Comparing the Biomechanical Stability of Cortical Screw Trajectory Versus Standard Pedicle Screw Trajectory for Short- and Long-Segment Posterior Fixation in 3-Column Thoracic Spinal Injury

Background

Information on the performance of posterior fixation with cortical screw (CS) versus pedicle screw (PS) trajectories for stabilizing thoracolumbar burst fractures is limited. Therefore, we sought to analyze stability with CS versus PS in short- and long-segment fixations using a 3-column spinal injury model.

Methods

Nondestructive flexibility tests: (1) intact, (2) intact + short fixation, (3) intact + long fixation, (4) after burst fracture, (5) short fixation + burst fracture, and (6) long fixation + burst fracture using thoracic spine segments (7 CS, 7 PS).

Results

With CS, the range of motion (ROM) was significantly greater with short-segment than with long-segment fixation in all directions, with and without burst fracture (P ≤ .008). With PS and burst fracture, ROM was significantly greater with short fixation during lateral bending and axial rotation (P < .006), but not during flexion-extension (P = .10). Groups with CS versus PS were not significantly different after burst fracture during flexion-extension and axial rotation, with short (P ≥ .58) or long fixation (P ≥ .17). During lateral bending, ROM was significantly greater with CS versus PS, without burst fracture (long fixation, P = .02) and with burst fracture (short and long fixation, P ≤ .001).

Conclusions

CS trajectory is a valid alternative to PS trajectory for thoracic spine fixation in 3-column spinal injuries, and long-segment fixation is superior to short-segment fixation with either.

Pedicled, vascularized occipital bone graft to supplement atlantoaxial arthrodesis for the treatment of pseudoarthrosis

Atlantoaxial pseudoarthrosis is a challenging postoperative complication. The use of a local, vascularized bone graft, without free tissue transfer, to support a revision atlantoaxial fusion has not been previously described. We report the first surgical patient who received a semispinalis capitis muscle pedicled, occipital bone graft for supplementation of a revision atlantoaxial arthrodesis. A 72-year-old female had a failed atlantoaxial fusion and developed neck pain from continued instability and fractured hardware. The fixation and fusion were revised and supplemented with a novel, pedicled occipital bone graft. A craniectomy was performed in the occipital bone while still attached to the semispinalis capitis muscle to provide graft vascularity. This graft was rotated inferiorly from the skull base to the C1 arch and C2 spinous process in order to supplement a revision atlantoaxial arthrodesis. The patient had excellent clinical recovery over 18-month clinical follow up. The bone graft harvesting and rotation were performed safely and without complication. The 6-month postoperative CT scan showed partial fusion into the graft. This novel surgical technique leverages the advantages of vascularized structural autograft without adding extensive time or morbidity to the procedure as observed in free-tissue transfers. It is a safe and useful salvage technique to supplement revision atlantoaxial fusion surgeries.

Adjustable Rigid Interspinous Process Fixation: A Biomechanical Study of Segmental Lordosis and Interbody Loading in the Lumbar Spine

Background

Rigid interspinous process fixation (ISPF) may serve as a minimally disruptive adjunct to lumbar interbody fusion. Previous biomechanical assessments of ISPF have demonstrated particularly advantageous outcomes in stabilizing the sagittal plane. However, ISPF has not been well characterized in regard to its impact on interbody load, which has implications for the risk of cage migration or subsidence, and sagittal alignment. The purpose of this study was to biomechanically assess in vitro the interbody load (IBL), focal lordosis (FL), and spinous process loading generated by in situ compression/distraction with a novel ISPF device capable of incremental in situ shortening/extension. Bilateral pedicle screw fixation (BPSF) was used as a control.

Methods

Two fresh frozen human lumbar spines were thawed and musculature was removed, leaving ligaments intact. Seven functional spinal units were iteratively tested, which involved a standard lateral discectomy, placement of a modified lateral cage possessing two load cells, and posterior fixation. BPSF and ISPF were performed at each level, with order of fixation was randomized. BPSF was first performed with maximum compressive exertion followed by 75% exertion to represent clinical application. The ISPF device was implanted at a neutral height and incrementally shortened/extended in situ in 1-mm increments. IBL and FL were measured under each condition. Loads on the spinous processes were estimated through bench-top mechanical calibration.

