Chemistry

Hydrogels composed of calcium cross-linked alginate are under investigation as bioinks for tissue engineering scaffolds due to their variable viscoelasticity, biocompatibility, and erodibility. Here, pyrrole was oxidatively polymerized in the presence of sodium alginate solutions to form ionomeric composites of various compositions. The IR spectroscopy shows that mild base is required to prevent the oxidant from attacking the alginate during the polymerization reaction. The resulting composites were isolated as dried thin films or cross-linked hydrogels and aerogels. The products were characterized by elemental analysis to determine polypyrrole incorporation, electrical conductivity measurements, and by SEM to determine changes in morphology or large-scale phase separation. Polypyrrole incorporation of up to twice the alginate (monomer versus monomer) provided materials amenable to 3D extrusion printing. The PC12 neuronal cells adhered and proliferated on the composites, demonstrati...

The University of Washington Bothell’s mechanical engineering program, which is three years old, has one course in materials science (Fundamentals of Materials Science) that lays the foundation for the mechanical and capstone design courses. Thus, it is paramount to the faculty that through this course, students gain a solid understanding as to how the materials selection and processing will ultimately affect their final product. Granta CES EduPack is a comprehensive materials science software program that is available to the students at the junior and senior level within the ME program. In past offerings, CES EduPack has been introduced at the end of the course at a basic level to introduce the students to concepts of materials selection. Prior students have not considered the software as a tool for materials selection in their mechanical design and capstone projects in the past, likely due to only having a brief exposure to the software mainly in the fundamental materials course. ...

and reference lists of articles. An extensive handsearch of the grey literature was also conducted. Randomised controlled trials and prospective cohort studies comparing braces with no treatment, other treatment, surgery, and different types of braces. Two review authors independently assessed trial quality and extracted data. RESULTS: We included two studies. There was very low quality evidence from one prospective cohort study with 286 girls that a brace curbed curve progression at the end of growth (success rate 74% (95% CI: 52% to 84%)), better than observation (success rate 34% (95% CI:16% to 49%)) and electrical stimulation (success rate 33% (95% CI:12% to 60%)). There is low quality evidence from one RCT with 43 girls that a rigid brace is more successful than an elastic one (SpineCor) at curbing curve progression when measured in Cobb degrees, but there were no significant differences between the two groups in the subjective perception of daily difficulties associated with wearing the brace. CONCLUSIONS: There is very low quality evidence in favor of using braces, making generalization very difficult. Further research could change the actual results and our confidence in them; in the meantime, patients' choices should be informed by multidisciplinary discussion. Future research should focus on short and long-term patient-centered outcomes, in addition to measures such as Cobb angles. RCTs and prospective cohort studies should follow both the Scoliosis Research Society (SRS) and Society on Scoliosis Orthopaedic and Rehabilitation Treatment (SOSORT) criteria for bracing studies.

Study Design Retrospective chart review and review of literature. Objective Few case reports of traumatic L5-S1 displacement have been presented in the literature. Here we present two cases of traumatic spondylolisthesis showing both anterior and posterior displacement, the treatment algorithm, and a review of the literature. Methods The authors conducted a retrospective review of representative patients and a literature review of traumatic spondylolisthesis at the L5-S1 junction. Two representative patients were identified with traumatic spondylolisthesis: one with an anterior dissociation, and the other with a posterior dissociation. Results Radiographic, computed tomography, and magnetic resonance imaging illustrated the bony and soft tissue injury found in each patient, as well as the final stabilization and outcomes. Operative stabilization was necessary, and both patients were treated with open reduction internal fixation. The patient with posterior dissociation had complete r...

