Super-Strong, Super-Stiff, and Super-Tough Fluorescent Alginate Fibers with Outstanding Tolerance to Extreme Conditions.

The combination of multiple physical properties is of great importance for widening the application scenarios of biomaterials. It remains a great challenge to fabricate biomolecules-based fibers gaining both mechanical strength and toughness which are comparable to natural spider dragline silks. Here, by mimicking the structure of dragline silks, a high-performance fluorescent fiber Alg-TPEA-PEG is designed by non-covalently cross-linking the polysaccharide chains of alginate with AIEgen-based surfactant molecules as the flexible contact points. The non-covalent cross-linking network provides sufficient energy-dissipating slippage between polysaccharide chains, leading to Alg-TPEA-PEG with highly improved mechanical performances from the plastic strain stage. By successfully transferring the extraordinary mechanical performances of polysaccharide chains to macroscopic fibers, Alg-TPEA-PEG exhibits an outstanding breaking strength of 1.27 GPa, Young's modulus of 34.13 GPa, and toughness of 150.48 MJ m-3, which are comparable to those of dragline silk and outperforming other artificial materials. More importantly, both fluorescent and mechanical properties of Alg-TPEA-PEG can be well preserved under various harsh conditions, and the fluorescence and biocompatibility facilitate its biological and biomedical applications. This study affords a new biomimetic designing strategy for gaining super-strong, super-stiff, and super-tough fluorescent biomaterials.

A fast response time gas ionization chamber detector with a grid structure.

The time response characteristic of the detector is crucial in radiation imaging systems. Unfortunately, existing parallel plate ionization chamber detectors have a slow response time, which leads to blurry radiation images. To enhance imaging quality, the electrode structure of the detector must be modified to reduce the response time. This paper proposes a gas detector with a grid structure that has a fast response time. In this study, the detector electrostatic field was calculated using COMSOL, while Garfield++ was utilized to simulate the detector's output signal. To validate the accuracy of simulation results, the experimental ionization chamber was tested on the experimental platform. The results revealed that the average electric field intensity in the induced region of the grid detector was increased by at least 33%. The detector response time was reduced to 27% -38% of that of the parallel plate detector, while the sensitivity of the detector was only reduced by 10%. Therefore, incorporating a grid structure within the parallel plate detector can significantly improve the time response characteristics of the gas detector, providing an insight for future detector enhancements.

Dichroic Behavior of Gold Nanoparticles Synthesized in Aqueous Solution with Insufficient Reducing Agent.

The spherical gold nanoparticles (AuNPs) typically are red in solution. However, in this study, the dichroic and spherical AuNPs were synthesized using a modified seeding growth method under reducing agent insufficiency in an aqueous solution. This particular AuNP solution is orange in reflected light and red in transmitted light. The reflectance curves confirm that the dichroic AuNPs are different from the classic AuNPs. With particle assembling, the AuNP solution is fainter orange in reflected light, but purple in transmitted light when the color of classic spherical AuNP solution is purple in both lights. Furthermore, the aggregated-nanogold solutions were added to HAuCl4 solutions with the addition of an insufficient amount reducing agent. The solution changed from faint orange to bright orange in reflected light and from purple to blue in transmitted light. It indicates that the gold assembling under a reducing agent insufficiency, not the shape of AuNP, causes the dichroic phenomenon. To the best of our knowing, this is the first study to report how the AuNP is synthesized, not the shape, affects the color of the AuNP.

Effects of pilates on patients with chronic non-specific low back pain: a systematic review.

[Purpose] To evaluate the effects of Pilates on patients with chronic low back pain through a systematic review of high-quality articles on randomized controlled trials. [Subjects and Methods] Keywords and synonyms for "Pilates" and "Chronic low back pain" were used in database searches. The databases included PubMed, Physiotherapy Evidence Database (PEDro), Medline, and the Cochrane Library. Articles involving randomized controlled trials with higher than 5 points on the PEDro scale were reviewed for suitability and inclusion. The methodological quality of the included randomized controlled trials was evaluated using the PEDro scale. Relevant information was extracted by 3 reviewers. [Results] Eight randomized controlled trial articles were included. Patients with chronic low back pain showed statistically significant improvement in pain relief and functional ability compared to patients who only performed usual or routine health care. However, other forms of exercise were similar to Pilates in the improvement of pain relief and functional capacity. [Conclusion] In patients with chronic low back pain, Pilates showed significant improvement in pain relief and functional enhancement. Other exercises showed effects similar to those of Pilates, if waist or torso movement was included and the exercises were performed for 20 cumulative hours.