Results

No significant differences in IBL were observed, but the ISPF device produced a significantly greater change in FL compared to the clinically relevant BPSF compression. IBL, as a function of ISPF device height, expressed linear behavior during compression and exponential behavior during distraction.

Conclusions

The novel ISPF device produced clinically effective IBL and FL, performing well in comparison to BPSF. Additionally, incremental ISPF device manipulation demonstrated predictable and clinically safe trends regarding loading of the interbody space and spinous processes.

The Barrow Biomimetic Spine: effect of a 3-dimensional-printed spinal osteotomy model on performance of spinal osteotomies by medical students and interns

Background

The Schwab osteotomy grading scale-a unified osteotomy classification system created in 2014 by Schwab et al.-is one of many concepts in spine surgery that require detailed knowledge of 3-dimensional (3D) anatomy. 3D-printed spine models have demonstrated increasing utility in spine surgery as they more quickly communicate information on complex 3D anatomical relationships than planar imaging or 2-dimensional images. The purpose of this study was to evaluate the utility of a custom, 3D-printed spine model to help surgical trainees understand and perform the Schwab osteotomy grading scale.

Methods

Eight participants were randomized into 2 groups: group 1 received written instructional materials about the Schwab osteotomy grading scale, whereas group 2 received both written materials and a 3D-printed model of the spine with osteotomy regions demarcated. All participants were administered written and practical examinations.

Results

The group randomized to receive the 3D-printed model performed significantly better on both the written assessment (mean score, 7.75±0.50 vs. 5.75±0.50, P=0.023) and the practical examination (mean score, 1.75±0.32 vs. 1.08±0.09, P=0.025) than the group that received only written instructions.

Conclusions

Our results support the conclusion that this 3D-printed spine model is an effective adjunct to help early surgical trainees understand the Schwab osteotomy grading scale. Participants who received the model in addition to the source manuscript demonstrated improved theoretical knowledge and better performance on practical tests of complex spinal osteotomies. Similar models are likely to have utility in surgical training programs and as patient education models.

Microalgae biomass from swine wastewater and its conversion to bioenergy

Ever-increasing swine wastewater (SW) has become a serious environmental concern. High levels of nutrients and toxic contaminants in SW significantly impact on the ecosystem and public health. On the other hand, swine wastewater is considered as valuable water and nutrient source for microalgae cultivation. The potential for converting the nutrients from SW into valuable biomass and then generating bioenergy from it has drawn increasing attention. For this reason, this review comprehensively discussed the biomass production, SW treatment efficiencies, and bioenergy generation potentials through cultivating microalgae in SW. Microalgae species grow well in SW with large amounts of biomass being produced, despite the impact of various parameters (e.g., nutrients and toxicants levels, cultivation conditions, and bacteria in SW). Pollutants in SW can effectively be removed by harvesting microalgae from SW, and the harvested microalgae biomass elicits high potential for conversion to valuable bioenergy.

Pedicled Vascularized Bone Grafts for Posterior Lumbosacral Fusion: A Cadaveric Feasibility Study and Case Report

STUDY DESIGN

Cadaveric feasibility study and case report.

OBJECTIVE

To determine if it is feasible to rotate pedicled vascularized bone graft (VBG) from L1 to S1 via a posterior approach.

SUMMARY OF BACKGROUND DATA

VBG has been used to successfully augment fusion rates in various skeletal pathologies. Pedicled VBG has numerous advantages over free-transfer VBG, including the maintenance of a robust vascular supply to the graft without the need for vascular anastomoses. Pedicled VBG options have not been well described for posterior lumbosacral fusion.

METHODS

A multidisciplinary team of plastic surgeons and neurosurgeons hypothesized that it is feasible to rotate pedicled VBG from L1 to S1 via a posterior approach. In six cadavers, two VBG donor sites were evaluated: posterior element (PE-VBG) and iliac crest (IC-VBG). A single case report of a patient with lumbar Charcot joint treated with IC-VBG is also presented.