horizontal) and T1 tilt (T1-S1 line and vertical) versus T1 tilt clinical (T1-S1 and vertical). The same regressions were repeated after stratifying into low (<30) and high (>30) BMI groups. RESULTS: Thirty-eight patients were enrolled. Sagittal deformity parameters were highly correlated (means: TPA 24.9°, TPAc 37.0°, r=.77; CPA 28.3°, CPAc 40.2°, r=.77; both p<.001). The TPA regression TPA = 1.0*TPAc −13.2 demonstrated that a 1°increase in TPAc reflects a 1°increase in TPA, and allows for estimation of TPA based on TPAc. Correlations for coronal parameters were also significant for PO (r=.54) and T1 tilt (r=.66), both p<.001. After stratification, correlations were higher in the low BMI group for TPA (.72 vs. .63), CPA (.72 vs. .63), and T1 tilt (.90 vs. .66). CONCLUSIONS: Spinal deformity patients are exposed to a substantial radiation burden. A reliable method of deformity assessment based on clinical photographs would allow for less frequent radiographic assessment. Photographic measurements of spinal deformity were developed and compared to analogous radiographic parameters. They were found to be highly correlated in both the sagittal and coronal planes. Correlations were generally higher in patients with low BMI. Such measurements in clinical photographs could replace X-ray imaging in certain scenarios or they can be a substitute where full spine radiographs are unavailable. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.

LLIF surgery was considered stand-alone when not paired with posterior fixation. Cohort fusion rate differences were calculated and tested for significance (p<0.05). All reported means were pooled. RESULTS: A total of 2,395 publications were assessed. Nineteen studies met inclusion criteria, including 663 patients and 1,025 vertebral levels. Mean age was 57.1 years with BMI 26.4 kg/m2. Mean fusion rate was 85.3% (range, 53.0%-100.0%). By number of levels, fusion rate was 89.2% (1-level), 90.5% (2-level), and 96.8% (≥3-level). Use of rhBMP-2 was reported in 32.6% of subjects. There was no difference in fusion rates between studies using rhBMP-2 (87.4%) and those in which rhBMP-2 was not used (83.9%, OR=1.33, p=0.553). Fusion rate was highest in DDD (100%) and lowest in ASD (54.0%). Fusion rate differences were not noted across construct types. All-complication rate was 32.7% and mean reoperation rate was 10.7%, with 2.0% reoperation due to pseudarthrosis. Of the studies comparing stand-alone to circumferential fusion, pooled fusion rate was found to be 78.9% vs 92.1% (p=0.428). CONCLUSIONS: Stand-alone LLIF yields high fusion rates overall. The wide range of reported fusion rates and lower fusion rates in studies involving subsequent surgical reoperation highlights the importance of employing a rigorous algorithm when indicating patients for stand-alone LLIF. Future research should focus on examining risk factors and patientreported outcomes in stand-alone LLIF.

loss). METHODS: Comparisons of the immediate postoperative GAP scores between MF the and MF-free groups were performed. We evaluated the discriminative ability of the GAP score based on the area under the receiver operating characteristic curve (AUROC). The Cuzick test was performed to determine whether there is a trend between the GAP score and the incidence of MF or revision surgery. Univariate logistic regression analyses were performed to explore the associations between the GAP score and the incidence of MF or revision surgery. RESULTS: No difference was observed in the GAP score between the MF and MF-free groups (MF vs MF-free; GAP: 5.9 §3.3 vs 5.2 §2.7, p=0.07). The Cuzick analysis showed no trend between the GAP score and the risk for MF or revision surgery. Likewise, the MF rate was not correlated with the GAP score, as shown by the ROC curve (AUC of 0.56 [95% CI 0.48 −0.63], p=0.124). Univariate logistic regression confirmed no associations between the GAP score and the incidence of MF or revision surgery (MF; MD [moderately disproportioned]:

Background Multiple studies describe the outcomes of patients undergoing single-level and multilevel posterolateral lumbar fusion (PLF). However, a comparison of outcomes between single-level and two-level PLF is lacking. The aim of this prospective cohort study was to compare outcomes between single-level and two-level instrumented PLF. Methods A total of 42 patients were enrolled at nine US centers between October 2015 and June 2017. Data included radiologic outcomes, visual analog scale (VAS) Back and Leg Pain, disability per the Oswestry Disability Index (ODI), and health-related quality of life (QoL) per 36-Item Short Form Survey version 2.0 (SF-36v2) at six weeks and three, six, 12, and 24 months. Results Twelve-month and 24-month follow-ups were completed by 38 (90.5%) and 32 (76.2%) subjects, respectively. The average age was 67 years, and 54.8% were female. Twenty-six received single-level PLF, and 16 received two-level PLF. In the single-level group, there was one reoperation, two postoperative infections, and one dural tear. In the two-level group, there was one postoperative infection. The surgeon computed tomography (CT)-based evaluation of fusion rate was 67.6% (25/37) at 12-month follow-up and 94.1% (32/34) at 24-month follow-up. The third-party evaluation of fusion rate was 52.8% (19/36) at six months, 81.1% (30/37) at 12 months, and 86.5% (32/37) at 24 months. There was a tendency toward a higher fusion rate in single-level compared with two-level PLF. The ODI, SF-36v2 Mental Component Score (MCS), and VAS Back Pain and Leg Pain outcomes improved by the first follow-up visit in both the single-level and two-level groups. Improvement in the ODI was 5.86 (95% confidence interval (CI): 0.03-11.69) points greater in the single-level group compared with the two-level group. Conclusions Compared with the two-level PLF subjects, single-level PLF subjects had better functional outcomes and reported higher satisfaction with the outcome of surgery but showed similar fusion, pain, and generic health-related quality of life outcomes. Both single-level and two-level PLF subjects demonstrated high fusion rates in association with improvements in pain, functional, and quality of life outcomes, as well as high satisfaction levels.