The Effect of Tai Chi Chuan on Obstacle Crossing Strategy in Older Adults.

The purpose of this study was to determine the effect of Tai Chi Chuan on the strategies of obstacle-crossing behavior in older adults aged over 65 years. Fifteen Tai Chi group (TCG) participants were compared with 15 general group (GG) participants. Kinematic parameters (by Vicon motion analysis system) and ground reaction forces (by Kistler force plates) were synchronously recorded. A two-way mixed-design ANOVA (α = 0.05) was used to test the effects of the group and the obstacle height. The TCG performed significantly faster stride velocities, longer stride lengths, and shorter stride times than GG while crossing the obstacles. TCG could also produce significantly larger forward ground reaction forces to propel the body and were able to make a significantly greater flexion angle of the hip of the leading leg compared with the GG. It was concluded that the TCG adopted a different strategy with GG to cross the obstacles and completed the crossing behavior more effectively.

Ground reaction force characteristics of Tai Chi push hand.

Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s(-1)) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant's body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.

A rapid response time gas detector with embedded glass plates for digital radiography systems.

The response time of a detector stands as a critical parameter in radiation imaging systems. However, the existing parallel plate ionization chamber detector manifests a noteworthy delay in response time, leading to the production of blurred radiation images. To enhance the image quality of radiation imaging systems, it becomes imperative to modify the electrode structure of the detector and consequently reduce the response time. We propose a gas ionization chamber detector incorporating a glass plate, resulting in a notably swift response time. The COMSOL software is employed to calculate the electric and weighting fields within the detector, while Garfield++ software is utilized to derive the output signal, including information on the response time. To validate the simulation data, an experimental ionization chamber underwent testing on a dedicated platform to acquire the output signal. The results revealed that the average electric field intensity in the induced region of the grid detector was increased by at least 10%. The detector response time was reduced to 50%-28% of that of the parallel plate detector. However, this improvement comes at the cost of a decrease in the detector's sensitivity. The incorporation of glass plates in a parallel plate detector offers a substantial improvement in the time response characteristics of a gas ionization chamber detector, thereby suggesting a valuable direction for future advancements in ionization chamber technology.

Changes in Combined Lifestyle Risks and the Transition of Activities of Daily Living in the Elderly Population of Taiwan: Evidence from the Taiwan Longitudinal Study on Aging.

Functional ability decline occurs with age. This study aims to investigate the associations between the lifestyle factors-exercising, food consumption, and smoking-and the functional ability of the activities of daily living (ADL) by gender. The data were obtained from the Taiwan longitudinal study on aging, a national cohort study. The cross-sectional results demonstrated that the frequency of exercising was negatively associated with ADL in both men and women. Dairy products were positively associated with ADL in men. The longitudinal results illustrated that current and consistent exercising were negatively associated with changes in ADL scores over 4- and 8-year periods in both men and women. Seafood consumption was negatively associated with changes in the subsequent 4-year ADL scores. Past smoking was positively associated with changes in subsequent 4-year ADL scores in men, while current smoking was positively associated with changes in subsequent 8-year ADL scores in women. Therefore, consistent exercising, food consumption, and smoking were associated with ADL functional ability in elderly people, and the associations differed by gender. Elders exercising consistently had good ADL performance and maintained their ADL ability better, especially women. Seafood consumption decreased the risk of ADL decline, while smoking increased the risk of ADL decline.

EI-MVSNet: Epipolar-Guided Multi-View Stereo Network With Interval-Aware Label.

