has a low rate of persistent neurological, psoas-related, and abdominal complications in patients with the appropriate indications and using a standardized surgical technique.

Polymethyl methacrylate augmentation and proximal junctional kyphosis in adult spinal deformity patients.

BACKGROUND: Proximal junctional kyphosis (PJK) is a complication following surgery for adult spinal deformity (ASD) possibly ameliorated by polymethyl methacrylate (PMMA) vertebroplasty of the upper instrumented vertebrae (UIV). This study quantifies PJK following surgical correction bridging the thoracolumbar junction ± PMMA vertebroplasty. METHODS: ASD patients from 2013 to 2020 were retrospectively reviewed and included with immediate postoperative radiographs and at least one follow-up radiograph. PMMA vertebroplasty at the UIV and UIV + 1 was performed at the surgeons' discretion. RESULTS: Of 102 patients, 56% received PMMA. PMMA patients were older (70 ± 8 vs. 66 ± 10, p = 0.021), more often female (89.3% vs. 68.2%, p = 0.005), and had more osteoporosis (26.8% vs. 9.1%, p = 0.013). 55.4% of PMMA patients developed PJK compared to 38.6% of controls (p = 0.097), and the rate of PJK development was not different between groups in univariate survival models. There was no difference in PJF (p > 0.084). Reoperation rates were 7.1% in PMMA versus 11.4% in controls (p = 0.501). In multivariable models, PJK development was not associated with the use of PMMA vertebroplasty (HR 0.77, 95% CI 0.38-1.60, p = 0.470), either when considered overall in the cohort or specifically in those with poor bone quality. PJK was significantly predicted by poor bone quality irrespective of PMMA use (HR 3.81, p < 0.001). CONCLUSIONS: In thoracolumbar fusions for adult spinal deformity, PMMA vertebroplasty was not associated with reduced PJK development, which was most highly associated with poor bone quality. Preoperative screening and management for osteoporosis is critical in achieving an optimal outcome for these complex operations. LEVEL OF EVIDENCE: 4, retrospective non-randomized case review.

A Lateral Expandable Cage with Independently Adjustable Anterior and Posterior Heights Can Improve the Pressure Distribution at the Cage-Endplate Interface: A Biomechanics Study.

OBJECTIVE: To investigate how the expansion trajectory of a lateral expandable cage affects pressure distribution at the cage-endplate interface under well-controlled biomechanical loading conditions. METHODS: Three unique vertical height expansion trajectories used by clinically relevant lateral expandable cages were evaluated: craniocaudal, fixed-arc, and independently adjustable anterior and posterior height expansion. Two biomechanical loading scenarios were performed. The first scenario used custom bone foam test blocks to assess resultant pressure distribution at varying test block lordotic angles and expansion heights. The second scenario simulated expansion using synthetic spine units and compared the pressure distribution following expansion. RESULTS: For an expandable cage with craniocaudal expansion, the pressure distribution at the cage-endplate interface was found to depend heavily on the lordotic angle of the test block (P < 0.001), but not expansion height (P = 0.634). The greatest maximum pressure occurred at higher test block lordotic angles. For an expandable cage with fixed-arc expansion, the pressure distribution shifted anteriorly throughout expansion. In the simulated expansion trials, an expandable cage with adjustable anterior and posterior height expansion was found to improve the pressure distribution at the cage-endplate interface, reducing the maximum pressure measurements by 22% and 14% in the craniocaudal and fixed-arc expansion, respectively. CONCLUSIONS: Of the cage designs evaluated in this study, an expandable cage with independently adjustable anterior and posterior heights lowered the maximum pressure measured at the cage-endplate interface and alleviated the potential of cage edge loading, both of which are important considerations that are fundamental for a successful fusion procedure and the mitigation of implant subsidence risk.

Lateral decubitus single position anterior posterior surgery improves operative efficiency, improves perioperative outcomes, and maintains radiological outcomes comparable with traditional anterior posterior fusion at minimum 2-year follow-up.