RESULTS

For the PE-VBG, the laminae and spinous processes were mobilized en bloc via Gill laminectomy on a unilateral sacrospinalis pedicle. Mean ± standard deviation (SD) length × width graft dimensions were 2.8±0.48 cm × 2.2±0.81 cm. The inter-transverse process (inter-TP) distance was less than the corresponding lamina length at all levels. For the IC-VBG, iliac crest was mobilized on a quadratus lumborum pedicle. Mean±SD length × width × thickness graft dimensions were 7.7±1.28 cm × 2.2±0.69 cm × 1.5±0.79 cm. The IC-VBGs reached from L1 (T12-S1) to S1 (S1-S3), and all IC-VBGs were able to cover three levels.

CONCLUSIONS

This feasibility cadaveric study and the case report are the first demonstrations that pedicled VBGs can be successfully applied to posterior lumbosacral spinal arthrodesis. Patients at high risk for nonunion may benefit from these strategies. Further clinical experience with these techniques is warranted.

LEVEL OF EVIDENCE

Level IV.

Biomechanical Testing of a 3D-printed L5 Vertebral Body Model

Background

We examined the biomechanical performance of a three-dimensional (3D)-printed vertebra on pedicle screw insertional torque (IT), axial pullout (APO), and stiffness (ST) testing.

Materials and methods

Seventy-three anatomically identical L5 vertebral body models (146 pedicles) were printed and tested for IT, APO, and ST using single-threaded pedicle screws of equivalent diameter (6.5 mm), length (40.0 mm), and thread pitch (2.6 mm). Print properties (material, cortical thickness [number of shells], cancellous density [in-fill], in-fill pattern, print orientation) varied among models. One-way analysis of variance was performed to evaluate the effects of variables on outcomes.

Results

The type of material significantly affected IT, APO, and ST (P < 0.001, all comparisons). For acrylonitrile butadiene styrene (ABS) models, in-fill density (25-35%) had a positive linear association with APO (P = 0.002), ST (P = 0.008), and IT (P = 0.10); similarly for the polylactic acid (PLA) models, APO (P = 0.001), IT (P < 0.001), and ST (P = 0.14). For the nylon material type, in-fill density did not affect any tested parameter. For a given in-fill density, material, and print orientation, the in-fill pattern significantly affected IT (P = 0.002) and APO (P = 0.03) but not ST (P = 0.23). Print orientation also significantly affected IT (P < 0.001), APO (P < 0.001), and ST (P = 0.002).

Conclusions

3D-printed vertebral body models with specific print parameters can be designed to perform analogously to human bone on pedicle screw tests of IT, APO, and ST. Altering the material, in-fill density, in-fill pattern, and print orientation of synthetic vertebral body models could reliably produce a model that mimics bone of a specific bone mineral density.

Challenges in the application of microbial fuel cells to wastewater treatment and energy production: A mini review

Wastewater is now considered to be a vital reusable source of water reuse and saving energy. However, current wastewater has multiple limitations such as high energy costs, large quantities of residuals being generated and lacking in potential resources. Recently, great attention has been paid to microbial fuel cells (MFCs) due to their mild operating conditions where a variety of biodegradable substrates can serve as fuel. MFCs can be used in wastewater treatment facilities to break down organic matter, and they have also been analysed for application as a biosensor such as a sensor for biological oxygen which demands monitoring. MFCs represent an innovation technology solution that is simple and rapid. Despite the advantages of this technology, there are still practical barriers to consider including low electricity production, current instability, high internal resistance and costly materials used. Thus, many problems must be overcome and doing this requires a more detailed analysis of energy production, consumption, and application. Currently, real-world applications of MFCs are limited due to their low power density level of only several thousand mW/m². Efforts are being made to improve the performance and reduce the construction and operating costs of MFCs. This paper explores several aspects of MFCs such as anode, cathode and membrane, and in an effort to overcome the practical challenges of this system.