Recent learning-based methods demonstrate their strong ability to estimate depth for multi-view stereo reconstruction. However, most of these methods directly extract features via regular or deformable convolutions, and few works consider the alignment of the receptive fields between views while constructing the cost volume. Through analyzing the constraint and inference of previous MVS networks, we find that there are still some shortcomings that hinder the performance. To deal with the above issues, we propose an Epipolar-Guided Multi-View Stereo Network with Interval-Aware Label (EI-MVSNet), which includes an epipolar-guided volume construction module and an interval-aware depth estimation module in a unified architecture for MVS. The proposed EI-MVSNet enjoys several merits. First, in the epipolar-guided volume construction module, we construct cost volume with features from aligned receptive fields between different pairs of reference and source images via epipolar-guided convolutions, which take rotation and scale changes into account. Second, in the interval-aware depth estimation module, we attempt to supervise the cost volume directly and make depth estimation independent of extraneous values by perceiving the upper and lower boundaries, which can achieve fine-grained predictions and enhance the reasoning ability of the network. Extensive experimental results on two standard benchmarks demonstrate that our EI-MVSNet performs favorably against state-of-the-art MVS methods. Specifically, our EI-MVSNet ranks 1st on both intermediate and advanced subsets of the Tanks and Temples benchmark, which verifies the high precision and strong robustness of our model.

Highly-Strong and Highly-Tough Alginate Fibers with Photo-Modulating Mechanical Properties.

The good combination of high strength and high toughness is a long-standing challenge in the design of robust biomaterials. Meanwhile, robust biomaterials hardly perform fast and significant mechanical property changes under the trigger of light at room temperature. These limit the application of biomaterials in some specific areas. Here, photoresponsive alginate fibers are fabricated by using the designed azobenzene-containing surfactant as flexible contact point for cross-linking polysaccharide chains of alginate, which gain high mechanics through reinforced plastic strain and photo-modulating mechanics through isomerization of azobenzene. By transferring molecular motion into macro-scale mechanical property changes, such alginate fibers achieve reversible photo-modulations on the mechanics. Their breaking strength and toughness can be photo-modulated from 732 MPa and 112 MJ m-3 to 299 MPa and 27 MJ m-3, respectively, leading to record high mechanical changes among the developed smart biomaterials. With merits of good tolerance to pH and temperature, fast response to light, and good biocompatibility, the reported fibers will be suitable for working in various application scenarios as new smart biomaterials. This study provides a new design strategy for gaining highly-strong and highly-tough photoresponsive biomaterials.

Photoresponsive heparin ionic complexes toward controllable therapeutic efficacy of anticoagulation.

Controllable heparin-release is of great importance and necessity for the precise anticoagulant regulation. Efforts have been made on designing heparin-releasing systems, while, it remains a great challenge for gaining the external-stimuli responsive heparin-release in either intravenous or catheter delivery. In this study, an azobenzene-containing ammonium surfactant is designed and synthesized for the fabrication of photoresponsive heparin ionic complexes through the electrostatic complexation with heparin. Under the assistance of photoinduced trans-cis isomerization of azobenzene, the obtained heparin materials perform reversible athermal phase transition between ordered crystalline and isotropic liquid state at room temperature. Compared to the ordered state, the formation of isotropic state can effectively improve the dissolving of heparin from ionic materials in aqueous condition, which realizes the photo-modulation on the concentration of free heparin molecules. With good biocompatibility, such a heparin-releasing system addresses photoresponsive anticoagulation in both in vitro and in vivo biological studies, confirming its great potential clinical values. This work provides a new designing strategy for gaining anticoagulant regulation by light, also opening new opportunities for the development of photoresponsive drugs and biomedical materials based on biomolecules.

A multifunctional bio-patch crosslinked with glutaraldehyde for enhanced mechanical performance, anti-coagulation properties, and anti-calcification properties.

Bio-patches for the treatment of valvular disease have been evaluated in clinical trials. It has been shown that failure of these devices, occurring within a few years of implantation, may be due to cytotoxicity, immune response, calcification and thrombosis. Some of these effects may be due to the glutaraldehyde crosslinking process used in the preparation of the materials. A number of studies have focused on strategies to control calcification, while others have concentrated on the prevention of micro-thrombus formation. In the present work, we have introduced amino-terminated poly(ethylene glycol) (NH2-PEG-NH2) as an intermolecular bridge, which not only eliminates free aldehyde groups to prevent calcification, but also introduces sites for the attachment of anticoagulant molecules. Furthermore, PEG, itself a hydrophilic polymer with good biocompatibility, may effectively prevent protein adsorption in the early stages of blood contact leading to thrombus formation. After further covalent attachment of heparin, modified bovine pericardium (BP) showed strong anti-calcification (calcium content: 39.3 ± 3.1 µg mg-1) and anti-coagulation properties (partial thromboplastin time: >300 s). The biocompatibility and mechanical properties, important for clinical use, were also improved by modification. The strategy used in this work includes new ideas and technologies for the improvement of valve products used in the clinic.