BACKGROUND CONTEXT: The advantages of lateral single position surgery (LSPS) in the perioperative period has previously been demonstrated, however 2-year postoperative outcomes of this novel technique have not yet been compared to circumferential anterior-posterior fusion (FLIP) at 2-years postoperatively. PURPOSE: Evaluate the safety and efficacy of LSPS versus gold-standard FLIP STUDY DESIGN/SETTING: Multicenter retrospective cohort review. PATIENT SAMPLE: Four hundred forty-two patients undergoing lumbar fusion via LSPS or FLIP OUTCOME MEASURES: Levels fused, operative time, estimated blood loss, perioperative complications, and reasons for reoperation at 30-days, 90-days, 1-year, and 2-years. Radiographic outcomes included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch, and segmental lumbar lordosis. METHODS: Patients were grouped as LSPS if anterior and posterior portions of the procedure were performed in the lateral decubitus position, and FLIP if patients were repositioned from supine or lateral to prone position for the posterior portion of the procedure under the same anesthetic. Groups were compared in terms of demographics, intraoperative, perioperative and radiological outcomes, complications and reoperations up to 2-years follow-up. Measures were compared using independent samples or paired t-tests and chi-squared analyses with significance set at p<.05. RESULTS: Four hundred forty-two patients met inclusion, including 352 LSPS and 90 FLIP patients. Significant differences were noted in age (62.4 vs 56.9; p≤.001) and smoking status (7% vs 16%; p=.023) between the LSPS and FLIP groups. LSPS demonstrated significantly lower Op time (97.7min vs 297.0 min; p<.001), fluoro dose (36.5mGy vs 78.8mGy; p<.001), EBL (88.8mL vs 270.0mL; p<.001), and LOS (1.91 days vs 3.61 days; p<.001) compared to FLIP. LSPS also demonstrated significantly fewer post-op complications than FLIP (21.9% vs 34.4%; p=.013), specifically regarding rates of ileus (0.0% vs 5.6%; p<.001). No differences in reoperation were noted at 30-day (1.7%LSPS vs 4.4%FLIP, p=.125), 90-day (5.1%LSPS vs 5.6%FLIP, p=.795) or 2-year follow-up (9.7%LSPS vs 12.2% FLIP; p=.441). LSPS group had a significantly lower preoperative PI-LL (4.1° LSPS vs 8.6°FLIP, p=.018), and a significantly greater postoperative LL (56.6° vs 51.8°, p = .006). No significant differences were noted in rates of fusion (94.3% LSPS vs 97.8% FLIP; p=.266) or subsidence (6.9% LSPS vs 12.2% FLIP; p=.260). CONCLUSIONS: LSPS and circumferential fusions have similar outcomes at 2-years post-operatively, while reducing perioperative complications, improving perioperative efficiency and safety.

Patient-level payment patterns prior to single level lumbar decompression are associated with resource utilization, postoperative payments, and adverse events.

BACKGROUND: Understanding patient-specific trends in costs and healthcare resource utilization (HCRU) surrounding lumbar spine surgery is critically needed to better inform surgical decision making and the development of targeted interventions. PURPOSE: 1) Identify subgroups of patients following distinct patterns in direct healthcare payments pre- and postoperatively, 2) determine whether these patterns are associated with patient and surgical factors, and 3) examine whether preoperative payment patterns are related to postoperative payments, healthcare resource utilization (HCRU), and adverse events. STUDY DESIGN/SETTING: Retrospective analysis of an administrative claims database (IBM Marketscan Research Databases 2007-2015). PATIENT SAMPLE: Adults undergoing primary single-level decompression surgery for lumbar stenosis (n=12,394). OUTCOME MEASURES: Direct healthcare payments, HCRU payments (15 categories), 90-day complications and all-cause readmission, 2-year reoperation METHODS: Group-based trajectory modeling is an application of finite mixture modeling that is able to identify meaningful subgroups within a population that follow distinct developmental trajectories over time. We used this technique to identify subgroups of patients following distinct profiles in preoperative direct healthcare payments. A separate analysis was performed to identify distinct profiles in payments postoperatively. Patient and surgical factors associated with these payment profiles were assessed with multinomial logistic regression, and associations with adverse events were assessed with risk-adjusted multivariable logistic regression. RESULTS: We identified 4 preoperative patient payment subgroups following distinct profiles in payments: Pre-Low (5.8% of patients), Pre-Early-Rising (4.8%), Pre-Medium (26.1%), and Pre-High (63.3%). Postoperatively, 3 patient subgroups were identified: Post-Low (8.9%), Post-Medium (29.6%), and Post-High (61.4%). Patients following the higher-cost pre- and postoperative payment profiles were older, more likely female, and had a greater physical and mental comorbidity burden. With each successively higher preoperative payment profile, patients were increasingly likely to have high postoperative payments, use more HCRU (particularly high-cost services such as inpatient admissions, ER, and SNF/IRF care), and experience postoperative adverse events. Following risk adjustment for patient and surgical factors, patients following the Pre-High payment profile had 209.5 (95% CI: 144.2, 309.7; p<.001) fold greater odds for following the Post-High payment profile, 1.8 (1.3, 2.5; p=.003) fold greater odds for 90-day complications, and 1.7 (1.2, 2.6; p=.035) fold greater odds for 2-year reoperation relative to patients following the Pre-Low payment profile. CONCLUSIONS: There are identifiable subgroups of patients who follow distinct profiles in direct healthcare payments surrounding lumbar decompression surgery. These payment profiles are related to patient age, sex, and physical and mental comorbidities. Notably, preoperative payment profiles may provide prognostic value, as they are associated with postoperative costs, HCRU, and adverse events. LEVEL OF EVIDENCE: III.