This study compared the locations of arm pain, sensory symptoms, and subjective complaints of arm weakness in subjects with cervical radiculopathy from MRI confirmed C6 and C7 nerve root compression. SUMMARY OF BACKGROUND DATA: Cervical radiculopathy is defined asarm pain, sensory and motor symptoms caused byirritation of a cervical nerve root. The C6 and C7 roots are most commonly involved, and differentiating symptoms associated with each root has proven difficult.Cervical MRI allows accurate identification of nerve root compression and therefore makes it possible to explore symptom patterns that may differentiate C6 from C7 radiculopathy. METHODS: 122 subjects with symptoms suggestive of cervical radiculopathy were recruited. Of these, 30 subjects had MRI confirmed C6 and 39 subjects C7 nerve root compression. By completing a study questionnaire, subjects reported specific arm weakness, andmarked the location of arm pain and tingling/numbness on graphic representations of the arm. Marked areas were interpreted by superimposing a grid that divided the arm into 54 distinct areas. The frequencies of reported symptoms with C6 and C7 were totaled and then compared with likelihood rations. Power analysis calculated that 27 subjects would be needed in each group based on the assumption that a 30 percentage point difference in frequency of specific symptom would be clinically useful for differentiating C6 from C7 radiculopathy. RESULTS: Arm pain and sensory symptoms were diffuse, and were not distinctly different for C6 or C7 radiculopathy. Some weakness was reported by 41 percent of subjects, with specific descriptions of weakness having limited value for differentiating between radiculopathies. CONCLUSION: The location of pain and sensory symptoms, and specific weakness complaints associated withsymptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting root involvementbased on symptoms.

Purpose Many investigators have reported the financial conflicts of interest (COI), which could result in potential bias in the reporting of outcomes for patients undergoing total disc replacement (TDR) rather than anterior cervical discectomy and fusion (ACDF). This bias may be subconsciously introduced by the investigator in a non-blinded radiographic review. The purpose of this study was to determine if bias was present when a group of spine specialists rated adjacent segment degeneration (ASD) following cervical TDR or ACDF. Methods Potential bias in the assessment of ASD was evaluated through the reviews of cervical radiographs (preand 6 years post-operative) from patients participating in the ProDisc-C FDA trial (ProDisc-C IDE #G030059). The index level was blinded on all radiographs during the first review, but unblinded in the second. Five reviewers (a radiologist, two non-TDR surgeons, and two TDR surgeons), two of whom had a COI with the ProDisc-C trial sponsor, assessed ASD on a three point scale: yes, no, or unable to assess. Intra-and inter-rater reliabilities between all raters were assessed by the Kappa statistic. Results The intra-rater reliability between reviews was substantial, indicating little to no bias in assessing ASD development/progression. The Kappa statistics were 0.580 and 0.644 for the TDR surgeons (p \ 0.0001), 0.718 and 0.572 for the non-TDR surgeons (p \ 0.0001), and 0.642 for the radiologist (p \ 0.0001). Inter-rater reliability for the blinded review ranged from 0.316 to 0.607 (p \ 0.0001) and from 0.221 to 0.644 (p \ 0.0001) for the unblinded review. Conclusions The knowledge of the surgical procedure performed did not bias the assessment of ASD. Keywords Bias Á Anterior cervical discectomy and fusion Á Total disc replacement Á Intervertebral disc degeneration Á Radiography