Comparison of EMG activity between maximal manual muscle testing and cybex maximal isometric testing of the quadriceps femoris.

Two methods have been used to produce a maximal voluntary isometric contraction (MVIC) of the superficial quadriceps femoris muscles for normalization of electromyographic (EMG) data. The purposes of this study were to compare the myoelectic activity of MVIC of manual muscle testing (MMT) versus Cybex maximal isometric testing. Eighteen normal subjects were recruited. MMT and Cybex testing for MVIC of the dominant leg were performed. EMG activities of the vastus medialis, vastus lateralis and rectus femoris were recorded during MMT and Cybex trials. EMG amplitude and median frequency obtained from the two methods (MMT and Cybex testing) were used for statistical analysis of these three muscles. Statistically, the difference in the mean of the EMG signal amplitude and median frequency between MMT and Cybex testing were not significant. Considering cost and time, MMT for MVIC technique appears to be reliable and highly valuable.

PPARα activation attenuates amyloid-ß-dependent neurodegeneration by modulating Endo G and AIF translocation.

The accumulation of a large amount of amyloid-ß (Aß42) in brain neurons is one of the debilitating characteristics of Alzheimer's disease. In this study, we determined the effects of peroxisome proliferator-activated receptor alpha (PPARα) activation on neuronal degeneration using a model of Aß42-induced cytotoxicity. We found that 0.5 µM Aß42 induced DNA damage and apoptosis in NT2N cells after 6 h of treatment. Co-treatment of Aß42-treated cells with Wy14643, a PPARα ligand, significantly increased cell viability after 24 h compared with cells treated with Aß42 alone. There were no differences in the protein levels of caspase-3, Bcl-2/Bax or p53 between cells treated with Aß42 alone and those treated with both Aß42 and Wy14643. However, the addition of Wy14643 significantly suppressed the Aß42-induced upregulation of Endo G and AIF protein levels. Immunohistochemical analyses further demonstrated that Wy14643 reduced the expression of Endo G and AIF translocated from the cytoplasm into the nucleus, which occurred concomitantly with the decrease in DNA damage in Aß42-treated cells. Our data clearly show that PPARα activation prevents DNA damage and neuronal cell apoptosis by decreasing the expression and translocation of AIF/Endo G to the nucleus in a caspase-3- and p53-independent pathway in the NT2N cell model. This role of PPARα in promoting neuron survival suggests a possible clinical application in treating Aß42-associated neurotoxicity in Alzheimer's disease.

Immediate effect of thermal capsulorrhaphy on glenohumeral joint mobility.

OBJECTIVES: To evaluate the effects of anterior thermal capsulorrhaphy of the glenohumeral joint by monitoring changes of magnitudes of the anterior and posterior displacements of the humeral head and ranges of motion of abduction and rotation in fresh cadaver shoulders. DESIGN: Single session repeated-measures design. BACKGROUND: Following thermal shrinkage anterior and posterior displacements of the head of humerus were decreased. However, no studies were focused on the ranges of motion of abduction and rotation of the shoulder joint immediately. The mobility of abduction and rotation are also important indexes for glenohumeral function. METHODS AND MEASURES: Nine fresh frozen shoulder specimens were used. The dorsal and ventral displacements of humeral head and ranges of motion of abduction and rotation of glenohumeral joint before and after thermal capsulorrhaphy were performed and monitored. Changes after thermal treatment in these linear and angular displacement variables were calculated as outcome measures. RESULTS: After anterior thermal capsulorrhaphy, significant (P < 0.001) decreases were found in displacements (-1.80 mm in dorsal direction and -1.24 mm in ventral direction), rotation range of motion (-3.93 degrees in lateral rotation and -2.60 degrees in medial rotation), and abduction range of motion (-3.15 degrees ). CONCLUSIONS: The results from cadaveric experiments showed that anterior thermal capsulorrhaphy immediately reduced the dorsal and ventral displacements and ranges of abduction and rotation of glenohumeral joint by a small amount. RELEVANCE: Radiofrequency electrosurgical system combined with arthroscopy has the potential to decrease the translations of the humeral head as well as the rotational range of motion of the glenohumeral joint.