NS2 is a key determinant of compatibility in reassortant avian influenza virus with heterologous H7N9-derived NS segment.

Influenza A viruses are common pathogens with high prevalence worldwide and potential for pandemic spread. While influenza A infections typically elicit robust cellular innate immune responses, the non-structural protein 1 (NS1) antagonizes host anti-viral responses and is critical for efficient virus replication and virulence. The avian influenza virus (AIV) H7N9 initially emerged in China in 2013 and has since crossed the avian-human barrier, causing severe disease in humans. To investigate the influence of the H7N9 NS gene (NS079) on viral replication and innate immune response, we generated several recombinant AIVs bearing various NS079 segments on the backbone of H6N1 (strain 0702). Intriguingly, the recombinant virus bearing the heterologous NS079 gene was highly attenuated compared with virus carrying the homologous NS gene (NS0702). Furthermore, we generated a NS079-0702R virus that expresses a chimeric NS gene in which part of the NS079 effector domain was replaced with the sequence from NS0702. The NS079-0702R virus exhibited significantly enhanced viral yield, approximately 100-fold more than virus bearing NS079. The high infection rate of NS079-0702R virus was reflected by strong induction of IFN and Mx expression in human A549 cells. Intriguingly, our in vitro comparative analysis suggested that the increased NS079-0702R infection capacity was independent of the ability of NS1 to interact with cellular partners, such as PKR and CPSF30. Since partial substitution of the effector domain from NS0702 altered the coding sequence of NS2, we further generated another recombinant virus with NS2 derived from H7N9. Surprisingly, the virus with H7N9-derived NS2 exhibited growth characteristics similar to NS079. Our data demonstrate that swapping NS2 components changes infection efficiency, suggesting a key role for NS2 as a determinant of viral compatibility upon reassortment. These findings warrant further investigation into the precise mechanisms by which NS2 contributes to viral replication and host immunity.1.

Single-position circumferential lumbar spinal fusion: an overview of terminology, concepts, rationale and the current evidence base.

PURPOSE: To provide definitions and a conceptual framework for single position surgery (SPS) applied to circumferential fusion of the lumbar spine. METHODS: Narrative literature review and experts' opinion. RESULTS: Two major limitations of lateral lumbar interbody fusion (LLIF) have been (a) a perceived need to reposition the patient to the prone position for posterior fixation, and (b) the lack of a robust solution for fusion at the L5/S1 level. Recently, two strategies for performing single-position circumferential lumbar spinal fusion have been described. The combination of anterior lumbar interbody fusion (ALIF) in the lateral decubitus position (LALIF), LLIF and percutaneous pedicle screw fixation (pPSF) in the lateral decubitus position is known as lateral single-position surgery (LSPS). Prone LLIF (PLLIF) involves transpsoas LLIF done in the prone position that is more familiar for surgeons to then implant pedicle screw fixation. This can be referred to as prone single-position surgery (PSPS). In this review, we describe the evolution of and rationale for single-position spinal surgery. Pertinent studies validating LSPS and PSPS are reviewed and future questions regarding the future of these techniques are posed. Lastly, we present an algorithm for single-position surgery that describes the utility of LALIF, LLIF and PLLIF in the treatment of patients requiring AP lumbar fusions. CONCLUSIONS: Single position surgery in circumferential fusion of the lumbar spine includes posterior fixation in association with any of the following: lateral position LLIF, prone position LLIF, lateral position ALIF, and their combination (lateral position LLIF+ALIF). Preliminary studies have validated these methods.

The Use of Distinctive Monoclonal Antibodies in FMD VLP- and P1-Based Blocking ELISA for the Seromonitoring of Vaccinated Swine.