Problematic effects of antibiotics on anaerobic treatment of swine wastewater

Swine wastewaters with high levels of organic pollutants and antibiotics have become serious environmental concerns. Anaerobic technology is a feasible option for swine wastewater treatment due to its advantage in low costs and bioenergy production. However, antibiotics in swine wastewater have problematic effects on micro-organisms, and the stability and performance of anaerobic processes. Thus, this paper critically reviews impacts of antibiotics on pH, COD removal efficiencies, biogas and methane productions as well as the accumulation of volatile fatty acids (VFAs) in the anaerobic processes. Meanwhile, impacts on the structure of bacteria and methanogens in anaerobic processes are also discussed comprehensively. Furthermore, to better understand the effect of antibiotics on anaerobic processes, detailed information about antimicrobial mechanisms of antibiotics and microbial functions in anaerobic processes is also summarized. Future research on deeper knowledge of the effect of antibiotics on anaerobic processes are suggested to reduce their adverse environmental impacts.

Minimally Invasive Single-Position Lateral Interbody Fusion With Robotic Bilateral Percutaneous Pedicle Screw Fixation: 2-Dimensional Operative Video

Lateral interbody fusion has distinct advantages over traditional posterior approaches. When adjunctive percutaneous pedicle screw fixation is required, placement from the lateral decubitus position theoretically increases safety and improves operative efficiency by obviating the need for repositioning. However, safe cannulation of the contralateral, down-side pedicles remains technically challenging and often prohibitive. In this video, we present the case of a 59-yr-old man with refractory back pain and bilateral lower extremity radiculopathy that was worse on the left than right side. The patient provided written informed consent before undergoing treatment. We performed minimally invasive single-position lateral interbody fusion with robotic (ExcelsiusGPS, Globus Medical Inc, Audubon, Pennsylvania) bilateral percutaneous pedicle screw fixation for the treatment of asymmetric disc degeneration, dynamic instability, and left paracentral disc herniation with corresponding stenosis at the L3-4 level. A left-sided minimally invasive transpsoas lateral interbody graft was placed with fluoroscopic guidance. Without changing the position of the patient or breaking the sterile field, an intraoperative cone-beam computed tomography image was obtained for navigational screw placement with stereotactic trackers in the iliac spine. Screw trajectories were planned using the robotic navigation software and were placed percutaneously in the bilateral L3 and L4 pedicles using the robotic arm. Concomitant lateral fluoroscopy may be used if desired to ensure the fidelity of the robotic guidance. The patient recovered well postoperatively and was discharged home within 36 h, without complication. Single-position lateral interbody fusion and percutaneous pedicle screw fixation can be accomplished using robotic-assisted navigation and pedicle screw placement. Used with permission from Barrow Neurological Institute.

Safety and accuracy of freehand versus navigated C2 pars or pedicle screw placement

BACKGROUND CONTEXT

C2 pedicle and pars screws require accurate placement to avoid injury to nearby neurovascular structures. Freehand, fluoroscopically guided, and computed tomography (CT)-based navigation techniques have been described in the medical literature.

PURPOSE

The present study aims to compare the safety and accuracy of the freehand technique versus stereotactic navigation for the placement of C2 pedicle and pars screws.

STUDY DESIGN/SETTING

This study was a retrospective review of consecutive patients treated with posterior fixation constructs.

PATIENT SAMPLE

A total of 220 consecutive patients were treated with posterior fixation constructs containing C2 pars or pedicle screws placed at our institution.

OUTCOME MEASURES

Computed tomography imaging was used to assess the accuracy of screw placement. Intraoperative complications and incidence of stroke or mortality within 30 days of the operation were analyzed.

METHODS

A retrospective review was conducted of consecutive patients treated with posterior fixation constructs containing C2 pars or pedicle screws placed by spine surgeons between January 1, 2010, and August 31, 2016. Clinical and radiographic data were collected and analyzed. Screw accuracy was graded independently by two reviewers according to the following criteria: grade A (no breach), grades B-E (breach with transverse foramen obstruction of 1%-25%, 26%-50%, 51%-75%, or 76%-100%, respectively), and grade M (medial breach). Screws were divided into acceptable (grades A and B) and unacceptable (grades C-E and M).

RESULTS

A total of 426 C2 pars or pedicle screws (312 freehand, 114 navigated) were placed in 220 patients (160 freehand, 60 navigated). Complications were similar between the groups: three vertebral artery injuries (two [1%] freehand, one [2%] navigated; p>.99), five deaths (four [3%] freehand, one [2%] navigated; p>.99), and one (2%) stroke in the navigated group (p=.61). Computed tomography imaging was available for accuracy grading of 182 screws (131 freehand, 51 navigated). No breaches (grade A) occurred in 113 of the freehand screws (86%) and in 34 of the navigated screws (67%) (p=.006). More screws had acceptable placement in the freehand group (123 of 131, 94%) than in the navigated group (42 of 51, 82%) (p=.02).