Determining the resting position of the glenohumeral joint: a cadaver study.

STUDY DESIGN: Single-session repeated-measures design. OBJECTIVE: To define the resting position of the glenohumeral joint by investigating the magnitude of the anterior and posterior displacements of the humeral head and medial and lateral rotation ranges of motion (ROMs) of the glenohumeral joint at different abduction angles in cadaver specimens. BACKGROUND AND PURPOSE: The resting position of a joint is the position in the joint's ROM at which the joint capsule has its greatest laxity. It is frequently chosen as the position for assessing and treating joints with dysfunction. However, no study has been conducted to determine the resting position of the glenohumeral joint. METHODS: Seven freshly frozen cadaver shoulder specimens (age at time of death [mean +/- SD] was 66.9 +/- 2.5 years) were studied. Specimens were mounted on a system that uses computer-controlled hydraulics and motors to induce and monitor translation and rotation movements of the glenohumeral joint. The magnitudes of total displacement (DTotal) of the head of the humerus and total ROM (RTotal) of the glenohumeral joint were measured in the plane of the scapula at 0 degrees (neutral), 30 degrees, 40 degrees, 50 degrees, 60 degrees, and the end range of glenohumeral joint abduction. The resting position was determined as the midpoint of the shared range of the 95% to 99.9% confidence intervals of the predicted abduction position where the peaks of displacement and rotation occurred. RESULTS: The DTotal measurements (mean +/- SD) at 0 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, and the end range of glenohumeral joint abduction were 30.53 +/- 9.35, 44.87 +/- 7.34, 45.35 +/- 8.53, 43.99 +/- 10.02, 39.63 +/- 9.85, and 23.80 +/- 10.42 mm, respectively. The RTotal measurements (mean +/- SD) for the same positions were 67.15 degrees +/- 15.87 degrees, 95.64 degrees +/- 24.26 degrees, 98.88 degrees +/- 29.56 degrees, 97.08 degrees +/- 30.17 degrees, 90.91 degrees +/- 28.73 degrees, and 63.48 degrees +/- 25.93 degrees, respectively. The resting position was located at 39.33 degrees +/- 4.37 degrees of glenohumeral abduction (45.13% +/- 7.58% of the available abduction ROM). The resting position (Y) varied linearly with the maximum available abduction ROM (X) (Y = 0.607X - 13.120, R2 = 0.679, F = 10.61, P = 0.023). There was a main effect of joint position on both displacement (P<0.001) and rotation ROM (P<0.001). CONCLUSION: In the plane of the scapula, the resting position of the glenohumeral joint (angle measured between the scapula and humerus) occurred at 39 degrees of abduction (45% of the maximum available abduction ROM) and varied linearly with the amount of available abduction ROM. This finding suggests that in patients with glenohumeral joint hypomobility the resting position is located closer to neutral and that evaluation and treatment should be initiated accordingly at a smaller angle of abduction than the traditional resting position. Our data were derived from cadaver specimens, therefore, caution should be taken when generalizing the results of the present study to a patient population.

Flatfoot diagnosis by a unique bimodal distribution of footprint index in children.

BACKGROUND: More than 1000 scientific papers have been devoted to flatfoot issue. However, a bimodal distribution of flatfoot indices in school-aged children has never been discovered. The purposes of this study were to establish a new classification of flatfoot by characteristic in frequency distribution of footprint index and to endue the classification with discrepancy in physical fitness. METHODS/PRINCIPAL FINDINGS: In a longitudinal survey of physical fitness and body structure, weight bearing footprints and 3 physical fitness related tests were measured in 1228 school-aged children. Frequency distribution of initial data was tested by Kolmogorov-Smirnov test for normality and a unique bimodal distribution of footprint index was identified. The frequency distribution of footprint index manifests two distinct modes, flatfoot and non-flatfoot, by deconvolution and bootstrapping procedures. A constant intersection value of 1.0 in Staheli's arch index and 0.6 in Chippaux-Smirak index could distinguish the two modes of children, and the value was constant in different age, sex, and weight status. The performance of the one leg balance was inferior in flatfoot girls (median, 4.0 seconds in flatfoot girls vs. 4.3 seconds in non-flatfoot girls, p = 0.04, 95% CI 0.404-0.484). DISCUSSION: The natural bimodality lends itself to a flatfoot classification. Bimodality suggests development of the child's foot arch would be a leap from one state to another, rather than a continuous growth as body height and weight. The underlying dynamics of the human foot arch and motor development will trigger research prospects.