The serum neutralization (SN) test has been regarded as the "gold standard" for seroconversion following foot-and-mouth disease virus (FMDV) vaccination, although a high-level biosafety laboratory is necessary. ELISA is one alternative, and its format is constantly being improved. For instance, standard polyclonal antisera have been replaced by monoclonal antibodies (MAbs) for catching and detecting antibodies, and inactive viruses have been replaced by virus-like particles (VLPs). To the best of current knowledge, however, no researchers have evaluated the performances of different MAbs as tracers. In previous studies, we successfully identified site 1 and site 2 MAbs Q10E and P11A. In this study, following the established screening platform, the VLPs of putative escape mutants from sites 1 to 5 were expressed and used to demonstrate that S11B is a site 3 MAb. Additionally, the vulnerability of VLPs prompted us to assess another diagnostic antigen: unprocessed polyprotein P1. Therefore, we established and evaluated the performance of blocking ELISA (bELISA) systems based on VLPs and P1, pairing them with Q10E, P11A, S11B, and the non-neutralizing TSG MAb as tracers. The results indicated that the VLP paired with S11B demonstrated the highest correlation with the SN titers (R2 = 0.8071, n = 63). Excluding weakly positive serum samples (SN = 16-32, n = 14), the sensitivity and specificity were 95.65% and 96.15% (kappa = 0.92), respectively. Additionally, the P1 pairing with Q10E also demonstrated a high correlation (R2 = 0.768). We also discovered that these four antibodies had steric effects on one another to varying degrees, despite recognizing distinct antigenic sites. This finding indicated that MAbs as tracers could not accurately detect specific antibodies, possibly because MAbs are bulky compared to a protomeric unit. However, our results still provide convincing support for the application of two pairs of bELISA systems: VLP:S11B-HRP and P1:Q10E-HRP.

Utilization of lateral anterior lumbar interbody fusion for revision of failed prior TLIF: illustrative case.

BACKGROUND: The use of the lateral decubitus approach for L5-S1 anterior lumbar interbody fusion (LALIF) is a recent advancement capable of facilitating single-position surgery, revision operations, and anterior column reconstruction. To the authors' knowledge, this is the first description of the use of LALIF at L5-S1 for failed prior transforaminal lumbar interbody fusion (TLIF) and anterior column reconstruction. Using an illustrative case, the authors discuss their experience using LALIF at L5-S1 for the revision of pseudoarthrosis and TLIF failure. OBSERVATIONS: The patient had prior attempted L2 to S1 fusion with TLIF but suffered from hardware failure and pseudoarthrosis at the L5-S1 level. LALIF was used to facilitate same-position revision at L5-S1 in addition to further anterior column revision and reconstruction by lateral lumbar interbody fusion at the L1-2 level. Robotic posterior T10-S2 fusion was then added to provide stability to the construct and address the patient's scoliotic deformity. No complications were noted, and the patient was followed until 1 year after the operation with a favorable clinical and radiological result. LESSONS: Revision of a prior failed L5-S1 TLIF with an LALIF approach has technical challenges but may be advantageous for single position anterior column reconstruction under certain conditions.

Lateral decubitus single position anterior-posterior (AP) fusion shows equivalent results to minimally invasive transforaminal lumbar interbody fusion at one-year follow-up.

PURPOSE: This study compares perioperative and 1-year outcomes of lateral decubitus single position circumferential fusion (L-SPS) versus minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) for degenerative pathologies. METHODS: Multicenter retrospective chart review of patients undergoing AP fusion with L-SPS or MIS TLIF. Demographics and clinical and radiographic outcomes were compared using independent samples t tests and chi-squared analyses with significance set at p < 0.05. RESULTS: A total of 445 patients were included: 353 L-SPS, 92 MIS TLIF. The L-SPS cohort was significantly older with fewer diabetics and more levels fused. The L-SPS cohort had significantly shorter operative time, blood loss, radiation dosage, and length of stay compared to MIS TLIF. 1-year follow-up showed that the L-SPS cohort had higher rates of fusion (97.87% vs. 81.11%; p = 0.006) and lower rates of subsidence (6.38% vs. 38.46%; p < 0.001) compared with MIS TLIF. There were significantly fewer returns to the OR within 1 year for early mechanical failures with L-SPS (0.0% vs. 5.4%; p < 0.001). 1-year radiographic outcomes revealed that the L-SPS cohort had a greater LL (56.6 ± 12.5 vs. 51.1 ± 15.9; p = 0.004), smaller PI-LL mismatch (0.2 ± 13.0 vs. 5.5 ± 10.5; p = 0.004). There were no significant differences in amount of change in VAS scores between cohorts. Similar results were seen after propensity-matched analysis and sub-analysis of cases including L5-S1. CONCLUSIONS: L-SPS improves perioperative outcomes and does not compromise clinical or radiographic results at 1-year follow-up compared with MIS TLIF. There may be decreased rates of early mechanical failure with L-SPS.