CONCLUSIONS

In patients with postoperative CT imaging (43%), the freehand technique was found to be more accurate than CT-based navigation for C2 pedicle or pars screw placement. Complication rates did not differ between the two techniques in this study.

The Barrow Innovation Center Case Series: Early Clinical Experience with Novel, Low-Cost Techniques for Bone Graft Containment in the Posterolateral Fusion Bed

BACKGROUND

A frequently encountered problem during posterolateral fusion (PLF) is bone graft displacement from the posterolateral space during closure. Commercially available solutions to this problem are seldom used because of their exceptionally high cost. The purpose of this report is to describe 3 novel, low-cost techniques we developed for bone graft containment during PLF.

METHODS

Three low-cost bone graft containment techniques are described: rapid suture weave, makeshift bone bag, and cellulose rooftop. Early clinical experience with these techniques is reported for a 5-patient case series.

RESULTS

One or more of these bone graft containment techniques were used in 5 patients who underwent PLF. Rapid suture weave was the least expensive (<$5.00) but required the longest additional time to perform (20 minutes). Makeshift bone bag and cellulose rooftop cost approximately the same ($48.00 and $46.00, respectively); the makeshift bone bag took less additional time (3 minutes) but created a potential barrier between the bone graft and the host site, whereas the cellulose rooftop took slightly longer to perform (5 minutes) but permitted direct contact between the bone graft and host site.

CONCLUSIONS

These 3 novel surgical techniques for bone graft containment in the posterolateral space add minimally to the cost and length of the procedure. Our early clinical experience suggests that these techniques are safe and effective. Additional clinical experience is warranted, and prospective data collection is ongoing.

Biomechanical evaluation of interbody fixation with secondary augmentation: lateral lumbar interbody fusion versus posterior lumbar interbody fusion

Background

Many approaches to the lumbar spine have been developed for interbody fusion. The biomechanical profile of each interbody fusion device is determined by the anatomical approach and the type of supplemental internal fixation. Lateral lumbar interbody fusion (LLIF) was developed as a minimally invasive technique for introducing hardware with higher profiles and wider widths, compared with that for the posterior lumbar interbody fusion (PLIF) approach. However, the biomechanics of the interbody fusion construct used in the LLIF approach have not been rigorously evaluated, especially in the presence of secondary augmentation.

Methods

Spinal stability of 21 cadaveric lumbar specimens was compared using standard nondestructive flexibility studies [mean range of motion (ROM), lax zone (LZ), stiff zone (SZ) in flexion-extension, lateral bending, and axial rotation]. Non-paired comparisons were made among four conditions: (I) intact; (II) with unilateral interbody + bilateral pedicle screws (BPS) using the LLIF approach (referred to as the LLIF construct); (III) with bilateral interbody + BPS using the PLIF approach (referred to as the PLIF construct); and (IV) with no lumbar interbody fusion (LIF) + BPS (referred to as the no-LIF construct).

Results

With bilateral pedicle screw-rod fixation, stability was equivalent between PLIF and LLIF constructs in lateral bending and flexion-extension. PLIF and LLIF constructs had similar biomechanical profiles, with a trend toward less ROM in axial rotation for the LLIF construct.

Conclusions

LLIF and PLIF constructs had similar stabilizing effects.