Loading effects of anterior cervical spine fusion on adjacent segments.

Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3-C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1); and C5-C6 segments that were fused via cage-instrumented plate fixation (group 2). Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM) of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3-C4) adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress-shielding effects. Furthermore, increased stress and ROM of the adjacent segments after long-term bone fusion may accelerate degeneration in adjacent segment.

Evaluation of unilateral cage-instrumented fixation for lumbar spine.

BACKGROUND: To investigate how unilateral cage-instrumented posterior lumbar interbody fusion (PLIF) affects the three-dimensional flexibility in degenerative disc disease by comparing the biomechanical characteristics of unilateral and bilateral cage-instrumented PLIF. METHODS: Twelve motion segments in sheep lumbar spine specimens were tested for flexion, extension, axial rotation, and lateral bending by nondestructive flexibility test method using a nonconstrained testing apparatus. The specimens were divided into two equal groups. Group 1 received unilateral procedures while group 2 received bilateral procedures. Laminectomy, facectomy, discectomy, cage insertion and transpedicle screw insertion were performed sequentially after testing the intact status. Changes in range of motion (ROM) and neutral zone (NZ) were compared between unilateral and bilateral cage-instrumented PLIF. RESULTS: Both ROM and NZ, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF, transpedicle screw insertion procedure did not revealed a significant difference between flexion-extension, lateral bending and axial rotation direction except the ROM in the axial rotation. The bilateral group's ROM (-1.7 ± 0. 8) of axial rotation was decreased significantly after transpedicle screw insertion procedure in comparison with the unilateral group (-0.2 ± 0.1). In the unilateral cage-instrumented PLIF group, the transpedicle screw insertion procedure did not demonstrate a significant difference between right and left side in the lateral bending and axial rotation direction. CONCLUSIONS: Based on the results of this study, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF have similar stability after transpedicle screw fixation in the sheep spine model. The unilateral approach can substantially reduce exposure requirements. It also offers the biomechanics advantage of construction using anterior column support combined with pedicle screws just as the bilateral cage-instrumented group. The unpleasant effect of couple motion resulting from inherent asymmetry was absent in the unilateral group.

Biomechanical evaluation of cervical spine fixation after healing in a destabilized cervical spine model in sheep: a comparison of the anterior plating and posterior wiring techniques.

BACKGROUND: We conducted biomechanical evaluation of the anterior plating and posterior wiring techniques for cervical spine stabilization after a course of healing in sheep. METHODS: Seventeen sheep were included, and six of which underwent sham operations (group A, n=6). The other eleven received complete C2-C3 destabilization, followed by intervertebral bone grafting and cervical stabilization either with anterior plating (group B, n=5) or posterior wiring (group C, n=6) techniques. These animals were killed 6 months later. Ligamentous spines (C1-C5) were subjected to the relevantly applied loads. The load-deformation data of the C2-C3 and C3-C4 functional units were recorded and analyzed. RESULTS: At the C2-C3 functional unit, group B had the least motion ranges in flexion, lateral bending, and rotation loads than did the other two groups. Significantly smaller motion ranges of lateral bending and rotation loads were found in group B than in group C (p<0.05). Compared with group A, group C had a decreased motion range in flexion load but showed increased motion range in rotation load. Consequently, group B had superior intervertebral fusion and less osteophyte than did group C. At the C3-C4 functional unit, group B showed significantly decreased motion ranges in extension and lateral bending loads (p<0.05), while group C did not. CONCLUSION: The results indicated that the anterior plate-stabilized spines were more stable over time than did the posterior-wired spines. This biomechanical advantage eventually resulted in superior intervertebral fusion masses in the former, although it also induced a slightly decreased motion range at the contiguous functional unit. In exclusively posterior wired-spines, the weakness for opposing rotation loads might contribute to the formation of osteophytes at the fusion functional unit. These data point out that the mode and stability of implant fixation systems greatly influence the biomechanical redistribution and bone-adaptive remodeling process during healing, which are closely related to the bone graft maturation and osteophytic formations at the fusion level and the occurrence of stiffening problems at the contiguous levels.