Escaping blood-fed malaria mosquitoes minimize tactile detection without compromising on take-off speed

To escape after taking a blood meal, a mosquito must exert forces sufficiently high to take off when carrying a load roughly equal to its body weight, while simultaneously avoiding detection by minimizing tactile signals exerted on the host's skin. We studied this trade-off between escape speed and stealth in the malaria mosquito Anopheles coluzzii using 3D motion analysis of high-speed stereoscopic videos of mosquito take-offs and aerodynamic modeling. We found that during the push-off phase, mosquitoes enhanced take-off speed using aerodynamic forces generated by the beating wings in addition to leg-based push-off forces, whereby wing forces contributed 61% of the total push-off force. Exchanging leg-derived push-off forces for wing-derived aerodynamic forces allows the animal to reduce peak force production on the host's skin. By slowly extending their long legs throughout the push-off, mosquitoes spread push-off forces over a longer time window than insects with short legs, thereby further reducing peak leg forces. Using this specialized take-off behavior, mosquitoes are capable of reaching take-off speeds comparable to those of similarly sized fruit flies, but with weight-normalized peak leg forces that were only 27% of those of the fruit flies. By limiting peak leg forces, mosquitoes possibly reduce the chance of being detected by the host. The resulting combination of high take-off speed and low tactile signals on the host might help increase the mosquito's success in escaping from blood-hosts, which consequently also increases the chance of transmitting vector-borne diseases, such as malaria, to future hosts.

Can algae-based technologies be an affordable green process for biofuel production and wastewater remediation?

Algae is a well-known organism that its characteristic is prominent for biofuel production and wastewater remediation. This critical review aims to present the applicability of algae with in-depth discussion regarding three key aspects: (i) characterization of algae for its applications; (ii) the technical approaches and their strengths and drawbacks; and (iii) future perspectives of algae-based technologies. The process optimization and combinations with other chemical and biological processes have generated efficiency, in which bio-oil yield is up to 41.1%. Through life cycle assessment, algae bio-energy achieves high energy return than fossil fuel. Thus, the algae-based technologies can reasonably be considered as green approaches. Although selling price of algae bio-oil is still high (about $2 L^-1) compared to fossil fuel's price of $1 L^-1, it is expected that the algae bio-oil's price will become acceptable in the next coming decades and potentially dominate 75% of the market.

Vascularized Spinous Process Graft Rotated on a Paraspinous Muscle Pedicle for Lumbar Fusion: Technique Description and Early Clinical Experience

BACKGROUND

Vascularized bone grafts (VBGs) are described as having superior osteogenicity, osteoconductivity, and osteoinductivity compared with other graft types and have been used in high-risk patients to augment arthrodesis. Pedicled VBGs are rotated on an intact vascular pedicle and therefore maintain all the benefits of VBGs but avoid many of the challenges and additional morbidity of free-tissue transfer. This study describes a novel surgical technique for rotating vascularized spinous process into the posterolateral space for augmenting arthrodesis in patients undergoing posterolateral fusion (PLF).

METHODS

A technique is described for rotating the spinous process into the posterolateral space on an intact vascular pedicle of paraspinal muscle. Early clinical and radiographic outcomes are reported for 4 patients who have undergone this procedure.

RESULTS

Four patients were treated with a single or 2-level PLF combined with posterior, anterior, or lateral interbody fusion and vascularized spinous process graft. Three-month postoperative computed tomography scans demonstrated a dislodged graft in 1 patient and successful arthrodesis in 3 patients. Additional operative time taken for graft harvest and implantation ranged from 22 minutes for the first patient to 6 minutes for the fourth patient.

CONCLUSIONS

Rotation of vascularized spinous process graft for augmentation of posterolateral arthrodesis in the lumbar spine is a potentially safe, effective surgical technique that results in successful arthrodesis in as little as 3 months but requires further study. This technique is expected to add little additional time or morbidity to the traditional lumbar PLF because it requires no separate incision or additional bone removal.

The Barrow Biomimetic Spine: Comparative Testing of a 3D-Printed L4-L5 Schwab Grade 2 Osteotomy Model to a Cadaveric Model

Introduction

The Barrow Biomimetic Spine project is an ongoing effort to develop a three-dimensional (3D)-printed synthetic spine model with high anatomical and biomechanical fidelity to human tissue. The purpose of this study was to evaluate the biomechanical performance of an L4-L5 3D-printed synthetic spine model in a lordotic correction test after Schwab grade 2 osteotomies as compared to human cadaveric spines that have undergone the same osteotomies and lordotic correction.

Methods

Ten different L4-L5 synthetic spine models were 3D printed. Each print varied in either the material used for the soft tissue components, the infill density of the bony and soft tissue structures, the pre-correction disc height, or the model orientation on the print bed. Each print was instrumented with pedicle screws and underwent a Schwab grade 2 osteotomy. Changes in disc height measurements and end-plate angle were compared against cadaveric data acquired using the same study method.

Results

A simple linear correlation analysis demonstrated that for horizontally printed models using PolyFlex (Polymaker, New York, NY, USA)(models 1-3, 8, 10), the pre-correction posterior disc height and lordotic correction were moderately correlated (r = 0.56), but this correlation did not achieve statistical significance (P = 0.12). Regression analysis demonstrated a very strong correlation between lordotic correction and change in posterior disc height (r = 0.92, P < 0.001). Models printed either vertically (models 4-6) or with low bone density and high soft tissue density (model 10) appeared to perform the most similarly to the cadaveric tissue.

Discussion

The 3D-printed synthetic spine models demonstrated predictable and reliable performance in a lordotic correction test based on their respective material qualities and print densities. The print variables tested further demonstrated that this model is capable of achieving high biomechanical fidelity to cadaveric tissue when subjected to the same lordotic correction test after Schwab grade 2 osteotomies.

Bioprocessing for elimination antibiotics and hormones from swine wastewater

Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater.

Divergent Bilateral Posterior Lumbar Interbody Fusion with Cortical Screw Fixation: Description of New Trajectory for Interbody Technique from Midline Exposure

BACKGROUND

A major drawback to use of cortical bone trajectory pedicle screws (CBTPSs) with traditional posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion grafts is that traditional graft insertion trajectories require wider posterior exposure. This wider exposure, beyond the limits otherwise required for CBTPS placement, negates a primary benefit of CBTPS fixation. The aim of this study was to define an alternative surgical technique for interbody graft placement that, when used in conjunction with CBTPS fixation, permits both minimal soft tissue dissection and optimal graft placement.

METHODS

A team of neurosurgeons specializing in treatment of spinal pathologies developed a surgical technique for insertion of bilateral PLIF grafts that complements the principles of CBTPS fixation. This technique is illustrated in a patient undergoing lumbosacral decompression, CBTPS fixation, and 3-column arthrodesis.

RESULTS

The described technique uses a divergent trajectory of bilateral PLIF grafts rather than the traditional parallel or convergent trajectories.

CONCLUSIONS

By aiming medially to laterally with the interbody graft, one recapitulates many advantages of CBTPSs, including avoidance of wide tissue dissection, greater intergraft volume available for bone grafting, and greater graft coverage of the hypophyseal ring. The prospective collection of outcome data for patients who undergo lumbosacral fusion using the divergent PLIF technique is ongoing.

Effects of C/N ratio on the performance of a hybrid sponge-assisted aerobic moving bed-anaerobic granular membrane bioreactor for municipal wastewater treatment

This study aimed to evaluate the impact of C/N ratio on the performance of a hybrid sponge-assisted aerobic moving bed-anaerobic granular membrane bioreactor (SAAMB-AnGMBR) in municipal wastewater treatment. The results showed that organic removal efficiencies were above 94% at all C/N conditions. Nutrient removal was over 91% at C/N ratio of 100/5 but was negatively affected when decreasing C/N ratio to 100/10. At lower C/N ratio (100/10), more noticeable membrane fouling was caused by aggravated cake formation and pore clogging, and accumulation of extracellular polymeric substances (EPS) in the mixed liquor and sludge cake as a result of deteriorated granular quality. Foulant analysis suggested significant difference existed in the foulant organic compositions under different C/N ratios, and humic substances were dominant when the fastest fouling rate was observed. The performance of the hybrid system was found to recover when gradually increasing C/N ratio from 100/10 to 100/5.

Occult Perforation with Circumferential Ischaemic Injury of the Sigmoid Colon following Seat-Belt Trauma: A Case Report

Seat-belt syndrome is defined as the presence of a seat-belt sign predominantly involving thoracolumbar vertebral fractures and intra-abdominal organ injury following the use of a seat belt during a traffic collision. Isolated sigmoid colon perforation occurring as part of seat-belt syndrome is rare. We report a 34-year-old patient who presented seat-belt sign after his car collided with a guardrail. The patient was initially haemodynamically stable and complained lower abdomen pain. Serial clinical examination with abdominal computed tomography (CT) scans illustrated sigmoid colon with ischaemic change without perforation. Exploratory laparotomy was performed and isolated sigmoid colon perforation was diagnosed. Therefore, in cases of persistent abdominal pain or tenderness despite an initially negative CT scan, repeated examinations of the abdomen with following abdominal CT are recommended because of the high risk of seat-belt sign and the possibility that the peritoneal symptoms can be hidden, such as in the retroperitoneal duodenum or sigmoid colon. Thus, we recommend using repeat abdominal CT as an adjunct to secondary survey for clarifying the haemodynamic status of patients with seat-belt trauma.

Analysis of overlapping surgery in patients undergoing microsurgical aneurysm clipping: acute and long-term outcomes from the Barrow Ruptured Aneurysm Trial

OBJECTIVE Overlapping surgery is a controversial subject in medicine today; however, few studies have examined the outcomes of this practice. The authors analyzed outcomes of patients with acutely ruptured saccular aneurysms who were treated with microsurgical clipping in a prospectively collected database from the Barrow Ruptured Aneurysm Trial. Acute and long-term outcomes for overlapping versus nonoverlapping cases were compared. METHODS During the study period, 241 patients with ruptured saccular aneurysms underwent microsurgical clipping. Patients were separated into overlapping (n = 123) and nonoverlapping (n = 118) groups based on surgical start/stop times. Outcomes at discharge and at 6 months, 1 year, 3 years, and 6 years after surgery were analyzed. RESULTS Patient variables (e.g., age, smoking status, cardiovascular history, Hunt and Hess grade, Fisher grade, and aneurysm size) were similar between the 2 groups. Aneurysm locations were similar, with the exception of the overlapping group having more posterior circulation aneurysms (18/123 [15%]) than the nonoverlapping group (8/118 [7%]) (p = 0.0495). Confirmed aneurysm obliteration at discharge was significantly higher for the overlapping group (109/119 [91.6%]) than for the nonoverlapping group (95/116 [81.9%]) (p = 0.03). Hospital length of stay, discharge location, and proportions of patients with a modified Rankin Scale (mRS) score > 2 at discharge and up to 6 years postoperatively were similar. The mean and median mRS, Glasgow Outcome Scale, Mini-Mental State Examination, National Institutes of Health Stroke Scale, and Barthel Index scores at all time points were not statistically different between the groups. CONCLUSIONS Compared with nonoverlapping surgery, overlapping surgery was not associated with worse outcomes for any variable at any time point, despite the complexity of the surgical management in this patient population. These findings should be considered during the discussion of future guidelines on the practice of overlapping surgery.

Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of V taper 2 and V taper 2H rotary NiTi files

The aim of this study was to compare the cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of conventional NiTi wire (V taper 2, V2) and CM wire (V taper 2H, V2H)-based files. Cyclic fatigue and torsional resistance of V2 and V2H were investigated by measuring the number of cycles to fracture, maximum torque at fracture, and maximum angle at fracture. The typical patterns of fatigue and torsional fractures were investigated using a scanning electron microscope (SEM). The metallurgical characteristics were investigated by differential scanning calorimetry (DSC) from -100 °C to 100 °C. The austenite finishing temperature (Af) of each instrument was also measured. The microstructures of the instruments were investigated by a transmission electron microscope (TEM) along with selected area diffraction pattern analysis. The results were statistically analyzed by Mann-Whitney U-test (p = 0.05). V2H showed significantly higher cyclic fatigue resistance and torsional resistance than V2. SEM images of the fractured surfaces showed typical patterns of fatigue and torsional fracture. The DSC analysis of V2 showed one small peak in both the heating and cooling curves. The Af of V2 was -0.32 °C. V2H showed two remarkable peaks in the heating curve and one remarkable peak in the cooling curve. The Af of V2H was 33.25 °C. The TEM analysis showed that both V2 and V2H are mainly composed of austenite. In conclusion, V2H showed higher cyclic fatigue resistance and torsional resistance than V2. The superior properties of V2H could be attributed to the annealing effect and possibly the martensite phase. SCANNING 38:564-570, 2016. © 2016 Wiley Periodicals, Inc.